It actually comes off the amplifier board. The PSU has one as well. Im sure I would be able to calculate the voltage at a given point if I had a better idea what I was doing, however.......Im painting by the numbers right now.Yes, the ones I listed are for the LED mod for replacing the Zener diodes.
The indicator LED is coming from power supply PCB, right? Sorry, I used a different set of PCBs for my F6 clone build, and not 100% sure about the diyAudio store PCB.
Thanks Mike, another question I’d like to add to my list is whether these amps change as they “break in“. Do amps “break in” or is that a popular myth?I don't know the answer regarding the cable splitter. However, the only way to run it balanced is to make it a monoblock. For two channels ran balanced, you would need four channel boards, two chassis and two power supplies.
There may be a workaround but I don't believe it'll actually be balanced.
Also would it be possible to install balanced inputs on the F6? Has anyone done it and have a wiring diagram?
I believe 6L6 has chimed in that he has not had "scorching" issues on the 3W resistors. I think the issue dates back to the old paper-based PCBs that didn't handle heat. I don't know what the coating was but I remember learning the hard way to raise the resistors as they would melt the coating and char the paper. I've not noticed any issues with, what I assume to be, glass-epoxy boards like diyAudio sells. Of course, mine have only been running for a few months now.I'd say " one more question " but that would suggest I'm almost done. So, another question. I seems soldering resistors so they touch the board isn't the best idea due to heat concerns. In the future I'll hold them off, but will these be an issue. And are any of the wild bends I have in these leads an issue. I would just rather correct now rather than compromise what I hope will be a great end product.
I couldn't stand it and got some desoldering practice. Things like that can haunt me. Especially if it sounds great, which it will if I do my part, I'll be thinking just that slight misstep will shorten it's life. Was actually good practice and it didn't cost much.I'm in the process of attempting balanced F6s but, as Mikerodrig27 pointed out, they amount to two stereo amps with a balanced XLR input. In my F6 journey, I ran across mention of doing balanced via a single board but it amounted to circumventing the phase splitter function of the transformer (and possibly that F6 signature sound). As it required some surgery on the signal board, my cost function didn't tip me towards attempting it.
This weekend, I'm hoping to get the 2nd set of boards mounted in my monoblocks and see if the DC offset is low enough to use.
There are a few issues that have had me dragging my feet:
1.) running in balanced mode, the output impedance doubles.
2.) running in balanced mode, the distortion signature changes.
3.) doubled the heat. Great in winter. Not so great in summer.
I've been enjoying these F6s "single-ended" so much that I've not been wanting to take them back apart.
If issue #1 causes a woolier bass response, I have a quad of F5 boards ready to pop in and try.
If issue #2 sours the sound enough, I may just revert back to single-ended operation. Or try an F4 setup. With a tube-based gain stage...
I believe 6L6 has chimed in that he has not had "scorching" issues on the 3W resistors. I think the issue dates back to the old paper-based PCBs that didn't handle heat. I don't know what the coating was but I remember learning the hard way to raise the resistors as they would melt the coating and char the paper. I've not noticed any issues with, what I assume to be, glass-epoxy boards like diyAudio sells. Of course, mine have only been running for a few months now.
Couple of questions
1. I've noticed that the bias voltage slowly keeps rising. When I set it at around 0.52V after 30 min of running I noticed that on cold start the bias is just about 0.47V and then slowly climbs up. Is this fine or should I set it so on cold start it is 0.5V and let it rise from there?
2. I've read that the offset won't remain steady at 0. It also seems to creep over time. What value is considered bad?