Salas hotrodded blue DCB1 build - Page 256 - diyAudio
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Old 11th January 2013, 09:02 PM   #2551
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Quote:
Originally Posted by Salas View Post
Well done guys, enjoy. Pinnocchio, impressive build.
Thanks!
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Old 11th January 2013, 10:40 PM   #2552
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What is the input impedance of the DCB1?

I am planning on using the o2 relay based att from amb.org and need the input impedance of the next stage for resistor calculation.

Also is 25k a good value for the attenuator impedance? I've read that 20k is the best option but would 25k reduce the overall performance of the dcb1?

Last edited by MASantos; 11th January 2013 at 10:46 PM.
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Old 12th January 2013, 01:57 AM   #2553
Salas is online now Salas  Greece
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220K input is what the pot drives. 25K pot is not that bad. Use even 10K if your sources can take it.
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Old 12th January 2013, 02:08 AM   #2554
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Default 220 kohm input and without pot.

Hi in our Hificlub we will use the buffer only for high impedanse sources. One member have a Audionote dac with 0,47 uf. as coupling caps. That is far to small for ordinary sources. Is it ok with the 220 kohm only and no pot ?
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Old 12th January 2013, 02:21 AM   #2555
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The sources will be a simplistic riia or similar phono stage, some dac to be decided yet, ocasional iphone or ipad. No old tuners or tape decks so would 10k be acceptable?
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Old 12th January 2013, 02:58 AM   #2556
Salas is online now Salas  Greece
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Don't know the output impedance of Apple gadgets. Find the one source's Zo value to be used that has the highest output impedance and use 10x pot that. If that means more than 25K, avoid that source. SNJFET RIAA is OK with 10K. You will have to augment its output coupling cap accordingly though.
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Old 12th January 2013, 02:58 AM   #2557
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Quote:
Originally Posted by Erlend Sæterdal View Post
Hi in our Hificlub we will use the buffer only for high impedanse sources. One member have a Audionote dac with 0,47 uf. as coupling caps. That is far to small for ordinary sources. Is it ok with the 220 kohm only and no pot ?
Yes.
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Old 12th January 2013, 06:02 AM   #2558
kroyin is offline kroyin  India
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Guys I cannot hear the relay click (12v relay note is jumpered)
Vout is +-9.3v
V across 10R resistors is 1.3V
All led glowing
Vgs of all mosfets 3.9V (+-30mV)
Input output not connected
No DC offset no voltage across relay diode.

What do I look at?

Thanks in advance

Last edited by kroyin; 12th January 2013 at 06:30 AM.
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Old 12th January 2013, 06:43 AM   #2559
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I had the issue that the timing circuit was not triggering correctly.

Try measuring the voltage across the relay coil to see if it should have operated.
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Old 12th January 2013, 06:55 AM   #2560
kroyin is offline kroyin  India
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Hmm when I touch multimeter leads across B & C of bc517 relay clicks
Does not look a cold solder or short on inspection
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