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Signalyst DSC1
Signalyst DSC1
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Old 26th December 2014, 04:09 AM   #41
Schussor is offline Schussor  United States
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Location: Ohio
Quote:
Originally Posted by mcluxun View Post
Also I went back to check on the source of noise.
It turns out my 5V supply is very malfunctioning (30-50mV AC can you believe that?).
I swapped in a SSLV. Problem solved.
Click the image to open in full size.
Congrats on your successful build!!!

I just posted on finding something like this DAC design on Computer Audio

The minimum DSD DAC - Page 3

Still don't know anything about how it works but would want to try building one though I have not done any active circuits before. What is your cost estimate?

Have you tried to compare the DAC to a commercial one yet?

How is the output implemented? Is there any DC on it?
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Old 26th December 2014, 04:49 PM   #42
mcluxun is offline mcluxun  United States
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Quote:
Originally Posted by Schussor View Post
Congrats on your successful build!!!

I just posted on finding something like this DAC design on Computer Audio

The minimum DSD DAC - Page 3

Still don't know anything about how it works but would want to try building one though I have not done any active circuits before. What is your cost estimate?

Have you tried to compare the DAC to a commercial one yet?

How is the output implemented? Is there any DC on it?
First of all, it's a DIY product so the expectations are it outperforms off-the-shelf products in the same price range.

as i mentioned here: Signalyst DSC1
The cost of it should be something ballpark $300.

Sound?
LeonBernieniv describes it as clear.
Im more leaning towards "real". DACs Ive owned are all in the range of $500-800, I ve never experienced this kind of sound signature, smaller sound stage, very clear picture, every note is presented with well defined edges.
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Old 26th December 2014, 06:05 PM   #43
mcluxun is offline mcluxun  United States
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Join Date: Nov 2010
Quote:
Originally Posted by mcluxun View Post
First of all, it's a DIY product so the expectations are it outperforms off-the-shelf products in the same price range.

as i mentioned here: Signalyst DSC1
The cost of it should be something ballpark $300.

Sound?
LeonBernieniv describes it as clear.
Im more leaning towards "real". DACs Ive owned are all in the range of $500-800, I ve never experienced this kind of sound signature, smaller sound stage, very clear picture, every note is presented with well defined edges.
The output stage if i understand it correctly is AD844 for i/v then lme49720 for LPF then lme49710 for gain.
DC in the output? I've got a few mV which shouldn't be a concern in any system.
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Old 26th December 2014, 10:19 PM   #44
Schussor is offline Schussor  United States
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Join Date: Apr 2005
Location: Ohio
Quote:
Originally Posted by mcluxun View Post
First of all, it's a DIY product so the expectations are it outperforms off-the-shelf products in the same price range.

as i mentioned here: Signalyst DSC1
The cost of it should be something ballpark $300.

Sound?
LeonBernieniv describes it as clear.
Im more leaning towards "real". DACs Ive owned are all in the range of $500-800, I ve never experienced this kind of sound signature, smaller sound stage, very clear picture, every note is presented with well defined edges.
Thank you.

I had two things in my system that have caused soundstages to shrink and move backwards, which in a magnepan Tympani setup is a real oddity. One is a bad match of power cord and amp. The other is Salen-Key filters - much worse while they break-in, which is apparently what Miska put in the DSC1.

In the case of the Fosgate amp with the Bryston power cable from the Bryston amp I switched it to the fat JPS power cable that was on the Classe DR9 and the problem was solved. The Bryston cable was just not a good match for the Fosgate.

You might get a kick up with replacing big film caps (I saw a few 2.2uF on the list) with cheap Dayton foil caps from Parts Express. I use them extensively in my crossovers. One of the reasons I gave up on my Marchand XM44 crossover was that there was not enough space in it for foil caps bigger than 0.01uF.
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Old 27th December 2014, 12:24 AM   #45
Signalyst is offline Signalyst  Finland
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Originally Posted by Schussor View Post
The other is Salen-Key filters - much worse while they break-in, which is apparently what Miska put in the DSC1.
There are many ways to design active Sallen-Key filters and the performance depends on the filter parameters and component selection. The ones in DSC1 are designed the way they are for a reason... So I don't think it is possible to make a blanket statement about SK filter sound.

I was also thinking about using MFB topology I used in my earlier DAC, but it is more demanding for the opamps used, so I settled for SK in this case. LME49713 would fit for MFB.
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Old 27th December 2014, 04:18 AM   #46
Schussor is offline Schussor  United States
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Originally Posted by Signalyst View Post
There are many ways to design active Sallen-Key filters and the performance depends on the filter parameters and component selection. The ones in DSC1 are designed the way they are for a reason... So I don't think it is possible to make a blanket statement about SK filter sound.

I was also thinking about using MFB topology I used in my earlier DAC, but it is more demanding for the opamps used, so I settled for SK in this case. LME49713 would fit for MFB.
I don't know enough to distinguish a well designed SK from a bad design or a compromised one. Like feedback, can be done right or can make a gain circuit sound like a rotary tool. I would not know how to tell the designs apart. So I like to avoid both.

What would the benefit of an MFB filter be over a SK? A quick read suggests using them where component variance is an issue, besides that it just makes you use another resistor you wouldn't have otherwise. Is there a time domain/waveform preservation benefit?

What about a passive filter with make up gain instead? Like Lampis? It makes a difference in RIAA eq. and crossovers, perhaps here too?

What is the LP filter alignment you use?
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Old 27th December 2014, 11:26 AM   #47
Signalyst is offline Signalyst  Finland
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Originally Posted by Schussor View Post
Is there a time domain/waveform preservation benefit?
No, there's none. The current one design is already optimized for both time and frequency domain performance, 7 kHz square wave performance is very good.

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Quote:
What about a passive filter with make up gain instead?
I don't like the idea and I certainly don't want to have any coils on the audio path. But of course everyone is free to experiment and come up with mods they like...

Large part of the resulting sonics depend on used oversampling filter and delta-sigma modulator. This design is intended to match well with HQPlayer's filters and modulators.
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Old 28th December 2014, 10:24 PM   #48
mcluxun is offline mcluxun  United States
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To me the beauty of an open chipless design like this is we can tweak more stuffs than just changing capacitors and adding coils.
I did try to use a pair of Cinemag input transformers in the amp section to get balanced output, that doesnt improve sound stage very much.
On top of my head right now lots things can be improved without changing design principals, e.g. better PS (tps7a4700s instead of LMs,LTs) more accurate resistor networks.
Also any news about DSC2?
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Old 28th December 2014, 11:17 PM   #49
mcluxun is offline mcluxun  United States
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Im thinking about upgrading my i3 computer so I can enjoy DSD512 or upper without clipping with 10 tabs opened in chrome.
My current setup glitches while im opening big tab pages in chrome and playing DSD256.

A question to Miska:
which is more important spec number of cores? cpu clock? size or speed of mem?
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Old 29th December 2014, 04:47 AM   #50
Schussor is offline Schussor  United States
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Originally Posted by Signalyst View Post
No, there's none. The current one design is already optimized for both time and frequency domain performance, 7 kHz square wave performance is very good.


I don't like the idea and I certainly don't want to have any coils on the audio path. But of course everyone is free to experiment and come up with mods they like...

Large part of the resulting sonics depend on used oversampling filter and delta-sigma modulator. This design is intended to match well with HQPlayer's filters and modulators.
The SK circuits for the filters should not be difficult to duplicate with RC LP filters, you may end up having one more gain stage depending on the number of poles and the Q of the filters. But then you are possibly high up enough in voltage to forego a real output stage.

One of the gain stages can be a transformer that can serve as a filter pole. That was what Ted Smith did. He wanted to forgo another active stage and RC filter and spec'd a custom wound trannie to work as a filter at his specified fc, and serve to be an output stage and decouple DC.

I have to say that as a result there is a hint of "transformer sound" to the PS Audio PW DSD. I think you can pick a transformer that is naturally (i.e. not by deliberate spec) rolling off at one of your preferred filter pole's fc and not necessarily use it for output.

A successful implementation of this passive RC + makeup gain is in Nelson Pass' First Watt B4 crossover. It can do 4th order filters with 2 gain stages and IIRC there might be a buffer at the output. I think the schematics were offered online at his DIY forum, might still be there.
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