Sub Caster anyone?

[earthtonesaudio]

Hey a picture or Mouser link to the TO-220 mica thing would be appreciated.
Or how about a name to call it. An insulator perhaps?

Mouser carries whole kits, with the rectangle of mica film, the non-conductive washer, and I think it comes with nuts and bolts too.  $0.77 for quantities of one.  Part number: 532-4880.

Or just search for TO-220 heatsink hardware.

-Alex

[ambulancevoice]

they have sockets for sub miniature tubes on ebay
or you can use an 8 pin DIL (for ICs) although you probably need longer leads for that
the 6111 is octal too, so make sure its an 8 pin socket
if the leads are still to short, your gonna have to get new 6111

[Berger]

I just finished building mine and I like it, but is there anyway to get some more gain out of it?

[frequencycentral]

Hmm - out of sheer impatience I ended up directly soldering my short legged 6111 directly to the board - I think I blew it (or it was bad anyway).

The LM317 based regulator works fine, but when I hook up power to the main circuit I get a DVM reading of 0v between +V and earth, and the 6.3v supply drops to about 1.8v. I checked and checked again my layout and other components. A continuity test between the two heater terminals of the 6111 showed positive.

This is my first valve build, so I might just plead ignorance if I blew it!

I have some 12au7s and sockets on order, so I can build a Valvecaster real soon, but am finding it difficult to source 6111s this side of the pond. If I can source some more I will desolder the blown one and use SIL sockets to mount another. What I really like about the 6111 though is that the entire circuit can be less than an inch and a half square.

What do you guys think? Is the heater really sensitive to heat???

[ambulancevoice]

What do you guys think? Is the heater really sensitive to heat???

nope, its sensitive to to much current and or voltage

[frequencycentral]

Bump! Bad 6111?

[ambulancevoice]

but a heater can over heat, and melt!
did the heater go RED when you soldered it to the board?

[frequencycentral]

Hmmm, dunno, didn't look at the time!

Whats really making me think its something to do with the heater is that there is high continuity and no virtually no resistance between the two pins. Something is dragging the whole circuit to ground!

Heyho - I'll try another tube when they arrive!

Thanks for your help ambulancevoice!

[Jered]

I just finished building mine and I like it, but is there anyway to get some more gain out of it?

  There certainly is. Raise your plate voltage. I'm using a 35 VDC 900 mA wall wart and running it to a 78M24 fixed regulator for the plate voltage and an adjustable regulator for the 6.3 V heater supply. This has so much gain that I am going to scale it back in the tube circuit itself. Running these at 24 volts just makes it so much easier to toy with. Its much easier to decrease gain within a circuit than it is to try and squeeze every little bit of gain out of a circuit that really doesn't have it.
  Just for the record. I've had problems with the LM317 for the heater voltage. I've used two motorola's and two fairchild's and all four worked for about an hour and died. I'm using a heatsink way oversized for the purpose. I swithched to an LM2931CT and its been problem free for two weeks now.
  This is a whole different beast at a higher plate voltage, 6021, 6111, and 6112 all work great. I'm going to try tacking on a CK5784WA sub mini and see what kind of tone that delivers.
  Try the higher plate voltage, it makes the subcaster a lot easier to taylor to your sound because you have more to work with. IMHO.
  Jered

[frequencycentral]

Seeing as how this thread is up top again - I got mine working - see my comments here:

http://www.diystompboxes.com/smfforum/index.php?topic=63479.480

Subcaster working!

All I did was remove C2, the 47nf cap across the supply rails and replace it with a different kinda 47nf cap. Weird. Hmmm, been bugging me for weeks!

So - I fired my Valvecaster into my Subcaster - WOW!!

It seems to me that the hassle of creating a 6.3 volt supply for the 6111 heater is a pain in the butt compared to powering a 12au7 heater at 12 volts. There really is no saving on space when you consider the extra circuitry required for the voltage regulator - and a heatsink on the LM317 too! There is a whole lot of heat generated by a 6111 in comparison to a 12au7. add that to the heat the LM317 gives out and you can warm the living room up nicely with a Subcaster!

My rule of thumb now will be to only use 6111's in pairs and run the heaters in series of 12 volts.

So - go ahead and build a Valvecaster. Or a dual Subcaster. Or a Pepper Shredder using two 6111's, like I'm doing next.

(sh*t, I would do it this weekend but I have to write some music for Volvo!)

Just don't build a single 6111 Subcaster!

[Jered]

Seeing as how this thread is up top again - I got mine working - see my comments here:

http://www.diystompboxes.com/smfforum/index.php?topic=63479.480

My rule of thumb now will be to only use 6111's in pairs and run the heaters in series of 12 volts.

              If you do that they will glow like a lightbulb and die. 5.7 V min-6.9 V max on the heaters.

So - go ahead and build a Valvecaster. Or a dual Subcaster. Or a Pepper Shredder using two 6111's, like I'm doing next.

(sh*t, I would do it this weekend but I have to write some music for Volvo!)

Just don't build a single 6111 Subcaster!

    Having built both I'll say this. If you just want to warm up your tone a little and add maybe a touch of gain, the Valvecaster works. If you want some high gain crunch, the subcaster wins hands down.
  Jered

[frequencycentral]

My rule of thumb now will be to only use 6111's in pairs and run the heaters in series of 12 volts.

- If you do that they will glow like a lightbulb and die. 5.7 V min-6.9 V max on the heaters.

Are you sure they will die? Surely if they are in series each tube will get it's 6 volts? That's what I've read on Dano12's 'parent thread'.

This kinda makes sense because the 12au7 has the 6 volt centre tap on the heater, so in effect it has two series 6 volt heater element either of which can run at 6 volts, or both in series at 12 volts.

So running the heaters of two 6111 tubes in series with 12 volts is just the same as running both halves of a 12au7 heater with 12 volts without using the centre tap.

Therefore, you should be able to run half a 12au7 heater (using the centre tap) in series with a 6111 heater at 12 volts.

Yes? Or no? I'd love for someone to confirm this or deny it.

[Jered]

  With the 12A_7 tubes it needs 12.6 volts for the heaters, which are pins 4 & 5, and the center tap is pin 9. So you have two ways to power the heaters. Run 6.3 volts to pin 4, 6.3 volts to pin 5, and ground pin 9. Or you can run 12.6 volts to pin 9, and ground pins 4 & 5.
  Can you run 12.6 volts to pin 5, and ground 4 & 9? I don't know, never tried it. I'm sure someone else here with more experience will chime in and let us both know.
  With the 6021, 6111, and 6112 submini's, you need 6.3 volts for the heaters, pins 3 & 6, but you don't have the luxury of a center tap. So its easiest to supply 6.3 volts to either pin 3 or 6 and ground the other. I guess you could run 3.15 volts to both pins, but then your just  making things hard on yourself. Unless they make V. regulators for just this purpose? i don't know they just might.
  Jered

[ambulancevoice]

  With the 12A_7 tubes it needs 12.6 volts for the heaters, which are pins 4 & 5, and the center tap is pin 9. So you have two ways to power the heaters. Run 6.3 volts to pin 4, 6.3 volts to pin 5, and ground pin 9. Or you can run 12.6 volts to pin 9, and ground pins 4 & 5.
  Can you run 12.6 volts to pin 5, and ground 4 & 9? I don't know, never tried it. I'm sure someone else here with more experience will chime in and let us both know.
  With the 6021, 6111, and 6112 submini's, you need 6.3 volts for the heaters, pins 3 & 6, but you don't have the luxury of a center tap. So its easiest to supply 6.3 volts to either pin 3 or 6 and ground the other. I guess you could run 3.15 volts to both pins, but then your just  making things hard on yourself. Unless they make V. regulators for just this purpose? i don't know they just might.
  Jered

the center tap only really needs to be used for the 6.3 volt heater situation
12.6v and its not really needed, just run it to pin 4 (or 5) and ground the opposite pin
or for center tap power, run half (6.3v) to pin 4 and the other half (6.3v again) to pin 5
6.3v and you run it to 4 and 5 (parallel) ground pin 9
or in case of center tap heater supply, run half the supply to 4 and 5 and the other half to pin 9 and ground the center tap on the power supply

and there are adjustable regulators, its used for the sub-caster.

[Jered]

  Why would you want to make the extra work for yourself? For a single tube application, 6.3 to pin 4 and 6.3 to pin 5,...done. Float pin 9 or ground it, it doesn't matter.
  As for the regulator, I stated "for just this purpose" meaning a 3.15 V. fixed regulator. I know they maked 6.2 V. fixed regulators among many others, 5,8,9,10,12, etc.

[Jered]

  Here is a good starting point for the 5784 sub mini pentode.  Great medium gain sound as is, but can probably be improved. I'm just a hack tuning the circuit by ear.
http://aronnelson.com/gallery/main.php/v/Jered/5784+circuit.jpg.html

[Jimmy-H]

  Here is a good starting point for the 5784 sub mini pentode.  Great medium gain sound as is, but can probably be improved. I'm just a hack tuning the circuit by ear.
http://aronnelson.com/gallery/main.php/v/Jered/5784+circuit.jpg.html

Great!

Does it sound different compared to a subcaster?
Keep us posted anyway with your results.
Maybe it is a good idea, to put a 6111 in front of the 5784.
I read somewhere, that the 6111 tube works better starting from 24V DC.
I think they meant better cleans, but that is good for driving the pentode more.

[Jered]

  Funny you should mention that. That's what's in front of me right now, but with a 6021 in the first stage. You are absolutely right about the voltage. At 24 or more volts the improvement in sound and responsiveness is dramatic. I've been testing everything at voltages between 12 and 32 volts.  6021, 6111 really come to life around 18 volts on up, 6112, 5784, 5703 really come to life 24 volts and up. To my ears anyway.
  Someone who knows what they are doing could probably make any of these sound good with 12 volts. Time will tell.

[frequencycentral]

Wow - I had forgotten about this thread - it was right at the start of my tube fetish. God, I've learned a lot since then!

The schematic looks good Jered . I have some 5672 submini pentodes - only five pin, unlike the 5784. I bought them to build some VCFs/VCAs - though I bought enough to have soem spare to experiment with something similar to your schematic - but that's way down the road yet - I have other fish to fry first.

Hey everyone - do me a favour and just let this particular thread die - no more replies please - I sound like such a newb/dork on page 1 !

[Jered]

Hey everyone - do me a favour and just let this particular thread die - no more replies please - I sound like such a newb/dork on page 1 !

   So where should we post subcaster updates?