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Old 11th August 2008, 07:34 AM   #441
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Default Re: deja vu ?

Quote:
Originally posted by Zen Mod


http://www.diyaudio.com/forums/showt...59#post1555159
Hmmm, not a deja vu. If using some kind of feedback in a op amp my limited knowledge would tell me that part of the eq must be in that loop. In the version before, both C4 and C5 goes to ground and then easy to adjust and understand, perhaps.......... at least very easy to build.
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Old 13th August 2008, 11:49 PM   #442
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Default DC On Input?

Hi, Sorry if this has been asked before.

Can the B1 take 2v DC on its input? I want to put the B1 directly after a voltage output DAC chip that has 2v DC on it.

I have a blocking cap on the both the input and output of the B1 right now but would like to omit the input cap if it's possible to do so safely. Will keep the output cap in place to block DC from the buffer to my amplifier input.

One less cap in the signal path seems like a good idea .

Anyone know if this is ok to do?

Thanks
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Old 13th August 2008, 11:57 PM   #443
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Default Re: DC On Input?

Quote:
Originally posted by TV Man
Hi, Sorry if this has been asked before.

Can the B1 take 2v DC on its input? I want to put the B1 directly after a voltage output DAC chip that has 2v DC on it.

I have a blocking cap on the both the input and output of the B1 right now but would like to omit the input cap if it's possible to do so safely. Will keep the output cap in place to block DC from the buffer to my amplifier input.

One less cap in the signal path seems like a good idea .

Anyone know if this is ok to do?

Thanks

you can't do that if you're using B1 with single supply
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Old 14th August 2008, 01:55 AM   #444
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Yes, it's single supply.

So we can't have any DC on the input of the buffer even if we have DC blockers on the output of the buffer to stop the DC from being passed to the component downstream. Is it a bias issue?

Thanks,
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Old 14th August 2008, 02:06 AM   #445
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Quote:
Originally posted by TV Man
Yes, it's single supply.

So we can't have any DC on the input of the buffer even if we have DC blockers on the output of the buffer to stop the DC from being passed to the component downstream. Is it a bias issue?

Thanks,

exactly - bias issue

you can try that , but only if you use split PSU , counting that lower JFet will do biasing and compensate that 2V shift ;
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Old 14th August 2008, 02:24 AM   #446
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Ok, thanks

I was looking at Mr. Pass' schematic on enjoythemusic.com thinking C100 and C200, the 1uf caps right after 1k ohm R102 and R202 would block DC at the input of the buffer making it unnecessary to have a DC blocker on the output of the component in front of the buffer.
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Old 14th August 2008, 02:35 AM   #447
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Quote:
Originally posted by TV Man
Ok, thanks

I was looking at Mr. Pass' schematic on enjoythemusic.com thinking C100 and C200, the 1uf caps right after 1k ohm R102 and R202 would block DC at the input of the buffer making it unnecessary to have a DC blocker on the output of the component in front of the buffer.



that's different than your previous asking ......

like this :
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Old 14th August 2008, 02:35 AM   #448
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Assuming that I'm understanding the question correctly, yes, the caps will block DC.
As long as the DC does not exceed the wattage rating of the pot--no problem at mid or low point, but possibly so at nearly full volume when the heat is dissipated across a very short length of resistive track--then you should be okay.

Grey
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Old 14th August 2008, 05:20 AM   #449
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Quote:
Originally posted by GRollins
Assuming that I'm understanding the question correctly, yes, the caps will block DC.
As long as the DC does not exceed the wattage rating of the pot--no problem at mid or low point, but possibly so at nearly full volume when the heat is dissipated across a very short length of resistive track--then you should be okay.
The input impedance of the circuit is very high, so it would take a
scary amount of input DC.
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Old 14th August 2008, 09:56 PM   #450
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You're right. I was trying to work from memory and obviously lost track of something, somewhere. I downloaded a copy of the schematic and scratched my head--can't reconstruct my line of reasoning. Oh, well...

Grey
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