PSI A21-M Monitor Review

[dfuller]

This boost at 1KHz is unusual, perharps an on-axis measurement on the specified acoustic center would be fair, since it's where they use to calibrate it. View attachment 517380

I agree. @amirm no chance you could have it recalculate with the design axis? It shouldn't need a second set of measurements if I understand how the NFS works...

 

[Exprymer]

The tweeter is performing absurdly well. Knowing that this thing is hand-made makes it even more impressive.

EDIT: KH150 as a comparison

 

[pierre]

This boost at 1KHz is unusual, perharps an on-axis measurement on the specified acoustic center would be fair, since it's where they use to calibrate it. View attachment 517380

Looking at the vertical contour https://www.spinorama.org/speakers/PSI Audio A21-M/ASR/asr/SPL Vertical Contour.html measurements are perfectly centered (or the NSF correct for it).

 

[Exprymer]

Looking at the vertical contour https://www.spinorama.org/speakers/PSI Audio A21-M/ASR/asr/SPL Vertical Contour.html measurements are perfectly centered (or the NSF correct for it).

The NFS uses a geometric reference for applying the spherical harmonics decomposition, so it may affect the whole spinorama indeed. However, since the vertical directivity is normally narrow near the crossover region, having the on-axis out of the place in which the product was calibrated is not optimal. Anyway, I hope Amir still have the time to share this with us, before moving to another sample.

 

[Tovarich007]

View attachment 517405

The tweeter is performing absurdly well. Knowing that this thing is hand-made makes it even more impressive.

EDIT: KH150 as a comparison
View attachment 517406

Why a hand-made tweeter should be less performing than one made by a modern automatic machine controlled digitally ? More tolerances dispersion ?

Of course, the equivalent Genelecs or Neumann have better measured performance, but the PSI measurements are good, though not extraordinary, and their sound is absolutely excellent.
I like also very much the Gens I have listened to. The Neumanns, for the moment i haven't yet listened to any model in good listening conditions, but I'm pretty sure they're superb sounding too.

It's in the end a question of taste, choice of model and of acoustics in the listening room. If I had the money, it would be a very tough choice for me between these 3 brands.

But I have to say I'm attracted by the simplicity and the tradition in the PSIs external and internal design. Analog filters and linear amps well done are not dead yet, this test, objective and subjective, is another proof.

 

[dfuller]

Why a hand-made tweeter should be less performing than one made by a modern automatic machine controlled digitally ? More tolerances dispersion ?

Humans are, as a general rule, less precise than machinery.

 

[LuckyNat]

It came out last year I think.

In terms of the model (disregarding any changes on the inside over the decades), it is 20 years ..

PSI A21-M was released in 2006.

The amps are not Class A/B but instead Class-G (not a commonly used topology - not sure Id know it existed if PSi Audio didn't use it and Id not read a review 15 years ago or so ..).

Part of the reason for being analogue may be due to some of the technologies they've been using all this time, e.g. Adaptive Output Impedance on their amps (an active driver damping system) and their phase correction system (using some form of all-pass analogue filters), which may well require the feedback to incorporate the crossovers themselves and therefore be analogue crossovers.

Apparently, the Adaptive Output Impedance circuitry and it's feedback from the driver, is sensitive enough to detect when the soundwaves from another speaker in the room is impacting on the movement of the driver cone (and presumably compensate for that?) . That's probably where the active bass trap technology came from..

Anyway, PSI Audio is definitely mostly known for their monitors in the studio/professional world .. but perhaps audiophiles may only know their room treatment products?

I believe all of their drivers are made in-house too - must add a lot to the cost.

 

[Exprymer]

Why a hand-made tweeter should be less performing than one made by a modern automatic machine controlled digitally ? More tolerances dispersion ?

Yes, Sr. In such a low weight membrane, the amount of glue must be very precise across the surroundings of the membrane, otherwise the stiffness is not homogeneous across the driver suspension. This would result in higher distortion and umbalanced response and directivity. Another factor is the glueing process of the voice coil in it, that when not positioned precisely, already unbalance the motor and can cause rocking modes and Rub & Buzz.

Other fact is the precision of the centralization of the membrane and coil to the motor, that when not done properly, also usually increase the harmonic distortion. It's safe to say that doing this by hand is not easy at all and likely requires several tries to get it done.

 

[MZKM]

Preference Rating
SCORE: 6.2
SCORE w/sub: 7.8

Frequency response: ±2.6dB 44Hz-20kHz

 

[YSC]

The FR and estimated in room looks like a 8030C with much deeper bass and a much more artistic and premium speaker (with the relevant price tag attached)

 

[Tovarich007]

I

Anyway, PSI Audio is definitely mostly known for their monitors in the studio/professional world .. but perhaps audiophiles may only know their room treatment products?

I believe all of their drivers are made in-house too - must add a lot to the cost.

In Europe, the pro oriented audiophiles who value accuracy (like me) know PSI for their monitors. Their room tretament products are not so well known and a bit heterodox in design, but efficient it seems.
Once again, it seems that brand images are different from each side of the Atlantic ocean.
And yes, their drivers are made in house.

 

[Tovarich007]

Yes, Sr. In such a low weight membrane, the amount of glue must be very precise across the surroundings of the membrane, otherwise the stiffness is not homogeneous across the driver suspension. This would result in higher distortion and umbalanced response and directivity. Another factor is the glueing process of the voice coil in it, that when not positioned precisely, already unbalance the motor and can cause rocking modes and Rub & Buzz.

Other fact is the precision of the centralization of the membrane and coil to the motor, that when not done properly, also usually increase the harmonic distortion. It's safe to say that doing this by hand is not easy at all and likely requires several tries to get it done.

Tthanks a lot for this very precise and quick answer.

 

[rebbiputzmaker]

I voted great, measurements are super nice regardless of price, which we all agree is not a good value.

I thought the bass has audible distortion, even at low levels. Is that a good thing for $6000 speakers?

 

[Exprymer]

I thought the bass has audible distortion, even at low levels. Is that a good thing for $6000 speakers?

This claim is indeed curious, given that the bass performance in the THD graphs is not deviant from other samples reviewed here.

 

[eddantes]

those visible screws - meh - not for 3K - should be smooth

 

[goat76]

those visible screws - meh - not for 3K - should be smooth

In a studio monitor, you want it to be easy to swap out a faulty driver.

 

[pierre]

The NFS uses a geometric reference for applying the spherical harmonics decomposition, so it may affect the whole spinorama indeed. However, since the vertical directivity is normally narrow near the crossover region, having the on-axis out of the place in which the product was calibrated is not optimal. Anyway, I hope Amir still have the time to share this with us, before moving to another sample.

Usually when the measurement is not taken facing the acoustic axis you see it in the contour plot that show some asymmetry.

Here the 0 degree angle is aligned with the acoustic axis. At 2kHz where the pinch is the most severe, the 0 is clearly in the middle. If the microphone had an offset you would see it on this contour plot.

Does that sounds reasonable?

 

[JustJones]

The amps are not Class A/B but instead Class-G (not a commonly used topology - not sure Id know it existed if PSi Audio didn't use it and Id not read a review 15 years ago or so ..).

According to PSI site the A21-M and smaller use A/B amplifiers

• Power: 280 + 45 W
• Frequency Range: 44Hz – 23kHz
• Peak max. SPL@1m: 115 dB
• Typical listening distance: 0.7 to 2 m
• 100% Analog – No DSP
• Flat Frequency response
• Perfect stereo image
• Handmade tweeter
• Class A/B amplifiers
• Individually calibrated
• 5+1 years warranty
• Handmade in Switzerland

The larger A23-M, A25-M and their main monitors use the class G and H amplifiers.

 

[xanalog]

Thank you for the review, @amirm,

I can hear mild hiss with my ear next to tweeter.

Have you ever preformed and/or been tempted to disassemble such an active speaker, and give its power-amp a stand alone shake down?

Yes, that is a new optimized waterfall graph to make it easier to see what is going on.

Thank you #2.

 

[amirm]

Have you ever preformed and/or been tempted to disassemble such an active speaker, and give its power-amp a stand alone shake down?

I have. Alas, it is often hard to get into the guts of the speaker. I have done this when the amp is separate.