Sub-mini tubes

[bancika]

I was thinking about building tube preamp (clone of some amp, not sure which one yet) but with sub-mini tubes. Can someone tell me which ones are similar to 12AX7 (are those 6021 maybe??) and where can I get them except for eBay
Thanks

[Peter Snowberg]

They're not made anymore so eBay is your best source.

None of them I have seen has the amount of gain found in the 12AX7.

The current consumption of the 6021 is the SAME as a larger 12AX7 so if you're not building missiles you are much better off using full sized miniature tubes.

[bancika]

Ok, which one is the closest and how much gain does it have compared to 12AX7...I like the idea of using sub-minis because they don't require sockets and I can stick them into smaller box

[mlabbee]

6021s are nice - gain is about 30 (compared to 100 for 12AX7?)  I built a preamp using one with a plate voltage around 180v and a Baxandall tone stack.  It's a fun little box.

[Peter Snowberg]

http://amps.zugster.net/projects/subminiature 

[andy123]

6021s are nice - gain is about 30 (compared to 100 for 12AX7?)  I built a preamp using one with a plate voltage around 180v and a Baxandall tone stack.  It's a fun little box.

Hi,

Did you ever finish your pencill pusher sub-mini amp?

I have managed to get a few 6021s and was thinking about putting one together.

Cheers Andy

[zeta55]

Try the 6112:s, gain of 70. That would get you rockin.

/Krister

[bancika]

I found them here http://www.radiodaze.com/tubes-10.htm
but 6112 cost 16$ each, 6021 are 3$

[mlabbee]

6021s are nice - gain is about 30 (compared to 100 for 12AX7?)  I built a preamp using one with a plate voltage around 180v and a Baxandall tone stack.  It's a fun little box.

Hi,

Did you ever finish your pencill pusher sub-mini amp?

I have managed to get a few 6021s and was thinking about putting one together.

Cheers Andy

I did, but wasn't thrilled with it's performance, plus I think I was saturating the OT (I decided to the two stages of one of the 6021s in parallel to boost the volume a bit and I think the OT I was using was too small).  I may go back to it someday, but pretty happy with the pre-amp version.  I might build another with three gain stqages instead of 2 to get a little more distortion when it's maxxed (the Baxandall tone stack, while very flexible saps gain).

[andy123]

I did, but wasn't thrilled with it's performance, plus I think I was saturating the OT (I decided to the two stages of one of the 6021s in parallel to boost the volume a bit and I think the OT I was using was too small).  I may go back to it someday, but pretty happy with the pre-amp version.  I might build another with three gain stqages instead of 2 to get a little more distortion when it's maxxed (the Baxandall tone stack, while very flexible saps gain).
[/quote]

Bummer to hear that. Which part of the performance wasn't good. Was the tone or the volume?

Had a search but didn't find any samples. Did you ever post any demos? I guess I should just breadboard it and have a listen :-)

I agree about the Bax. stack. I put one in my microchamp and it knocked quite a bit of gain out. I ended up putting in a switch to give me the option to bypass it.

Andy

[brad]

Gains of 30 may not be enough for a preamp, but I'm sure they could be used for something.  Be creative!

What about a tube based PWM using Otto Schmitt's Thermionic Trigger Circuit? 

[zeta55]

I've tried 6111:s, 6021:s and 6112 in preamp circuits. All worked well with different amounts of gain. I guess it all depend on what you hook it upp to, and what kind of sound you wan't from it.

/Krister

[zachary vex]

...
The current consumption of the 6021 is the SAME as a larger 12AX7 ...

actually, the 6021 uses MORE heater current.

[MetalGuy]

One 6021 triode stage has gain of 30 but  2pcs of them /4 triode stages/ should give you enough even for a high gain preamp.

[Sir H C]

Last weekend I bought a bunch of mini tubes for $10.  6021s, 5703, 5783, 5784, 6011, 5896, 5899, 5977, 5902, and others.  Only two sockets though.  Was thinking of making *something* from them, could be fun.

[zeta55]

I found them here http://www.radiodaze.com/tubes-10.htm
but 6112 cost 16$ each, 6021 are 3$

Well, I bought mine for say about $4 used. Quite a differnce.

[mlabbee]

One 6021 triode stage has gain of 30 but  2pcs of them /4 triode stages/ should give you enough even for a high gain preamp.

If I recall, when I breadboarded my pre-amp - two stages, without the tone stack, it was more than enough gain (with these values:  http://img.photobucket.com/albums/v514/mlabbee/Pencil%20Pusher/Tube_Pre_Amp_Final.jpg).  The tone stack really calmed it down - it was kind of insane without it.  I might try a tone stack bypass switch with the final version and see how it sounds.  does gain not determine distortion?

[Solidhex]

Yo

  Just had a pair of jan 5896 submini tubes come my way. Trying to learn a little about what applications they could have amp/pedal wise. Any recommendations for what to use them in? I'd love to make a Fenderish sounding mini amp.

--Brad

[Renegadrian]

I am a big fan of valve pedals, and tried some, and will start breadbording with some "pencils" I've got...

Let's learn something more about your pencils
http://www.nj7p.org/Tube4.php?tube=5896

They are dual diodes. At the moment I only made/studied dual triodes circuits, as found in almost every preamp...Some used a pentode in the pre stage too, with good results...But no I don't know about dual diodes implementation...

Try googling around, both for the valve number and for duble diodes schematics...

[frequencycentral]

Yo

  Just had a pair of jan 5896 submini tubes come my way. Trying to learn a little about what applications they could have amp/pedal wise. Any recommendations for what to use them in? I'd love to make a Fenderish sounding mini amp.

--Brad

You could try using them as diode clippers in a distortion circuit. I've considered this before but not tried it.