Tube boost + overdrive running off a 9 volt battery

[Jimmy-H]

> you want you heaters at a minimum of 12.2v,12.6 is optimum for 12A_7 tubes.

Thanks jered, I thought we were shooting for 6.3v. Is the 6.3 for the 6111 tube is it? I'll crank up the voltage on the heaters a bit more ,Thank you . JOHNO

Yeah, the 6111 tube only work with 6.3 volt.
The normal tubes work with 6,3 volt when using the center tap as ground.(this also doubles the current you use)
Otherwise 12.6 volt without the center tap.

[Jimmy-H]

Oh sorry, asked for the wrong thing heh, what I meant to ask was
which value of C1 other than standard 47nF would you choose if you only could choose between two values (a two way switch)

You could try 2n2 or 4n7.
But you could also try some other values (those caps are not that expensive)
Experiment a littlebit, and when you find the right ones you like, put them in!!

[Jimmy-H]

I'm in for the high gain circuits...Eager to see your work!!! 

Yep so am I!!!

[Renegadrian]

Jimmy, and all my fellow tube friends, did you check the VERO double valvy layout I added in the gallery?
it should work but I'd like you to check it...
In the LAYOUT GALLERY search for TWINCASTER.

PS actually it's 2 layout, with and without the R1 at the beginning at the second stage. Someone said it's better to add that res...

[Jimmy-H]

Jimmy, and all my fellow tube friends, did you check the VERO double valvy layout I added in the gallery?
it should work but I'd like you to check it...
In the LAYOUT GALLERY search for TWINCASTER.

PS actually it's 2 layout, with and without the R1 at the beginning at the second stage. Someone said it's better to add that res...

Hi Adriano,

Sorry that I didn't check it earlier.
I never use stripboard.
But as far as I can see, the layout should work!! 

I used this schemo to check:

[Renegadrian]

Yes, that's from that schem - thanks for checking, Jimmy!!! I appreciated that...

[stephanovitch]

Hi,
do you think it's possible to supply the heat circuit of 12ax7 with only 3,3V for one triode section?
I ask this because the cooltron serie of Vox, use this technic to decrease current consumption.

[frequencycentral]

Hi,
do you think it's possible to supply the heat circuit of 12ax7 with only 3,3V for one triode section?
I ask this because the cooltron serie of Vox, use this technic to decrease current consumption.

3.3v for one triode? There are two triodes in a 12ax7, therefore 3.3v for each is 6.6v right? The two triodes share a common heater - you could supply the heater with 6.6v using the centre tap, but 6.3v is preferable. However, using the centre tap at 6.3v consumes 300ma, whereas using 12.6v and not using the centre tap uses just 150ma.

Having said that, running the entire circuit at 9v ( as some people do, including myself) give the heater just 9v, and the circuit works just fine.

So, the rule seems to be: less volts = more ma

[frequencycentral]

.......................although interestingly enough, all the Cooltron range are rated at 95ma...............

http://www.voxamps.co.uk/pedals/cooltron.asp

[Jimmy-H]

Hi,
do you think it's possible to supply the heat circuit of 12ax7 with only 3,3V for one triode section?
I ask this because the cooltron serie of Vox, use this technic to decrease current consumption.

3.3v for one triode? There are two triodes in a 12ax7, therefore 3.3v for each is 6.6v right? The two triodes share a common heater - you could supply the heater with 6.6v using the centre tap, but 6.3v is preferable. However, using the centre tap at 6.3v consumes 300ma, whereas using 12.6v and not using the centre tap uses just 150ma.

Having said that, running the entire circuit at 9v ( as some people do, including myself) give the heater just 9v, and the circuit works just fine.

So, the rule seems to be: less volts = more ma

First, VOX uses 12Au7 TUBES.
I don't think 12AX7 sound very well with that low voltage.
I never tried to use a heater voltage of 3.3 volts.
But eeh the VOX pedals are working!
I don't know how it sounds.

Less voltage isn't always more Current.
Because if you use 9 volts without the centre tap, the current Will be less then 300 mA.(just maths )

So just try, and let us know, what it sounds like with 3.3 volt!!

[frequencycentral]

"Here's what makes the COOLTRON system tick. The COOLTRON circuit basically operates by using two very special signal paths. The first is the "servo circuit," which provides the right conditions between the plate of the tube and the grid. This achieves controllable, stable parameters for the tube and provides the correct operating conditions for the tube to function as it would if run at a higher voltage. The second circuit is a patented power supply that provides a low voltage, low current supply to the heater elements in the tube. Since the tube is now running at such a reduced supply level, the anode current is much smaller than normal. This means that the amount of heat required at the cathode to achieve sufficient cathode current emission is much smaller – hence the ability to run the heaters at a lower level and for COOLTRON pedals to run for 16 hours on 4 x AA batteries!"

[Jimmy-H]

"Here's what makes the COOLTRON system tick. The COOLTRON circuit basically operates by using two very special signal paths. The first is the "servo circuit," which provides the right conditions between the plate of the tube and the grid. This achieves controllable, stable parameters for the tube and provides the correct operating conditions for the tube to function as it would if run at a higher voltage. The second circuit is a patented power supply that provides a low voltage, low current supply to the heater elements in the tube. Since the tube is now running at such a reduced supply level, the anode current is much smaller than normal. This means that the amount of heat required at the cathode to achieve sufficient cathode current emission is much smaller – hence the ability to run the heaters at a lower level and for COOLTRON pedals to run for 16 hours on 4 x AA batteries!"

Hee Rick you really did your research!!!!

[Renegadrian]

I don't know if you agree with me, but I have a bad opinion about those hybrid pedals, the Valvy is special to me as all the sound comes from the tube only, and the tube itself is not surrounded by trannies and other things...

[frequencycentral]

I don't know if you agree with me, but I have a bad opinion about those hybrid pedals, the Valvy is special to me as all the sound comes from the tube only, and the tube itself is not surrounded by trannies and other things...

Yes Adriano I agree - the less components the better.

At the moment I'm working on a circuit which may be of interest - a single tube tremolo - 9 volt of course. The one on the breadboard uses a 6111 but I will use a 12au7 for the finished pedal. It uses a LM13700 VCO, and has two speeds, selectable by stompswitch. It slowly speeds up/slows down when you stomp the speed change switch. There is a nice light valve crunch if you play harder. I will post it when its finished!

[JOHNO]

Great work freq ,its crossed my mind to make a valve trem like in the old fenders but im not that switched on yet. Im just wondering how long it will be before some company stooge gets hold of the valvy and we start seeing them in the stores.

[dano12]

So, who is going to be the first to do a valvecaster->386->1 to 1 matching transformer?

There's magic to be found there....

[Darkness, Darkness]

Hi Dano12, I was just wandering if it would be ok to add a phase inverter stage, possibly plugged in a 1:1 transformer at the end of a valvecaster or valvecaster-like 

I need more parts to test this....I will have to wait for my next parts order ! By the time, do you think the idea of the phase inverter / transformer is relevant in such circuit ?

[Aren]

So, who is going to be the first to do a valvecaster->386->1 to 1 matching transformer?

There's magic to be found there....

I'm puzzled here... a transformer after a 386? 
I had a few thoughts about adding an impedance matching transformer after my cleaned out version of the valvecaster that will create a tube DI, but after a 386? what's the deal there?

[aka_basse]

gaah!

Took long enough for the banzai shipment, (with several items backordered - including the tube).  When I finally get it.... there's no box. They forgot the box. Getting pretty pissed...

[Darkness, Darkness]

gaah!

Took long enough for the banzai shipment, (with several items backordered - including the tube).  When I finally get it.... there's no box. They forgot the box. Getting pretty pissed...

For my last orders some items were back ordered too. It took a bit more than one week to be shipped ... and most of the time I usually get the back ordered parts in a separate shipment (at no extra shippment costs) Last time I thought they forgot one item (as they did not have noticed it on the order list as they usually do)  But I finally got it a couple of days later

personaly I think the service is good  but you need a bit of patience  Good luck !