Buckeye 3 Channel Purifi Amp Review

[Buckeye Amps]

Step 5, do you need a new lock washer as well? I see in Step 3 you take one off.

You do not

 

[Calleberg]

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...

View attachment 263237

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.

@pma is more and more becoming my favorite contributor over here at ASR. Thank you for sharing your knowledge here PMA!

Now that we have established that steel connectors can be problematic in this kind of application. I just can't resist teasing those of you that has a bad case of audiophilia nevrosa with some additional information... Guess what the loudspeaker driver terminals are normaly made of... yes thats right. it's STEEL...

 

[pma]

@pma is more and more becoming my favorite contributor over here at ASR. Thank you for sharing your knowledge here PMA!

Thank you, though I know I am often sharp, harsh and impatient . My goal is to do things technically right and reliable. It is a long path, but I like sharing some gained knowledge, if just at least someone is interested.

Re the steel issue, it is inaudible and occurs only at high current level. It was just good to find it and not to blame electronics of the input buffer.

 

[RickS]

Now that we have established that steel connectors can be problematic in this kind of application. I just can't resist teasing those of you that has a bad case of audiophilia nevrosa with some additional information... Guess what the loudspeaker driver terminals are normaly made of... yes thats right. it's STEEL...

Correct, am still investigating this but here is what I found from a Sound Stage interview of Lars Risbo of Purifi…

Purifies reliance on speakONs intrigued me, so I asked them about it. Lars Risbo:

Nearly all binding posts and/or banana plugs available we found to be magnetic and added measurable hysteric distortion. The cheapest plastic speakON passed the test. It seems that Benchmark Media Systems came to the same conclusion with their very low distortion AHB2 amplifier.​

 

[Calleberg]

Thank you, though I know I am often sharp, harsh and impatient . My goal is to do things technically right and reliable. It is a long path, but I like sharing some gained knowledge, if just at least someone is interested.

Re the steel issue, it is inaudible and occurs only at high current level. It was just good to find it and not to blame electronics of the input buffer.

I have quoted some of your post for that very reason. Being Technically correct, reliable and also in my experience objectively presented without coloration from personal bias.

And yes, the steel thing is a non issue, obviously at the other end of the speaker cables connected to that Buckeye amp there is going to be a loudspeaker driver of some sort. The material in the terminals of that driver is not going to be even remotely relevant for the performance of said driver because it has so many other shortcomings that dwarfs whatever little impact the terminal material could have

But it is easy to forget sometimes that whatever the equipment and regardless of how good they measure, the real bottle neck are the speakers, and for the most part they are not going to be anywhere near as revealing as an AP analyzer

 

[Head_Unit]

If it had to be returned to be fixed (say the customer doesn't want to or isn't comfortable opening it up) I would obviously cover shipping costs.

I gotta pinch myself that I'm really reading this. Consdering the good service, what's a little rising THD between friends? Heck you can just reprogram the government micronanobots in the COVID and flue and shingles vaccines to allow you to ignore it...

 

[Too Many Notes]

Correct, am still investigating this but here is what I found from a Sound Stage interview of Lars Risbo of Purifi…

Purifies reliance on speakONs intrigued me, so I asked them about it. Lars Risbo:​

​

Nearly all binding posts and/or banana plugs available we found to be magnetic and added measurable hysteric distortion. The cheapest plastic speakON passed the test. It seems that Benchmark Media Systems came to the same conclusion with their very low distortion AHB2 amplifier.​

I have quoted some of your post for that very reason. Being Technically correct, reliable and also in my experience objectively presented without coloration from personal bias.

And yes, the steel thing is a non issue, obviously at the other end of the speaker cables connected to that Buckeye amp there is going to be a loudspeaker driver of some sort. The material in the terminals of that driver is not going to be even remotely relevant for the performance of said driver because it has so many other shortcomings that dwarfs whatever little impact the terminal material could have

But it is easy to forget sometimes that whatever the equipment and regardless of how good they measure, the real bottle neck are the speakers, and for the most part they are not going to be anywhere near as revealing as an AP analyzer

This changes everything. Dylan, please create a guide on how to replace the steel binding posts in our speakers with your brass tabs.

 

[Futility]

Hope this video I found saves someone a few minutes.

Tab/spade connector crimping:

 

[Home Theater Nerd]

I've been using a Buckeye 3-channel Purifi amp for five months now and it has been outstanding. I have very efficient, transparent speakers and the power has been crystal clear without a hint of noise or distortion. As an end user I can attest that the issues detected in this thread have been totally inaudible. Nonetheless, I sent Dylan an email when he announced the fix and he got replacement parts out to me within about a week. Following the posted instructions was a cinch - it took longer to take the amp out of the rack than to pop the cover and swap the tabs and nuts. I got it back up and running last night and it sounds ... exactly the same (crystal clear without a hint of noise or distortion).

I also remember that Dylan's first response to this inaudible issue, before he troubleshot the cause and knew the cost to him, was to promise to make it right at no cost the end user. Even if it meant him replacing the boards - and even if it meant him covering shipping! @Buckeye Amps , thanks for the fantastic customer service, I'll be buying more amps from you!

 

[walt99]

Dylan, enjoying my 8ch 252 and I appreciate what you are doing, keep up the good work!
Now I’m thinking of going to an 8ch Purify, any options there?

 

[Buckeye Amps]

Dylan, enjoying my 8ch 252 and I appreciate what you are doing, keep up the good work!
Now I’m thinking of going to an 8ch Purify, any options there?

Not from me, to be upfront and honest.

In an effort to always be honest and save my customers money I can say that there is almost zero audible gain using something like the Purifi or the new NCx Hypex outside of the front three channels.

MAYBE if someone listens critically to 5ch music using a Purifi for the two surround speakers MIGHT produce a very very subtle improvement. But in 99 out of 100 use cases, I urge customers to save the money and not pay more for Purifi outside of their LCR speakers.

 

[Too Many Notes]

Correct, am still investigating this but here is what I found from a Sound Stage interview of Lars Risbo of Purifi…

Purifies reliance on speakONs intrigued me, so I asked them about it. Lars Risbo:​

​

Nearly all binding posts and/or banana plugs available we found to be magnetic and added measurable hysteric distortion. The cheapest plastic speakON passed the test. It seems that Benchmark Media Systems came to the same conclusion with their very low distortion AHB2 amplifier.​

Previous joking aside, this intrigues me the more I think about it. In theory, could the measurable distortion added by the above components be higher than, say, the extra distortion measured by Amir that was caused by the previously installed steel tabs? In other words, could replacing the tabs in the Buckeye be a complete waste of time if one otherwise uses banana plugs or has speakers with binding posts?

 

[pma]

You care too much.

 

[Calleberg]

Previous joking aside, this intrigues me the more I think about it. In theory, could the measurable distortion added by the above components be higher than, say, the extra distortion measured by Amir that was caused by the previously installed steel tabs? In other words, could replacing the tabs in the Buckeye be a complete waste of time if one otherwise uses banana plugs or has speakers with binding posts?

Dont forget the connectors on the drivers inside the speakers. 99 times out of 100 its a faston on a STEEL tab... ahh the horror....

 

[Buckeye Amps]

I would suggest not worrying about such rabbit holes.

The goal is for the known components to measure/operate as intended. Hence me wanting to fix the Purifi and get the appropriate/expected measurements.

But to start to ruminate on “is the source before or after the amp introducing distortion in the form of steel/magnetic components” is an exercise in futility. There are dozens of other things in our hobby that make more audible differences to put thought into.

 

[RickS]

Previous joking aside, this intrigues me the more I think about it. In theory, could the measurable distortion added by the above components be higher than, say, the extra distortion measured by Amir that was caused by the previously installed steel tabs? In other words, could replacing the tabs in the Buckeye be a complete waste of time if one otherwise uses banana plugs or has speakers with binding posts?

The speaker distortion is so much higher than these hysteric (micro)distortions, it does seem rather obsessive to go chasing after them aggressively. From a practical perspective, they are unlikely to be audible.

My investigation has been to further my understanding of what I consider to be an electrical outlier. As I posted earlier, I was caught off guard when troubleshooting the problem as I unwittingly placed another steel tab in the signal path. For the record, am not ripping open any of my speakers to replace steel parts.

 

[Too Many Notes]

I would suggest not worrying about such rabbit holes... There are dozens of other things in our hobby that make more audible differences to put thought into.

This is exactly my point.

 

[charlielaub]

Dont forget the connectors on the drivers inside the speakers. 99 times out of 100 its a faston on a STEEL tab... ahh the horror....

Sure but a driver, even a really good one, has 100 times or more the distortion of a good amplifier. So the added distortion from a steel tab is insignificant to the drivers' own distortion levels.

Edit: I just saw that others mentioned this before me.

 

[Calleberg]

Sure but a driver, even a really good one, has 100 times or more the distortion of a good amplifier. So the added distortion from a steel tab is insignificant to the drivers' own distortion levels.

Edit: I just saw that others mentioned this before me.

Yes, yes, that was my point too, but the smiley got deleted... Aah, there it is...

 

[Hapo]

...I can see where a person in the USA might as well get a Buckeye as a Nord...