Why not thinner the legs with abrasive paper? Done it with great success in the past
Enhance your workshop's tool collection by purchasing (product 1) and (product 2) and (product 3) . Now you can make the leads fit the holes.
Here's the case I put together. Made some dumb mistakes (like making the power switch hole in the wrong place so I had to make it again), and there's a bunch more tweaks I want to do (I replaced the input caps (again) with Nichocon caps which are even better (though the difference is small), but now I'm going to move back to the power supply, which was delayed because I accidentally blew up the transformer and had to buy another one. However, I have it all set and the case drilled and so it should be ready soon.
Can I use lsj74 quad with idss value of 11.4ma?
In this case, should I increase ccs value to more than 10ma?
Thanks
In this case, should I increase ccs value to more than 10ma?
Thanks
Hi, I have built the ACP+ incorporating additional DPDT switch into the chassis as shown in the photos attched as I am planning of having a selectable high/low impedance switch while not affecting the line out net Rout value.
I have drafted out the wiring diagram as shown in the attached for your reference. Does it looks correct?
Wil
Ir's been over five years since I have looked at this so it took me a while to get my head back into it, but I think it looks right. 🤓
Just wanted to do a follow up post that adding the dpdt (on-on) switch as per my earlier wiring diagram doesn’t really work the way i wanted it to be.
Switching to low R actually added all the resistors in series together at the line out to ground. No problem switching to high R so I’ll just leave it as it is until i find another switching solution to do that.
Reason to do this mod is that both my HD600/650 are 300ohm. The bass will sound boomy when cranked up on the original 32ohm output. This mod result in a more articulated bass.
I compared the modded ACP+ to my other opt tube amp and i can confirm that they are quite close in terms of sound quality. The ACP+ is definitely more clean and accurate. Both have the transparency that works very well with the Sennheiser.
I would like to thanks Nelson Pass and the community for creating this opportunity for me to experience building this wonderful HPA. Oh ya and it did paired very well with my bridged ACA on my desktop setup.
Switching to low R actually added all the resistors in series together at the line out to ground. No problem switching to high R so I’ll just leave it as it is until i find another switching solution to do that.
Reason to do this mod is that both my HD600/650 are 300ohm. The bass will sound boomy when cranked up on the original 32ohm output. This mod result in a more articulated bass.
I compared the modded ACP+ to my other opt tube amp and i can confirm that they are quite close in terms of sound quality. The ACP+ is definitely more clean and accurate. Both have the transparency that works very well with the Sennheiser.
I would like to thanks Nelson Pass and the community for creating this opportunity for me to experience building this wonderful HPA. Oh ya and it did paired very well with my bridged ACA on my desktop setup.
Attachments
Hi all, I actually redid my power supply a while a go, but forgot to take a picture. So here's the revised internals of my Sigma11 power supply for my ACP+ with the hot glue removed and components screwed in properly:
I also made a video for my YouTube channel in which I talk in some depth about the process of building the power supply and the ACP+, compare it to my other preamp/headamps and show some detailed distortion measurements. Let me know if you have any questions or comments, happy to discuss.
I also made a video for my YouTube channel in which I talk in some depth about the process of building the power supply and the ACP+, compare it to my other preamp/headamps and show some detailed distortion measurements. Let me know if you have any questions or comments, happy to discuss.
@ericrosenfield I watched your video and hoped you might comment on what differences you hear/measure between the two commercial power supplies and the one you built.
Oh you're right! I completely forgot about that even though I open the video with a long explanation of power supplies. That's an oversight.
The short answer is that the Jameco linear power supply sounds a little better--clearer mostly--than the stock one, and the custom power supply sounds better than that--clearer and a bit more muscular I'd say. However, the differences are relatively small and not night and day. (This is from memory, though when I get a chance I'll do another comparison and make sure it conforms to my memory.)
Thanks for the video and the mods, I'll try them out soon when parts arrive.
Also, have you tried digital volume control and running the amp as a power amp? Meaning you open the potentiometer volume all the way and use your dac as volume control, if your dac has volume control. I tend to get better audio that way.
I have high efficiency speakers (98 dB) and have tried my ACP+ as a power amp. It sounded great, but the bass seemed a bit weak.