Brainstorming Purifi 1et400a amps

IMO

I just stepped over this @ASR.

Can somebody tell me why they use 2+1sense wires per leg on the shown image?
Is it just to cover for high current situations!?!?

When I was looking at some of the DIY build images I can't recall to see a sense wire
going to the outer binding posts. Obviously there are different ways to handle this.
Or perhaps the impact when choosing different positions can simply be neglected.

I am going to use wires to the eval board for the output to the speaker binding posts. I do not think I am going to bother extending the sense wiring to the binding posts-to me this seems like much ado about (nearly) nothing. I suspect that as long as the output wiring is relatively short, and of sufficient gauge, there will be little to no actual advantage, and perhaps even problems could develop (RF pickup by sense wiring, possible?). I will likely just make the sense connection on the eval board. My speaker output wiring will be short, ~3", and 12 AWG.
 
Mike has a setup for measuring ripple noise down to 0.4uV. And he said with the right surrounding components, the LT3045/3094's have 10x less ripple noise, higher PSRR, and lower output impedance than the Belleson SPX. He made a bunch of TO-220 format regulators based on them for a DAC project that was cancelled. He has no use for them and is willing to sell for $20 each. Can be set to any voltage up to 18v + or - by changing the value of R1.

I just stepped over this @ASR.

Can somebody tell me why they use 2+1sense wires per leg on the shown image?
Is it just to cover for high current situations!?!?

When I was looking at some of the DIY build images I can't recall to see a sense wire
going to the outer binding posts. Obviously there are different ways to handle this.
Or perhaps the impact when choosing different positions can simply be neglected.

From the purifi reference build
 

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Folks.

Got a question.

The Hypex PS and my Anaview amp are well protected against microphonic effects.
Pretty much every part that could vibrate is glued to each other to basically form a "solid block".

The Purifi doesn't have that! No nothing.

1. Has anybody thought about this? Why didn't they consider it? I thought meanwhile
this method would have been a proven standard.

2. Does anybody know what kind of stuff these pros (Hypex/Anaview,...) use to glue
the parts? I might consider to give it a try.

Thx.
 
Doubt...

Folks.

Got a question.

The Hypex PS and my Anaview amp are well protected against microphonic effects.
Pretty much every part that could vibrate is glued to each other to basically form a "solid block".

The Purifi doesn't have that! No nothing.

1. Has anybody thought about this? Why didn't they consider it? I thought meanwhile
this method would have been a proven standard.

2. Does anybody know what kind of stuff these pros (Hypex/Anaview,...) use to glue
the parts? I might consider to give it a try.

Thx.

I doubt that the glue you see on those products is used to reduce microphonic "problems". I suspect it is more to increase reliability and reduce problems caused by vibration during shipping.
Silicone is the material to use if you want to, but remember if you do start smearing everything with silicone, any re-cappong you might want to do later will be much, much, more difficult.
 
I now brought the Purifi to life. By now it's on air for 3 days.

I'm running it at lowest gain. My DAC is single-ended.

First impression.

Nice.
Dynamics are great. Low level dynamics (even at low volume) are great.
Very clean. Nice 3D with a lot of air around the instruments.
Not much, if anything at all, to complain about.

And. It's overall better then my Anaview AMS0100-2300.

But. It's not day and night. And it's not a WOW-what an-amp experience.
Which I'd guess is the situation when having a very neutral amp at hand.

However. Considering the huge difference on the price tag, I think I paid 150€ for the Anaview,
which has the PS onboard, I'd consider the Anaview in the lead on the price/performance mark.

Let see. It's just two days. Things might improve after some more hours being on air.
Therefore above should be considered an early stage impression.

Enjoy.
 
It's the PreGain stage that gets bypassed on the EVAL1.
I feed a Khadas Toneboard right into the EVAL1 board.
With the PreGain setting at 0dB the amp nicely matches the DAC.

I ran my DAC also right into the Anaview.

I have a wifi & time controlled relay setup that turns all parts of the chain properly on and off to avoid nasty thumps btw.


****

A general thought.

I am wondering why these Purifi folks havn't considered to go full digital. Especially
with Lyngdorf on the team. All this DAC/amp integration mess would finally come to end.


Enjoy.
 
I am wondering why these Purifi folks havn't considered to go full digital.


Depends on what you mean by "full digital". Bruno has explained several times why he believes a truly digital class D amp (so with a digital feedback loop) is not a good idea (it is very hard to deal with the inevitable feedback lag) and why his designs (just like the vast majority of all class D designs) are analog.
 
It's the PreGain stage that gets bypassed on the EVAL1.
I feed a Khadas Toneboard right into the EVAL1 board.
With the PreGain setting at 0dB the amp nicely matches the DAC.

I ran my DAC also right into the Anaview.
.


I asked because my DAC sounds better through a pre-amp than when connected directly to my amp. But it technically can be fed directly to the amp. I'm using a TEAC NT-505.
Incidentally, I had not heard of the Toneboard before, but it looks very interesting. Can it stream via USB from a computer? I'm curious about small, inexpensive DAC's that can "do the job". I assume you would consider the Toneboard to be such a one.

Thanks for any comments would share.
Ron
 
How did you compare, and how did you match levels?
To be honest it was not done very scientifically:

Case 1: DAC unbalanced out to amplifer inputs, and I used the volume control on the DAC.

Case 2: DAC out to Emotiva XMC-1 in, XMC-1 out to amplifier. DAC set to fixed output (0 dB).
But it was not unusual for volume on DAC to be set close to 0dB when using it direct to the amp, so it had a chance to sound good.
I didn't "match" as in A/B, I just used it for awhile both ways and found the sound much more satisfying through the pre-amp.
Incidentally prior to purchasing the Emotiva I was using a Marantz 6012. In this case I preferred the DAC direct to the amplifier.
Ron
 
To be honest it was not done very scientifically:

Case 1: DAC unbalanced out to amplifer inputs, and I used the volume control on the DAC.

Case 2: DAC out to Emotiva XMC-1 in, XMC-1 out to amplifier. DAC set to fixed output (0 dB).
But it was not unusual for volume on DAC to be set close to 0dB when using it direct to the amp, so it had a chance to sound good.
I didn't "match" as in A/B, I just used it for awhile both ways and found the sound much more satisfying through the pre-amp.
Incidentally prior to purchasing the Emotiva I was using a Marantz 6012. In this case I preferred the DAC direct to the amplifier.
Ron


I assume you know that a small level difference (1-2 dB) isn't perceived as a volume difference, but a difference in clarity/depth/quality.
 
I assume you know that a small level difference (1-2 dB) isn't perceived as a volume difference, but a difference in clarity/depth/quality.
Yes, but I wasn't "A-B'ing" the sound, I was using it. I could turn it as loud or soft as I wanted. And if I was expecting one to sound better than the other, it would have been the direct connection (without the pre-amp). But in any case I'm not claiming anything but my subjective opinion. Perhaps in a truly blind listening test the result would be different:scratch1:.
 
Depends on what you mean by "full digital". Bruno has explained several times why he believes a truly digital class D amp (so with a digital feedback loop) is not a good idea (it is very hard to deal with the inevitable feedback lag) and why his designs (just like the vast majority of all class D designs) are analog.

I am aware of B. Putzeys opinion. Therefore I said "...with Lyngdorf (Tact) in the team..." ;)

Putzey IMO misses the point though.

1st.
Several solutions have shown that full-digital works extremely well.
Many entry level solutions I've tested myself in the past were lacking the quality in the digital input and DSP section though.
That brought me back to DAC -> amp setups.

2nd.
The DAC -> amp integration is always tricky - especially for us users. And it's us to get it done!
The issues that usually pop up in that area, can easily be worse than the issue Putzey sees
when looking at the amp technology isolated.
What I'm saying. You need to look at the whole chain. If you just want to sell amps looking
at the whole chain is of course gonna be a problem.


3rd
Another huge advantage could be a high voltage volume control on the output stage.
No losses throughout the entire chain. I think TI offers such a solution for years.


****


However.

The key issue IMO is that such a full digital solution usually can't be sold in volumes.

A simple analog amp you can attach to millions of different sources. And that's what really matters in business. Selling large volumes.

I do think - it's 2020 - and thinking about a digital "preamp" feeding digital into a full digital amp should be considered the right direction
into the future for everybody involved.



Enjoy.
 
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