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Old 15th March 2012, 02:19 PM   #331
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Quote:
Originally Posted by audiodesign View Post
Using DAC with a single power supply like ESS, Crystal, WM8740, WM8741, AKM4396, PCM1794 should be necessary a RC network to skip DC bias otherwise the output transformer can saturates the core.
I thought those had balanced outputs? If they don't then yeah, I agree.
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Old 17th March 2012, 03:20 AM   #332
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Yes, if the primary only ever sees a differential signal, then the common mode DC means nothing.
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Old 17th March 2012, 07:37 AM   #333
WDYSUN is offline WDYSUN  Italy
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Quote:
Originally Posted by audiodesign View Post
Using DAC with a single power supply like ESS, Crystal, WM8740, WM8741, AKM4396, PCM1794 should be necessary a RC network to skip DC bias otherwise the output transformer can saturates the core.
Hi audiodesign,

we know you did several projects involving the use of transformers. Could you suggest some schematic for the ESS?

Best
Pietro
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Old 17th March 2012, 09:49 AM   #334
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Pietro,
using DAC with output current I don't consider a good choice the output transformer.
The best I/V is a resistor followed by a vaccum tube stage as voltage amplifier like my DAC End with AD1865.
The output trasformer with RC network is a good choice using DAC with voltage output.

Someout have the complete of the ES9018 ?
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Old 17th March 2012, 03:41 PM   #335
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Quote:
Originally Posted by audiodesign View Post
Pietro,
using DAC with output current I don't consider a good choice the output transformer.
The best I/V is a resistor followed by a vaccum tube stage as voltage amplifier like my DAC End with AD1865.
The output trasformer with RC network is a good choice using DAC with voltage output.

Someout have the complete of the ES9018 ?
Well, everyone is entitled to their opinion, but Sowter at least does not agree with you:
SOWTER DAC I/V TRANSFORMERS

See also Audio Note's DAC.

I have not the time, money or patience to bother testing every possible configuration so I just listen to the experts and form my own opinion from that.
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Old 26th March 2012, 09:05 PM   #336
RollE2k is offline RollE2k  Sweden
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If i'm building this inside my Pre-amp case, and planning on running Voltage out - wouldn't the best way for me be just connect the outputs from the dac to the volume-pot, and then directly to the grid of the amplifying tubes? or would i need any dc-blocking caps between the dac and the tube input? and it's maybe still better running through a transformer?
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Old 27th March 2012, 09:48 AM   #337
waltube is offline waltube  Italy
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Pietro,

look at post nr. 200
I am testing a circuit with Buffalo + trafos (3575 OCC Sowter) + tube output.
It is running very good; I will prepare an article for Audiocostruzione in Italy.
This is the best solution, for me ( different opinion from my friend Andrea), because you can separate completely the digital gorund from analog ground. Also, you can arrange the frequency response changin only one resistor at the secondary.

Walter
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Old 28th March 2012, 09:54 AM   #338
Ciu is offline Ciu  France
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Hello Walter

I don't really understand how it's works (or sings )...
The Dac is wired "Current mode" vith 25R
The transfo is 1:1
The CF is about 0.95 (?)
Where does the 2 volts output comes from ?
May be a schematic would help
Thanks !
Richard

Last edited by Ciu; 28th March 2012 at 09:55 AM. Reason: wrong writings
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Old 28th March 2012, 03:56 PM   #339
waltube is offline waltube  Italy
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Hi Ciu,

there is a 6922 ( each channel) with one section at gain followed by a CF .
I am palying with some adjustments ( sonic aspects) but the voice is very good.
Next future I will display the complete schematic.
I have the possibility to measure this dac with a 5000 Audio Precision test equipment; the firsts results are very good ( look the diagram).


Ciao

Walter
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Old 28th March 2012, 04:41 PM   #340
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Quote:
Originally Posted by Ciu View Post
The Dac is wired "Current mode" vith 25R
Technical point: You aren't truely using current mode unless the impedance is close to 0R.
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