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Old 21st July 2012, 10:12 AM   #251
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Quote:
Originally Posted by massimo View Post
With a 3.300uF o/p cap?
Great catch. I see your point. Charging and discharging this cap by the input resistance of F5 willl be long. Load the [Amp Camp Amp] with a 33-100 Ohm resistor. I read it somewhere that Mr. Pass prefers any amp to do some work. Or resize the ouput cap!
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Old 21st July 2012, 10:24 AM   #252
flg is offline flg  United States
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R14?
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Old 21st July 2012, 11:50 AM   #253
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Originally Posted by flg View Post
R14?
Thanks flg. The existing R14 = 1K Ohm [in amp] is to discharge the output capacitor. I see this Amp Camp Amp [ACA for short] doing double duty. A switch at its output to select either 'power amp' or 'pre-amp'. Either way, a volume control at its input is needed. Music Source to ACA to loudspeaker or music source to ACA to F5 or other to loudspeaker.
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Old 21st July 2012, 12:20 PM   #254
Jay is offline Jay  Indonesia
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I thought the Amp#1 was for beginners. Couldn't possibly compete with the other preamps already discussed in this thread, or I've missed something.
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Old 21st July 2012, 12:45 PM   #255
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Originally Posted by Jay View Post
I thought the Amp#1 was for beginners. Couldn't possibly compete with the other preamps already discussed in this thread, or I've missed something.
Your analysis may well be correct in the end. Still, your [bolded] statement is nonetheless a hypothesis. Prove it either way by doing the experiment. Maybe you [or others] have already built other low power Pass amplifiers of topology [opposed drains of output stage] like ACA [Zen, Aleph etc.]. Your hypothesis can then be easily/readily tested, and/or this experiment was already done.
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Old 21st July 2012, 04:20 PM   #256
Zen Mod is offline Zen Mod  Serbia
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that hypothesis is tried long ago

there are myriad of much better solutions , for preamp duty

but - if using it as is for preamp amuses you , that's also completely valid reason
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Old 21st July 2012, 05:02 PM   #257
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Thank you Zen Mod. Case closed.
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Old 22nd July 2012, 07:18 PM   #258
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Thank you Zen Mod. Case closed.
There was an earlier request for a headphone ACA. I have a simple and painless method to do so for any amp devoid of a headphone port. Please visit the last 4 threads in Headphone Systems entitled "Does anyone make their own headphones". Best
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Old 22nd July 2012, 08:06 PM   #259
Jay is offline Jay  Indonesia
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There was an earlier request for a headphone ACA. I have a simple and painless method to do so for any amp devoid of a headphone port. Please visit the last 4 threads in Headphone Systems entitled "Does anyone make their own headphones". Best
Yeah, the ACA#1 looks suitable for headphone amp. Actually, it seems also suitable for power amplifiers (strictly with high impedance speakers), but may be not. I'm curious myself with this topology. I cannot find anything wrong except visually, i.e. use of N-N that forces feedback resistor to connect input to output.

I'm building the ACA#1 with IRFP460 (which gives better simulated performance than IRFP240), starting today and hope to be completed tomorrow (today I have finished the chassis, PCB, simulation and parts gathering). Unfortunately this is for a friend so I will not be able to review its performance (It needs time to review the performance as I guess there will be some kind of "boring effect", even tho the current drive is good).
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Old 3rd August 2012, 12:20 AM   #260
Mr. dB is offline Mr. dB  United States
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Pardon me for being dense, but do I understand correctly that some people are suggesting the BA3 input board for a line-stage preamp?
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