Tube boost + overdrive running off a 9 volt battery

[KorovaMilkBar]

hello! i just got a package from mouser and i messed up on the potentiometers. they are 1 b50k and 2 b100k (the plans call for a100k). they are also the receding (sp) thumbdial kind. so are these any good or should i head to radioshack? thanks!

mike.

p.s. i should be getting the tube anyday now, soon as i do i will be working away on this! im so excited!

anyone?

[Ripthorn]

The taper will be off, which means the adjustment will seem a bit choppy and hard to find the sweet spot.  You can still use them, but if you can afford it, I would suggest getting the right ones because that will just make life easier.

[svstee]

OK, I was comparing my 6111 to my 12au7 vavlecaster and noticed that the 6111 has quite a bit more bass. the 12au7 had plenty, so I'm a little concerned. Any way to get a hair less bass out of it? Also the 6111 doesn't break up as early unless you have a guitar with very hot pickups or some kind of boost in front of it. I assume this a result of running a 12v circuit at 9v, but what would I change to improve this (beside running it at 12v)?

[Ripthorn]

With tubes there is no real substitute for more voltage.  In terms of bass, you can change the input and output caps.  I built a tube booster with a .01 input and .047 output and that seemed to regulate the bass.  Also look at any cathode bypass caps, lower values will reduce the bass.

[biggy boy]

I believe lowering the value of the cap between the two stages will also roll of some bass too.

Glen

[Ripthorn]

That is true, I guess I just lumped that with either the output or input cap because it is the output of one stage and input of the other.  You can also do some parallel resistor/capacitor things to tailor the frequency response between stages as well.

[Renegadrian]

Found THIS googling...

[Renegadrian]

http://www.dogstar.dantimax.dk/tubestuf/graphics/dz_tone.gif

http://www.triodeel.com/comp1.jpg

[frequencycentral]

Found THIS googling...

JKowalski is a member here too, surprised he hasn't mentioned it on this thread too. Innovative use of a charge pump to up the plate voltage!

[CynicalMan]

This circuit looks too good to be true! I'd like to try it out with this tube:
http://tdsl.duncanamps.com/show.php?des=6J6A
I will be running off of proper heater voltage. What I'd like to know is, since the plates of the two triodes are connected, can I connect the cathode of the second tube to the gain pot instead of ground?
Also, are there any parameters in the datasheet I missed that would prevent it being used for audio or for low voltage?

[frequencycentral]

This circuit looks too good to be true! I'd like to try it out with this tube:
http://tdsl.duncanamps.com/show.php?des=6J6A
I will be running off of proper heater voltage. What I'd like to know is, since the plates of the two triodes are connected, can I connect the cathode of the second tube to the gain pot instead of ground?
Also, are there any parameters in the datasheet I missed that would prevent it being used for audio or for low voltage?

The plates are not internally connected, but the cathodes are. You could tie the cathodes to ground and use an interstage gain control though.

[CynicalMan]

The plates are not internally connected, but the cathodes are. You could tie the cathodes to ground and use an interstage gain control though.

Right, cathode. I'm not good with tubes yet. 

And the datasheet looks OK?

[frequencycentral]

The plates are not internally connected, but the cathodes are. You could tie the cathodes to ground and use an interstage gain control though.

Right, cathode. I'm not good with tubes yet. 

And the datasheet looks OK?

Well its a medium mu twin triode, as is the 12au7, so worth a try. Jus't remember you can't use the regular Valvecaster gain control, it needs to be and interstage gain control.

http://www.pmillett.com/tubedata/HB-3/Receiving_Tubes_Part_2/6J6-A.PDF

[frequencycentral]

I wonder if it would be possible to use a number of 1n4148 in series to drop the voltage........each one has a voltage drop of 0.7v if I recall. So four in series would drop 2.8 volts. Never tried it..........I wonder if it would work?

I've just been reading the 'Heaters' page over at Valve Wizard. Merlin says: " A pair of ordinary high-current silicon diodes can be added to the heater chain to drop the heater voltage by about 0.7V. (If using a DC heater supply, only one diode will be needed.)"

So I guess he means 1n400*, using four in series would drop 2.8v, using eight (seems a little excessive) would drop 5.4v.

There's also some really good info about series/parallel heaters and pairing mismatched heaters.

http://www.freewebs.com/valvewizard/heater.html

[biggy boy]

The Valve Wizard is great!
I've learned a lot from him, over the past month or so.
He was even kind enough to answer a couple of questions I asked him via Email.

glen

[glenn.b]

This is my first post here, on this site. I guess it is fitting that my first post be a request for help.  I have just finished building this based on Dano's schematic and layout all the way back at the beginning of this thread.  All I can manage to do is get a loud hum when I plug this into my amp.  I have noticed that if I put my hands on the input/ output jacks and press down just slightly, I can hear a very static filled, quiet sounding strum of my guitar strings.  I was hoping maybe that one of you that has been here would have an idea...Any good ideas / thoughts/ suggestions would be much appreciated.  Thank you

[Renegadrian]

Welcome aboard! 

Does the tube light up?! Have you checked the pins? Maybe you read them au contraire?! How is the thing powered? Tube is 12AU7?! Tell us more - pics appreciated too.
Let's make another Valvy work!!!

[frequencycentral]

This is my first post here, on this site. I guess it is fitting that my first post be a request for help.  I have just finished building this based on Dano's schematic and layout all the way back at the beginning of this thread.  All I can manage to do is get a loud hum when I plug this into my amp.  I have noticed that if I put my hands on the input/ output jacks and press down just slightly, I can hear a very static filled, quiet sounding strum of my guitar strings.  I was hoping maybe that one of you that has been here would have an idea...Any good ideas / thoughts/ suggestions would be much appreciated.  Thank you

Posting your voltages at all 9 pins is an essential part of debugging. Here's mine, running at 12 volts, with the gain control set to maximum:

Pin 1: 3.02v
Pin 2: -0.518v
Pin 3: 0.00v
Pin 4: 0.00v
Pin 5: 11.97v
Pin 6: 8.21v
Pin 7: -1.285v
Pin 8: 0.00v
Pin 9: 5.91v

If you are running at 9 volts, all your voltages will be 25% less than mine.

Also worth reading this: http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[lunchie]

Today I found this article on makezine ... I thought that somebody could be interested ...

http://www.electricwestern.com/diytubes.html

[glenn.b]

Thank both of you for the welcome!

Ok, this is pretty awful, but the values coming off my pins are way higher than yours, and I am only using a 9volt.  As far as pics I have tried to capture it, but normally the pic overexposes , due to me trying to shoot it to close.   My pins(sigh) are 1:9.24                                                                         
                                                                                                                                                      2:8.51                     
                                                                                                                                                      3:000
                                                                                                                                                      4:9.33
                                                                                                                                                       5:9.34
                                                                                                                                                      6:9.34
                                                                                                                                                      7:8.93
                                                                                                                                                      8:000
                                                                                                                                                      9:9.33

      Almost like there is a complete open.  Anyway there it is-geez, I know I'm new to this!