Zaph Audio ZA5.2 DIY Kit Speaker Review

[Selah Audio]

Given the specs on the drivers, system impedance, series inductor losses, and baffle step compensation the 82dB sensitivity is reasonable. Commercial speakers of similar size / impedance / bass extension would be in the same range.

 

[Prana Ferox]

Thanks for building this one, Winkleswizard.

Regarding consistency, a DIY builder can of course completely do their own thing (or just screw up) but with these simple box 2-ways it's pretty easy to stick to the design, if that's the intent. At the risk of summoning our resident Spaniard, a lot of the variation can come from the internal treatment of the enclosure. In the build thread, WW shows a moderate amount of foam lining. Removing some of this may or may not give back some bass, along with other effects.

 

[napilopez]

Unfortunately, not true.

1. Olive's resonance studies show resonances as low as 28 dB down (barely a blip on a response curve) can be detectable. I try to target all my crossovers for at least that much rejection.

2. The driver resonances also show up as elevated distortion and this is not detectable in frequency response. You can roll off the resonance 1000 dB with an upstream low pass, won't matter because the distortion is generated in the driver after the filter.

@DDF could you point me to a specific paper or two? Trying to deepen my understanding of resonances.

 

[tktran303]

The only speaker I ever enjoyed listening in mono as a single unit in my Australian living room (30’ W x 20’ L x 12’ H) was a speaker that had a U shaped frequency response.

It was also 83 dB/2.83V sensitive, but had boosted bass between 100Hz down to 40Hz, and an upward tilt between 10-20Khz.

Kind of a “loudness” EQ boost to compensate for the low sensitivity, I suspect.

So after seeing this speakers’ frequency response- that Amir didn’t enjoy this speaker in his application; mono, big room... well that’s no surprise to me.

 

[DDF]

@DDF could you point me to a specific paper or two? Trying to deepen my understanding of resonances.

Sure thing, here's the best I've ever come across. Used it for many years to help set speaker design targets:
"The Modification of Timbre by Resonances: Perception and Measurement", Olive, Toole, JAES Vol 36, no 3, 1988
- shows how the ability to hear peaks is related to Q, and what signals best allow us to hear particular types of resonance;
- example: resonances delayed less than 1 ms are easier to hear using pink noise;
- in semi-reverberant fields, pink noise or transients work equally well in detecting resonances.
- etc!

 

[napilopez]

Sure thing, here's the best I've ever come across. Used it for many years to help set speaker design targets:
"The Modification of Timbre by Resonances: Perception and Measurement", Olive, Toole, JAES Vol 36, no 3, 1988
- shows how the ability to hear peaks is related to Q, and what signals best allow us to hear particular types of resonance;
- example: resonances delayed less than 1 ms are easier to hear using pink noise;
- in semi-reverberant fields, pink noise or transients work equally well in detecting resonances.
- etc!

Thank you! Toole's book refers to this paper heavily in the section on resonances but I'd not read the paper itself yet. As usual, looks like there are more insights to be gained.

 

[Juhazi]

John "Zaph" Krutke is one of the most pedantic diy speaker designers. He has retired from this hobby, sad to say.

http://www.zaphaudio.com/ZA5/

ZA5.x series of speakers share same nominally 5" midwoofer designed by the man himself and a nice Vifa tweeter without a waveguide. It is supposed to be an easy but exceptionally good entry level recipe/kit. Zaph used only 3dB baffle step compensation, because typical placement of this kind of small monitor is close to wall or on desk, which helps low bass remarkably.

The sensitivity of ZA5.2 can be read from on-axis response which is run with 2.86V - and is ~82dB

There are many other ZA5 models with multiple midwoofers for anyone wanting more spl capacity. Models with 4 woofers have 89dB sensitivity.
---
Philosophically, I think it is not wise to diy this kind of simple speaker. Labor time, tools and materials cost/benefit is huge

 

[Vuki]

I know that Amir put "conflict of interest" disclaimer in every harman product review, but nevertheless bashing this measurement-wise quite OK looking speaker doesn't seem appropriate in light of the revel f35 review:
Amir's conclusion:
"While in the "budget" portion of Revel line, and too low priced to be considered as "high-end" by the audio industry, the Revel F35 objectively and subjectively produces stellar performance. A bit of low frequency EQ is all it took for it to sound good without any fiddling with location, toe-in, room treatment, etc, etc. "

Maybe with a bit of EQ Zaph could also produce stellar performance?

 

[tuga]

Sure thing, here's the best I've ever come across. Used it for many years to help set speaker design targets:
"The Modification of Timbre by Resonances: Perception and Measurement", Olive, Toole, JAES Vol 36, no 3, 1988
- shows how the ability to hear peaks is related to Q, and what signals best allow us to hear particular types of resonance;
- example: resonances delayed less than 1 ms are easier to hear using pink noise;
- in semi-reverberant fields, pink noise or transients work equally well in detecting resonances.
- etc!

What have you done?

Now people will start thinking that perhaps there's more to speaker performance than just frequency response curves...

 

[Dogmeat88]

As far as I remember, Zaph audio specify this kits mostly for home theater use, with subwoofer support. Then design choices become more clear.
It is great that Amir was able to review Zaph kit. If someone could send Zaph SR71 and Zaph ZRT to Amir for a review, it would be great too

 

[maty]

...Zaph used only 3dB baffle step compensation, because typical placement of this kind of small monitor is close to wall or on desk, which helps low bass remarkably...

That is the key. To listen at moderate volume.

The manufacturer graph is explicit:

Therefore no surprise.

 

[thewas]

The only speaker I ever enjoyed listening in mono as a single unit in my Australian living room (30’ W x 20’ L x 12’ H) was a speaker that had a U shaped frequency response.

It was also 83 dB/2.83V sensitive, but had boosted bass between 100Hz down to 40Hz, and an upward tilt between 10-20Khz.

Kind of a “loudness” EQ boost to compensate for the low sensitivity, I suspect.

So after seeing this speakers’ frequency response- that Amir didn’t enjoy this speaker in his application; mono, big room... well that’s no surprise to me.

Thank you for the confirmation, as I had written also in another thread, when listening to a single loudspeaker vs. a pair, you have less bass due to the addition of 2 loudspeakers which tends to close to 6dB in bass region (coherent signals) vs. the rest of the frequency spectrum were the addition tends to rather 3dB (non coherent signals), so a loudspeaker with a bass boost like the M16 will sound closer to what we are used from a neutral stereo pair.

 

[tuga]

Thank you for the confirmation, as I had written also in another thread, when listening to a single loudspeaker vs. a pair, you have less bass due to the addition of 2 loudspeakers which tends to close to 6dB in bass region (coherent signals) vs. the rest of the frequency spectrum were the addition tends to rather 3dB (non coherent signals), so a loudspeaker with a bass boost like the M16 will sound closer to what we are used from a neutral stereo pair.

That's a really good argument for the need to use a pair of loudspeakers when assessing preference.
Using just one speaker for that purpose is absurd.

 

[thewas]

That's a really good argument for the need to use a pair of loudspeakers when assessing preference.
Using just one speaker for that purpose is absurd.

Or at least it should be compensated with a bass boost or highly crossed sub or even better with bass EQed to the same target curve at the LP.

 

[MZKM]

I don't sweep beyond 20 kHz where these resonances often show.

John Atkinson measures up to 30kHz I believe, that way IMD can appear in the audible range if you play high-res/vinyl and if the tweeters don’t like ultra-sonics. Thoughts?

 

[QMuse]

Unfortunately, not true.

1. Olive's resonance studies show resonances as low as 28 dB down (barely a blip on a response curve) can be detectable. I try to target all my crossovers for at least that much rejection.

2. The driver resonances also show up as elevated distortion and this is not detectable in frequency response. You can roll off the resonance 1000 dB with an upstream low pass, won't matter because the distortion is generated in the driver after the filter.

Read this post Toole wrote on another forum:

Resonances originate in transducers, in mechanical resonances in enclosures, and in acoustical resonances in enclosures. They all exhibit themselves in anechoic measurements and if they are energetic enough we hear them. This 29 year old paper explains it all in great detail:
Toole, F.E. and Olive, S.E. (1988). “The modification of timbre by resonances: perception and measurement”, J. Audio Eng. Soc., 36, pp. 122-142.

Putting an accelerometer on the wall of a cabinet is not a reliable indicator of the audibility of a resonance (sorry John Atkinson). For example, some panel resonances radiate sound effectively and others do not, but both exhibit vibration at a point on the panel. Harman and other advanced designers use scanning laser vibrometers to reveal patterns, polarity and amplitude of panel movement which guides the placement of structural reinforcements to reduce acoustical radiation from the resonance. When it is below the audible threshold in the anechoic frequency responses all is well (see the paper, or my books). It is not necessary to have foot thick concrete enclosures to eliminate audible resonances, good engineering can do it in rectangular wooden boxes.

 

[QMuse]

John Atkinson measures up to 30kHz I believe, that way IMD can appear in the audible range if you play high-res/vinyl and if the tweeters don’t like ultra-sonics. Thoughts?

I'm not sure there is enough energy in the 20-30kHz range to provoke any kind of audible IMD issue.

 

[tuga]

A resonance decays slower than the rest of the spectrum.
Even if it only produces a blip in the frequency response, it may be audible because it will continue to "ring" for a short while.
And mid-range/mid-woofer driver break up resonances generally happen in the range where the ear is most sensitive (1.5 to 5kHz / violin and listener fatigue territory).

https://www.stereophile.com/content/bw-john-bowers-silver-signature-loudspeaker-measurements

 

[edechamps]

I explained that in the intro to the review. I used to use 0.7 Hz resolution. I moved it up a few notches to 2.7 Hz. Sean Olive's research relies on frequency resolution of 2 Hz so this is a close fit. I compared the graphs between two runs (0.7 versus 2.7) and other than down in 20 to 40 Hz, there is not much difference. There is dramatic reduction in file size and good bit of reduction in test time so I like to stick with the new standard.

Thanks, that makes sense. I should have read the review more closely

 

[edechamps]

Olive's resonance studies show resonances as low as 28 dB down (barely a blip on a response curve) can be detectable. I try to target all my crossovers for at least that much rejection.

If I remember the study correctly, resonances this low in amplitude are only audible if they also have very low Q (e.g. Q=0.1). That makes them more than a "blip" on the response curve. The extreme case is a spectral tilt, which we can easily detect even if the slope is very small, but it's also quite visible on a frequency response graph too.

Also note that the study was only about detection thresholds, not preference. The impact of low-Q, low-amplitude (i.e. "broad trends" in frequency response) on preference is controversial.