Salas hotrodded blue DCB1 build - Page 257 - diyAudio
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Old 12th January 2013, 08:11 AM   #2561
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I haven't got the schematic at hand at the moment, I'm at work. Q7 is acting as a zener, wasn't doing the job properly on mine. I just replaced it with a zener diode.

Also Q8 must be the Darlington specified for it to work properly.

Last edited by KatieandDad; 12th January 2013 at 08:13 AM.
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Old 12th January 2013, 08:33 AM   #2562
Salas is offline Salas  Greece
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I would rather lean towards that particular bc517 needs some aid. Try a 33-100nF ceramic across b-c.
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Old 12th January 2013, 08:39 AM   #2563
kroyin is offline kroyin  India
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Quote:
Originally Posted by KatieandDad View Post
I haven't got the schematic at hand at the moment, I'm at work. Q7 is acting as a zener, wasn't doing the job properly on mine. I just replaced it with a zener diode.

Also Q8 must be the Darlington specified for it to work properly.
All I got is a handdrawn circuit in tea bags blog,can you point me to the circuit which you are receding to.
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Old 12th January 2013, 08:45 AM   #2564
Salas is offline Salas  Greece
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Do that with the Miller capacitor first. What brand and type is the relay? Is that issue on an official board?
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Old 12th January 2013, 09:05 AM   #2565
kroyin is offline kroyin  India
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Quote:
Originally Posted by Salas View Post
I would rather lean towards that particular bc517 needs some aid. Try a 33-100nF ceramic across b-c.
That actually helped..I get 2mv offset & relay click..thanks.
No ceramic though I have 100nf fkp mks fks..what is better?

Yes official black board,relay is Panasonic tq2-12
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Old 12th January 2013, 09:13 AM   #2566
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The type of capacitor here is not important as it is only operating the relay.
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Old 12th January 2013, 09:22 AM   #2567
Salas is offline Salas  Greece
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So it got solved, cool. First time a BC517 had to be aided. Wondering about its make. As for that cap's dielectric, indifferent as K&D wrote already.
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Old 12th January 2013, 01:51 PM   #2568
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Still regarding sources is it safe to assume that a well implemented dac like the odac or buffalo will have the guts to drive the dcb1?

the "weakest" source would be the phono stage, ios devices will be only ocasional so not critical at all!

Also, the dcb1 will be driving a F5Turbo, isn't the output impedance of the dbc1 kind of highish for it?
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Old 12th January 2013, 03:29 PM   #2569
Salas is offline Salas  Greece
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The phono has around 65 Ohm output Z only. You may need 5.6uF output cap in it for 10K pot though. DCB1's output Z is about 260 Ohm.
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Old 14th January 2013, 08:42 AM   #2570
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Hello all.
I must admit. I really really like this dcb1.
I have a couple of questions I hope someone can answer

1. I notice some people make the dcb1 balanced. What are the benefits of this? and what are the drawbacks? I am thinking soundwise....
2. Is it possible to use as an analog stage in a good dac? (it probably is )
3. If I want to do the above and use lightspeed and dcb1 as a linestage. Would the "chain" be like this?
dac_digital -> dcb1_analog_stage -> lightspeed_pot -> dcb1_preampbuffer -> poweramp

Or can I make it even simpler (and possible) better if the electric parameters of dac_digital, dcb1, poweramp are good for this?

It may seem as if me somewhat expensive Audio Note OPT based preamp is getting an early retirement.......

Actually (this may seem a bit strange). The dcb1's sound is not that far from the AN. But it is more quiet...

Maybe it is the sound of nothing?

Thanks in advance.
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