Tube boost + overdrive running off a 9 volt battery

[tranceracer]

I was wondering if it is necessary to let the preamp tube to warm-up before applying the plate voltage (even if it is around 12V) in order to extend their life? Or is it more a concern for power amp tubes, or tubes that run at "regular B+ voltages" (200V and +).

I'm not sure if pre warming tubes at this small voltage will extend the life that much but I did notice that as my 12AU7 pre warms up the overdrive tone actually gets less grit (which I like) and gets a little smoother.  My GT 12AU7 seems pretty steady but some other tubes' character changes a little as they warm up.

[Renegadrian]

I know it is a complete different circuit from the boosters I tried to couple with the Valvies, but I had to report that the 3dB gain of the Tillman Preamp are a nice add, it clears the sound a little too, and it doesn't get boomy at all, so let me suggest you this...

PUT A TILLMAN PREAMP BEFORE A VALVECASTER!!!

After all, it's just a simple circuit, so you can just try...But I believe it won't disappoint you...

[Jered]

I lost track after the first 8 pages but has anybody tried a tone stack instead of just a tone control?  If so what were the results?

Try a Baxandall and a source follower. I haven't tried it, just a hunch.
  Jered

[Ripdivot]

The Baxandall has a lot of loss and will eat up quite a bit of signal.

[Albot]

First time i've ever tried a tube project.
I do have a ECC85 and in a bit unsure as if i should treat it as an replacement for the 12au7.
I've been looking at some data sheets and i found that the only diffrences are the heater current wich is a bit higher on the ECC85 and the absence of the center tapped heaters. Have i missed something or could i just pop it into this circuit?

http://www.radiomuseum.org/tubes/tube_ecc85.html

[juancra]

ECC type tubes are "cousins" of the american made 12a_7 family. You can use that one in this proyect.

[Renegadrian]

From the http://www.nj7p.org/ site...

12AU7
Heater Voltage ................................ 6.3/12.6 V
Heater Current ................................ 0.3/0.15 A

ECC85
Heater Voltage ................................ 6.3 V
Heater Current ................................ 0.435 A

Also, ecc85 is missing the 9 pin heater connection...Also, thee heaters cannot work on 12V but only in 6V???
Anyway some ecc's stand in the 12a*7 yes, (in fact ecc82 is the equivalent for our 12AU7) but for what I read this ecc85 is not part of that family...Dunno if thie ecc85 can work in this circuit, but just try it out man...After all, if your first tube isn't the best, you can easily get a bunch of ol' 12AU7/ECC82 for so little $$ on ebay...

[Albot]

Sure thing, will do.
Just thought i'd ask in case i missed something. thanks for the replys.

[Jered]

The Baxandall has a lot of loss and will eat up quite a bit of signal.

Exactly, that's why you need the source follower.

[Jered]

  Keep it simple. An N-chan JFET, 10k resistor, and a .1 output cap.
  Jered

[Albot]

I tried building this although i got a problem.
My heaters run at full voltage (9.0 from pin 5 to 4).
I got pin 5 directly connected to R2 (220k) on the opposite side of pin 1 on the tube socket, is that the problem?

I skipped the tone controll and the only substitutions are a film cap for output cap and an ECC85 as tube (not put in when messuring voltages).

[Renegadrian]

Albot, R2 is between pins 5 and 1 - that is correct...So the problem is somewhere else...Maybe the ECC85 we were arguing about...maybe you should stick to the tubes that are guaranteed to work (12AU7 and 12AT7) and experiment later on...
A silly question...Did you try to run it at 6V?

[Albot]

But am i supposed to read 9v between pin 4 and 5 with no tube in? I do.
I tried to start it up fist on 9 v and the tube lit up quite yellow quite like a light-bulb so i quickly turned it off and then accutlay tested it with 6v just to see if the heaters survived the light-bulb experience,  it seems like they did
Didn't try to hook it up to an amp though.. maybe i should?

[Renegadrian]

But am i supposed to read 9v between pin 4 and 5 with no tube in? I do.
ACTUALLY I REALLY DON'T KNOW...BUT YES, I BELIEVE...9V HAS AN ENTER AND AN EXIT POINT IN PINS 4 AND 5.

I tried to start it up fist on 9 v and the tube lit up quite yellow quite like a light-bulb
MAYBE THE CIRCUIT ISN'T GOOD FOR THAT TUBE, 12AU7s DON'T LIGHT THAT MUCH...

MY THOUGHT...VALVECASTER AND ECC85 AREN'T MADE TO BE TOGETHER...

[Albot]

You know.. i think it is something with the heaters.. when messuring the tube pins i get pretty much no resistance (3 OHM) is there more across the 12au7 heater pins??

even at 6 v the heaters start out at red then clinmb up to a very light yellow/orange and i hear the wallwart starting to sizzle (boiling caps?) so i think it pulls current like a madman!! no idea why though.

I'd better pick up a 12 au7 soon, would be nice to know if i should have 9v across pin 4 and 5 before trying it out though.

[Fender56]

According to ECC85 datasheets, you must have 6.3V between pin 4 & 5, not 9V.

[dav_]

Hello from Geneva !
I build this tube boost last week and it work great 

The box is not finish...
I used a 12au7 from electroharmonix and 15v 500mA power supply regulated by a lm7812.
And I used the "pcb-less wiring diagram" from beavisaudio, there just one error, the Gain pot is wiring wrong
A little sample with my es335 guitar, I'm not a good guitar player but this is only for fun
http://tflash.free.fr/12au7vavlecaster12v/MIC-2008-04-15_18h11m48s.wav
Sorry for my English this is not my language...

[gluedtogether]

I am trying a slight variation - single tube, 2 switches to go between clean boost and drive. I did the clean mod, changing R2 and R3 to lower values. I am putting a switch between pin  three and the gain pot. Works fairly well so far. the clean boost in not a huge volume boost as is, but does fatten the sound and provide a decent boost. then kicking the gain in has been a nice addition.

I just picked up a box so I will post picks when I am done.
here is my post on the switch- probably going to a dpdt. Was trying to use a spare spdt, but can't use that and get an led going for the second switch
http://www.diystompboxes.com/smfforum/index.php?topic=67292.0

[Renegadrian]

dav, without offense,for sure, but I surely have seen better fx...
Also, you mean the error on the original layout was on the tone, wired the opposite pins...

[MikeH]

For the record- I plugged an EC885 into mine and it works just fine.