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ACP+ Preamp/HPA for Yarra Preamp
ACP+ Preamp/HPA for Yarra Preamp
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Old 17th June 2020, 06:29 PM   #21
MShipmanPE is offline MShipmanPE  United States
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I’ll ask a dumb question. Any resistor changes for HD650 or if I buy a pair of the ESS 422H.

Got any noise floor / harmonic profile graphs?
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Old 17th June 2020, 07:29 PM   #22
xrk971 is offline xrk971  United States
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ACP+ Preamp/HPA for Yarra Preamp
This thing runs a pretty hot bias current at 140mA - it can handle 32ohm headphones like 422’s just fine. Certainly 300ohm like HD650 will be more than enough current.
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Old 17th June 2020, 10:43 PM   #23
pwagner is offline pwagner  United States
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Like to join the GB for 2 prepopulated boards if you get the minimum # necessary. Otherwise, I take 2 non prepopulated.


pwagner / SMT prepopulated / 2 boards / USA
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Old 18th June 2020, 05:23 AM   #24
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by MShipmanPE View Post
Iíll ask a dumb question. Any resistor changes for HD650 or if I buy a pair of the ESS 422H.

Got any noise floor / harmonic profile graphs?
Havenít had a chance to measure it yet. Will see what I can do.
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Old 18th June 2020, 06:59 AM   #25
xrk971 is offline xrk971  United States
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GB status update.

Quote:
MShipmanPE / SMT Prepopulated / 2 boards/ USA
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
Pwagner / SMT Prepopulated (if enough interest) / 2 boards / USA
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Old 20th June 2020, 10:02 AM   #26
adn6244 is offline adn6244  Singapore
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Hi X,
Is this project suitable to be used as preamp for class D amp? If not, could you recommend one from your shop?

Kit
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Old 20th June 2020, 02:32 PM   #27
xrk971 is offline xrk971  United States
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Are you looking for a neutral preamp or one that imparts some SE Class A flavor to the sound? What Class D amp? How much gain do you need?

The Yarra preamp is a great choice because it is a foundation upon which low cost modules like this ACP+, or any number of 7 or 8 other preamp topologies can be selected and used by swapping out the daughterboard.

The ACP+ is a very nice sounding quite neutral preamp with a SE Class A flavor. It is very powerful and can drive low impedance loads like 32ohm headphones.

For general purpose preamp use, I recommend the Melbourne daughterboards.

For simple to build and great resolution and a bit of SE Class A sound, the Hakuin is tops.
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Old 20th June 2020, 07:21 PM   #28
adn6244 is offline adn6244  Singapore
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I am looking for preamp for TPA3255 amp that I'm planning to buy or build. At the moment I have a 3116 amp with a bad volume control.

So it's either Yarra + Melbourne or Hakuin/ACP+ depending on the sound signature I'm after.
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Old 20th June 2020, 07:28 PM   #29
thompsontechs is offline thompsontechs  United States
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ACP+ Preamp/HPA for Yarra Preamp
My advice.... Build them all! The only way to know for sure.
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Old 20th June 2020, 07:49 PM   #30
adn6244 is offline adn6244  Singapore
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If I have the time, that's ideal !

Can I connect 6 ACP+ or Hakuin to single volume pot and use it as multi channel preamp?
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