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Old 9th July 2013, 01:09 PM   #21
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Quote:
Originally Posted by AudioLapDance View Post
Give it up for da man!

Andrea Ciuffoli DAC 1.0

Attachment 355569

DAC 1.0

Old school, baby!
Cool, I haven't sen this for many years but this is the circuit that I built way back ... around 2000? Or thereabouts. But with one small change - I never installed the resistor/cap combination from the centre tap of the tx primary, to ground. No good reason, I built the circuit first without these components and it worked just fine (it still does!) so I never bothered to add them in. Am I missing anything important?
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Old 17th July 2013, 07:05 PM   #22
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Originally Posted by audiorado View Post
Hi Dave and other Guys...
...thanks a lot for all answers.And yes Dave your sugestions work best.Dave if you could be so nice,can you tell me if I can use this Lundahl transformers with TDA1543 dac to??I just become some dac board from my good friend with TDA1543 in non oversampling mode with direct output via capacitor(47uF electrolitic).Si I would use now in the place of the output capacitors this lundahl LL1527 transformers.Is this posibile??And if yes,would I need some aditional parts (resitors,capacitors)on the primary or secondary site of the transformers??

Rado
Hi, I didn't get a message about your response in my email. Sorry for the late reply. Well... I don't have any TDA1543 here. If the output has a standing offset current like a TDA1541A without a current source, I'd suggest using a capacitor to block that before the transformer. Which Lundahl are you using? I'll try to help you. Dave
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Old 17th July 2013, 07:06 PM   #23
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Quote:
Originally Posted by hazard500 View Post
Cool, I haven't sen this for many years but this is the circuit that I built way back ... around 2000? Or thereabouts. But with one small change - I never installed the resistor/cap combination from the centre tap of the tx primary, to ground. No good reason, I built the circuit first without these components and it worked just fine (it still does!) so I never bothered to add them in. Am I missing anything important?
I think your fine without that filter. That was the only place I have ever seen that configuration used. Dave
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Old 17th July 2013, 07:25 PM   #24
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Talking TDA1543 with Lundahl LL1527?

Hi audiorado, I think your using the LL1527. I will assume 1:1 Line level configuration ~ 800 Ohms primary. Take a multimeter set to low VDC. Measure the output pin of the DAC or DAC side of the electrolytic capacitor to ground. You may see anything from a Volt to mV's. If you get a few milliVolts's. It should be possible to use the transformer without the capacitor. Otherwise, I have used 10 uF Polypropylene capacitor with 10 K Ohm series resistor to the transformer. Good bass too. Let me know what you measure, check both channels. I can draw that up for you and post the wiring. Hope that helps. Dave
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Old 18th July 2013, 10:12 PM   #25
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Originally Posted by Torchwood421 View Post
I think your fine without that filter. That was the only place I have ever seen that configuration used. Dave
Thanks for the reply Dave. Any idea what is the purpose of the filter?
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Old 19th July 2013, 12:49 AM   #26
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Smile Filter network....

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Originally Posted by hazard500 View Post
Thanks for the reply Dave. Any idea what is the purpose of the filter?
It appears to establish a ground reference at the center point of the transformer. At very low frequencies it should remove rubbish. When I used the Lundahl LL1690, the designer of that DAC left the center point unterminated. I found no issues with that. My CS4398 DAC is dead quiet without signal. It does have a relay based mute. So that may not be a good comparison.
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Old 21st July 2013, 11:50 AM   #27
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Is anybody using the LL1676 or 1674? How do they compare with the LL1690?
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Old 22nd July 2013, 07:13 AM   #28
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Default DAC CS4390+lundahl LL1527 passive output

Hi Dave.....
...sorry for late response,I was on holydays and just came beck home.Thanks a lot for al your help.In the next days I will try the option with my lundahls LL1527 and TDA1543 and see what I get from this combo.Your instruction are verry verry helpful,and many thanks for your help.In the min time I have buy some lundahls LL1690 to.
So I will try the diference between the LL1527 and LL1690 to.
But becouse the LL1690 seems to be bether becouse thay have amorphos core I will try to sell the LL1527 tranys.
SO IF SOMEONE WILL NEED A PAIR OF THE LUNDAHLS LL1527 IN VERRY GOOD CONDITION,you could email me for the price and shipping options.I buy this from sweden a 6 months ago for about 160 euro(caa.200usd)!
I will report back in next days,when I will try the non-os tda1543 dac with transformer output.
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Old 22nd July 2013, 08:03 AM   #29
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HI all,

I'm embarassed to make some stupid question to very experts as you,
but I have a micromega DUOBS and DUOPRO2 dacs , wich are 1 bit ( IMHO very good), but " IC output stage.

So, I have thinked to modd with a sowter transformer , but I have no idea if the dac CHIPS ( Philips?) are voltage output or current output.

Is it possible put a transformer in both cases ,or only if they are "current output"....?

Thanks for help

Paolo

VEnEZIA, Italy

Last edited by inertial; 22nd July 2013 at 08:04 AM. Reason: forgot title
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Old 23rd July 2013, 01:03 AM   #30
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Location: Prior Lake, MN
Default 1 Bit dac

Quote:
Originally Posted by inertial View Post
HI all,

I'm embarassed to make some stupid question to very experts as you,
but I have a micromega DUOBS and DUOPRO2 dacs , wich are 1 bit ( IMHO very good), but " IC output stage.

So, I have thinked to modd with a sowter transformer , but I have no idea if the dac CHIPS ( Philips?) are voltage output or current output.

Is it possible put a transformer in both cases ,or only if they are "current output"....?

Thanks for help

Paolo

VEnEZIA, Italy
1 bit dac's are usually voltage out devices. Voltage out is good because you don't need any additional Opamps. Can you pop the hood and get the chip number off the dac? I can look it up and see what needs to be done. I use transformers with the TDA1541A... The transformer operates as a passive filter after the I/V. here is a link to my just finished dac. DAC gallery Discrete I/V and Edcor's. My best sounding dac to date for pure sound quality. Dave
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