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PSB Alpha P5 Speaker Review

amirm

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This is a review and detailed measurements of the PSB Alpha, 2-way budget speaker. I purchased it a couple of months ago from Amazon. Cost is US $349 there including Prime shipping.

If you are not familiar with PSB, those are initials of Paul Barton. Paul worked under/with Dr. Folyd Toole while at Canadian NRC so calls from same set of research as Harman folks. The speaker in question won streophile product of the year award in 2019.

It is hard to stand out in the crowded market of budget 2-way speakers but PSB makes an attempt with upside down configuration (tweeter on the bottom) and slick magnetic grill (not shown):

PSB P5 Bookshelf 2-way speaker Stereo Review.jpg


Back panel is ordinary sans a screw for rear mount (which then makes you wonder about the rear port):

PSB P5 Bookshelf 2-way speaker Back Panel binding post Stereo Review.jpg


Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I used over 800 measurement point which was not quiet enough to compute the sound field of the speaker within 1% (it slipped to a bit more than that in higher frequencies but still not significant). Measurement axis is the tweeter center.

Temperature was 80 degrees. Measurement location is at sea level so you compute the pressure.

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.

Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

PSB P5 Bookshelf 2-way speaker  Spinorama CTA-2034 Frequency Response Measurement.png


Oh no! This can't be right. On-axis response is quite uneven and directivity error very apparent -- against two of the key findings of Dr. Toole while at NRC and later at Harman. Fortunately we have stereophile magazine review of the same:

919PSBA5fig3.jpg


The black curve is basically what we have. The resolution of stereophile graphs are very low so is not as clear as my measurements but otherwise, it is very close.

What a shame.

Going along, naturally off-axis response is poor as well:

PSB P5 Bookshelf 2-way speaker  Spinorama CTA-2034 Early Window Frequency Response Measurement.png


Usually I say put a rug on the floor but here, the dip in vertical direction is helping pull that bump from on-axis response.

Putting the two together we get a mystery:

PSB P5 Bookshelf 2-way speaker  Spinorama CTA-2034 Predicted In-room Frequency Response Measur...png


A number of you have advocated to only post measurements in these reviews. This is for you: what does this say about the sound you get in your room? I bet you can't tell other than bass boost. There is just so much wrong with that response.

Digging into what may be going on with close in measurements of each component in the speaker we get:

PSB P5 Bookshelf 2-way speaker Driver and Port Measurement.png


Look at what is coming out of the rear port (orange). That peak is so high that it pushes the on-axis response up with it.

Impedance graph points to some of the same resonances:

PSB P5 Bookshelf 2-way speaker Impedance and phase Measurement.png


As does the waterfall graph: (anechoic)

PSB P5 Bookshelf 2-way speaker CSD waterfall Measurement.png


Speaker Distortion Measurements
As usual, we start with the distortion measurements using our Klippel KA3 analyzer at 86 and 96 dB SPL @ 1 meter to see trends:

PSB P5 Bookshelf 2-way speaker Relative Distortion Measurement.png


[head hits the table.] What we see at 86 dB SPL is what I expect to see at 96 dB SPL! This woofer/port are going nuts.

Here is the same at absolute level (anechoic as above):

PSB P5 Bookshelf 2-way speaker Distortion Measurement.png


You better like all your bass and midrange with good bit of distortion!

Switching audio analyzers, we get this for 32-tone resembling "music:"

PSB P5 Bookshelf 2-way speaker Multitone Distortion Measurement.png


There is so much distortion that made me spell "up to" wrong. :)

Here is our amplitude compression test:

PSB P5 Bookshelf 2-way speaker Amplitudue Compression Measurement.png


PSB P5 Bookshelf 2-way speaker 100 Hz FFT Distortion Measurement.png


Speaker Directivity Measurements
Here is our beamwidth in horizontal axis (ideal response would be all horizontal lines):

PSB P5 Bookshelf 2-way speaker beamwidth Measurement.png


We get the typical ± 50 degree beamwidth. The width becomes wider in crossover region due to mismatch between woofer's beam width and tweeter's (3 kHz).

In 3-D we see:

PSB P5 Bookshelf 2-way speaker Horizontal Directivity Measurement.png


And vertically:

PSB P5 Bookshelf 2-way speaker Vertical Directivity Measurement.png


Good thing the tweeter is at the bottom because you want to keep your ears at a positive angle to it.

Subjective Listening Tests
First 5 second impression was: "oh, there is bass there." Not deep bass mind you, but bass impression. From then on, I am kind of lost for words to describe the tonality. Female vocals sounded too warm and did not have their delicate higher pitch sound. Male vocals were somehow a bit lost in the music. OK, I am making stuff up now. I went into this part of the test being unhappy, and walked out unhappy.

I tried to EQ some of the faults but did not get far. Getting rid of response below 30 Hz helps with distortion as usual. Fixing resonances seemed to do some good but tonality would change too. So I gave up.

Testing for ability to play deep bass was a fail when playing this track from Burak Malçok's album: Sakli Nefes, Toz Ruhu


The very low frequency bass is almost inaudible but it easily caused the P5 woofer to bottom out. I swapped out the P5 for Revel M16 and it too struggles with this track but played at probably 2X the level (still insufficient).

Conclusions
I tell you, this is a depressing day. I run into Paul at shows and we always talk about his time at NRC, etc. As I have noted all along, nothing about this speaker follows said research. Price pressure must have been way too high and severe compromises made. As a statement of where the press is, John Atkinson after talking about all the flaws in the measurements of the P5, finishes with:

1596760709650.png


Was reality suspended when John got to the conclusion section? How can this be an excellent response with variations in on-axis response, resonances, port noise/resonance, etc., all of which were observed by JA?

But no, while Paul I am sure capable of excellent design, the Alpha P5 is definitely not an example of such.

Let's hope we get one of the higher end models of PSB to test soon, lest this poor impression sticks in our mind forever about the brand. :(

-----------
As always, questions, comments, recommendations, etc. are welcome.

I am too depressed in the way this speaker review came out. So please excuse me if I can't come up with anything cute to beg for money. I hope you donate anyway using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

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MZKM

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Fortunately we have stereophile magazine review of the same:

919PSBA5fig3.jpg


The black curve is basically what we have. The resolution of stereophile graphs are very low so is not as clear as my measurements but otherwise, it is very close.

What a shame.
Granted, he got a response that is basically flat from 800Hz-19kHz, sans the 4kHz notch; this is not what we have here.

__________
Impedance graph points to some of the same resonances:

index.php
They state it is 8ohm nominal and 4ohm minimum. I would for sure call this a a 6ohm nominal speaker.
 
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Webninja

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I had high hopes for PSB, as the alpha’s were my first speakers. Maybe the other PSB’s will have better measurements.

Thanks @amirm for both the measurements and your observations. I’ve learned more from your reviews than decades of what I thought was thorough magazine articles.
 

Vini darko

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MZKM

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The more of these preference scores I see the less sense they make.
Ranks similar to the Klipsch RP-600M, also headless, though the Q Acoustics 3020i also is a 4 but didn't get headless, but with a sub score but it a good deal higher than this and the Klipsch.
 

Blumlein 88

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The more of these preference scores I see the less sense they make.
Yes, just eye balling the spin data I would never have guessed a score so high. Not that it is high, but it is higher than I thought it would get by a good bit. Maybe the score thing is just a bad idea.
 

MZKM

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Granted, he got a response that is basically flat from 800Hz-19kHz, sans the 4kHz notch; this is not what we have here.

__________

They state it is 8ohm nominal and 4ohm minimum. I would for sure call this a a 6ohm nominal speaker.
Here is my attempt to do the same +/- 30-degree response Stereophile uses, at 300Hz and up:
chart (84).png
 

MZKM

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Yes, just eye balling the spin data I would never have guessed a score so high. Not that it is high, but it is higher than I thought it would get by a good bit. Maybe the score thing is just a bad idea.
Look at the Early Reflections & PIR, besides the boost at 800Hz, it's pretty smooth in my graph.
 

LDKTA

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Woah... This is not what I expected at all. I must say, it does match up with my subjective listening impression of these loudspeakers though. I found them to sound absolutely terrible.
 

Matias

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Isn't it just the scale of the scoring with sub that needs interpretation? Like "above 8 is really good, close to 6 is really bad"?
 

Matias

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Same response times three. I hope Paul wasn't in the NRC chamber when they measured it:

Yet his initials are on the end product. If I were him I would double check every design.
 
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MZKM

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Isn't it just the scale of the scoring with sub that needs interpretation? Like "above 8 is really good, close to 6 is really bad"?
If thinking out of 10 and traditional US school grades, a 6/10 is just shy of failing. So yeah, I wouldn’t get anything less than a 7/10 (though, as I learned at university, a C- is passing but isn’t enough to advance, so one has to retake the course and get at least a C).
 

Haint

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Amirm, since this appears to be one of the worst examples of distortion across the board, was it something that especially stood out in your listening test?
 

MZKM

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Same response times three. I hope Paul wasn't in the NRC chamber when they measured it:

View attachment 76982
They even report a lower sensitivity than I do (they use “listening window”: +/-15° H & V), but even at 0° you can clearly see it’s not 87dB as stated, and since he uses their chamber, it is very odd that he chose to report 87dB.

From their documents:
“The P5 was perfectly tuned inside the anechoic chamber of Canada’s acoustic research facilities to produce a perfectly flat frequency response that lets you enjoy the subtleties of your music and movies with lifelike detail.”
 
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