Buckeye 3 Channel Purifi Amp Review

[musicforcities]

There appears to be several or more peeps looking for a class D amp with big VU meters. A common request although finding suitable big VU meters is apparently not so easy.

It’s like piping motor sounds through the stereo of electric cards …comfort eye candy. But yeah, they need to be nice ones which are rare. The old luxman ones were gorgeous. No blue leds allowed either.

 

[Audiomn]

View attachment 260240

Cool stuff guys, but please start a new thread.

 

[Buckeye Amps]

Enough people have actually made this comment over the last year that they would be interested in VU meters that I feel I should give an official answer: I myself do not plan on offering them as an add on option.

However, I do work very closely with @Rick Sykora who does custom work/builds. If anyone was seriously considering one of my amps but is holding out for VU meter integration (or another such visual modification along those lines), there is no harm sending him a message to get his thoughts, etc.

 

[Sokel]

There appears to be several or more peeps looking for a class D amp with big VU meters. A common request although finding suitable big VU meters is apparently not so easy.

I have try HARD to find the source of the Audio Research meters but no success
(no more OT,I promise!)

 

[Rick Sykora]

Enough people have actually made this comment over the last year that they would be interested in VU meters that I feel I should give an official answer: I myself do not plan on offering them as an add on option.

However, I do work very closely with @Rick Sykora who does custom work/builds. If anyone was seriously considering one of my amps but is holding out for VU meter integration (or another such visual modification along those lines), there is no harm sending him a message to get his thoughts, etc.

While somewhat OT, good VU analog meters are simply hard to find. The last ones I used were plastic and needed a custom glass bezel to protect them. I looked again today and no real change. With supply chain issues, they are seemingly not a priority. Many legacy products that have VU meters are often too expensive to consider retrofitting with new amplification.

As for more on topic news, as @Buckeye Amps reported, the distortion rise is reproducible by those closest to the situation. The challenge has been validating potential remediation as the designer has had test equipment issues. As many know, supply chain issues have hampered test equipment availability too. The designer has had to consider alternative test equipment and, along with personal priorities, progress has been slower than expected. He is pursuing multiple potential solutions and expects to have resolved very soon. Stay tuned and will update as soon as we can!

 

[AdamG247]

While somewhat OT, good VU analog meters are simply hard to find. The last ones I used were plastic and needed a custom glass bezel to protect them. I looked again today and no real change. With supply chain issues, they are seemingly not a priority. Many legacy products that have VU meters are often too expensive to consider retrofitting with new amplification.

As for more on topic news, as @Buckeye Amps reported, the distortion rise is reproducible by those closest to the situation. The challenge has been validating potential remediation as the designer has had test equipment issues. As many know, supply chain issues have hampered test equipment availability too. The designer has had to consider alternative test equipment and, along with personal priorities, progress has been slower than expected. He is pursuing multiple potential solutions and expects to have resolved very soon. Stay tuned and will update as soon as we can!

And with that, let’s get back on topic. This is an Official Review Thread and we try to keep the conversation on topic. Please start a new thread to further discuss VU meters. Please and thank you for your understanding and support.

 

[Fuzzy]

I bought the 2 channel version of this Purifi amp from Dylan at Buckeye last year and received it in September. So I have been following this thread with interest and doing my best to understand the issue. I am using the Buckeye amp with a direct XLR feed from a RME ADI-2 dac. The dac is connected by usb from a Intel NUC running JRiver. Speakers are Ohm Walsh 3 with replacement drivers. The Buckeye amp took the place of a venerable Adcom amp. I have been using the low gain setting on the Buckeye Purifi amp. With my old ears I am very pleased with the music I am hearing. I believe this amp is distinctly better than any amplifier I have ever had in this system. I use a Benchmark amp and pre-amp in my upstairs system. I haven't been able to hear anything that seems like it could be the distortion that was found in the testing. It is just clear and quick and the lower frequencies sound particularly good. I am pretty sure my ears are the weak link in the chain at this point. I really do appreciate the perspectives that everyone is bringing to this.

I found Dylan to be a great and responsive guy when I was ordering the amp and have been impressed with how he is handling this situation. I would buy his work again.

Thanks!

 

[Rick Sykora]

Looks as though Buckeye's buffer designer also had a dummy load issue. I talked to him today and found he was using some PE dummy loads. I had bought the same ones and returned them. I found they could not be used for measuring low distortion situations. Might have found this sooner but we had limited interaction as it seemed desirable for my testing to be blacker box than his.

Since nobody else complained about the PE dummy loads, I was not sure it was a common problem. In hindsight, seems likely they exhibit the VcR characteristic that Amir discusses here: https://www.audiosciencereview.com/forum/index.php?threads/asr-dummy-load-configuration.8026/page-5

So, the good news is the designer should not have to resort to a pricey AP rental as he was able to get a clean measurement once the PE dummy loads were replaced. More importantly, should also mean he should be able to determine potential remediations fairly soon.

 

[Walter]

@Rick Sykora and @Buckeye Amps I have to really applaud how you are keeping everyone updated on this.

 

[Too Many Notes]

Look as though Buckeye's buffer designer also had a dummy load issue. I talked to him today and found he was using some PE dummy loads. I had bought the same ones and returned them. I found they could not be used for measuring low distortion situations. Might have found this sooner but we had limited interaction as it seemed desirable for my testing to be blacker box than his.

Since nobody else complained about the PE dummy loads, I was not sure it was a common problem. In hindsight, seems likely they exhibit the VcR characteristic that Amir discusses here: https://www.audiosciencereview.com/forum/index.php?threads/asr-dummy-load-configuration.8026/page-5

So, the good news is the designer should not have to resort to a pricey AP rental as he was able to get a clean measurement once the PE dummy loads were replaced. More importantly, should also mean he should be able to determine potential remediations fairly soon.

Been following along and appreciate the update. Sounds like good news. Just placed an order for a 3-channel Purifi and super excited! I have faith the cause of this (minor) distortion issue will be determined and resolved. It's clear that Dylan stands behind his products and his zero-BS approach is very confidence inspiring.

 

[Buckeye Amps]

So, not ready to call the distortion issue officially fixed, but we are very comfortable that we have found the culprit. We have a few more variables/variations to test to be 100% sure, along with a 3rd party measuring/testing as well, but we can reproduce distortion-free measurements by replacing the culprit in every different variation we have tried so far.

The great news: if the results hold up, it will be a super simple fix. Won't say more yet. But for those who have been patient and waiting, I think there is finally light.

 

[Audiomn]

So, not ready to call the distortion issue officially fixed, but we are very comfortable that we have found the culprit. We have a few more variables/variations to test to be 100% sure, along with a 3rd party measuring/testing as well, but we can reproduce distortion-free measurements by replacing the culprit in every different variation we have tried so far.

The great news: if the results hold up, it will be a super simple fix. Won't say more yet. But for those who have been patient and waiting, I think there is finally light.

This is awesome news! <Fingers crossed>

 

[Too Many Notes]

So, not ready to call the distortion issue officially fixed, but we are very comfortable that we have found the culprit. We have a few more variables/variations to test to be 100% sure, along with a 3rd party measuring/testing as well, but we can reproduce distortion-free measurements by replacing the culprit in every different variation we have tried so far.

The great news: if the results hold up, it will be a super simple fix. Won't say more yet. But for those who have been patient and waiting, I think there is finally light.

 

[amper42]

So, not ready to call the distortion issue officially fixed, but we are very comfortable that we have found the culprit. We have a few more variables/variations to test to be 100% sure, along with a 3rd party measuring/testing as well, but we can reproduce distortion-free measurements by replacing the culprit in every different variation we have tried so far.

The great news: if the results hold up, it will be a super simple fix. Won't say more yet. But for those who have been patient and waiting, I think there is finally light.

Great News. Let's have the Buckeye Purifi retested by @amirm and the review updated before we pop the champaign cork. As we have learned, measurements can be tricky and are not a normal function at Buckeye amps yet. Maybe that will change in the future?

 

[pma]

Glad to see that @Buckeye Amps is on the right track. Same care to be followed during measurements, 4 point method preferred.

 

[Too Many Notes]

Great News. Let's have the Buckeye Purifi retested by @amirm and the review updated before we pop the champaign cork. As we have learned, measurements can be tricky and are not a normal function at Buckeye amps yet. Maybe that will change in the future?

Was meant as encouragement and optimism for being on the right track. But sure, let’s be grumps about it.

 

[Audiomn]

Great News. Let's have the Buckeye Purifi retested by @amirm and the review updated before we pop the champaign cork. As we have learned, measurements can be tricky and are not a normal function at Buckeye amps yet. Maybe that will change in the future?

I have confidence that Buckeye’s and Rick’s testing is sufficient and I think we all appreciate Too Many Notes .gif

 

[Buckeye Amps]

Thanks everyone!

It was a very simple fix which is likely how it was overlooked initially (plus the issues with the load resistor when first doing testing and "debugging"). So simple, in fact, I even verified the principle science/theory behind it with Purifi themselves and they backed up what we found. Will also give a shotout when the time comes to a member on here who had the thought of what the issue was days after the review.

Just getting a few logistics in place before making a full post on all the details, options for fixes, etc. Though I know some may still want to wait for the re-test by Amir, which I obviously also support.

 

[Rick Sykora]

Ok, the moment of truth has arrived...

As @Buckeye Amps mentioned, the board designer and I have been going at this diagnosis feverishly. Admittedly, should have found sooner, but I made a critical test error and (as mentioned) the designer had been plagued by a bad dummy load that obscured his measurements until just recently. Since I have been working closely on the troubleshooting, Dylan is allowing me to represent the team to share our finding. In the end, the designer found the cause.

And the culprit is...



The binding post connection tab.

Unknown to @Buckeye Amps when he bought the binding posts, the tab is primarily made of steel. Steel is a relatively poor conductor and like a loose or oxidized connection can cause distortion. As with some others, I thought the culprit was the input board, but fortunately it was not. Honorable mention goes to @pma. Within his first few posts in this thread, he mentioned problems with ferrous materials in the signal path. We just had to find it.

Anyway, @Buckeye Amps is working on lining up parts and plans to address this issue in customer units and his production. He will share more details soon. Both of us are planning corrective actions to avoid this issue recurring.

P.S. (for those wanting some additional insight, please read on...)

I mentioned a critical error on my part. Tbh, there may have been more than one, but the key one was when I tested the amp speaker binding post by replacing it with a different binding post that also had a steel tab. Later when I tested the Purifi EVAL1 board (with built-in banana jacks) alongside the Buckeye board, the Purifi passed the test. At that point, was pretty convinced the culprit was the input board. I then tried several ways to alter the board grounding, but none worked.  So, the troubleshooting effort turned towards the board designer as he had more intimate knowledge of the design. Lesson learned!

 

[Buckeye Amps]

Which also means none of those who chose the speakON upgrade option are affected.