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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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ACP+ Preamp/HPA for Yarra Preamp
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.

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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Old 27th November 2020, 01:01 AM   #67
xrk971 is offline xrk971  United States
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Join Date: Oct 2012
Location: Metro DC (Virginia)
ACP+ Preamp/HPA for Yarra Preamp
GB status 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 *Pre-Order Placed*
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*
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Old 27th November 2020, 08:29 PM   #68
xrk971 is offline xrk971  United States
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Hi Folks,
We are going to test out the lower bias current configuration before committing to get the BOM for all the prepopulated SMT boards. So this will take another week or so then we will be in production. I have the PCBs and solder stencil already. Just need to order the MELF resistors and the opto and BJT. We are moving forward with this. Please place your pre-order soon if you are interested in the prepop'd board as the window is closing soon.
Thanks,
X
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