Tube boost + overdrive running off a 9 volt battery

[merlinb]

Well putting the cap after the pot failed completely.  It started to fart out when hitting the strings hard, so its gone back to before the pot.
I'll put up with the crackle. 

You need a cap before and after the pot, AND a resistor from grid to ground (about 100k), if you want to eliminate the crackle.

[juansolo]

I was going to add a resistor to ground on another build, but not the second cap.  Thanks Merlin.  I'll give it a go.

I assume its the lack of any DC on the grid that causes the issues when the cap is after the pot?

[merlinb]

I was going to add a resistor to ground on another build, but not the second cap.  Thanks Merlin.  I'll give it a go.
I assume its the lack of any DC on the grid that causes the issues when the cap is after the pot?

Yes, if you have no resistor after a coupling cap then you will get a 'charge pumping' effect every time the grid draws current on positive half-cycles, because the cap has no resistor to discharge through on negative half-cycles. This causes the farting noises you hear!

[iccaros]

the issue is current through the pot as I have found with no coupling @ all you get the same noise.. With a capacitor the cap will discharge or charge as current changes so it cancels the current changes of the pot.

That is the theory I am sticking with..  

I agree you need the grid leak resister as the pot was doing that before, but I would try between 100K as suggested and 500K .. @ these voltages its not really necessary for the tube as it is in higher voltage setups but it acts like a pull down resistor.  You could also do a pull up instead, between 600K and 1M  to +12. This would give a like effect, but is more radical to your design.

[juansolo]

That took 5 minutes, and works perfectly.  My ears are ringing, I thought the amp was on the gain channel, but it was on the clean, this thing is SO loud!

Thanks Merlin.

[Anon]

I don't get any hum, I have the 15v going through a capacitor/7812/capacitor setup, and it's really clean
Actually the output is powering all my pedals at 12v

I was wondering how you wired it. I had the 35V side going to the anodes and the 15V side going to the filament. I used a 7812 to convert the 15V to 12V. All I got was a loud hum with all the HP printer adapters. All of the grounds were connected properly. When I went back to the 15V radio shack adapter there is no hum

that is filtering, I bet you money if you put the HP power supply to a o scope you would see a ac spike from the Switching power. Make sure your adapters say filtered and not switching..  Computers can having low frequency switching.. as they are no bothered by the noise at those frequencies. but audio equipment.. That is another story..

I have a 30v dc adapter from RS that is dead quite.  but hook up the HP printer one and I get noise..

Is there something I can build to filter out the hum?

[ThunderShowers]

I don't get any hum, I have the 15v going through a capacitor/7812/capacitor setup, and it's really clean
Actually the output is powering all my pedals at 12v

I was wondering how you wired it. I had the 35V side going to the anodes and the 15V side going to the filament. I used a 7812 to convert the 15V to 12V. All I got was a loud hum with all the HP printer adapters. All of the grounds were connected properly. When I went back to the 15V radio shack adapter there is no hum

that is filtering, I bet you money if you put the HP power supply to a o scope you would see a ac spike from the Switching power. Make sure your adapters say filtered and not switching..  Computers can having low frequency switching.. as they are no bothered by the noise at those frequencies. but audio equipment.. That is another story..

I have a 30v dc adapter from RS that is dead quite.  but hook up the HP printer one and I get noise..

Is there something I can build to filter out the hum?

http://www.beavisaudio.com/projects/Huminator/index.htm

[iccaros]

If its in the audio range?? you would have to filter on the power input. If you had a scope you could see what frequency was spiking as you are most likely hearing  a harmonic from the heater and roll that off. other wise you are guessing. Look at your adapter, does it show two output voltages as mine does.. It may be heterodyning and which case no..  http://en.wikipedia.org/wiki/Heterodyne

[akkor68]

Hi, I'm new in electrics and I built the pedal according to the schematic:

The tube lights up but I only get noise from the pedal. If I turn the volume pot to max it stops, but nothing else happens.
What could be the problem?
I think I might have soldered C3 in the wrong direction. The positive leads to pin 6 doesn't it?

[zambo]

yep. + on pin 6 and - on the tone pot. Check r1 and r4 as they are often culprits of no sound. got a picture to look at? that helps. if not, look back some pages and get the voltages to compare.

[CheopisIV]

Got some pics (finally)  Breadboard and boxed up.  Next hurdle, fancy decal!

Here's a link to the album.
---> LINK <---



edit:
(Was going to link pics, but this computer is limiting me and I can't get direct links to work properly.  Will try again when I get home!)

[iccaros]

Got some pics (finally)  Breadboard and boxed up.  Next hurdle, fancy decal!

Here's a link to the album.
---> LINK <---



edit:
(Was going to link pics, but this computer is limiting me and I can't get direct links to work properly.  Will try again when I get home!)

what voltage do you have on the heater? I have only seen them shine that bright when the voltage is high

[CheopisIV]

I'll put the voltages up later tonight as well, but they're not far off the last ones I posted.  This particular tube lights up a lot compared to some of the others I've had in the circuit.  This was taken with the 12V adapter just for the glow effect, they're not nearly as bright at 9V.

[deadastronaut]

put leds under them....they look nice lit up. 

[CheopisIV]

put leds under them....they look nice lit up. 

I wanted to put a green one under it but my sockets are all a bit different; this one had way too small a hole for my 5mm LEDs to fit!  Some of my other sockets are a perfect fit though, so on my next one I'll be doing it for sure.  They do look badass with the LED underneath though! 

[ThunderShowers]

I never did Show this. Custom Stainless box I made for these. Don't ask for one, it's not cost effective.

[iccaros]

I never did Show this. Custom Stainless box I made for these. Don't ask for one, it's not cost effective.

I like it...

[iccaros]

I'll put the voltages up later tonight as well, but they're not far off the last ones I posted.  This particular tube lights up a lot compared to some of the others I've had in the circuit.  This was taken with the 12V adapter just for the glow effect, they're not nearly as bright at 9V.

if you are running it off 12v your good, and I have a LED to make mine bright also.. so I like it.. My pot on my lm317 died when mine got that bright..

[CheopisIV]

Here we go!  Heaters are at 12.33 on this one, but it's an unusable adapter due to the whine.  I have an order in to Mouser for a bunch of parts for some charge pump/regulator kits though, so I'm hoping to put something together for a functional 12V Valvecaster with low noise and higher output.  I run it off a 9V 400ma adapter to play with.

I'm so in love with this pedal, such a clear and useable boost!  It retains my Tele twang like no other boost can and even plays real nice with my Les Paul.  I'm going to let a friend use it at his next band practice tomorrow; gonna be hard to hand it over! 

[juansolo]

That took 5 minutes, and works perfectly.  My ears are ringing, I thought the amp was on the gain channel, but it was on the clean, this thing is SO loud!

Thanks Merlin.

Updated schematic.  May need to refresh browser.