Thanks all. I have already purchased and installed the Vishay resistors I mentioned previously. Just wanted to make sure they wouldn't cause an issue vs the Panasonic. Definitely overkill in terms of price, but as long as they will work for this application, I'm ok with it.
Thank you Dennis! So far so good. Just wish I could find more time to work on it. Appreciate the help.
Sorry for the delay in reply. It was not a tight squeeze and seemed to fit the board very well. I'm getting closer on this project. I have finished the power supply board, amp boards, mounted the amp boards to heat syncs, and now beginning to wire up the PSU. Realized I can't find my crimp tool so had to order one of those. I'm definitely enjoying this project as opposed to a kit as there is a good bit more thinking involved even with the amazing instructions provided here.
So glad to hear that the guide I put together is still helping people! Let me know if you have any edits to propose (other than component substitutions, which would be a never-ending chore, given fluctuations in inventories).
Thanks flohmann and JeyDee.
I got the PSU built and tested yesterday and so far it looks like everything is checking out.
One thing that I noticed that I am assuming is a minor anomaly instead of an issue, is that the positive voltage coming off of the Power Supply board is 25.30V while the negative voltage is -25.25V. Is that a large enough of a difference to troubleshoot or is that within the realm of normal?
While hooked to the dim bulb tester the voltage was the same at positive and negative terminals but while connected directly to the wall there was that minor fluctuation.
Next up will be powering up the amp boards for testing!
I got the PSU built and tested yesterday and so far it looks like everything is checking out.
One thing that I noticed that I am assuming is a minor anomaly instead of an issue, is that the positive voltage coming off of the Power Supply board is 25.30V while the negative voltage is -25.25V. Is that a large enough of a difference to troubleshoot or is that within the realm of normal?
While hooked to the dim bulb tester the voltage was the same at positive and negative terminals but while connected directly to the wall there was that minor fluctuation.
Next up will be powering up the amp boards for testing!
Got the amp put together and it sounds great! This was one of the most fun projects I've worked on in recent memory. Thanks again to @flohmann for the great guide. I made some dumb mistakes along the way (eg. accidentally destroying the power switch by pulling out one of the lugs due to the super tight Panduit quick disconnects. Funny enough, I learned how to disassemble and completely rebuild the switch which is a new skill I never knew I was going to need lol. I did order a new switch since the first one was compromised but I did make it work temporarily.)
I have been experimenting with the bias. I currently have the bias set to 430mV even though the build guide said to aim for 400mV. I read on the other thread a lot of folks were biasing for 430mV due to it possibly lowering distortion. Just curious what the general consensus is here and what most of you all are setting bias to? I feel that with the higher bias the sound is possibly more "powerful" with a stronger low end, but the dynamics are a bit less and the sound is a bit more one dimensional.
I have been experimenting with the bias. I currently have the bias set to 430mV even though the build guide said to aim for 400mV. I read on the other thread a lot of folks were biasing for 430mV due to it possibly lowering distortion. Just curious what the general consensus is here and what most of you all are setting bias to? I feel that with the higher bias the sound is possibly more "powerful" with a stronger low end, but the dynamics are a bit less and the sound is a bit more one dimensional.
@gwompki You are hearing the changes in the AC gain of the current source more than actual differences in the bias. (Although both are changing)
The right answer is to set it where you like it the best, as it’s your system. A general consensus doesn’t matter. If this is on the hotter side of bias, make sure things are still staying cool enough.
The right answer is to set it where you like it the best, as it’s your system. A general consensus doesn’t matter. If this is on the hotter side of bias, make sure things are still staying cool enough.
I am happy for you. I have built it and all measurements looks ok, but the sound for me is disappointing. I would like to know what speakers you have. Thanks.
Yeah... my observations are the same. I also settled at 430mV bias. I can clearly hear the change in sound character, from the moment I turn the amp ON (480mV bias)... until the bias settles at 430mV.
Any chance you can show us the inside photos?? We might be able to provide a few pointers on how to improve the sound... I think you mentioned in one of the posts Dynaudio speakers... I also have Dynaudio speakers, but the sound is great. Once you get the amp running stable, you could consider removing the C1 (this will improve the sound even further... a lot!)... and the short circuit protection...
I did not solder in the bypass C6, C7, because the dudes here said those were not there in the original.
So I reused them as filter caps in the PSU, instead. 🙂
Maby i should have A/B tested it, but since i Really, Really like the sound of them amps i am in no real hurry about just that.
But? Perhaps sometime in the far, far future. In another galaxy… 🎷🙂🎸
So I reused them as filter caps in the PSU, instead. 🙂
Maby i should have A/B tested it, but since i Really, Really like the sound of them amps i am in no real hurry about just that.
But? Perhaps sometime in the far, far future. In another galaxy… 🎷🙂🎸
That's great that you can run classA amp without heatsink. That's the biggest expense in classA amps. Congrats to that.
I build few versions of AlephJ and they all required big modushop 4U chassis and worked very well with any speakers i tried.
Great amp.
Well, that's because you have to get the basics right first. Using CAT5 wires to connect the MOSFETs to the PCB is not good at so many levels.... the damping factor will suffer a lot (there'll be no control of the bass cone excursion at all, especially with 4 ohms driver...) and you will have oscillations happening as well, which are hard to capture (you'll need a fast oscilloscope... at least 100MHz or faster).
Once you mount the MOSFETs straight onto the AMP PCB, there are still many dangers lurking, that could degrade the final performance.
Place the MOSFETs onto the AMP PCB first, wire the amp up and then show us the photos of what you did... I am sure we'll be able to help further. You should be able to get a really great-sounding amp.
Then, in the end, you can remove the C1 cap and see if you like the sound better without it.