ACP+ PCB Updates.
While I was building another ACP+, I had difficulty to get exact 10mA CCS with J113.
On-semi J113 with 121ohm only had 7-8mA, old stock Vishay J113 had only 5-6mA.
I do not think it is manufacturer dependency, but J113's Vgs/Idss spread.
Getting good combination of J113 and Resistor value will be pain.
I have updates on my ACP+ PCB design.
1. Both Axial and Radial Capacitor can be used for C1. (8mm diameter for Radial Capacitor)
2. J113 now changed to LM317L. J112 (J113) still can be used in reverse direction.
Note 125Ω for R4 is still valid for LM317L also!
3. Trimmer can be mounted in R4's place (3296W) when J112 is used for CCS.
Then the user can set exact 10mA CCS.
While I was building another ACP+, I had difficulty to get exact 10mA CCS with J113.
On-semi J113 with 121ohm only had 7-8mA, old stock Vishay J113 had only 5-6mA.
I do not think it is manufacturer dependency, but J113's Vgs/Idss spread.
Getting good combination of J113 and Resistor value will be pain.
I have updates on my ACP+ PCB design.
1. Both Axial and Radial Capacitor can be used for C1. (8mm diameter for Radial Capacitor)
2. J113 now changed to LM317L. J112 (J113) still can be used in reverse direction.
Note 125Ω for R4 is still valid for LM317L also!
3. Trimmer can be mounted in R4's place (3296W) when J112 is used for CCS.
Then the user can set exact 10mA CCS.
Attachments
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But oh so appropriate considering it was unveiled at Burning Amp!
Cool build! Volume pot seems to be hot
Dirk
Hi, Nisbeth,
Thanks for your reply.
I uesd to make some projects on spare boards. Unfortunately, they all were failed. So, I think the better way for me is to find some PCB to make ACP+.
Do you have some boards for me. I love to pay for it.
I have some extra boards. You can message me with your shipping info.
Bruce
For anyone wanting to implement this into their M2X builds, X has started a group buy for the small format boards that complement M2X and his Yarra motherboard . I am keen to try this for sure ..dB
Does the front end then become like a Pass A3?
Secondly , if I replace the outputs with IXTA6N50 (power J-Fets) , adapting some values , would it then become like a J2 (and become a MeToo)?
I looked in the store but found none and no anouncement (pre-order). Did I look at the right place?
Hi, Nisbeth,
Thanks for your reply.
I uesd to make some projects on spare boards. Unfortunately, they all were failed. So, I think the better way for me is to find some PCB to make ACP+.
Do you have some boards for me. I love to pay for it.
Same problem on this side of the globe. Mostly one channel OK, the other different and debugging gives bugs in my head
so I have a cabinet with partial builds and many many variants of power supplies.
when done properly , you'll not hear bloody difference between CCS variants
much more
Why not use a single resistor, no CCS at all? Hiraga said that would give lower harmonic distortion, and so it simulates: 87 vs 80 db
Would there be a bloody difference in hearing?
[I don't know, still trying to get a PCB ; and working on an ACA for headphone right now]
Why not use a single resistor, no CCS at all? Hiraga said that would give lower harmonic distortion, and so it simulates: 87 vs 80 db
I think you had better tell Nelson Pass quickly, that you believe he has made a mistake in the design of ACP+. Otherwise he might make the same mistake again.
Of course not ! I hold him in high esteem.
I am just playing around with what I have at hand.
Or in my mind.I hope I'm not the only one here like that.
Hi,
i had some pcbs left ... version from withmatt
Costs: 12,50€ (I ordered the min sets)
Shipping in padded envelope (no tracking, no insurance) to:
- Germany (without islands): 2€
- Shipping in EU: 4€
- other countries please ask
For other shipping options please ask also. Please contact me via PM, thanks.
i had some pcbs left ... version from withmatt
Costs: 12,50€ (I ordered the min sets)
Shipping in padded envelope (no tracking, no insurance) to:
- Germany (without islands): 2€
- Shipping in EU: 4€
- other countries please ask
For other shipping options please ask also. Please contact me via PM, thanks.
Attachments
Driving a step up transformer?
Hi,
I have a question about what loads the ACP can drive.
I have a MoFo, and I'm experimenting with adding an Edcor XMS10k/150 transformer on the front end to step up the input signal. This works as expected with a Schiit Vali 2, but when driven by the ACP there's no bass. This is quite obvious when listening to music, and I double checked by playing white noise and sampling it with an audio analyzer app on my phone - photos attached.
To complicate things, I notice the transformer I received from an ebay seller (with a high feedback score) doesn't look quite the same as the one in the picture from Edcor - the bobbin on mine is white, while Edcor explicitly calls out theirs as blue. Even if I did end up w/ a counterfeit ($15/ea), I don't think that would explain the performance difference between the two pre-amps. The DC resistance I measure on the two coils is 63R and 490R, with the pre driving the lower one.
I tried adding some resistance (>1000) in front of the transformer to bring the load seen by the ACP back to its preferred 33R, but that didn't seem to make any difference.
Does anybody have any idea what might be going on? I would much prefer to use the ACP over the Schiit.
Hi,
I have a question about what loads the ACP can drive.
I have a MoFo, and I'm experimenting with adding an Edcor XMS10k/150 transformer on the front end to step up the input signal. This works as expected with a Schiit Vali 2, but when driven by the ACP there's no bass. This is quite obvious when listening to music, and I double checked by playing white noise and sampling it with an audio analyzer app on my phone - photos attached.
To complicate things, I notice the transformer I received from an ebay seller (with a high feedback score) doesn't look quite the same as the one in the picture from Edcor - the bobbin on mine is white, while Edcor explicitly calls out theirs as blue. Even if I did end up w/ a counterfeit ($15/ea), I don't think that would explain the performance difference between the two pre-amps. The DC resistance I measure on the two coils is 63R and 490R, with the pre driving the lower one.
I tried adding some resistance (>1000) in front of the transformer to bring the load seen by the ACP back to its preferred 33R, but that didn't seem to make any difference.
Does anybody have any idea what might be going on? I would much prefer to use the ACP over the Schiit.
