Review and Measurements of Purifi 1ET400A Amplifier

[mocenigo]

Regarding Purifi builds, I am as always very interested in how to "concoct" your own power supply (just because).

The easiest approach: Hypex SMPS1200A400

OR: take a regulated Connex supply configured for +-65V. In order to get the gate drive supply would a regulated +16V fine, then connecting its 0V to the -65V of the main supply?

Also, since two low noise discrete voltage regulators for the OPAMP (for the modulator?) are already included on the FE02A, I suppose providing your own regulated supply for them necessary. Correct? So to feed them any good +-18V through J3 pins 5,6 and 7 would be ok (I suppose the "audiophile" way would be to use a linear supply ;-) ) However, and more importantly, does anybody here know how much current the modulators draw?

Roberto

 

[Julf]

No. I am asking for studies showing correlation between standard measurements and more elaborate ones. I am not that naive. If discrepancies are below a certain level then this is proved.

I think we should take this to a separate thread, but are you aware of the work done in this field at Harman International?

 

[mocenigo]

I think we should take this to a separate thread, but are you aware of the work done in this field at Harman International?

You are right., we should create a different thread. Also, I am not aware of this work. Do you have references? Finally somebody that can provide information without being smug or resorting to name calling and mockery!!!

 

[Julf]

You are right., we should create a different thread. Also, I am not aware of this work. Do you have references?

Lots of AES papers, but this is a good start: https://seanolive.blogspot.com/

 

[DonH56]

Decent reference: https://www.amazon.com/Sound-Reprod..._1?keywords=floyd+toole&qid=1578511514&sr=8-1

 

[March Audio]

I can assure I do not lack the critical thinking. All I am asking is evidence that simpler tests cover more complex situations. So, yes, my knowledge is lacking and I would like this to be remedied. As Alan said, yes "we do IMD" and other tests. I have not seen evidence these tests are sufficient. I did not say they are not sufficient - I want to know.

Regarding my rude comments to Amir, well, on that I was out of line and I apologise to Amir, but speaking in a more polite way, the fact remains that the validity of his methodology is debated, and inconsistencies have been pointed out here as well. So, please show me papers that prove that simpler tests allow us to bound distorsions in all cases. I am eager to learn.

I am a professional mathematician and I can read those papers. I am not mentioning this to brag, but it was just to mention that you can point to me to real studies. Taking about "32 waves that go up and down", as Alan did, is puerile at the very least. My current job is easy to find, and I have a global responsibility where, if I do a mistake, literally billions of people may be affected. In the past a slip of mine led to a potential 900 million devices being vulnerable. I have experience being wrong and owning it. What I do not accept is "you have no clue", a salad of buzzword (all of which I know well) and then being dismissed.

Returning to critical thinking, using (1) measurements that prove that devices are not ideal, and then (2) claiming that you can extrapolate from these measurements in an ideal way is a logical fallacy, and not one I have done. [OTOH I can accept even heuristic arguments that combined distortion byproducts are so low that they fall under the noise floor, and therefore they can be ignored.]

I started on the wrong foot. Mocking (as Alan did) repeats my mistake, I gave a bad example.

Roberto

Roberto

No one cares what your professional status is so you can stop referring to it. In this area you clearly do have some lack of knowledge so it might be better to listen to what's said instead of saying things like "Amir doesn't know what he is doing" or "this place is full of mental people" or that I am "purile".

A transient is just a change of amplitude state. It doesn't matter if it is repetitive. John has covered most of it so I won't repeat. The 32 tone test is not steady state as clearly shown above.

Yes we do IM tests. What do you think the 32 tone is doing?

TIM was figured out over 40 years ago. Going "ooohhh there might be stuff we don't know" is not a very convincing argument. You have to have reasons to suspect this. Next step is to make sure your suspicions have basis, i.e. if you think you hear something perform controlled listening tests to verify its real and not bias, imagination or other.

I had forgotten about the teapot, thanks Julf for reminding me of that one.

 

[March Audio]

Is this square wave a transient?

Does it stop being a transient because I make it happen more often?

 

[JimB]

Is this square wave a transient?

View attachment 45080

Dunno - looks a bit slow to me.

 

[March Audio]

Also, before it crops up, no a square wave is not a faster transient than a sine wave.

A square wave (or any signal, music or whatever) rise time is dictated and limited by the system bandwidth, in this case 24kHz.

Same square wave at a smaller timebase so we can see the rise time.

sine wave close to system bandwidth limit at same timebase

overlaid

 

[March Audio]

@Thomas savage sorry to make work but can you move the last couple of pages into another more appropriate thread?

thanks

 

[Billy Budapest]

Waiting for a manufacturer to implement Purifi modules without silly boutique discrete opamp input boards.

 

[March Audio]

Waiting for a manufacturer to implement Purifi modules without silly boutique discrete opamp input boards.

@Billy Budapest
Nudge nudge

https://www.audiosciencereview.com/...-audio-p451-purifi-1et400a-mono-blocks.10138/

 

[Billy Budapest]

@Billy Budapest
Nudge nudge

https://www.audiosciencereview.com/...-audio-p451-purifi-1et400a-mono-blocks.10138/

I was about to post “Never mind, I see March Audio has done this in their unit.”

 

[Thomas savage]

@Thomas savage sorry to make work but can you move the last couple of pages into another more appropriate thread?

thanks

Somebody give me post numbers and a thread title and I will. I'm not crawling through trying to separate it all as I don't really know what your discussing.

This place is a free resource , can folks start thinking beyond themselves and start new threads when they want to divert from OP significantly.

Doing so not only helps the original thread but also helps the new discussion get seen and adds value to it and us all.

It's not asking much but for some reason the simple task appears beyond many of you. In the end your devaluing your own contributions by not doing this.

Cheers

 

[mocenigo]

Waiting for a manufacturer to implement Purifi modules without silly boutique discrete opamp input boards.

Looks like that a Neurochrome universal buffer and a little adapter, or the Purifi EVAL1 connector board with the buffer bypassed, would be a great choice. Use the SALAS SSL v1.3 UltraBiB, or the DIYinHK (recommended to me by Tom Christensen), or the ATL Sulzer regulator to power it, and you are fine. I am also waiting to see if Alan can offer his modules separately (really!).

 

[mocenigo]

@Thomas savage sorry to make work but can you move the last couple of pages into another more appropriate thread?

thanks

agree

 

[Billy Budapest]

Looks like that a Neurochrome universal buffer and a little adapter, or the Purifi EVAL1 connector board with the buffer bypassed, would be a great choice. Use the SALAS SSL v1.3 UltraBiB, or the DIYinHK (recommended to me by Tom Christensen), or the ATL Sulzer regulator to power it, and you are fine. I am also waiting to see if Alan can offer his modules separately (really!).

I’m not much of a DIYer, unfortunately. I’ve built and upgraded my own computers but that’s about as far as I go with hardware.

 

[mocenigo]

I’m not much of a DIYer, unfortunately. I’ve built and upgraded my own computers but that’s about as far as I go with hardware.

Yes, but
1) bypassing the onboard buffer is easy, it is just a matter of moving jumpers
2) you have to solder just a few cables in place
3) the ATL Sulzer regulator comes already assembled, so you just have to connect it to a transformer and to the neurochrome buffer, with screw terminals

and then it is mostly done (needs a case)

 

[ironhorse128]

What would be the cheapest option to buy a finished amp based on a Purifi 1ET400A in Europe?
Everthing I saw till now is well above 2.000€ (e.g. nordacoustics, apollonaudio).

 

[Voxy]

What is the smallest form factor for a dual mono implementation in a single chassis? Just curious how small designers can push this.