Page 1

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

“Times have changed. With more and more audiophiles embracing computer and server-based audio, their systems are looking more and more like the “pro” systems used to make recordings.”.

PSI A225-M3,M4&M5 / typical characteristics subject to change without prior notice / © RELEC SA.


Relec SA électroacoustique rte de Lausanne Z.I. Les Petits-Champs 11A +B 1400 Yverdon-les-Bains VD Switzerland ___________________________________________________________________________________________________________________________________________________________________________________________

CPR Compensated Phase Response System by PSI Audio Technical description In a multi-way speaker system, the crossover filters as well as the transducers introduce distortion of phase and by consequence of the variations of group delays. The group delays in low frequencies are more important than in high frequency’s. They provoke a time related separation of the low and high frequencies which then is responsible for the hollow sound of multi-way speaker systems. In a limited frequency range, an all pass filter allows to intervene on the phase without influencing the amplitude. The CPR system consists of several all pass filters who each act in a specific range of frequency in order to obtain a wide area of Compensated Phase Response. This then provides a constant group delay. Thanks to the CPR system the placement of sound in the actual sound space is highly accurate. This technology allows designing of surround sound systems with different types of PSI Audio speakers while maintaining an accurate phase response.

Phase response [ °] 180 90 Acoustical phase response of a multi way 0 speaker without CPR* - 90 - 180

20

50

100

200

500

1k

2k

5k

10k

20k f [Hz]

[ °] 180 90 Acoustical phase response PSI Audio 0 speaker with CPR+AOI - 90 - 180

20

50

100

200

500

1k

2k

5k

10k

20k f [Hz]

*C P R : Compensated Phase Response system *A O I : Adaptive Output Impedance system

______________________________________________________________________________ 21/06/2002

1


Relec SA ĂŠlectroacoustique rte de Lausanne Z.I. Les Petits-Champs 11A +B 1400 Yverdon-les-Bains VD Switzerland ___________________________________________________________________________________________________________________________________________________________________________________________

Practical advantage of CPR and impact on stereo application The human ear is very sensitive to group delays or phase irregularities of sounds. The human brain detects such irregularities easily and processes them in to space related information’s like the positioning of a sound source. All traditionally designed speaker systems suffer to a certain degree of such irregularities. These irregularities are the reason why some speakers produce a wider and deeper room perception hence a better-weaker reproduction of the sound image. Such phase irregularities are desirable on creative tools like equalizers, compressors, reverbs and delay units when creating a certain desired sound, whilst being an important part of the creative process of sound engineering. But as the speaker system represents the reference tool of every sound engineer, these irregularities represent a highly disturbing factor and should certainly not be present in the reference tool when trying to design specific sound or its positioning in the sound image. As a sound recording tends go through various processes (recording, mixing and mastering) in which maybe various people, locations and therefore speaker systems will be involved, it may well occur that corrections will be applied, due to phase irregularities, that may not even be present on the actual recording. The PSI Audio speakers feature the unique CPR system that provides a Compensated Phase Response that removes such irregularities and therefore provides a much more accurate reference tool to the sound engineer. The stereo image and the projected room are of an extreme accuracy and therefore provide a more precise working tool.

CPR impact on surround sound applications Unfortunately every traditional speaker design has a different phase response and therefore the phase inaccuracy phenomenon tends to get worse in surround sound applications, where the role of room information and positioning becomes an even higher priority and critical part of the sound engineering process. This is one of the reasons why speaker manufacturers strongly recommend using speakers of the same type when creating a surround sound system. The CPR system by PSI Audio will feature an extremely accurate and superior surround sound image and therefore a much improved working environment. One of the big advantages of the CPR system is also that for the first time a user can mix different types of speakers from one manufacturer (PSI Audio) in a surround sound system, whilst maintaining perfectly accurate phase response. Not only will the PSI Audio surround system sound much more accurate and therefore provide a superior working tool, but it can also introduce significant cost and space savings when investing in a new monitoring system.

______________________________________________________________________________ 21/06/2002

2


Relec SA ĂŠlectroacoustique rte de Lausanne Z.I. Les Petits-Champs 11A +B 1400 Yverdon-les-Bains VD Switzerland ___________________________________________________________________________________________________________________________________________________________________________________________

AOI Adaptive Output Impedance System by PSI Audio

Technical description In low frequencies a loudspeaker behaves like a high-pass filter; therefore the damping depends on its mass, on compliances (mechanical and acoustical suspension) and of the source resistance. In high frequencies, the resonances correspond to the deformations of the membranes. The masses in movement are parts of the mobile mass. Compliances depend on the elasticity of the material. The resistances are the internal damping and the source resistance. For an ideal damping in a wide area of frequency, the source impedance must be adapted to every range of frequency for every transducer. The AOI system is constituted by a detection of the movement of the membrane and the moving coil, as well as by a counter reaction filtering. Therefore the damping rate is continuously ideally adjusted according to the frequency. The AOI system allows the reproduction of sound without transducer coloring over the whole frequency range.

Impulse behaviour

Electrical input signal

Acoustical output of a multi way speaker without CPR*

Acoustical output PSI Audio speaker with CPR+AOI

0

1.0

*C P R : Compensated Phase Response system *A O I : Adaptive Output Impedance system

2.0

3.0

4.0

5.0

6.0

7.0 t [ms]

______________________________________________________________________________ 21/06/2002

1


Relec SA ĂŠlectroacoustique rte de Lausanne Z.I. Les Petits-Champs 11A +B 1400 Yverdon-les-Bains VD Switzerland ___________________________________________________________________________________________________________________________________________________________________________________________

Practical advantage The PSI Audio speakers featuring the AOI system have much superior impulse behavior to traditional amplifier designs. Whilst the transducer travels to its intended position the AOI circuitry seamlessly adapts the amplifiers output impedance to insure ideal acceleration of the membrane to reproduce the desired impulse. Once the transducer reaches the end of the impulse the AOI circuitry provides a break in order to act against an overshooting of the transducer. The AOI circuitry is almost capable of reproducing a square wave and therefore increases accuracy by marring the transducer and the amplifier in to a perfect couple. A nice side effect of the AOI system is that the membranes of a PSI speaker do not produce parasite sounds when other speaker systems in the room are in use. When air pressure is produced by other sources than the PSI speakers the AOI will detect this and tighten the damping of its transducers in order not to produce parasite sounds not originating by the speaker system in use. In today’s times where much more importance is given to the low end reproduction of sounds especially when using sub woofer technology in surround sound systems the importance of a monitoring system that has an accurate and not a flattering reproduction becomes essential. The result of the AOI featured PSI Audio speaker range is a speaker family with a highly accurate impulse behavior with a minimum of transducer coloration.

______________________________________________________________________________ 21/06/2002

2


Relec SA Electroacoustique Z.I. Les Petits-Champs 11A +B 1400 Yverdon-les-Bains VD Switzerland

PSC Command principle PSC enables to control the standby mode of your loudspeakers through the signal cable. This command is generated by pulling up simultaneously the voltage of the entries (2) and (3) of the XLR. A voltage of +5 to 25V DC referenced to the ground is necessary to control the standby mode.

*PSC : Phantom Standby Control : LIMITER

INPUT

1=Gnd 2=Hot 3=Cold

PSC*

TEMP. SENS Hi. ± V

Low ± 18V

POWER LIMIT / STANDBY MAINS

TRANSF.

RECT.

STANDBY

REG.

The front panel LED is slightly lit in red during the standing mode.

Command principle schematic + 5 to 25V DC ON=>STANDBY Electronic Balanced output

R <= 22KOhms

(2)

(2) C* >= 10uF

(3)

(3)

(1)

(1)

CONNECT ONLY TO: True Balanced XLR INPUT With PSC*

*This schematic is only applicable for gears equiped with serial capacitors. Other more elegant solutions are also easily applicable.

PSI technology documents, typical characteristics subject to change without prior notice / © RELEC SA. More info: www.psiaudio.com


A14-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

A14-M Our Entry-Level model

PSI A14-M8 / typical characteristics subject to change without prior notice / Š RELEC SA.


Features Metal handle for easy handling and for mic. stand or installation. Volume control on the front panel. Protection circuits with overload indicator. Designed for stereo and multichannel monitoring. Magnetically shielded for use close to video monitors. Optimised directivity by phase coherency. Flat frequency response. Real balanced input. Orininal Technologies* : CPR, AOI, PSC, ALG.

A 14-M Technical Data [dB]

SPL@1m Active A14-M

-10dB Roll Off

+10

0

-10

-20

-30

20

100

50

500

200

[Deg]

5k

2k

1k

20k [Hz]

10k

ACOUSTIC PHASE Active A14-M

+540 +450 +360 +270 +180 +90 0 -90 -180

20

100

50

500

200

[dB]

5k

2k

1k

20k [Hz]

10k

Max Continuous SPL 1m A14-M

130

120

110

Power RMS Program power Continuous Max SPL, 1m Program Max SPL, 1m Response at -6dB Tolerances Phase tolerances Dispersion (P.N. 4 - 16 kHz) at -6 dB Crossover frequency Woofer's dim. Ext. / Diaphragm Tweeter's dim. Ext. / Diaphragm Dimensions cabinet W x H x D mm Net Weight

70+30 W 100 W 101 dB (single) 112 dB (pair) 56 - 22000 Hz ±2.5 dB (65Hz - 18kHz) ±45° (260Hz - 16kHz) 100° x 100° (H x V) 3.5 kHz Ø 147 mm / Ø 104 mm Ø 70 mm / Ø 20 mm 163 x 243 x 170 5.5 Kg

100

16k

12k5

8k

10k

6k3

4k

5k

3k15

2k

2k5

1k6

1k

1k25

800

630

500

315

400

250

200

125

160

100

63

80

50

31

40

25

90

*Further information: www.psiaudio.com

Description The A14-M full range speaker is the smallest member of the PSI Audio A-Series professional studio monitor range. Housed in an extremely compact cabinet the A14-M is designed to implement highest possible SPL and broad bandwidth. The A14-M is ideal for studio application where the ultimate in precision and portability is required. Packed into its compact dimensions, is all the technology of its larger brothers. The powerful bi-amplified output features the unique “AOI” output stages, while the active crossover, with integrated “CPR”, delivers unprecedented impulse behavior – with excellent stereo imaging. The crossover is also optimized for maximum phase coherence, projecting a wide horizontal and vertical ideal listening area. Designed to work in harmony with the full range of A series monitors the A14-M also makes ideal rear speakers in a surround sound setup, or can be developed in to a more powerful system by adding the A225-M sub – thus protecting your investment.

Typical characteristics - all rights reserved. All data subject to change without prior notice.


A14-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

All mesurement in anechoic room acoustical axis at 1 meter temperature 23±2°C humidity 50±20%

CPR*

POWER

*C P R : Compensated Phase Response system. *A O I : Adaptive Output Impedance system. *PSC : Phantom Standby Control (on Master series). LEVEL

INPUT

1=Gnd 2=Hot 3=Cold

ROLL OFF

HP

AOI*

HP

POWER

LP

LIMITER

AOI*

LP

PSC*

TEMP. SENS Hi. ± 45V

115/220V

Low ± 18V

POWER LIMIT MAINS

ON/OFF

[dB]

FUSE

TRANSF.

RECT.

STANDBY

REG.

SPL@1m A14-M

-10dB Roll Off

+10

90

70+30 W 100 W Sym, 10k Ohms 0.775 V

-10

-20

-30 20

50

500

200

100

[dB]

1k

2k

5k

10k

20k [Hz]

2k

5k

10k

20k [Hz]

2k

5k

10k

20k [Hz]

THD@-10dBu/1m A14-M

-20

-96 dBA -30

24 Vpp -40

101 dB (single) -50

112 dB (pair) -60 20

56 - 22000 Hz ±2.5 dB (65Hz - 18kHz)

50

500

200

100

[Deg]

1k

ACOUSTIC PHASE A14-M

+540

< 1.8% (95Hz-15kHz)

+450 +360

±45° (260Hz - 16kHz)

+270 +180

100° x 100° (H x V)

+90

2 Way(s)

-90

0

-180 20

50

500

200

100

1k

3.5 kHz Ø 147 mm / Ø 104 mm Ø 70 mm / Ø 20 mm 1 x XLR F / 3P 1=GND, 2=(+), 3=(-) MDF

[dB]

Max Continuous SPL 1m A14-M

130

120

110

100

8k

10k

12k5

16k

10k

12k5

16k

6k3 6k3

8k

4k

5k 5k

3k15 3k15

4k

2k

2k5 2k5

1k6

115/230V (50-60Hz)

2k

[Q]

6.2 / 5.5 Kg

1k6

1k

163 x 243 x 170

1k25

800

630

500

315

400

250

200

125

160

100

63

80

50

31

40

25

90

Directivity Factor A14-2M

10

5

1.4 - 6 - 100 W

PSI A14-M8 / typical characteristics subject to change without prior notice / © RELEC SA.

1k25

1k

800

630

500

400

315

250

200

160

125

100

80

63

50

1 40

5 - 40 °C

2

31

< 75% / < 90%

25

Puissance RMS Power RMS Puissance programme Program power Impédance d'entrée Input Impedance Sensibilité pour 100 dB @ 1m Sensivity for 100 dB @ 1m Rapport signal sur Bruit Signal to Noise Ratio Saturation d'entrée Input Overload Niveau max. continu, 1m Continuous Max SPL, 1m Niveau max. programme, 1m Program Max SPL, 1m Réponse à -6 dB Response at -6dB Tolérances Tolerances Distorsions THD Distortion THD Phase tolérances Phase tolerances Dispersion (B.R. 4 - 16 kHz) à -6 dB Dispersion (P.N. 4 - 16 kHz) at -6 dB Système System Fréquence de coupure Crossover frequency Dim. basses Ext. / Membrane Woofer's dim. Ext. / Diaphragm Dim. aigues Ext. / Membrane Tweeter's dim. Ext. / Diaphragm Connecteurs Connectors Signal entrée Signal input Matériaux du boîtier Box Material Dimensions boîtier L x H x P mm Dimensions cabinet W x H x D mm Poids brut / net Gross / Net Weight Tension de secteur Voltage Consommation Consumption Standby-Quiescent-Max Humidité Moy / Max Mean / Max Humidity Température externe External Temperature


A14-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

All dimensions are in mm

Mounting:

Bottom view

243

70

Front

163

1 x UNC 3/8’’ like mic stand

121

Front

Minimum well-aired space

85

170

Side view

Acoustical axis:

150

80

Front view

Measurement environment: Large anechoical room Temperature 23±2°C Humidity 50±20% PSI A14-M8 / typical characteristics subject to change without prior notice / © RELEC SA.


TEST | NAHFELD NAHFELD-MONITOR MONITOR | PSI Audio A 14 14-M M

Auch kleine Nahfeldmonitore wie der A 14-M des Schweizer Lautsprecherspezialisten PSI Audio sc schlagen mitunter große Schatten, in denen sich manch massiger Konkurrent – schneller als ihm lieb ist – wiederfindet.

Musik&Equipment

Schlagschatten

PSI Audio A 14-M 





Klangliche Neutralität und tonale Ausgewogenheit Sehr gutes Impulsverhalten und präzise Signaltrennung Clevere, multifunktionale Bügelkonstruktion

– Summary Der A 14-M von PSI Audio entpuppt sich als präziser Kompakt-Monitor, der klanglich nicht auffällt und damit beste Voraussetzungen zum professionellen Arbeiten bietet.

88

April 2009 Professional audio Musik & Equipment

Von Michael Nötges

B

ereits der Test des Nahfeldmonitors A 17-M (Ausgabe 1/2009) sorgte für Begeisterung in der Redaktion von Professional audio. Die Lautsprecher zeigten sich in Bestform und sammelten nicht zuletzt aufgrund ihrer hohen Impuls- und Signaltreue fleißig Sympathiepunkte. Grund genug, mit dem A 14-M auch dem kleinsten Ableger der hierzulande noch eher unbekannten Schweizer Lautsprechermanufaktur PSI Audio auf

den Zahn zu fühlen. Kennern ist Alain Roux, Inhaber und Unternehmensgründer der Firma Relec Sa, zu der auch PSI Audio gehört, bereits seit Mitte der 1970er-Jahre ein Begriff. 1975 entwickelte der Schweizer die ersten Lautsprecher und gehört heute in Fachkreisen zu den anerkannten Monitor-Spezialisten. Die Maxime von PSI Audio ist damals wie heute, das Optimum an klanglicher Präzision zu erreichen. Das gilt auch für den kleinsten PSIMonitor, den A 14-M. Obwohl er mit ei-


nem Stückpreis von rund 740 Euro knapp 400 Euro günstiger ist, als sein großer Bruder, der A 17-M, hat der Hersteller keinesfalls an der PSI-typischen technischen Finesse gespart und ihm sowohl das proprietäre CPR-System (Compensated Phase Response) zur analogen und frequenzabhängigen Phasenkorrektur mittels mehrerer All-Pass-Filter, als auch das AOI-System (Adaptive Output Impedance) für definiertes Einund Ausschwingverhalten der Membranen spendiert. Stark vereinfacht gesagt, überwacht die analoge AOI-Schaltung die Membranbewegung, analysiert sie und passt anhand der gewonnen Werte den Dämpfungsfaktor der Endstufen dynamisch an den Frequenzgang an. Das Ergebnis der beiden PSISpezialitäten sei eine deutlich verbesserte Detailauflösung, bessere Stereoabbildung, Ortungsschärfe und Tiefenstaffelung sowie ein optimiertes Impulsverhalten.

Impulsiver Alpenzwerg Beim A 14-M handelt es sich, wie bei allen PSI-Monitoren, um einen aktiven Zweiwege-Bassreflex-Lautsprecher. Allerdings ist das Nesthäkchen bei einem Gewicht von insgesamt 6,2 Kilogramm kaum höher als ein DinA5-Blatt und eignet sich aufgrund seiner kompakten Bauweise besonders für platzkarge Abhörsituationen in Ü-Wagen sowie Surround-Setups oder als edler Desktop-Lautsprecher. Der kompakte Nahfeldmonitor ist mit einer aktive Frequenzweiche – die Übergangsfrequenz liegt bei 3,5 Kilohertz – und zwei Endstufen bestückt, die für den Hoch- sowie Tiefmitteltöner 30 beziehungsweise 70 Watt an Dauerleistung bereitstellen. Das kompakte Gehäuse aus MDF ist mit weinrotem Lack überzogen, wobei der dezente Metallic-Look das etwas nüchterne Äußere geschmackvoll aufwertet. Die Gehäusefertigung hat PSI Audio nach Sainte-Croix, einer kleinen Gemeinde im Juragebirge, verlagert. Entwicklung, Montage und das elektronische Design finden im Hauptquartier in Yverdon statt. Zur Installation des A 14-M ist ein Montagebügel an den Seiten des Gehäuses verschraubt. Weist er nach oben, dient er der hängenden Installation, klappt man ihn unter den Gehäuseboden, bestimmt er den Neigungswinkel zur Aufstellung der Monitore auf Meter-Bridge oder Desktop – eine einfache wie gleichzeitig clevere und praxisnahe Lösung. Der Kalottenhochtöner des A 14-M stammt vom französischen Hersteller AAC. Damit schlägt der Kleine von PSI Audio etwas aus der Art. Ansonsten setzt der Hersteller auf selbstentwickelte Spezialanfertigungen, die von der taiwanesischen Firma Ly Yuan Electronics gefertigt werden. Der Referenzmonitor A 25-M ist sogar mit handgefertigten und penibel optimierten Hochtönern aus eigenem Hause bestückt. Anyway, die Gewebekalotte des Hochtöners sitzt jedenfalls hinter einem Schaumstoffschutz verborgen, inmitten des schallführenden Wave Guides. Ein robustes Schutzgitter bewahrt die Gewebemembran des Tiefmitteltöners vor versehentlichen Beschädigungen im mobilen Einsatz. Die Bassreflexöffnung befindet sich als schmaler Spalt auf der Vorderseite, was für eine wandnahe Aufstellung ohne klangliche Verfälschungen von Vorteil ist. Von Vorteil ist in solchen Fällen außerdem der von vorne erreichbare Regler zur stufenlose Anpassung der Eingangsempfindlichkeit (-∞ bis 0 dBu), der ansonsten nach der Installation nicht mehr erreichbar wäre. Eine grüne LED informiert über die Betriebsbereitschaft. Bei drohender Überlastung der Elektronik blinkt selbige zunächst rot und signalisiert damit den Einsatz des integrierten Limiters. Leuchtet sie durchgängig rot, gilt es die Eingangsempfindlichkeit zu senken. Die Elektronik ist überlastet. Auf der Rückseite finden sich lediglich der XLR-Eingang, sowie ein Trim-Poti zur fließenden Kalibrierung des Roll-Off-


TEST | NAHFELD-MONITOR | PSI Audio A 14-M

den praktischen Bügel zu schätzen, der sowohl bei der Desktop- als auch erhöhter Sockel-Aufstellung die Monitore optimal ausrichtet. Dann freuen wir uns über die Möglichkeit die Eingangsempfindlichkeit anzupassen, ohne hinter das Gehäuse greifen zu müssen. Somit ist in unserem Fall eine schnelle und präzise Pegelanpassung zu den zum Vergleich angeschlossenen Focal CMS 50 (3/2009) möglich. Erster Eindruck: Der A 14-M ist klanglich unauffällig. Das ist keineswegs negativ zu verstehen, denn er überzeugt unmittelbar durch sein ausgewogenes Klangbild, das keinerlei tonale Verfälschungen aufweist. Schönfärberei liegt dem Schweizer völlig fern, vielmehr erfüllt er nüchtern und präzise seinen Job. Im Gegensatz zum CMS 50 wirkt er besonders im unteren Mittenbereich etwas schlanker und im Bass-Bereich behält er seine akkurate Wiedergabe selbst bei höheren Abhörpegeln bei. Dass der kleine Schweizer bei Frequenzen unterhalb 100 Hertz (siehe Frequenzgang) an seine Grenzen stößt, kann ihm beim besten Willen nicht vorgehalten werden. Für ein wirkliches Full-Range-System empfiehlt sich daher ganz einfach der passende Subwoofer wie beispielsweise der A 225M von PSI Audio. Aber auch ohne, weiß der A 14-M zu gefallen. Vor allem sein sehr gutes Impulsverhalten und die breitbandige Auflösung führen zu präziser Stereoabbildung mit sehr guter Ortungsschärfe. Sowohl die Phantommitte, und zwar ganz unabhängig vom vorliegenden Programmmaterial, als auch die einzelnen Instrumente sind zielsicher auszumachen und führen zu einer sehr gelungen Raumdarstellung und exakter Tiefenstaffelung. Dabei erweist sich der unauffällige Charakter als echte Stärke, treten die Monitore in den Hintergrund, sodass sich der Klang – vorausgesetzt der Sweetspot wird nicht verlassen – von den Lautsprechern löst. Unauffällig heißt auch, dass sich der A 14-M als neutrales Werkzeug entpuppt, das sich beim TestMischen eines Tracks zur Aufdeckung von Schönheitsfehlern, zur Anpassung

von Hallräumen und für Effekteinstellungen empfiehlt. Die genaue Positionierung der Instrumente im Stereopanorama gelingt ohne Probleme und die Gegenprobe mit den KRK Exposé 8 (Ausgabe 8/2007) beweist, dass sich unterm Strich vorzüglich mit dem A 14-M arbeiten lässt.

Der Frequenzgang des A 14-M ist für einen Kompakt-Monitor vorbildlich. Für ein wirkliches Full-Range-System empfiehlt sich der Einsatz eines Subwoofers, um auch Frequenzen unterhalb 100 Hertz optimal wiederzugeben.

FAZIT: Der A 14-M ist im besten Sinn ein unauffälliger Nahfeldmonitor. Klanglich ausgewogen, mit hoher Detailauflösung, sehr gutem Impulsverhalten und präziser Ortungsschärfe, entpuppt sich der Alpenzwerg als nüchternes Abhör-Werkzeug, das sich besonders für SurroundSetups, Ü-Wagen oder beengte Studioumgebungen empfiehlt. Rund 730 Euro pro Stück ist ein stolzer aber aufgrund des hohen Qualitätsniveaus durchaus fairer Preis. 

Das Roll-Off-Filter ermöglicht zum einen die Anpassung des A 14-M an die akustischen Abhörbedingungen, zum anderen zur optimalen Anbindung eines Subwoofers.

Filters. Dieser dient zur Absenkung des Bassbereichs unterhalb 100 Hertz um maximal 10 Dezibel. Wichtig ist der RollOff zur optimalen Anpassung des Systems an einen Subwoofer, oder um den Tieftonbereich an den Raum anzupassen, wenn die Monitore direkt an einer Wand oder in einer Ecke platziert sind.

Präzises Kompakt-Werkzeug Im Hör und Praxistest von Professional audio erweist sich der A 14-M als wirkliches Schätzchen. Zunächst lernen wir

90

April 2009 Professional audio Musik & Equipment

Steckbrief Modell

A 14-M

Hersteller Vertrieb

PSI Audio Synthax GmbH Am Pfanderling 60 85778 Haimhausen Tel.: 08133 913810 Fax: 08133 918119 gmbh@synthax.de www.synthax.de Zweiwege-AktivBassreflex-Lautsprecher 163 x 170 x 243

Typ Abmessungen BxTxH [mm] Gewicht [kg] Preis [UVP, Euro]

6,2 738

Ausstattung

Lautsprecher Ø Bassmembran 1 [mm] Ø Hochtönermembran [mm] Ausgangsleistung Tieftonkanal 1 und 2 [Watt] Ausgangsleistung Hochtonkanal [Watt]

2 104 24 70 30

Regelmöglichkeiten

Lautstärke/Eingangsempfindlichkeit ROLL OFF

stufenlos regelbar: -∞ bis Referenz-Pegel 0 dBu) Bass-Absenkung (stufenlos, maximal -10 dB)

Ein- und Ausgänge

Eingänge

1 x symmetrisch XLR

Zubehör

Handbuch, Netzkabel Besonderheiten

Überlastungsschaltung, AOI- und CPR-System und PSC Bewertung

Verarbeitung Ausstattung Bedienung Messwerte Klang

sehr gut gut sehr gut sehr gut gut bis sehr gut

Gesamtnote Preis/Leistung

Oberklasse gut bis sehr gut gut bis sehr gut


A21-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

A17-M

Our entry(next)level

Your Next-Level model

PSI A21-M3 & M4 / typical characteristics subject to change without prior notice / Š RELEC SA.


Features Very large bandwidth in a compact cabinet. Protection circuits with overload indicator. Magnetically shielded for use close to video monitors. Designed for stereo and multichannel monitoring. Very high SPL in a compact cabinet. Optimised directivity by phase coherency. Flat frequency response. Real balanced input. Orininal Technologies* : CPR, AOI, ALG, PSC.

A 17-M Technical Data [dB]

SPL@1m A17-M

-10dB Roll Off

+10

0

-10

-20

-30

20

50

100

200

500

[Deg]

1k

2k

5k

10k

20k [Hz]

ACOUSTIC PHASE A17-M

+540 +450 +360 +270 +180 +90 0 -90 -180

20

50

100

200

500

[dB]

1k

2k

5k

10k

20k [Hz]

Max Continuous SPL 1m A17-M

130

120

110

Power RMS Program power Continuous Max SPL, 1m Program Max SPL, 1m Response at -6dB Tolerances Phase tolerances Dispersion (P.N. 4 - 16 kHz) at -6 dB Crossover frequency Woofer's dim. Ext. / Diaphragm Tweeter's dim. Ext. / Diaphragm Dimensions cabinet W x H x D mm Net Weight

80+40 W 120 W 104 dB (single) 115 dB (pair) 44 - 23000 Hz ±2.5 dB (50Hz - 20kHz) ±45° (150Hz - 20kHz) 90° x 90° (H x V) 3.6 kHz Ø175 mm / Ø130 mm Ø 100 mm / Ø 25 mm 200 x 320 x 230 8.4 Kg

100

16k

12k5

8k

10k

6k3

4k

5k

3k15

2k

2k5

1k6

1k

1k25

800

630

500

315

400

250

200

125

160

100

63

80

50

31

40

25

90

*Further information: www.psiaudio.com

Description A classic near-field precision monitor, the A17-M is the ideal entry model to the PSI Audio range. Perfectly suited for surround sound and near-field applications, the A17-M is ideal for studio application where the ultimate in precision is required. Its compact form incorporates the full range of PSI Audio’s outstanding technologies. The powerful bi-amplified output features the unique “AOI” output stages, while the active crossover, with integrated “CPR”, delivers unprecedented impulse behavior – with excellent stereo imaging. The crossover is also optimized for maximum phase coherence, projecting a wide horizontal and vertical ideal listening area. Designed to work in harmony with the full range of A series monitors the A17-M also makes ideal rear speakers in a surround sound setup, or can be developed in to a more powerful system by adding the A225-M sub – thus protecting your investment.

Typical characteristics - all rights reserved. All data subject to change without prior notice.


A17-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

CPR*

POWER

*C P R : Compensated Phase Response system. *A O I : Adaptive Output Impedance system. *PSC : Phantom Standby Control (on Master series). LEVEL

INPUT

1=Gnd 2=Hot 3=Cold

ROLL OFF

HP

AOI*

HP

POWER

LP

LIMITER

AOI*

LP

PSC*

TEMP. SENS Hi. ± 45V

115/220V

Low ± 18V

POWER LIMIT MAINS

ON/OFF

[dB]

FUSE

TRANSF.

RECT.

STANDBY

REG.

SPL@-10dBu/1m A17-M

-10dB Roll Off

+10

90

80+40 W

-10

120 W

-20

Sym, 10k Ohms

-30

0.775 V

20

50

500

200

100

[dB]

1k

2k

5k

10k

20k [Hz]

2k

5k

10k

20k [Hz]

2k

5k

10k

20k [Hz]

THD@-10dBu/1m A17-M

-20

-96 dBA -30

24 Vpp -40

104 dB (single) -50

115 dB (pair) -60 20

44 - 23000 Hz ±2.5 dB (50Hz - 20kHz)

50

500

200

100

[Deg]

1k

ACOUSTIC PHASE A17-M

+540

< 1.5% (100Hz-12kHz)

+450 +360

±45° (150Hz - 20kHz)

+270 +180

90° x 90° (H x V)

+90

2 Way(s)

-90

0

-180 20

3.6 kHz Ø 175 mm / Ø130 mm Ø 100 mm / Ø 25 mm 1 x XLR F / 3P

50

500

200

100

[dB]

1k

Max Continuous SPL 1m A17-M

130

120

110

1=GND, 2=(+), 3=(-) 100

MDF

8k

10k

12k5

16k

10k

12k5

16k

6k3 6k3

8k

4k

5k 5k

3k15 3k15

4k

2k

2k5 2k5

1k6

1k

1k25

800

630

500

315

2k

115/230V (50-60Hz)

1k6

[Q]

9.5 / 8.4 Kg

400

250

200

125

160

100

63

80

50

31

40

25

90

200 x 320 x 230

Directivity Factor A17-M

10

5

1.4 - 6 - 100 W

PSI A17-M5 / typical characteristics subject to change without prior notice / © RELEC SA.

1k25

1k

800

630

500

400

315

250

200

160

125

100

80

63

50

1 40

5 - 40 °C

2

31

< 75% / < 90%

25

Puissance RMS Power RMS Puissance programme Program power Impédance d'entrée Input Impedance Sensibilité pour 100 dB @ 1m Sensivity for 100 dB @ 1m Rapport signal sur Bruit Signal to Noise Ratio Saturation d'entrée Input Overload Niveau max. continu, 1m Continuous Max SPL, 1m Niveau max. programme, 1m Program Max SPL, 1m Réponse à -6 dB Response at -6dB Tolérances Tolerances Distorsions THD Distortion THD Phase tolérances Phase tolerances Dispersion (B.R. 4 - 16 kHz) à -6 dB Dispersion (P.N. 4 - 16 kHz) at -6 dB Système System Fréquence de coupure Crossover frequency Dim. basses Ext. / Membrane Woofer's dim. Ext. / Diaphragm Dim. aigues Ext. / Membrane Tweeter's dim. Ext. / Diaphragm Connecteurs Connectors Signal entrée Signal input Matériaux du boîtier Box Material Dimensions boîtier L x H x P mm Dimensions cabinet W x H x D mm Poids brut / net Gross / Net Weight Tension de secteur Voltage Consommation Consumption Standby-Quiescent-Max Humidité Moy / Max Mean / Max Humidity Température externe External Temperature


A17-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

All dimensions are in mm

Mounting

135

Panel screwing area depth 16mm

30

Front

200

Bottom view

70

320

Gravity center

Front

30

160

140

65

30

Minimum well-aired space

100

230

Side view

Acoustical axis

190

100

Front view

Measurement environment: Large anechoical room Temperature 23±2°C Humidity 50±20% PSI A17-M5 / typical characteristics subject to change without prior notice / © RELEC SA.


A21-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

A21-M The 2-way Reference Model

PSI A21-M3 & M4 / typical characteristics subject to change without prior notice / Š RELEC SA.


Features Very high SPL in a compact cabinet. Compatible with industry standard mouting systems. Protection circuits with overload indicator. Magnetically shielded for use close to video monitors. Designed for stereo and multichannel monitoring. Optimised directivity by phase coherency. Flat frequency response. Real balanced input. Amplifier unit acoustically uncoupled from speaker cabinet. Orininal Technologies* : CPR, AOI, ALG, PSC.

A 21-M Technical Data [dB]

SPL@1m A21-M

-10dB Roll Off

+10

0

-10

-20

-30

20

50

100

200

500

[Deg]

1k

2k

5k

10k

20k [Hz]

2k

5k

10k

20k [Hz]

ACOUSTIC PHASE A21-M

+540 +450 +360 +270 +180 +90 0 -90 -180

20

50

100

200

500

[dB]

1k

Max Continuous SPL 1m A21-M

130

120

110

Power RMS Program power Continuous Max SPL, 1m Program Max SPL, 1m Response at -6dB Tolerances Phase tolerances Dispersion (P.N. 4 - 16 kHz) at -6 dB Crossover frequency Woofer's dim. Ext. / Diaphragm Tweeter's dim. Ext. / Diaphragm Dimensions cabinet W x H x D mm Net Weight

100

16k

12k5

8k

10k

6k3

4k

5k

3k15

2k

2k5

1k6

1k

1k25

800

630

500

315

400

250

200

125

160

100

63

80

50

31

40

25

90

*Further information: www.psiaudio.com

Description The A21-M high power near / mid-field precision monitor covers a broad frequency spectrum, allowing the user to be in full control of their audio production. Its unique and highly optimised assets make it perfect for near, mid-field and surround sound applications where ultimate precision is required. The powerful bi-amplified output stages features the unique “AOI” output stages and has a protection circuit, which can be monitored via the red LED on the front panel. The active crossover, with integrated “CPR”, gives the A21-M unprecedented impulse behavior – with excellent stereo imaging. The crossover is also optimized for maximum phase coherence, projecting a wide horizontal and vertical ideal listening area. The electronics are housed in a unit mechanically isolated from the speaker cabinet to avoid resonance at high sound pressure levels. Designed to work in harmony with the full range of A series monitors the A21-M also makes ideal front speakers in a surround sound setup, or can be developed in to a more powerful system by adding the A225-M sub – thus protecting your investment. Typical characteristics - all rights reserved. All data subject to change without prior notice.


A21-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

CPR*

POWER

*C P R : Compensated Phase Response system. *A O I : Adaptive Output Impedance system. *PSC : Phantom Standby Control (on Master series). LEVEL

INPUT

1=Gnd 2=Hot 3=Cold

ROLL OFF

HP

AOI*

HP

POWER

LP

LIMITER

AOI*

LP

PSC*

TEMP. SENS Hi. ± 45V

115/220V

Low ± 18V

POWER LIMIT MAINS

ON/OFF

FUSE

[dB]

TRANSF.

RECT.

STANDBY

REG.

SPL@-10dBu/1m A21-M

-10dB Roll Off

+10

90

120+50 W 170 W Sym, 10k Ohms 0.775 V

-10

-20

-30 20

50

500

200

100

[dB]

1k

2k

5k

10k

20k [Hz]

2k

5k

10k

20k [Hz]

2k

5k

10k

20k [Hz]

THD@-10dBu/1m A21-M

-20

-96 dBA -30

24 Vpp -40

108 dB (single) -50

119 dB (pair) -60 20

38 - 23000 Hz ±2 dB (44Hz - 20kHz)

50

500

200

100

[Deg]

1k

ACOUSTIC PHASE A21-M

+540

< 1.4% (90Hz-12kHz)

+450 +360

±45° (190Hz - 20kHz)

+270 +180

90° x 90° (H x V)

+90

2 Way(s)

-90

0

-180 20

50

500

200

100

1k

2.4 kHz

100

8k

10k

12k5

16k

10k

12k5

16k

6k3 6k3

8k

4k

5k 5k

3k15 3k15

4k

2k

2k5 2k5

1k6

115/230V (50-60Hz)

2k

[Q]

14.8 / 13.4 Kg

1k6

1k

250 x 400 x 300

1k25

800

630

500

315

400

250

200

125

160

100

63

90 25

MDF

110

80

1=GND, 2=(+), 3=(-)

120

50

1 x XLR F / 3P

Max Continuous SPL 1m A21-M

130

31

Ø 100 mm / Ø 25 mm

[dB]

40

Ø 217 mm / Ø 170 mm

Directivity Factor A21-M

10

5

1.2 - 5 - 120 W

PSI A21-M3 & M4 / typical characteristics subject to change without prior notice / © RELEC SA.

1k25

1k

800

630

500

400

315

250

200

160

125

100

80

63

50

1 40

5 - 40 °C

2

31

< 75% / < 90%

25

Puissance RMS Power RMS Puissance programme Program power Impédance d'entrée Input Impedance Sensibilité pour 100 dB @ 1m Sensivity for 100 dB @ 1m Rapport signal sur Bruit Signal to Noise Ratio Saturation d'entrée Input Overload Niveau max. continu, 1m Continuous Max SPL, 1m Niveau max. programme, 1m Program Max SPL, 1m Réponse à -6 dB Response at -6dB Tolérances Tolerances Distorsions THD Distortion THD Phase tolérances Phase tolerances Dispersion (B.R. 4 - 16 kHz) à -6 dB Dispersion (P.N. 4 - 16 kHz) at -6 dB Système System Fréquence de coupure Crossover frequency Dim. basses Ext. / Membrane Woofer's dim. Ext. / Diaphragm Dim. aigues Ext. / Membrane Tweeter's dim. Ext. / Diaphragm Connecteurs Connectors Signal entrée Signal input Matériaux du boîtier Box Material Dimensions boîtier L x H x P mm Dimensions cabinet W x H x D mm Poids brut / net Gross / Net Weight Tension de secteur Voltage Consommation Consumption Standby-Quiescent-Max Humidité Moy / Max Mean / Max Humidity Température externe External Temperature


A21-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

All dimensions are in mm

Mounting

400

Front

4 x M6 (Omnimount®) (120 series)

Gravity center

200

175

50

90

Minimum well-aired space

150

Front

250

Bottom view

70

300

Side view

Acoustical axis

255

125

Front view

Measurement environment: Large anechoical room Temperature 23±2°C Humidity 50±20% PSI A21-M3 & M4 / typical characteristics subject to change without prior notice / © RELEC SA.


Sound On Sound : Est. 1985

In this article:

PSI Audio A17M & A21M Active Monitors Reviews : Monitors

Published in SOS July 2011 Print article : Close window

 

These compact monitors from Swiss company PSI incorporate some very clever technology, including ‘Class-G’ amplification, that helps put them in a class of their own! Hugh Robjohns

P

SI Audio is almost certainly an unfamiliar name to most, yet I predict  these intriguing Swiss monitor-speaker manufacturers will quickly become as well known and highly thought-of as the many well-established high-end manufacturers, such is the quality of their products. PSI Audio started out as Relec SA in the late 1970s, the brainchild of Alain Roux, and have been producing a broad range of hi-fi, PA and studio monitoring loudspeakers for over 30 years, both under their own name and as OEM manufacturers. However, the PSI Audio brand is now being marketed more actively worldwide, and the company’s innovative products are being brought to the attention of a far wider audience. PSI Audio’s production facilities are split across two sites. The speaker cabinets are made in St Croix, a small town in the Swiss Jura mountains with a strong history in the craft of making fine musical instruments  and lavish music boxes, since the 19th century. Product development, electronics design, manufacture and assembly are performed at Yverdon alongside Lake Neuchâtel. This facility, built in 1989, accommodates  a 150-cubic-metre anechoic chamber, seven metres high and incorporating four tons of isolation material, which is employed in the testing and development of PSI’s loudspeaker designs.

Technology Overview Like most manufacturers, PSI Audio claim to use several unique technologies in their speaker designs, each with a catchy name. In this case the relevant ones are AOI, CPR, PSC and Class G.  The first stands for Adaptive Output Impedance: the ability of the power amplifiers to adjust their output impedance to optimise the impulse behaviour and damping of the connected drive units. In essence, the circuitry determines the movement of the speaker diaphragm by analysing the current flow between amplifier and driver, and then adjusts the impedance as necessary to control that movement, maintaining as closely as possible a near-ideal impulse response. So as the transducer travels to its intended position, the AOI circuitry maximises current flow to provide the best diaphragm acceleration to reproduce the transient impulse as accurately as possible. Once the transducer reaches the end of the impulse, the AOI circuitry then acts to provide an active brake, minimising diaphragm overshoot. PSI Audio claim that this technology makes their system “almost capable of reproducing a square wave”, and that the system is sensitive enough to detect parasitic driver resonance if other loudspeakers are being used in the room, and will damp it out automatically! The result is extremely low coloration and an impressively tight transient behaviour, even at low frequencies and despite using a ported-cabinet design. CPR, or Compensated Phase Response, is a technology that corrects the additive phase shifts and group  delays inherent in conventional crossover filters and mechanical transducers. It achieves this with carefully designed all-pass filter stages, and the result is a remarkably precise stereo image and an accurate sense of  space in the recording environment. PSC stands for Phantom Standby Control, and is a simple system to enable remote on/off switching. When  a voltage of between 5 and 25 V is applied via 22kΩ resistors to both lines of the balanced audio input (relative to the cable screen), the speaker is forced into a standby state. In most cases, large-value DC-blocking capacitors will be required, to protect the output of the monitoring controller (or other audio source) from the DC control voltage. Presumably some users will find this a useful facility, but DC blocking  capacitors are known to be a source of low-level signal distortion, and the switch sensing — although the only practical arrangement given the use of a phantom system on the audio connection — seems inverted. Most remote switching systems use an external voltage to switch the speakers on, not off! Suffice to say I made no  use of this option.

Technology Overview PSI A-Series Monitors Listening Conclusion Alternatives Class-G Amplification PSI A17M & A21M £2599/£4169

pros Stunning performance. Compact size. Pin-sharp stereo imaging and a wide sweet spot. Remarkably tight lowfrequency control and bass extension. Efficient, cool-running power amplifiers. Unusual but attractive red colour scheme. Closely matched tonality across different models.

cons Scarily expensive.

summary Small- and medium-sized two-way active monitors capable of delivering exceptional accuracy and neutrality, with remarkable LF control and extension, and precise stereo imaging. information A17M £2598.85 (pair), A21M £4169.38 (pair). Prices include VAT. eMerging UK +44 (0)20 8941 6547. Click here to email www.emerginguk.com www.psiaudio.com


Finally, Class G is an unusual amplifier topology that aims to achieve a power efficiency approaching that of  Class-D ‘switching’ amps, while maintaining the linearity of Class-AB amplifiers. The ‘Class-G Amplification’  box on the next page explains the concept in more detail.

PSI A-Series Monitors For this review I was supplied with two pairs of two-way, active PSI Audio monitors: the diminutive A17M model, which employs an approximately six-inch bass/mid-range driver, and the larger A21M, with about an eight-inch unit. Both models share the same one-inch tweeter, the same basic cabinet construction, and the same amplifier chassis configuration. There is a smaller  model in the range (the A14M), as well as a larger three-way system (A25M), a centre-channel model with a bass/mid driver on either side of the tweeter (A214M), a dedicated subwoofer (A225M), and a floor-standing model (the A215M) in a similar configuration to the A214M. All models employ unusual but attractive burgundy paint-finished MDF cabinets with a horizontal, slotted port vent across the bottom of the front  baffle, below the bass/mid driver. A metallic-black cabinet finish is available on special order, but at greater cost. The dimension and weight of the smaller A17M model are 320 x 200 x 230mm (HWD) and 8.4kg, while the larger A25M measures 400 x 250 x  300mm (HWD) and weighs 13.4kg.

Both of the monitors under review feature the same rear-panel controls, including knobs for input sensitivity and low-frequency response.

Specifications for the desktop-sized A17M give a programme-peak SPL of an impressive 115dB per pair at one metre. Frequency response is quoted as 44Hz to 23kHz at the -6dB points, a figure that narrows to 50Hz to 20kHz ±2.5dB. The crossover frequency is 3.6kHz, and the amplifiers supply 80W and 40W for the bass/mid driver and tweeter, respectively. The larger A25M is quoted as managing 119dB SPL for programme peaks (per pair again), and a response of 32Hz to  23kHz at the -6dB points or 38Hz to 20kHz ±1.5dB. The crossover is also lower, at 2.4kHz, and the amplifiers are up-rated to 120W and 50W. Both models feature an electronically balanced input with an impedance of 10kΩ, and a nominal sensitivity of 0dBu for 100dB SPL at one metre. The tweeter is set at the bottom of an unusually deep waveguide machined into the front baffle, and is consequently very well protected from accidental damage. This restricts the HF dispersion above about 4kHz to roughly 90 degrees in both the horizontal and vertical planes, which will help to minimise unwanted reflections from mixing consoles, computer workstations and side walls — no doubt contributing to the excellent stereo imaging. A front-panel LED illuminates green when the speaker is powered, and red when in standby mode, or when the heat- or volume-protection circuitry is operating. The rear panel is metal and acts as a cooling heatsink for the amplifiers. It also carries just three controls:  a mains on-off rocker switch, and rotary controls for level and LF roll-off. An IEC mains inlet incorporates a fuse  and voltage selector, and both models employ a linear power supply with a substantial toroid mains  transformer. The input level control spans a 20dB range, maximum sensitivity being 0dBu for 100dB SPL at one metre,  while the bass attenuation control covers a 10dB range, starting from about 200Hz in the A21M and 250Hz in  the A17M. This control is intended to correct for the boundary effect bass-boost when the speaker is placed close to room walls or corners. My review was conducted with the speakers in a free-field situation, with the bass control set to its 0dB calibrate position, but the handbook recommends settings of -4dB for a half-space (near a back wall) situation and -7dB for a quarter space (corner) placement. These settings are less than the  theoretical -6 and -12dB figures, and clearly there is room for experimentation and personal preferences in finalising the calibration. When the partnering A225M dual subwoofer is being used with either the A21M or A17M, the handbook recommends setting the bass roll-off to its maximum attenuation to optimise the integration and power handling.

Listening I did much of my auditioning with the speakers mounted well away from side and rear walls, and driven from a Grace M902B monitor controller. From the  outset it was clear that both the A17M and A21M were something special, and frequent direct comparison with my reference PMC three-way IB1s quickly confirmed that fact! The level of performance was immediately and obviously far higher than that of the vast majority of similarly sized monitors. Moreover, the tonal matching between the two models was extremely close, which is always a sign of meticulous design and attention to detail. Both models exhibited a bass extension and power handling that belied their  modest cabinet sizes, and both exhibited remarkable transient behaviour and control, with pin-sharp stereo imaging. Tonally, these speakers are extremely neutral and accurate — voiced along the lines of classic British monitors from

The amplifier PCB. On the right is the toroidal mains transformer, while to the left, you can see the diodes used to control the output stages’ 


ATC, PMC and Harbeth — and completely free from the upper mid-range presence hype that is so often used to convey a (false) impression of detail  and resolution.

biasing and switching.

Instead, these speakers provide real detail and superb resolution across the bandwidth, and do so without any sense of fatigue even after hours of critical listening. The top end is gloriously smooth and natural, yet wonderfully revealing and precise. The mid range enjoys negligible levels of the harmonic distortion that so often masks the mid-range clarity in inferior designs. Indeed, the mids come across as totally uncoloured, and both monitors passed my very critical spoken-voice tests with ease, delivering complete naturalness and accurate spectral balances without any hint of boominess, boxiness or sibilance. Moving down to the bottom end, the bass control — the ability to stop and start bass notes and separate bass guitars from kick drums — was remarkable, delivering a performance more associated with sealed-cabinet designs rather than ported construction. Bass extension was also impressive, particularly for the very compact A17M. Simple crossed-pair stereo recordings were portrayed with immensely precise stereo imaging that remained surprisingly stable across a wide listening area, and I was left in no doubt at all as to the absolute position when  panning instruments across the soundstage. It sounds like a basic requirement — and it is — but it’s surprising how many speakers present vague or blurred imaging. Room acoustics and reverberation filled the space between the speakers very linearly and naturally, and with a good sense of depth when auditioning appropriate  material. Dynamics were reproduced naturally, with superb transient punch and clarity, and without any hint of monitor compression, even at silly listening levels. In fact, these speakers seem very comfortable working at levels that few similarly sized speakers would be able to cope with — and given the very low levels of coloration you will find yourself listening at much louder levels than you think you are if you’re not careful! Working on a mix with these monitors was a joy, making compression and equalisation decisions very  intuitive and natural, simply because you can hear what you’re doing so easily. Flaws in recorded tracks are obvious; over-compressed commercial music and low-rate MP3s are exquisitely unpleasant to audition, just as they should be!

Conclusion Reviewing monitor loudspeakers is always a challenge. The technology involved in the vast majority of cases is  very mature and with few significant variations. Consequently, the vast majority of monitors perform adequately and comparably to their peers at any given price level. Very few are unusably poor, but equally, very few stand out as exceptionally good. In fact, I can count those models I have reviewed that I would suggest fall into the  ‘outstanding’ category on the fingers of one hand. My list would include PMC’s AML1 (September 2001), Earthworks’ Sigma 6.2 (April 2003), and K+H’s O300 (October 2004), with honourable mentions going to Acoustic Energy’s AE22 (May 2008) and, although I didn’t review it, Event’s Opal (August 2009). However, the time has now come to introduce my second hand to the count, because I have to add a new  contender for the honour: PSI Audio’s A21M monitor (and the A17M too). In short, these speakers are extraordinary and deliver a level of performance and accuracy that vanishingly few two-way designs can match, and which would shame a great many three-way offerings. There is no denying that they are expensive, but the cost is comparable to the few other monitors of similar performance and size. Auditioning is highly recommended for serious high-end monitoring applications.     0

Alternatives Compact two-way active monitors capable of delivering a similar or better level of performance to these PSI Audio monitors are scarce, but potential short-list alternatives should include the truly astonishing PMC AML2 (priced at $10,499 per pair), the superb ATC SCM20A SL Pro ($6700), and Geithain RL904 ($6200). At a slightly more affordable level, the PMC TB2SA MkII ($3699) and similarly sized but three-way, sealed-cabinet Neumann (formerly K+H) O300 monitors ($7016) should also be considered solid contenders. Class-G Amplification Most readers will be broadly familiar with the concept of amplifier classes such as Class A, B, AB and D. Put very simply, a Class-A amplifier employs an output device (a valve or transistor) which conducts linearly on both the positive and negative halves of the audio signal. This approach has very low distortion, but is pretty inefficient and results in a lot of energy being wasted as heat. The Class-B topology improves the efficiency significantly, by using separate output devices to handle the positive and negative halves of the audio signal, but with the drawback that the transition from one side to the other results in ‘crossover distortion’. Class AB is a blend of these two ideas, biasing the output devices in such a way as to combine much of the Class-B efficiency while retaining the Class-A linearity, and this has been the dominant high-quality amplifier topology for decades. In recent years, however, Class-D amplifiers have become more popular, mainly because they offer very substantial efficiency gains compared to Class-AB designs. Instead of employing output devices to vary the output current linearly, Class-D amplifiers work by switching the output devices either fully on or off at an ultrasonic frequency, the on and off durations (or ‘pulse width’) being modulated by the audio signal. An output filter averages the resulting current pulses to reconstruct the audio signal and remove the ultrasonic switching artifacts. The idea is closely related to the sampling process in a digital converter, although there is 


no quantising stage involved, and it remains a completely analogue system. PSI’s approach in its range of active monitor speakers uses a less familiar amplifier topology called Class  G. This maintains the inherent linearity of the Class-AB approach while improving significantly on its efficiency. At its heart, the design employs a low-power Class-AB amplifier, operating on relatively low power-rail voltages, which does most of the work. However, the output-stage circuitry is supplemented with additional output devices connected to much higher-voltage power rails. Most of the time, only the low-power amplifier operates, and the additional output devices are turned off — thus improving efficiency. But when the required output signal amplitude exceeds the voltage range of the low-power stage, these additional high-voltage output devices are switched on to facilitate the required higher-voltage signal peaks. Controlling the switching of the high-voltage output devices is critical to avoid another form of ‘crossover distortion’, but when optimised this approach works extremely well, running virtually as cool as a Class-D design, but with the established audio quality and freedom from electromagnetic interference radiation artifacts of a traditional Class-AB amp. The output-stage biasing and switching is usually achieved with a number of diodes — far more than you would expect to find in a normal Class-AB amplifier — and these can be seen in the output stages of the amplifier chassis in the PSI monitors (see photo overleaf).

Published in SOS July 2011

 

All contents copyright © SOS Publications Group and/or its licensors, 1985-2012. All rights reserved. The contents of this article are subject to worldwide copyright protection and reproduction in whole or part, whether mechanical or electronic, is expressly forbidden without the prior written consent of the Publishers. Great care has been taken to ensure accuracy in the preparation of this article but neither Sound On Sound Limited nor the publishers can be held responsible for its contents. The views expressed are those of the contributors and not necessarily those of the publishers. Web site designed & maintained by PB Associates | SOS | Relative Media


A225-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

A225-M True Music has BASS.

Deep Bass.

PSI A225-M3,M4&M5 / typical characteristics subject to change without prior notice / Š RELEC SA.


Features Designed for stereo and multichannel monitoring. Phase and amplitude response compatible with all PSI Audio monitors. Built in anti-resonance system in a double box cabinet. Protection circuits with overload indicator. Magnetically shielded for use close to video monitors. Flat frequency response. Real balanced input with outputs for satellite systems.

A 225-M [dB]

SPL@1m A225-M

Acoustic SUM

Class G low temperature amplifier stage. Amplifier unit acoustically uncoupled from speaker cabinet. Orininal Technologies* : CPR, AOI, PSC.

Monitor with -10dB Roll Off

+10

0

Technical Data

-10

-20

-30

20

50

[Deg]

100

200

500

1k

2k

5k

10k

20k [Hz]

500

1k

2k

5k

10k

20k [Hz]

ACOUSTIC PHASE A225-M

+540 +450 +360 +270 +180 +90 0 -90 -180

20

50

100

200

[dB]

Max Continuous SPL 1m A225-M

130

120

110

Power RMS Program power Continuous Max SPL, 1m Program Max SPL, 1m Response at -6dB Tolerances Crossover frequency Woofer's dim. Ext. / Diaphragm Dimensions cabinet W x H x D mm Net Weight

200 W 300 W 111 dB (single) 116dB / half space 24 - 100 Hz ±2 dB (28Hz - 65Hz) 90Hz 2x Ø 258 mm / Ø 210 mm 320 x 700 x 500 38.4 Kg

100

16k

12k5

8k

10k

6k3

4k

5k

3k15

2k

2k5

1k6

1k

1k25

800

630

500

315

400

250

200

125

160

100

63

80

50

31

40

25

90

Further information: www.psiaudio.com

Description An exceptional piece of acoustic design, the A225-M sub-woofer/bass extension is equally suited to use as a mono sub-woofer in a surround sound application or as a bass extension in a stereo system. Designed to work in harmony with the A225-M Sub, all PSI Audio ‘A’ series speakers feature a frequency response roll-off function that, when combined with the A225-M Sub, extends the frequency range down to an incredible 24 Hz, whilst maintaining a flat response. The powerful class G outputs feature PSI Audio‘s unique “AOI” output stages, giving the A225-M an unprecedented impulse behavior. Each driver and amplifier unit is secured by a protection circuit, which is monitored by a red LED on the front panel. The electronics are housed in a unit mechanically isolated from the speaker cabinet to avoid resonance at high sound pressure levels. To provide stability and avoid cabinet resonance A225-M is built with a double-box design, combining two cabinets into a single beautifully finished unit.

Typical characteristics - all rights reserved. All data subject to change without prior notice.


A225-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

5.1 SYSTEM

STEREO SYSTEM LR

LEVEL CAL

LINK 1 IN 1 IN 2 LINK 2

LINK 1 IN 1 IN 2 LINK 2

Sub in

A225-M

-10dB ROLL OFF

INPUT 2

Other channels direct to monitors. Roll off at cal

LEVEL CAL

A225-M

-10dB ROLL OFF

*A O I : Adaptive Output Impedance system. *PSC : Phantom Standby Control (on M series). LEVEL

INPUT 1

1=Gnd 2=Hot 3=Cold

HP

CLASS G POWER

LIMITER

LP

PSC*

AOI*

TEMP. SENS Hi. ± 57V

115/220V

Low ± 18V

POWER LIMIT MAINS

FUSE

TRAFO

RECT.

STANDBY

REG.

Sym, 10k Ohms 0.775 V -116 dBA 24 Vpp 111 dB (single)

SPL@-10dBu/1m A225-M

Acoustic SUM

Monitor with -10dB Roll Off

+10

0

-10

-20

-30 20

50

500

200

100

[dB]

1k

2k

5k

10k

20k [Hz]

2k

5k

10k

20k [Hz]

10k

20k [Hz]

THD@-10dBu/1m A225-M

-20

116dB / half space -30

24 - 100 Hz -40

±2 dB (28Hz - 65Hz) -50

< 1.5% (50Hz-200Hz) -60 20

1 Way(s) 90Hz

50

[Deg]

500

200

100

1k

Monitor with -10dB Roll Off

ACOUSTIC PHASE A225-M

+540

2 x Ø 258 / Ø 210 mm

+450 +360

2 x XLR F / 2 x XLR M

+270 +180

1=GND, 2=(+), 3=(-)

+90 0

MDF / double box

-90 -180 20

50

500

200

100

1k

5k

2k

320 x 700 x 500

100

16k

12k5

8k

10k

6k3

4k

5k

3k15

2k

2k5

1k6

1k

PSI A225-M3,M4&M5 / typical characteristics subject to change without prior notice / © RELEC SA.

1k25

800

630

500

315

400

250

200

125

90 160

5 - 40 °C

110

80

< 75% / < 90%

120

100

1.7 - 4 - 200 W

Max Continuous SPL 1m A225-M

130

63

115/230V (50-60Hz)

[dB]

50

43.1 / 38.4 Kg

31

Poids brut / net Gross / Net Weight Tension de secteur Voltage Consommation Consumption Standby-Quiescent-Max Humidité Moy / Max Mean / Max Humidity Température externe External Temperature

[dB]

300 W

40

Système System Fréquence de coupure Crossover frequency Dim. basses Ext. / Membrane Woofer's dim. Ext. / Diaphragm Connecteurs Connectors Signal entrée Signal input Matériaux du boîtier Box Material Dimensions boîtier L x H x P mm Dimensions cabinet W x H x D mm

ON/OFF

200 W

25

Puissance RMS Power RMS Puissance programme Program power Impédance d'entrée Input Impedance Sensibilité pour 100 dB @ 1m Sensivity for 100 dB @ 1m Rapport signal sur Bruit Signal to Noise Ratio Saturation d'entrée Input Overload Niveau max. continu, 1m Continuous Max SPL, 1m Niveau max. programme, 1m Program Max SPL, 1m Réponse à -6 dB Response at -6dB Tolérances Tolerances Distorsions THD Distortion THD

EMI LP


A225-M

info@psiaudio.com www.psiaudio.com

SWISS MADE BY RELEC SA 1400 YVERDON

All dimensions are in mm

Mounting 260

60

Front

320

Bottom view

700

Front

350

Panel screwing area

Minimum well-aired space

60

80

60

70

500

Side view

Acoustical axis 160

350

160

350

Front view

Measurement environment: Large anechoical room Temperature 23±2°C Humidity 50±20% PSI A225-M3,M4&M5 / typical characteristics subject to change without prior notice / © RELEC SA.


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