"Le Craquement Thermionique" !!

[frequencycentral]

Got this on the breadboard right now, I've had it in mind for weeks but only just got around to trying it. It's basically a SHO with modifications running into a BM tonestack running into a 5840 submini pentode which has switchable triode/pentode mode. Embarrasingly enough, I don't have access to a microphone for a few days, so soundclips will have to wait. Quite versatile, with the 'Le Craquement' knob at minimum it functions as a tube based booster with the benefit of a nice flexible tonestack. Tweaking in some 'Le Craquement' overdrives the tube stage, with subtle variations available from the triode/pentode switch. I'm running it at 12 volts, should work well at 9 volts too but with a little less boost and gain on tap.

5840 submini pentodes are available from Aron's store: http://diystompboxes.com/zencart/index.php?main_page=product_info&cPath=19&products_id=49

[doc_drop]

I knew I just ordered a couple of Aron's 5840's for a good reason.    I will have to breadboard this one up after I get TubeDROP off of there.

But one question. Pourquoi "Thermionique"?

[raulgrell]

I knew I just ordered a couple of Aron's 5840's for a good reason.    I will have to breadboard this one up after I get TubeDROP off of there.

But one question. Pourquoi "Thermionique"?

I'll venture a guess: you heat the tubes to release electrons from the filament in the tubes... this makes ions...

and yeah... Therm = heat, ionique = ionic..

... ?

[frequencycentral]

The name is more interesting than the circuit? 

http://fr.wikipedia.org/wiki/Thermo%C3%AFonique

[Ben N]

That looks fantastique, Rique! But damn... another must-build for the list! Now if I can only find that stash of mini-pentodes I have somewhere.
Mod-wise, I imagine it would work well with quite a few tonestacks: Bax or near-Bax, a la Colorsound Overdriver or Dr. Z Route 66, or Dumble "clean", with switches for "jazz" and deep and whatnot, or TMB, a la Trainwreck.

[frequencycentral]

Well, this is pretty nice, works well as a tube boost, treble boost and mild overdriven tube sound. There's more gain of course if the tonestack is bypassed. With this in mind, I thought I'd try another version, keeping to the basic concept of a SHO varient overdriving a tube stage with a BM type tonestack, but this time using a submini dual triode to isolate the tonestack and allow the tube stage to be driven harder by the SHO varient. I've just got some 6021, so I'll try it with both 6111 and 6021. This will be tomorrow's little experiment:

[frequencycentral]

Ok a new take on the 5840 version. I'm in lurv with this one!

[Toney]

Nice work Rick.
For those that Vero (go Vero!) there is a layout of the booster section in the Gallery. I'll marry it to the tranny-boost sections and post if I get the time.   http://www.aronnelson.com/gallery/main.php/v/Toneys-Album/Booster+5840.gif.html
I"m betting this thing really sizzles.

[doc_drop]

I got this up on my breadboard yesterday. First, let me say that even the first vesrion is my favorite low voltage tube circuit ever! The SHO input to the tube sounds great. I guess having 2 10M resistors on the front end does make a difference.

With Rick's "super-hot" mod, this little circuit can really crank out some overdriven tube sounds. I like the idea of having it switchable though, since you don't always want to clip your signal into scream territory.

My plan is to have this circuit in front of my Tube DROP circuit in a box.

http://www.diystompboxes.com/smfforum/index.php?topic=83494.0

Between the triode/pentode switch, the hot/superhot switch, the different gains hitting the 3 different tubes, etc. this will be my ultimate tube overdrive/distortion/or simple warmth front end...

But seriously, if you like tubes, play with this circuit. It is really, really sweeeeeeeeeeeet!

[frequencycentral]

Here's my layout, the tube is mount on the board, as are two of the pots, and the status LED. The tube will be visible through a slot in the top of the box, backlit by the blue LED when the effect is on.........

[doc_drop]

I'm lovin' the ICI1 "chip". Nice cheapo socket for the NOS ole skool IC!

[Ben N]

Rick, does the tube get warm? I.e., can it be built into the enclosure or does it have to poke its little head up for some air?

[frequencycentral]

Rick, does the tube get warm? I.e., can it be built into the enclosure or does it have to poke its little head up for some air?

Well it doesn't have to poke it's little head out, but it's nice to see some action........  Tubes at these voltages get warm but not hot. Now the output triodes on my Superfly, with 185v hitting the plates, they get too hot to touch - mmm, nice!

I'm lovin' the ICI1 "chip". Nice cheapo socket for the NOS ole skool IC!

Yeah but a non standard width for an IC socket, unless you use SIL strips, mine will be soldered anyway.

[StereoKills]

Very nice Rick!

So........got any soundclips on the way soon? 

[doc_drop]

Yeah but a non standard width for an IC socket, unless you use SIL strips, mine will be soldered anyway.

I thought it was just a standard 8 pin IC socket? It seems like that would work well? 

I just solder these little guys myself, but I liked the idea of a cheap socket since I have tons of those from a Futurlec value pack...

[frequencycentral]

Oh, re the above layout - I've got a 'blind spot' with depicting 7806 type devices in DIYLC (remember the Clari?), I guess because they don't have a flat side, anyway something to watch out for.

So........got any soundclips on the way soon?  

I foolishly left the microphones at the rehearsal space, so I'll record some on Friday.

Yeah but a non standard width for an IC socket, unless you use SIL strips, mine will be soldered anyway.

I thought it was just a standard 8 pin IC socket? It seems like that would work well?  

I just solder these little guys myself, but I liked the idea of a cheap socket since I have tons of those from a Futurlec value pack...

No, it's only 3 pads across, as opposed to 4. I have used SIL strip as submini tube sockets in a few Murder One builds though, this one also has an internal LED to help in siting the tubes legs in the sockets - the guy wanted to try a few different tubes in the preamp section, 6111, 6021, 6112:

[doc_drop]

Ah, I see. It only jumps one row, not two.

Anyway, thanks for the layout. Now I won't have to work up a perf layout 'cause I can just use yours!

[phector2004]

don't wanna be a pain in the anus, but any sound clips?? 

[frequencycentral]

It's gonna be a couple of weeks before I build mine, and it's not on my breadboard anymore - that has something even more exciting in it right now. I should catch up with my current build commitments in a couple of weeks, then I'll build Le Craquement. I dunno if doc-drop built his yet? Doc?

[phector2004]

nice 

just a side thought...

can you drop that triode in to replace a tranny? (with re-biasing, of course!)