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Zaph Audio ZA5.2 DIY Kit Speaker Review

amirm

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This is a review and detailed measurements of the Zaph Audio ZA5.2 2-way ported stand-mount speaker. It was kindly built and sent to me by member @Winkleswizard. This is what he has post on the cost: "A kit for pair of ZA5.2 MTs is about $292 (with binding posts) and pair of cabinets would be about $50 (from PE). So, assuming free shipping to me, the total cost is about $342."

The build for the unit I received was quite substantial:

Zaph Audio ZA5 DIY Speaker Kit Audio Review.jpg

Clever use of textured paint to give something extra to an otherwise bland sides. That said, it cannot compete in looks with either vinyl wraps or painted enclosure from commercial suppliers.

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 anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

All measurements are reference to tweeter axis with the grill removed. Frequency resolution is 2.7 Hz. Previous tests used 0.7 Hz resolution which hugely inflated the storage requirements and was well beyond what research calls for. I scanned at 0.7 Hz as well and difference was negligible so I will be going with this resolution from here on.

All measurements are relative to tweeter center.

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

Zaph Audio ZA5 DIY Speaker Kit CEA-2034 spinorama Audio Measurements.png


I must say, I was impressed with how flat the response is on-axis (red arrow). The dips in mid frequency though don't track the same way in early window (dashed blue) so causes the directivity index (dashed blue at the bottom) to vary. This is usually due to mismatch of the directivity of the woofer and tweeter.

Note the very low sensitivity. You better have lots of wattage to drive these little speakers.

Predicted in-room response is somewhat ragged and depending on how you draw the line through it, may have too little slope (i.e. sound bright):
Zaph Audio ZA5 DIY Speaker Kit CEA-2034 spinorama Predicted In-Room Response Audio Measurements.png


Impedance is higher than many mass market speakers:

Zaph Audio ZA5 DIY Speaker Kit impedance.png


Distortion seems to show the struggle of the little midwoofer driver trying to produce bass:

Zaph Audio ZA5 DIY Speaker Kit distortion.png


Here is the waterfall:

Zaph Audio ZA5 DIY Speaker Kit CSD Waterfall.png


And contours:

Zaph Audio ZA5 DIY Speaker Kit Horizontal contour.png


Zaph Audio ZA5 DIY Speaker Kit Vertical contour.png


Speaker Listening Tests
In use the ZA5 in my main system sounded quite bright. This was not due to tilted up highs but lack of any bass to speak of. There isn't lower bass. There isn't midbass. As predicted from measurements, efficiency is quite poor causing me to turn up my amplifier to very high amplification levels (1000 watts on tap) to drive them. Before you got any bass the highs were killing you and the midwoofer would start to bottom out. On the latter though, it took a ton of power before it mildly stepped into that region.

With one speaker and in a very large space, these speakers don't do it for me subjectively.

Conclusions
On-axis performance is surprisingly good as is craftsmanship of @Winkleswizard. Ultimately though, there is just no bass response and with it, music is not music. For a few hundred dollars you want to have bass. I know you can add a sub but that limits the audience a ton.

So personally I don't think we have shown the DIY route has merit with this sample, sad to say.

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

With the stock market crashing, I am not feeling like I have any assets left. Could use some money to change my mood. So please donate using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

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beefkabob

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Do one of these tests show how, as volume increases, the frequency response changes?
 

MZKM

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Cahudson42

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one of these tests show how, as volume increases, the frequency response changes?
This is a question I have had with all of the spinoramas. By fixing at 2.83v, any SPL differences due to efficiency would seem to invalidate speaker to speaker comparisons.

Can a more knowledgeable member explain (or point to URL explanation) why the test input should not all be normalized at a specific SPL and distance (depending on near-field or full room) rather than a fixed 2.83v where SPL can vary all over the place depending on efficiency?
 

hardisj

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Do one of these tests show how, as volume increases, the frequency response changes?

No. You'd need to do compression testing for that.

Edit: If Amir provided the 10v distortion testing as fundamental vs n-th order then maybe you could glean that information but even then, I don't believe he's nailed down his testing methods to where you could even make a direct apples vs apples comparison there, either. Besides that, I wouldn't expect the SPL to change appreciably with a simple sine sweep. To see how the linear response varies wrt SPL you'd need to do compression testing. Klippel has a module for that (DIS module is one). I have that. If you guys want Amir to provide that (and assuming he even wants to get in to that additional testing), ya'll are gonna have to chip in and help fund it I imagine because list price for the non-Pro version is 3300 Euro.
 
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MZKM

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Can a more knowledgeable member explain (or point to URL explanation) why the test input should not all be normalized at a specific SPL and distance (depending on near-field or full room) rather than a fixed 2.83v where SPL can vary all over the place depending on efficiency?
SoundStage/NRC does a linearity/compression test, usually from 76dB to 96dB if memory serves, it usually shows less than 1dB of difference, usually no more than 2dB.

Also, it saves Amir time, even if a bit. Once these measurements become more spaced out, maybe he'll have time.
 

DDF

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Speaker Listening Tests
In use the ZA5 in my main system sounded quite bright. This was not due to tilted up highs but lack of any bass to speak of.

It will also be due to the tweeter integration, where flat on axis was achieved without due consideration for the off axis 2-5 kHz tweeter bloom. Pretty standard for allot of DIY designs especially from that era.
 

hardisj

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Hard pass based on the sensitivity alone. Though, if I were listening somewhat nearfield and/or had a baby in the next room then the FR looks decent enough. The THD is pretty abysmal, though, but again, low sensitivity and 5" midwoofer doesn't exactly exude "crank it to max, baby!". I'm assuming baffle step compensation is what knocked this guy down in to the low mid-80's?
 
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amirm

amirm

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This is a question I have had with all of the spinoramas. By fixing at 2.83v, any SPL differences due to efficiency would seem to invalidate speaker to speaker comparisons.
It is a requirement in the standard that all passive speakers be tested with 2.83 volts input. It is assumed that this is low enough power for distortion to not play a role (or compression). I have done some level tests in the past and you would be hard pressed to change the frequency response in any meaningful way.
 

Cahudson42

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SoundStage/NRC does a linearity/compression test, usually from 76dB to 96dB if memory serves, it usually shows less than 1dB of difference, usually no more than 2dB.
Thanks! Does this also apply to additional effects such as resonances? Case in point - the 'terrible' B652. I don't run these at 86db. More like 70-75. The cabinet doesn't shake. The woofer doesn't flap in the wind. Sounds tolerable...

So while basic fr may not vary over a 76-96 SPL range, can the same be assumed for resonance and room effects?

Would there be any disadvange to normalize the Spinorama to a specific SPL/distance, other than difficulty?
 

ta240

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These are all about the experience of the build. Perhaps a father and son/daughter project. Is this Zaph Audio ZA5 actually the Zaph Audio ZA5.2 model or is this ZA5 a older model?

http://zaphaudio.com/ZA5/
https://www.madisoundspeakerstore.com/2-way-speaker-kits/zaph|audio-za5.2-tm-2-way-pair/

I was under the impression that those are the same. Isn't the ZA5.2 is just a version of the ZA5. The description for the ZA5.2 on the madisound site links to the ZA5 section on the zaph audio site. And the ZA5 page at zaph audio mentions the 5.2 in multiples places
ZA5.2 - TM vented 2-way
ZA5.2s - TM sealed 2-way
ZA5.2iw - 2-way in-wall system

I'd love to see the SR71 tested, that has been on my bucket build list for awhile.
 

MZKM

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Thanks! Does this also apply to additional effects such as resonances? Case in point - the 'terrible' B652. I don't run these at 86db. More like 70-75. The cabinet doesn't shake. The woofer doesn't flap in the wind. Sounds tolerable...

So while basic fr may not vary over a 76-96 SPL range, can the same be assumed for resonance and room effects?

Would there be any disadvange to normalize the Spinorama to a specific SPL/distance, other than difficulty?
I don’t see how room effects play a role. As for resonances, that would show up in the FR response.
Here are all the SoundStage/NRC measurements where you can compare linearity.
 

Rick Sykora

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Thanks @amirm for the compliments and the testing. I will add some color from my experience with these speakers. Bear in mind, am the builder and not the designer (that would be John Krutke).
  1. Originally did not intend to finish them at all. What you see is a (mediocre IMO) protective (first coat) of Duratex paint. It will be sanded down and recoated for a better finish.
  2. I have used them with and without a subwoofer. Without the subwoofer and in a small room, I find the bass quite sufficient, but as Amir pointed out, it is small woofer. The designer’s site is pretty clear about the need for a subwoofer.
  3. Am a bit surprised by the low sensitivity as do not use very high power amps and have not had any obvious issues driving them to high levels. The impedance chart indicates they are built to spec so am a bit baffled.
 
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Cahudson42

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As for resonances, that would show up in the FR response.
Would for that to not make a difference, would not the resonance effects need to be linear/proportional with fr/SPL. ? Would seem reasonable to verify that is indeed the case.. Has it? (sorry to beat a dead horse...last comment/sidetracting)

Resonances are interesting things - witness Tacoma Narrows...
 

MZKM

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Would for that to not make a difference, would not the resonance effects need to be linear/proportional with fr/SPL. ? Would seem reasonable to verify that is indeed the case.. Has it? (sorry to beat a dead horse...last comment/sidetracting)

Resonances are interesting things - witness Tacoma Narrows...
Resonances have to appear in the frequency response curves, or else they are so low level that it’s not important.
 
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