"Promiscuous Girlfriend" Dirty fun with 5840 submini tubes

frequencycentral · Post by **frequencycentral** » 06 Jul 2009, 16:00

I've been working on this one on and off for the past month or so. It's evolved into something with quite a few interesting tonal possibilities.

First off, you'll notice that it has switchable diode clipping, this idea was suggested to me by Derringer, so I tried it and it worked well, adding a bit of sizzle to the boost and overdrive. There is a slight volume loss when the 'Dirt' switch is engaged, though there's enough boost in the circuit to compensate for this.

This design originally started out as a low voltage circuit, as it developed I thought it would be nice to get the voltages a little higher, so I added a little charge pump circuit based around a MAX1044 to get up to around 35 volts. Thanks to R.G. for his +18, +25, or +33 from one 9V battery on which the charge pump circuit is based.

The tonestack is based on the BM tonestack, with just a few value changes to suit the circuit.

What does it do? Well it does clean boost with the Gain set at minimum, flick on the Dirt switch and you get some nice diode clipping too. Turn up the Gain and you'e into overdrive territory with diode clipping, flick the Dirt switch off and you get even more overdrive. All with some nice tonal variations courtesy of the tonestack. So many types of dirty, hence the name "Promiscuous Girlfriend".

I've done perf and PCB layouts, John Lyons has kindly consented to make up some PCBs for anyone whose interested. My good forum buddy Toney is putting together a vero layout too, so all bases are covered.

So, tubes available from Small Bear, layouts in three different formats, PCB availability - what are you waiting for?

Perf layout, unverified, I'll build it soon.

PCB layout and PnP, unverified, but pretty much identical to the perf layout, so when the perf is verified so will be the PCB.

Here's some soundclips, they don't explore every possibility but give a bit of a flavour.

Signal path:

Squier Telecaster Custom (bridge humbucker) >>> Promiscuous Girlfriend >>> Roland Bolt 60 watt tube combo >>> Shure SM58 >>> Event Echo Gina 24 soundcard >>> Wavelab

No other processing.

The first clip has the effect bypassed, then with minimum Gain and the Dirt switched off: http://files.getdropbox.com/u/967492/By ... 0Boost.mp3

Minimum Gain, Dirt switched on: http://files.getdropbox.com/u/967492/lo ... 20Dirt.mp3

Maximum Gain, Dirt switched on, Tone set low: http://files.getdropbox.com/u/967492/hi ... 20Tone.mp3

Maximum Gain, Dirt switched on, Tone set high: http://files.getdropbox.com/u/967492/hi ... 20Tone.mp3

Maximum Gain, Dirt switched off, Tone set low: http://files.getdropbox.com/u/967492/hi ... 20Tone.mp3

Maximum Gain, Dirt switched off, Tone set high: http://files.getdropbox.com/u/967492/hi ... 20Tone.mp3

frequencycentral · Post by **frequencycentral** » 06 Jul 2009, 23:10

frequencycentral · Post by **frequencycentral** » 07 Jul 2009, 19:24

culturejam · Post by **culturejam** » 07 Jul 2009, 19:36

It works?

By the way, I may need to pick your brain soon regarding a solid-state preamp / submini tube power amp project I'll be fiddling with soon.

frequencycentral · Post by **frequencycentral** » 07 Jul 2009, 21:13

Dunno yet! The soundclips I posted were from the one on my breadboard. I need to build the pot board next and wire it all up before it gets tested. I'm sure it'll work just fine though, I have a pretty good success rate!

Fire away with the solid-state preamp / submini tube power amp project brain picking. I'd be glad to help.

Rick

frequencycentral · Post by **frequencycentral** » 15 Jul 2009, 20:23

earthtonesaudio · Post by **earthtonesaudio** » 16 Jul 2009, 11:07

I just looked closer at the pictures-NICE job on the mechanical!

Post by **modman** » 20 Jul 2009, 09:33

https://www.diystompboxes.com/wpress/?p=67

frequencycentral · Post by **frequencycentral** » 20 Jul 2009, 09:39

modman wrote:https://www.diystompboxes.com/wpress/?p=67

Wot? Never the twain?

Gibson78 · Post by **Gibson78** » 21 Jul 2009, 15:09

Can I use other sub-mini tubes for this project? 6111's? 6021's?

Cheers and Beers!

frequencycentral · Post by **frequencycentral** » 02 Aug 2009, 11:49

Gibson78 wrote:Can I use other sub-mini tubes for this project? 6111's? 6021's?

Cheers and Beers!

Both those tubes you quote are dual triodes, whereas this design uses two pentodes, so no it's not a straight swap. I used a couple of 6111's to make a Pepper Shredder a while back, running the heaters in series from 12 volts. Here's a link to the Pepper Shredder, though you'd have to observe the correct pinouts, as subminis differ in pinouts to miniature tubes: http://www.tube-town.net/diy/lov/lov02- ... r-eng.html

Post by **Brink** » 07 Aug 2009, 22:49

What's the lifespan of a submini tube? I don't see it being very easy to replace them.

frequencycentral · Post by **frequencycentral** » 08 Aug 2009, 10:46

Brink wrote:What's the lifespan of a submini tube? I don't see it being very easy to replace them.

They were designed to be part of proximity fuses in missiles. Shock tested to 450G, altitude tested to 60,000 ft, fatigue rated for sinusoidal vibration of 60 cycles per second at 2.5G. The military were happy with that, I am too.

criszu · Post by **criszu** » 08 Mar 2010, 03:16

how is the 5840's heat???
can I use it in homerecord???
and what those blue caps?? vishay multi-layer ceramic??
I like the sound, the dirty one.

thank's