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ACP+ Preamp/HPA for Yarra Preamp
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Old 21st November 2020, 04:01 PM   #61
Bones13 is offline Bones13  United States
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Thanks, I have some of those, so I’m good. Just wondered if you had an obscure source for the Fisher stuff.
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Old 21st November 2020, 08:55 PM   #62
xrk971 is offline xrk971  United States
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Regarding the Fischer heatsinks: Just need to know someone in Germany.

The ACP+ as designed is really for driving headphones. So the bias current is a rather high 150mA. It runs too hot with these tiny heatsinks.

dBel84 did the following changes to drop the current and it runs at 40C.

R111 = 3K
R115 = 3R2
R117 = 10R

I seem to recall these settings were for about 70mA bias current. Plenty as a preamp and even for higher impedance headphones.
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Last edited by xrk971; 21st November 2020 at 08:59 PM.
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Old 22nd November 2020, 12:01 AM   #63
Bones13 is offline Bones13  United States
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Any way you could offer the lower bias option before the SMT work gets done?

And what would you recommend to do the same for the Hakuin board?
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Old 22nd November 2020, 02:53 AM   #64
xrk971 is offline xrk971  United States
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We were already thinking of lowering the bias for the SMT prepop’d boards. The Hakuin is already set at a lower bias and heat is not an issue.
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Old 22nd November 2020, 02:55 AM   #65
Bones13 is offline Bones13  United States
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TYVM!
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Old 22nd November 2020, 01:07 PM   #66
xrk971 is offline xrk971  United States
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GB update:

Quote:
MShipmanPE / SMT Prepopulated / 2 boards/ USA *Pre-Order Placed*
Carl_Huff / bare PCB / 2 boards / USA
mnichols30030 / bare PCB / 2 boards/ USA
Thompsontechs / bare PCB / 2 boards / USA God Bless it in these trying times!
Aljordan / SMT Prepopulated / 2 boards / USA *Pre-order Placed*
Pwagner / SMT Prepopulated (if enough interest) / 2 boards / USA
jwjarch / bare PCB / 2 boards / USA * Order Placed*
meanie / SMT Prepopulated / 2 boards / SGP
diy40 / SMT Prepopulated / 2 boards / USA
Itsmee / SMT Prepopulated / 2 boards / UK *Pre-order Placed*
Bones13 / SMT Prepopulated / 2 boards / USA *Pre-order Placed*
Afoor / bare PCB / 2 boards / USA *order placed*
Thank you Mshipman!
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