The Amp Garage

A MOSFET reducer, just like a zener in the same position, just places the high voltage CT one zener-voltage below the negative end of the first filter cap. As long as nothing else is connected and referenced to the CT, this all works fine, as the high voltage winding is galvanically isolated, and w...

As you can see, I settled on three sockets, 7, 8, and 9-pin. Anything else can be jury-rigged, and you can see several examples of that pictured in this thread.

I recall one uT3 build with just three sockets, all hard-wired, two as I described above, plus a second noval for EL84's.

I believe Tony D is using uTMax https://ampgarage.com/forum/viewtopic.php?p=450229#p450229 It has been around for quite some time (2015, maybe?), originally intended to increase voltage and current capability of the uT3. The uT3+ with 400V max Va/Vs and high-current mod is more than adequate now. I ...

Raoul Duke wrote: ↑Fri Apr 12, 2024 8:28 pm Are the LM7812CT and L7812CV functionally interchangeable?

Looks that way. One is STMicro and the other is TI. There will be different suffixes for different manufacturers or things like NoPb.

FWB on an isolated winding with CT unused should not have caused a problem unless there was some error. Possibly incorrect grounding?

What I meant was that one could start with any value for R1 and Rs (within reason) and as long as they can get to half of Vdd and ~ 9v, they will achieve the desired effect. I get stuck on the different values from layout to layout thinking R1 and Rs are part of the bigger “recipe” when in fact the...

Regarding the FET: so I could start with the plans values and work from there then because the “mega” isn’t so much dependent on the actual values - but rather the end result (however you get there)? I don't understand what you're saying there. You could use the 8k2 in the divider (with the 150k) b...

Nice, good to hear it worked out, and your monitors have a new lease on life!

OT secondary has one end grounded and has very low resistance, heater winding is also very low resistance and has a grounded center tap, so yes.

Move this to the For Sale/Trade section?

Sounds fine to me. Here is a case where I've tested the unloaded voltage on a current project with the PT and choke tack-soldered to the board, Heater circuit is not connected, of course. https://ampgarage.com/forum/viewtopic.p ... 85#p464385 No fuse, I just brought it up slowly with a Variac.

Trying to understand the “mega boost”/PAB in this amp. I understand that there’s some variation based on the individual amp - so the first question is: 1. Is PAB the same as “mega boost”? If not - what is the difference? Is it something unique not in the layout or schematic? BM stack has a single g...

I might just have to give it a try. What did Merren have to say about? Did he have any explanation as to why it would matter?

You have to try it yourself Franco, lossy mp3's are not going to cut the mustard. I had to live with it for a while to properly understand what I was hearing. The A/B box allows you to hear the difference straightaway, subtle, but noticeable... it takes a matter of time to determine whether you pre...

For the built-in D'lator I believe the best plan is making the D'lator signal grounds at the loop jacks. Do you have a branch off the screen filter for the loop power? That should be pretty clean; the negative leads of the extra filters can be grounded with the screen filter.