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Old 5th November 2019, 02:34 PM   #21
2 picoDumbs is offline 2 picoDumbs  Australia
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I’m burning with envy
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"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass
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Old 5th November 2019, 04:02 PM   #22
Dennis Hui is offline Dennis Hui  Canada
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Fantasic! Thank you Papa (and Jim)
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Old 5th November 2019, 07:23 PM   #23
Antoinel is offline Antoinel  United States
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Quote:
Originally Posted by Vix View Post
Nice

Fulfills three audiophile wishes:

1.Has the right amount of H2 (so, no need for H2 generator)
2. It is a hi-end headphone amp
3. And, can also serve as 1 Watt amp
Hello Vix.

I have Grado Labs's Model SR 80 headphones [$99 many moons ago] which are 32 Ohms/phone. Using the scope, I find that music signals of amplitude equal to 100 mV peak to peak is plenty drive for my comfortable and extended listening. Thus, the amp's required output current calculates to 0.0011 A (rms). And the power dissipated in each phone is [0.0011A X 0.0011A X 32 Ohms X 1000= 0.039 milli Watts.

H2 negative phase [H2np] is very small at this power level per the graph showing distortion versus output power [in milliwatts]. I do not know how to translate the 1% [H2np] which is suggested by Mr. Pass for/in high power amplification to that at this earphone level. The very low distortion of this amp driving my Grado's operates in a state like that of STASIS; meaning at a constant voltage across and a constant current through the amplifying devices.This amp is accurate.

Best
Anton
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Old 5th November 2019, 07:26 PM   #24
JSA1971 is offline JSA1971  Canada
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Quote:
Originally Posted by 6L6 View Post
Photos of the not-quite-final BAF'19 Workshop PCB, but close enough that it's fine for illustration.
Looks Great!
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Old 5th November 2019, 07:26 PM   #25
JSA1971 is offline JSA1971  Canada
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Quote:
Originally Posted by Dennis Hui View Post
Fantasic! Thank you Papa (and Jim)
+1 👏🏻
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Old 5th November 2019, 08:01 PM   #26
MEPER is offline MEPER  Denmark
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Could be fun to built it and add real speaker terminals so it can be both a pre, headphone and "integrated" amp. Seems to be close to a real 1W RMS power amp into 8 ohm?
Output transistors could be mounted on real heatsinks or just chassis. The ACA chassis may be used?
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Old 5th November 2019, 08:14 PM   #27
6L6 is offline 6L6  United States
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You'll need extremely efficient speakers (like Nelson's 99dB Tannoys) to actually get away with using it as an integrated amp. Remember that it's being powered by a 500mA wall wart! Those people so inclined will be able to take the output from the headphone jack or the line out RCA jacks.

Including speaker jacks would lead to many people trying it and being disappointed.
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Old 5th November 2019, 08:29 PM   #28
batty is offline batty  Australia
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Thanks again Nelson, this will be high on my RADAR.
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I have gone from 85 watts class AB amplification to an ACA.Gone on to the M2X.
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Old 5th November 2019, 11:50 PM   #29
aspringv is offline aspringv  Australia
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Well, dang.

I've the parts at home to make something quite close though, and some cases that might do the trick.... Hmmmm.
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Old 6th November 2019, 12:20 AM   #30
woofertester is offline woofertester  United States
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Very happy to see this released. The BA3 pre was awesome. Looking forward to building this NP creation. Thank you Mr. Pass for sharing.
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