OD with cathode follower

[10thTx]

For those of you who like experimenting with new ideas built around Dumble topology .........

I added a cathode follower behind the first triode in the OD section.

I built this and like it. Has more of a Marshally tone with Dumblish sustain to my ears. More smooth crunch and less creamy vowel tone.

With respect, 10thtx

[jurgen]

interesting

[erwin_ve]

For those of you who like experimenting with new ideas built around Dumble topology .........

I added a cathode follower behind the first triode in the OD section.

I built this and like it. Has more of a Marshally tone with Dumblish sustain to my ears. More smooth crunch and less creamy vowel tone.

With respect, 10thtx

Cool design; any change you can post soundclips? I'm interested in how it sounds.

[ic-racer]

I believe the standard topology HRM circuit layout can be converted to a cathode follower with just a few simple changes under the goop. I have not tried it yet:

https://tubeamparchive.com/download/file.php?id=10588

[boldaslove6789]

So would this config be relevant to the "Ripper Circuit"?

[ER]

No, should be off the final stage more like a plexi TS.

This one has a recovery stage following TS more like a tweed fender. This would probably be more gainy, not in a clipping way but in a signal way with the recovery after dumping the signal to ground in the tone stack.

-ER

[renshen1957]

For those of you who like experimenting with new ideas built around Dumble topology .........

I added a cathode follower behind the first triode in the OD section.

I built this and like it. Has more of a Marshally tone with Dumblish sustain to my ears. More smooth crunch and less creamy vowel tone.

With respect, 10thtx

Hi,

Wouldn't the cathode follower be better after the pentode to isolated it from the load of the loop? Just a thought.

Regards,

Steve

PS This is very reminiscent of the Tweed Deluxe Overdrive on the Hoffman Amps forum.

[dave g]

Yeah, the DC coupled cathode follower changes the way that the stage before it clips! In practice, there is really only an attenuation difference of about 2 dB between a plate driven FMV tonestack and a CF driven tonestack. The magic of the CF is how it pulls its grid current from the plate of the preceding stage, causing it to clip sooner and softer!

[10thTx]

I continued to experiment with a cathode follower in the OD section. I placed it following the 5879 pentode. It no longer has the Marshall crunch tone to it, for some reason.

The result has turned out to have excellent sustain and a nice blooming tone to it. It does not have as much of a vowel/wah tone as the original design did. While the sustain is comparable to the original TOS, I think the OD tone is actually clearer (not cleaner) sounding, IMO. So chording sounds a little more articulate, I think.

This originally was a Tweed Overdrive Special & this version with the CF after the 5879 in the OD has given me the smoothest and creamiest OD of any TOS version that I've tried.

With respect, 10thtx

If you'd like an editable version of the schematic and layout there is one here:
http://www.el34world.com/Forum/index.ph ... #msg106079

[da Geezer]

EXCELLENT!

Thanks for sharing your results! I'm going to try that OD section in my next build.......

G

[talbany]

With the way it's setup now you wouldn't need a loop with a buffer just a return amp..(Dumble did this on several 2nd gen amps)
You could use the other half of V2 build it right in before the PI and add a send /return control on back..You could put a switch on the back bypassing the return amp if you like it the way it is (or add a jumper if you like the effects of the return amp)..It would then be an ODS(basically) w/built in loop w/single knob tone control..Kinda cool!!

Tony

[10thTx]

With the way it's setup now you wouldn't need a loop with a buffer just a return amp..(Dumble did this on several 2nd gen amps)
You could use the other half of V2 build it right in before the PI and add a send /return control on back

Am I understanding you correctly .......... do you mean something like this?

With respect, 10thtx

[talbany]

Looks about right. you now have a buffered loop...

Tony

[rob@tele]

I guess that for the clean mode you will still need a buffer/cathode follower. V1b will be the effects driver in clean mode and will be loaded wrongly if you would use an effect with low input impedance. In OD mode v2a will be the driver for the effects and as it is a cathode follower it will indeed have the proper output impedance.

[Structo]

So no tone stack on the clean channel?

Mid boost and PAB?