modifying my touring amp with Dumble tone stack..Which one?

[Colossal]

Imo,

Note that your values for R4 and R9 are reversed on both your schematic and layout. Refer to #102...unless your values are intentional, of course...

Thanks Colossal. I've moved towards a low plate classic circuit. The first two cathodes are 1.5k. I think that's what you are referring to

I was referring to the SPICE shematic shown in your first post. The values shown there are 102, but with the CL1 and CL2 cathode resistors reversed. But if you are going Low Plate, then all is moot. Carry on!

[imo1]

I decided to rebuild the board instead of trying to make it work around it. I realized it was a bit convoluted, so I took a bunch of stuff back out and focused on getting a solid layout.

I overly annotated to use as a checklist for my build. I've run through the layout a couple of times now and am not seeing any mistakes, but it's not built yet,

I'm building this largely modeled after Rootz's CRS version, but with a low plate, slightly different EQ section.
Should be making sound in the next week or so!

CR mod_new board.png

[Guy77]

I decided to rebuild the board instead of trying to make it work around it. I realized it was a bit convoluted, so I took a bunch of stuff back out and focused on getting a solid layout.

I overly annotated to use as a checklist for my build. I've run through the layout a couple of times now and am not seeing any mistakes, but it's not built yet,

I'm building this largely modeled after Rootz's CRS version, but with a low plate, slightly different EQ section.
Should be making sound in the next week or so!
CR mod_new board.png

This will make a great sounding amp. I built the one in the layout you posted from rootz's original post ( amazing post by the way). Then I built it again without the 2nd Master volume pot on the back of the amp as your layout describes and I liked it even better! I found the signal was hotter without the 2nd master in the back

Cheers

Guy

[imo1]

Thanks Guy!just confirming that you removed the master before the PI and kept the clean master
Did you put a resistor there or completely remove?

[Guy77]

Thanks Guy!just confirming that you removed the master before the PI and kept the clean master
Did you put a resistor there or completely remove?

Its the Master just before the Phase Inverter which I kept. In your layout its the Master at the rear of the amp. This is the same Master setup that Dumble used on his Overdrive Amps as well. Its the Master on the front of the amp in your layout which I omitted .

Cheers

[imo1]

Glad I checked. That seemed weird to keep the other one, without one for the power amp.
Did you put any resistance in its place?

[Guy77]

Glad I checked. That seemed weird to keep the other one, without one for the power amp.
Did you put any resistance in its place?

I changed the 470k resistor from the Receive jack (that meets the 68K resistor) to a 1M resistor.

[imo1]

That’s great as it seemed weird to me to have the two masters.
I would love to hear more about your build. What pre/eq did you go with? What is your playing style? I know there is tweaking involved to get these to each players space, but I am trying to start close to where I think intersects with my playing

[Guy77]

That’s great as it seemed weird to me to have the two masters.
I would love to hear more about your build. What pre/eq did you go with? What is your playing style? I know there is tweaking involved to get these to each players space, but I am trying to start close to where I think intersects with my playing

I actually build it like how you listed it in your layout (Low Plate).
I find I like this the best nice and smooth sounding on the cleans.

Guy

[imo1]

I had to wait for a bit for some board building parts. I had never installed eyelets before, and ordered the wrong depth for my board. I finally got them in, and they are solidly in, but the bottoms were a bit narrow. Definitely made installing multiple components challenging.

Ive got the 22U on the signal board. I know there are builds that have this, but I was a bit paranoid about having it on the board. Guess I will see once I get everything together.

Ive got most of the switches in and wired. I will probably install the board tomorrow(go through the schematic one more time while I am doing it). Power supply board is solid and voltages(unloaded) are good.

IMG_1669 (1).jpeg

[imo1]

So I have a working amp! Realizing that the existing chassis/power board wasn't the best starting place for this circuit, as the wiring and routing was pretty complicated. I also could have made a simpler amp, but this was what I was interested in.
I am chasing a ground buzz right now, but digging the overall tone, and pleasantly surprised by the strength of the reverb!

IMG_1675.JPG

[imo1]

I'm also trying to figure out why the second half of the OD circuit is a bit low voltage wise. Ive got 190 at the first stage, and then 164 at the second. Pulling almost 2V at the cathode.
The PAB boost sounds amazing on this amp, and I'm digging the mid boost as well!

[imo1]

Got the OD sorted. It was a new, old stock, tube that was a bit weak on one side.

I'm getting a decent 120 buzz going, independent of volume. The amp itself, outside of this, is relatively quiet.
I'm assuming it's something with the grounds. I'm not hearing much 60 cycle.

-I followed the grounding scheme from the OD style amps. I have pre-amp, including power supply caps, front panel, cathodes, etc grounded at the input jack solder lug. I also have the ground from the OD relay ground bypass here
-I have PT caps(first 3), and PT ground and HT center tap right by the PT. I also have the ground from the output of the relay power here.

-I have back OD, PAB switches, RVB send pot, and send and return jacks grounded around V4 solder lug.

-Speaker outputs and PT cathodes are grounded right by PT.

Possible issues in my mind are:
-relay power ground going to main PT ground
-the presence pot with a 1U grounded to the buss bar that terminates at preamp
-speaker out possibly needing to move to PT/Big cap ground

If anyone has any experience with this design and where to look first, I would be very grateful!

Best

Ian

Im getting a dedicated 6.3 transformer for my relays and will move the 100R resistors to the PT cathodes once i get it.

[imo1]

-I switched relay power and relay switch ground to their own ground point
-switched first 22U, after choke, to ground point by power tubes.
-I have left the presence ground at the buss bar.
-Ive also left the bias ground at the power tube ground point, where the bias pot also grounds. (this makes the most sense to me)

I will check in the AM and report back

[Reeltarded]

pull preamp tubes fire it up only PI and power.. if it hums with PI reboot without it.. lets see if we can pin it down by address