"Promiscuous Girlfriend" So many types of dirty with 5840 Submini Pentodes

[markeebee]

My mum will be so chuffed that you've used her picture!

[frequencycentral]

My mum will be so chuffed that you've used her picture!

That's not you mum Mark (or is it???), that's Grog, vocals/bass in the UK band Die So Fluid, she looks like she'd rip off my testicles with her teeth if she found out I used her image on a pedal with such a name!

[Renegadrian]

Nice graphic...Still I have to say this project didn't get me interested as the previous ones...Gotta work on some mini-amp soon...

[frequencycentral]

Nice graphic...Still I have to say this project didn't get me interested as the previous ones...Gotta work on some mini-amp soon...

I kinda know what you mean, as there are so many tube projects to choose from now. If it was 'just another tube overdrive' I couldn't have brought myself to build it. Fact is, the tonal palette is much broader than say the Valvy or Pepper Shredder - but I know you won't like the diodes Adriano, but give them a chance!

[Renegadrian]

Rick, your project is quite good, and let's say it covers a submini tube territory, a "promiscous" overdrive, and that's quite good, so your effort is appreciated.  .
I am towards other tube "territories" ATM, not necessarily submini and with some extra gain in mind.
Said that it's good to have different projects (tremoloes, overdrive, boosters, heavy distortion, amps and so on) to choose from...

[doitle]

Rick, your project is quite good, and let's say it covers a submini tube territory, a "promiscous" overdrive, and that's quite good, so your effort is appreciated.  .
I am towards other tube "territories" ATM, not necessarily submini and with some extra gain in mind.
Said that it's good to have different projects (tremoloes, overdrive, boosters, heavy distortion, amps and so on) to choose from...

Higher gain will hopefully be one of my project goals in the amp I've been working up a design for and acquiring parts on. So far I've got a 6112 which is quite a bit higher gain than the 6111. (20 vs 70) I've been trawling around ebay because I really had hoped to run two 6112s cascaded and possibly have a clean/lead or rhythm/lead switch capability for bypassing one of them. I've still got a long way to go before I understand enough to have that all going though Yet the tubes are almost here! If only I didn't have work and school and could just sit around all day learning tube amplifier design...

[Ripthorn]

Well, doitle, I just finished a somewhat similar project (I will update the thread when I get home tonight), but let me tell you, you can get a very good amount of distortion with 6021's.  I found the 6112's to be lower in output level, but I still have yet to do a project built around them to play to their strong suits.  If you want to hear what a 6021 and 6111 can do, look for my thread later tonight about the Kitchen Sink submini amplifier.

Rick, I must say that I wasn't too won over by this myself, but I also find straight up pentode clipping to not be as musical as triode clipping.  Don't know why, but I think the 6418 is the only pentode I've ever really heard that I thought "Now that sounds good, regardless of what type of tube it is".  But hey, you are pushing the field further and I respect you for that.  I'm still looking forward to a submini wah (I have actually thought of doing the colorsound inductorless wah with a 6111, wouldn't that be fun?).  Actually, now that I think of it, I have a boatload of 6418's, maybe I should wire one up in triode mode and put it in a wah...I'll have to breadboard that tonight.  Again, nothing but respect, but just not my flavor (momma always told me to stay away from promiscuous girls...).

[doitle]

I certainly look forward to your thread update Ripthorn.

Also, you found the 6112s to be lower output? Shouldn't they naturally be higher output since they have a higher mu? Just as far as my understanding goes in an identical circuit and with enough headroom shouldn't that mean that you would have a higher gain with the 6112 than the 6111 which in turn would mean your output signal would be larger?

[Ripthorn]

Both Rick and I found that if we put the 6112 into a circuit designed around the 6111 (or 6021) that the output level was lower, though you could get more clipping.  Strange, I know, but that is what happened at least in my case and Rick said he found the same.  Best way to decide is go on and do it.  You could well use the 6112 for two stages and a 6021 or 6111 for the other two stages and see what works best (6112 before 6111 or vice versa).  I'm gonna try to breadboard the submini inductorless wah tonight and start a thread about that because that idea hasn't left my head since I typed it up.

[doitle]

Nothing could have prepared me for how tiny these tubes are! I just got a box of 6205 Pentodes I bought off Ebay. The seller was nice enough to include an extra one. Now if my 6112 would arrive I could get to bread boarding! I suppose I better solve my transformer quandry rather quickly too or I wont be able to actually proceed on testing out amp designs...

[frequencycentral]

While you wait why don't you breadboard Adriano's 6205 design: http://www.diystompboxes.com/smfforum/index.php?topic=76372.0

[frequencycentral]

I suppose I better solve my transformer quandry rather quickly too or I wont be able to actually proceed on testing out amp designs...

If you're not sure which transformer you need and want to try a few different designs you could get a Hammond 125ASE for single ended or 125A for P/P. They have a gazillions different secondary winding options.

[doitle]

Oh neato I will certainly try out that lone wolf. I'll have to do some thinking as to how to get the 6.3V for the filament... If it is rated for 6.3V AC for the filament then a 9V DC supply would be almost dead on. 6.3VAC rectified would be roughly 6.3V*1.414 or 8.9V. I wonder if it would work at all with such a low B+... My LT1054 samples are still in shipment and so I dont have any way to boost the voltage really as of yet. I do have this transformer I pulled out of a clock radio that I THINK has a 36V and 24V secondary but I'm not sure and still need to learn more about working with transformers. I just measured the resistances accross the primary and the 2 secondaries and that's the ratio I came up with.

Also I've got a CB radio partially taken apart with two transformers in it that I have to desolder at so me point today. I really wish I knew how to tell some things about a transformer by measuring it or looking at it rather than having to just hook it up and hope it doesn't explode and take some voltages.

[frequencycentral]

I'll have to do some thinking as to how to get the 6.3V for the filament... If it is rated for 6.3V AC for the filament then a 9V DC supply would be almost dead on. 6.3VAC rectified would be roughly 6.3V*1.414 or 8.9V.

It wants 6.3 volts, AC or DC.

9 volts DC will decrease the life of the tube and will burn out the heater if run for any length of time.

There's a few ways to get 6.3 volts - 7806 voltage regulator, a little LM317 based circuit, or a voltage drop resistor.

[Ripthorn]

You can also use a 6.2V zener diode.

[frequencycentral]

[doitle]

How could it operate the same from 6.3V AC or DC. 6.3VDC would be equivalent to 4.5V RMS AC. Maybe there is a better datasheet floating around somewhere for this tube. The one I have is sparse in information about the heater.

Anyhow I'll probably just do a little KVL and drop extra voltage across a resistor.

Any ideas though about it's operation on low B+ like the valvecaster? I'm writing two papers for an art summer school class so I can't try it out yet but I will get to experimenting as soon as I can!

[Ripthorn]

You know Rick, after looking at that box, you should have called the dirt control "cheat" or something (though is it cheating if you know she's promiscuous?).  Looks great though, another amazing project with mad perf skills.

[SpencerPedals]

This thing sounds a lot like a little tube amp I built out of an old aircraft radio.  Almost a nasally compression thing going on when cranked up.  It's not a sound you find in a lot of other pedals.  Nice work, per usual, Rick.

[doitle]

I just came across these on Ebay and was thinking of buying one as an output transformer. Sounds pretty versatile and I don't think I'd ever try to build something greater than 10W.

http://cgi.ebay.com/Tube-amp-10-15-watt-output-transformer-6L6-6V6-6BQ5-etc_W0QQitemZ390069236209QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item5ad1f031f1&_trksid=p3911.c0.m14&_trkparms=65:12|66:1|39:1|72:1205|293:2|294:25

Seems like a good deal and I'd definitely buy one if I just knew whether they would work for these kinds of projects or not for sure. I know the seller is good because I just received a 6112 from him today. I really need to finish these papers and get to experimentin'!