dumble stompbox.

[pamaz67]

Hello all.
First of all, I don't know if it's allowed or not. Not a problem if this post is going to be deleted. I 'm not connected in any way with the builder i will mention. In this case, I'm just an happy customer and have not direct connection with the builder.
I was searching for a dumble sounding preamp stompbox in order to make a compact pedalboard that allows me to plug in in any "return" plug of an amplifier , while having a sound that is if not always the same, let's say always similar and "dumble signed"
I stumbled on a stompbox that is named D-Drive from Garland Amplifiers. The guy who build this, seems to be an American guy who is living in Bulgary.
The D Drive is a 102 full tube preamp, supplied with a 12 v external power supply, in the shape of a large stompbox .
It works in a great way and is a really sturdy construction.
Some demos are available on youtube.
I've made my pedalboard with this d-drive thing, a zoom cdr70, and an ir loader in order to be able to drive also a mixing console direcly. Everything works in a very satisfactory way, and is dead silent . Works very well also using a solid state power amp. It's clear that a full tube amp is a better sounding thing. But this is contained in a pedaltrain metro 16. Therefore it's really a sort of "swiss army knife D solution".

let me know what you think about it, if you have a chance to test it.

Paolo Mazza

[Synchu]

The guy is a Bulgarian from Bulgaria and runs a commercial/boutique building service/shop. It is good quality stuff.
Here's one of the D Drive pedal demos (plugged in a Two Rock amp FX return):
https://www.youtube.com/watch?v=Ox4lUdAE6ck

These days it is relatively easy to build a tube preamp in a pedal - the tricky part is in the tweaking (same goes for the full-blown amps, though), given all the parts that you're missing from the full circuit.

Niki

[dorrisant]

How do you get the harmonics out of a preamp with no PI to trim properly?

[ijedouglas]

How do you get the harmonics out of a preamp with no PI to trim properly?

Harmonics should be generated in the preamp.

[dorrisant]

It is my understanding that a Dumble amp will not "sing" if the PI isn't unbalanced correctly. You may get the same gain structure that you want along with tone, but the PI through to the OT secondary are all a part of the harmonic content.

School me if I'm wrong, I think you can get close, but no banana.

Also note in the video linked above, he is running into the return jack of a Two Rock (Dumble clone). Try this with a Fender style amp, or whatever you choose that isn't a Dumble derivative (most will not afford a TR) and the sing will go away. This video is not a true representation of what the pedal does and I'm afraid most buyers would be stuck trying forever to dial in the tone that was advertised to them. Seems shameful to me.

[ijedouglas]

It is my understanding that a Dumble amp will not "sing" if the PI isn't unbalanced correctly. You may get the same gain structure that you want along with tone, but the PI through to the OT secondary are all a part of the harmonic content.

While the PI/OT may contribute to the "sing" or harmonic structure I don't think it is solely responsible. I do think that a poorly adjusted PI will kill the sing though.

This video is not a true representation of what the pedal does and I'm afraid most buyers would be stuck trying forever to dial in the tone that was advertised to them. Seems shameful to me.

Totally agree

[dorrisant]

While the PI/OT may contribute to the "sing" or harmonic structure I don't think it is solely responsible. I do think that a poorly adjusted PI will kill the sing though.

I totally agree.

Well... If you've ever run through 5+ 12AX7s and still haven't found the "sing", you'll probably understand. Been doing this a lot lately. When you hear it sing, you can't unhear it. Then when it doesn't sing, you keep trying more tubes... I went through about seven on a D-Fifty the other day and I swear the 1st one was the best. Probably go back to that one.