Tube Amp Archive

Well... then it is correct. I think that I went through most of the thread, but I haven't seen that stated by Mr. Benson :) Still think that xFB is a better fit for the circuit and intend to keep it. EB are more suitable for op-amp (~TL072) driven circuits. To each its own I guess. Niki Yeah, that ...

Synchu wrote: ↑Tue May 18, 2021 5:56 am I don't really see how xEB is "correct"?

This is what Benson puts in there is what he's saying.

The good news is that I don't plan on playing the amp with the volume off. :) Took this to band practice last night, and it did really well. Does particularly well with certain drive pedals - super rich, harmonic overdrive. My main kinda 'base' drives are a Bondi Sick As (modified Klone), and a Sey...

The good news is that I don't plan on playing the amp with the volume off. :) Took this to band practice last night, and it did really well. Does particularly well with certain drive pedals - super rich, harmonic overdrive. My main kinda 'base' drives are a Bondi Sick As (modified Klone), and a Seym...

I think I have it figured... put the PI balance ground to the negative side of the node C/D caps, grounded the reverb to the chassis on the same lug as the preamp, but on a separate lead. It's not *silent* but it's dang quiet. If I roll that PI balance all the way counter clockwise it is quietest (a...

The reverb signal grounding can be really fussy and easily creates ground loops depending on the grounding scheme of the tank. Ya know, If the cap isn't the issue. Mike This may be where I need to look next. Replaced that cap w/ a .047uF cap, and things are much improved, if not fixed. The hum/buzz...

Moving the ground for the balance pot waaaay down to the end w/ the preamp ground does seem to have gotten rid of the bad hum... but also introduced a far more irritating oscillating click and static... I have the power amp grounded to the same lug as the CT for the PT primary - is this a bad idea?...

Moving the ground for the balance pot waaaay down to the end w/ the preamp ground does seem to have gotten rid of the bad hum... but also introduced a far more irritating oscillating click and static... I have the power amp grounded to the same lug as the CT for the PT primary - is this a bad idea? ...

mikeywoll wrote: ↑Wed Apr 21, 2021 3:34 pm
Ground for the trim pot? That should be pre-amp as well.

Grid resisters on the tube? Hiss sounds like RFI.

Mike

I'll start with the trim pot ground.

pullshocks wrote: ↑Wed Apr 21, 2021 5:44 am
Do you have the DC heaters implemented? If still running AC heaters, did you try connecting the 6.3 V center tap to the junction of the 6V6 cathodes and the Cathode resistor + cap?

I still have AC heaters, but I did move my 6.3v CT to that junction.

Anyone still running AC heaters and gotten rid of the hum? Wondering if that's what I need to look at next... have the parts, need to figure out space.

Hrm... well, made the following changes to mine tonight: Added a 4th node, and switched to 22/47/22/22 with 4.7K between nodes B and C and C and D. Sent node D to the preamp. Sent grounds for nodes C and D to the same ground as the preamp. Swapped V2 pins 2/7. Replaced the 1K resistor on the reverb ...

I find the switch very subtle. Look forward to trying this. Thanks for posting. Yep, I've found the switch to be *incredibly* subtle. I finally grabbed a few minutes this morning to update the layout I made with all of the changes from this thread... Attached are the new layout and a version where ...

My transformer is 300 - 0 - 300 (ClassicTone 40-18028), and I used a 5Y3 to get the voltage down into range, and I'm hitting pretty dang close to spec.

Yeah, the grid resistor placement is not not a universal rule, but in some cases can be necessary. The original amp has them on the tube, which is why I figured it's worth mentioning. Mike Fair enough - part of this specific layout was trying to get things to work into this tweed chassis I was alre...