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DIY Purifi Amp builds

rusty75

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TL;DR: I would like to upgrade my set and match the tube buffer used in VTV...but am a bit of a beginner.

I do apologize for just jumping in here and possibly hijacking a thread.
So I have just purchased the Eigentakt Eval1 stereo set and recommended PSU, and the kit from Ghent audio.

Then of course I search further and find a YouTube video about the VTV module with the tube input buffer.
I would like to upgrade my board as well, and add a vacuum tube buffer board.

This is where I got confused and a bit lost in the 131 pages of this thread...

what are the steps to take to add the same/a similar as what VTV have done?

thank you kindly for any information.
 
Last edited:

mSpot

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TL;DR: I would like to upgrade my set and match the tube buffer used in VTV...but am a bit of a beginner.

I do apologize for just jumping in here and possibly hijacking a thread.
So I have just purchased the Eigentakt Eval1 stereo set and recommended PSU, and the kit from Ghent audio.
Contact VTV and they should be able to guide you. A problem is that the Ghent case was specifically designed to fit the Eval1. You'll have to supply your own input connectors and the VTV boards won't simply drop in. You'll probably need to drill mounting holes in the case.
 

Meanpeak

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I saw this new supply that may help us solve the split of the DC cables like above.


I wish it was there 3 months ago :confused:
 

tomchr

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There's also this: https://neurochrome.com/collections/connectors-parts/products/hypex-smps-splitter
SMPS_Splitter.jpg


Tom
 

Streamc

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What is pros and cons bypassing input buffer? I have SMSL 300MK2 and turn input buffer of ET400 off.
 

Streamc

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Shifting the duty of keeping the SNR low to whatever part of the signal chain is now responsible for gain.
I need to compare output amps of SMSL M300 mk2 in mode with amplification to 4.4V to system of them+input buffer opamps.
 

Streamc

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Not sure I follow. Compare in what way?
Do some calcs. Both DAC and input buffer have SNR. If Input buffer is Used Dac output would not used in max amplification mode.
If DAC amp would be used SNR of it would decrease.
 

tomchr

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What is pros and cons bypassing input buffer? I have SMSL 300MK2 and turn input buffer of ET400 off.
Lower gain in the power amp -> better gain structure.

For the best signal-to-noise ratio you want to attenuate the signal as little as possible. Also, you generally want to avoid having gains after attenuation. The goal is to keep the signal as high as possible for as long as possible through the playback chain.

It's interesting that gain structure has only been gaining attention in the audio community within the past decade or so. It's been a well-established concept in RF design for decades. You might be able to glean some insight by looking at noise figure optimization in RF in addition to looking into gain structure within audio.

Tom
 

tomchr

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True that! The input impedance of the Purifi modules is quite low.

Tom
 

Streamc

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Cons is that input impedance is lowered. From my little experience, some DAC tend to distort a bit more. The best is a unity gain buffer to keep the input impedance high.
without amplification, yes? Or with Vout to Vin ratio = 1.
 

Streamc

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Lower gain in the power amp -> better gain structure.

For the best signal-to-noise ratio you want to attenuate the signal as little as possible. Also, you generally want to avoid having gains after attenuation. The goal is to keep the signal as high as possible for as long as possible through the playback chain.

It's interesting that gain structure has only been gaining attention in the audio community within the past decade or so. It's been a well-established concept in RF design for decades. You might be able to glean some insight by looking at noise figure optimization in RF in addition to looking into gain structure within audio.

Tom
What is attenuation?
 
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