Analogue output sustituted by transformer

kabee33 · 6th May 2010, 01:50 PM

Hello together

I want to substitute OPA output-stage of my CDP by transformers, do you have any experience? DACs are AD 1862 (1mA, 2.1kOhms) I tried one of 200:200 Ohms but low frequencies are weak. 600:600 is better but not perfect.

Can anybody give some advise? CDP is Denon DCD 2560.

Thank you kabee

qusp · 6th May 2010, 02:38 PM

I suggest getting some lowish value trimpots and putting them from each leg to ground and trim till you find the right loading, then you can either substitute them with set value high quality resistors, or get a transformer that matches that impedance

kabee33 · 6th May 2010, 03:19 PM

Thank you I will try

Bill Fuss · 7th May 2010, 10:06 PM

Quote:

Originally Posted by kabee33

Hello together

I want to substitute OPA output-stage of my CDP by transformers, do you have any experience? DACs are AD 1862 (1mA, 2.1kOhms) I tried one of 200:200 Ohms but low frequencies are weak. 600:600 is better but not perfect.

Can anybody give some advise? CDP is Denon DCD 2560.

Thank you kabee

Forget the 2.1kohms output impedence, the dac needs to see a near zero ohm load. You need a trafo of around 18-20/1 ratio. Check the Lundahl website.

kabee33 · 8th May 2010, 08:23 AM

Thank you Bill.

Do you recommend step up or step down? Volume is same like OP-Amp with 1:1 tranformer now.

Bill Fuss · 8th May 2010, 02:25 PM

Step up, similar to MC trafos. Please try the Lundahl, and Sowter websites. GOOGLE is your friend.

Sure, it works now, but what does it sound like. I've been using 1/1 trafos with Vout dacs but this is different, unless the 1862 is a special case that I'm not aware of.

Maybe someone with direct experience with the 1862 will chime in.

6th May 2010, 01:50 PM	#1
kabee33 diyAudio Member Join Date: Jun 2009	Analogue output sustituted by transformer Hello together I want to substitute OPA output-stage of my CDP by transformers, do you have any experience? DACs are AD 1862 (1mA, 2.1kOhms) I tried one of 200:200 Ohms but low frequencies are weak. 600:600 is better but not perfect. Can anybody give some advise? CDP is Denon DCD 2560. Thank you kabee

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6th May 2010, 02:38 PM	#2
qusp Sometimes a square peg fits a round hole just fine diyAudio Member Join Date: Oct 2009 Location: Brisbane, Australia	I suggest getting some lowish value trimpots and putting them from each leg to ground and trim till you find the right loading, then you can either substitute them with set value high quality resistors, or get a transformer that matches that impedance

6th May 2010, 03:19 PM	#3
kabee33 diyAudio Member Join Date: Jun 2009	Thank you I will try

8th May 2010, 08:23 AM	#5
kabee33 diyAudio Member Join Date: Jun 2009	Thank you Bill. Do you recommend step up or step down? Volume is same like OP-Amp with 1:1 tranformer now.

8th May 2010, 02:25 PM	#6
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	Step up, similar to MC trafos. Please try the Lundahl, and Sowter websites. GOOGLE is your friend. Sure, it works now, but what does it sound like. I've been using 1/1 trafos with Vout dacs but this is different, unless the 1862 is a special case that I'm not aware of. Maybe someone with direct experience with the 1862 will chime in.

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