My Latest Build

[JazzGuitarGimp]

Well, I've got the new octal sockets installed. See [https://tubeamparchive.com/viewtopic.php?t=28627]

I have the screen grid dissipation under control. See [https://tubeamparchive.com/viewtopic.ph ... 417#357417]

I have updated the schematic in the post #4, as I have made a few changes:
I added R132 (2.7K, 5W) on the power supply page, in the screen grid feed. And I have removed the 5AR4 in favor of 1N4007 SS rectification. The B+ node was about 10V short of what I was aiming for, not to mention taking out a tube means one less thing to fail.

Up next will be getting the ODS 124 OD preamp finished. Relay circuits will come later, so I will disconnect the output of the Fender clean preamp and hardwire the ODS preamp into the EFX loop.

[JazzGuitarGimp]

I've been chasing down a few gremlins in the amp before moving on to the OD preamp. One of which is that I had a substantial amount of bleed from the clean preamp to the phase inverter - this actually stepped over the d-lator circuit, which sits between the preamp and the PI. With both the preamp Gain and Level controls all the way up, and with the Master Volume all the way down, I have guitar signal at the speaker that would be too loud to use in an apartment! I chased this one over a period of several days. It turns out the eyelet board I bought from Weber is conductive! So I am in the process of laying out a board that will be fabbed from FR-4.

[Theashe]

Here is a sound clip of DaGeezer's amp demonstrating the clean (with 3 gain stages) vs. the D-style OD.

Don't know it for a fact, but I am wondering if the 3 gain stage clean does a better job of allowing comparable volumes between the clean and OD? Just a thought?

https://soundcloud.com/dageezer/twin-ultraphonix-test-1

Sounds amazingly good to me! Plus I am a huge fan of his playing!

With respect, 10thtx

Digging up an old post, but I loved the sound of this amp. I was wondering if you know if there's a schematic for it anywhere on the site?

All the best,

Dave

[M Fowler]

Here is a sound clip of DaGeezer's amp demonstrating the clean (with 3 gain stages) vs. the D-style OD.

Don't know it for a fact, but I am wondering if the 3 gain stage clean does a better job of allowing comparable volumes between the clean and OD? Just a thought?

https://soundcloud.com/dageezer/twin-ultraphonix-test-1

Sounds amazingly good to me! Plus I am a huge fan of his playing!

With respect, 10thtx

Digging up an old post, but I loved the sound of this amp. I was wondering if you know if there's a schematic for it anywhere on the site?

All the best,

Dave

DaGeezer stated on video site: SF Twin Reverb w/MV (100w) modded to Dumble RF102 specs Look in the Dumble file section for Robben Ford #102 for schematic and layout.

[Theashe]

DaGeezer stated on video site: SF Twin Reverb w/MV (100w) modded to Dumble RF102 specs Look in the Dumble file section for Robben Ford #103 for schematic and layout.

Will do, thanks.

[M Fowler]

http://el34world.com/Forum/index.php?topic=16105.0

https://tubeamparchive.com/viewtopic.php?t=20345

https://tubeamparchive.com/files/fender ... od_120.pdf

[JazzGuitarGimp]

A bit of progress. I've actually had the pc board in house for a number of weeks now, but life keeps getting in the way. Below are before and after pics attached. The third pic is of the conductive board, the second pic is the nearly finished pc board. I still have a few dozen more components to populate on the pc board. I'll be ordering them in the next few days. I've built a few features into the pc board:
- A VVR for the output screens node
- Four MOSFET drivers (one for each output tube) for class AB2 operation
- A standard bias supply so that I can bypass the MOSFET drivers for AB1 operation.
- Relay switching of the two channels (A/B/Y modes available)
- Distributed power supply filtering.

The pc board is a four-layer design with signal and power traces on the inner two layers. The bottom layer (first picture) is the ground plane, which is divided into nine sections, allowing each sub-circuit to be grounded to the chassis at any desired point. The top layer is a shield plane - one contiguous plane that does not tie to any of the circuitry on the board, but has one solder pad at each end of the board (only one will be used) to tie to chassis.

[xtian]

Daaaaamn, Lou. Amazeballs.

Is there really that little to do outside up north?

[Colossal]

That looks great!

[JazzGuitarGimp]

Thanks guys. This is my second whack at doing a full-amplifier pcb layout. The first one was successful, but it didn't feature a high-gain preamp - nor did it have AB2 drivers. I've been wondering about AB2 for several years now, and now I will get to experience it for myself. I am going to start with the standard AB1: PI AC-coupled to the grids, then I will switch over to the DC-coupled AB2 drivers and hopefully find out if all my 'wondering' was worth the effort.

While waiting for the remaining parts to come in, I need to drill new mounting holes in the chassis, and wire the RF-102 preamp tone stack (these components are not on the pc board.)

I really enjoy doing this stuff - I just wish I had more time and money to throw at it..... too much stuff to do "outside".... chop fire wood, paint the house, re-skin the pump shed, put up fences, repair the riding mower, build a chicken coop and run, build raised beds for the wife's vegetable garden.... and those are just the ones that come quickly to mind.....