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Old 8th January 2015, 08:14 AM   #61
Schussor is offline Schussor  United States
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Default This is more typical - use this then

Quote:
Originally Posted by TNT View Post
Appalling distorsion figures for those trafos....

//
Here is a passive DI box ART Pro Audio

Note the specs are an order of magnitude lower. The trannies inside are not better. This model has a switchable 3rd order Bessel low pass at 30khz. So if the losses at the trannie are not enough, then you can switch this filter on.

Street price about $40

This one is better spec'c and provides +14db gain
Ebtech LLS-2 2-Channel Line Level Shifter | Sweetwater.com
http://www.ebtechaudio.com/llsheinf.pdf

Cost $80
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Old 8th January 2015, 08:28 AM   #62
Signalyst is offline Signalyst  Finland
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Quote:
Originally Posted by mcluxun View Post
A question to Miska:
which is more important spec number of cores? cpu clock? size or speed of mem?
Clock and RAM speed are critical factors as long as there are at least two cores. Fairly large cache doesn't harm either... 3.4 GHz quad-core is good minimum baseline for DSD512.
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Old 8th January 2015, 08:31 AM   #63
Signalyst is offline Signalyst  Finland
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Originally Posted by Schussor View Post
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.
It becomes heavy to drive such low-impedance network (to keep noise down).

Quote:
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.
You mean this?
FIRST WATT B4

By quick glance the block diagram in the manual looks exactly like standard SK design.
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Old 8th January 2015, 08:44 AM   #64
Schussor is offline Schussor  United States
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Originally Posted by blackhole View Post
At the output of Amanero I have only one 33 Ohm resistance in series, a capacitor in parallel and the transformer. I don't need a coupling capacitor because of transformer. I don't need a higher resistance (this also because of transformer).

The isolation from Usb ground is made by a Gefen USB extender. Power amplifier ground is isolated with the output transformer.

The S/N is not exceptional, should be around 85/90 dB, but this configuration has been made for a tube power amplifier whose real S/N could be around the same. So no record dynamic range. Moreover the output signal is lower than 2 V
The output transformers of tube power amplifier will work also as a final filter before the signal is sent to the speakers (Audiostatic eletctrosatic modified).

The sound signature is of a very transparent sound. The sound is the opposite of dark but is not bright, because high frequencies are smooth and "liquid". There is an impression (as in all DSD reproduction I have tried) of a bass a little less present.

Confronting to iFI DSD micro in DSD there is no story: this configuration is a lot better, immediately more transparent. iFi idsd micro (to my knowledge) should use the analogic internal filter of the DAC chip and an active buffer. In my case on the signal path there are not transistors, chips, no feedback, only one resistance, one capacitor in parallel, one transformer.
I have been looking to see how this can be done easily

At this point I am looking at using a canned USB-to I2S DSD converter such as the Gustard U12 or U10 (TCXO 0.1ppm clocks and XMOS with sample rate/type indicator display) like bay 111470778001

And the DI boxes for transformers, either
The one with 14db gain,
Ebtech LLS-2 2-Channel Line Level Shifter | Sweetwater.com
Or the one with the Bessel filter but no gain
ART DUALZDirect | Sweetwater.com

Then my ony issue would be to make an HDMI to TRS cable and figure out what wires to use off the HDMI carrying the I2S DSD signal. Do you happen to have a URL for that?
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Old 8th January 2015, 08:52 AM   #65
Schussor is offline Schussor  United States
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Quote:
Originally Posted by Signalyst View Post
It becomes heavy to drive such low-impedance network (to keep noise down).



You mean this?
FIRST WATT B4

By quick glance the block diagram in the manual looks exactly like standard SK design.
Yes, for even order networks and 2/3 SK and 1/3 passive for 3rd order. And IIRC you can do 2nd order with both gain stages engaged but without the SK loop closed.
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Old 22nd March 2015, 02:56 PM   #66
jamesblonde is offline jamesblonde  Italy
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Would love to hear more sound impressions and comparisons
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Old 3rd April 2015, 12:02 PM   #67
gentlevoice is offline gentlevoice  Denmark
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Hi all,

Very interesting thread, indeed ;-)

As it is I bought the components to make this DAC some months ago and now am gettiing closer to making a DSD DAC. This made me look closer into Jussi's schematic and I'm honestly not quite sure I understand what happens in the four shift registers ...

Any of you can just briefly explain what happens? It seems to me that there's some kind of averaging done (?) when then 1 bit signal passes through the registers ... Or may it be something else?

I am comfortable with the analog output stage - just would appreciate a brief explanation of the what happens in the shift registers.

Cheers

Jesper
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Old 3rd April 2015, 10:14 PM   #68
mcluxun is offline mcluxun  United States
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Quote:
Originally Posted by gentlevoice View Post
Hi all,

Very interesting thread, indeed ;-)

As it is I bought the components to make this DAC some months ago and now am gettiing closer to making a DSD DAC. This made me look closer into Jussi's schematic and I'm honestly not quite sure I understand what happens in the four shift registers ...

Any of you can just briefly explain what happens? It seems to me that there's some kind of averaging done (?) when then 1 bit signal passes through the registers ... Or may it be something else?

I am comfortable with the analog output stage - just would appreciate a brief explanation of the what happens in the shift registers.

Cheers

Jesper
Your first Digital to Analog Converter build | Hackaday

not exactly the same thing, but this link could be a good visualization of the use of shift register.
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Old 5th April 2015, 11:49 AM   #69
gentlevoice is offline gentlevoice  Denmark
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Hi mcluxun,

Thanks for your reply & link - but looking at the link & the video it seems as if it's more to do with an R2R DAC (which could be interesting as well) than with a shift register...? Or maybe I missed something?

I somehow wonder why Jussi didn't just use a flip-flop (e.g. potatosemi) and a suitable filter after the flip-flop ...

Bewildered

Jesper
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Old 5th April 2015, 12:00 PM   #70
abraxalito is offline abraxalito  United Kingdom
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Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
The shift register is an 'analog' FIR filter - otherwise called a transversal filter. Bruno uses one on the output of his latest and greatest Mola-Mola DAC. One of the benefits of using the transversal filter is reduced jitter sensitivity as DSD decoding is notably extremely jitter sensitive.

I suspect that Jussi's circuit will suffer in terms of dynamics - getting a clean enough power supply is going to be a challenge as a shift register DAC will on average have about 6dB PSRR.
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