Tube boost + overdrive running off a 9 volt battery

[trad3mark]

sigh...

tried the vero you suggested, and still nothing. the tube doesn't even glow (it did on a previous vero). Very disheartening, but i'm going to give it a rest for the day. I've college work to do.

i'll post up some pics later, maybe someone could take a look.

[Renegadrian]

Be sure about pins 4 and 5. one must receive 12V and the other must be tied to ground.
It seems you counted the pins in the correct way, anyway you may want to check the link below for reference

[Renegadrian]

I just received an email from an italian builder, he wanted to share his experiments and the results he has with different tubes...

ecc82 electro harmonix = perfect sound as expected
ecc82 electro harmonix gold pin = less gain
gt 12ax7a = bad
sovtek 12ax7 = bad
gt 12ax7wc = little overdrive and gain but good sound
vintage ei yugoslavia 12ax7 = lots of gain and harmonics

I tried to use an ax7, I have a recent JJ around, but it gave an horrible sound, and discarded the idea of using one in a Valvy...I then just discovered that SOME ax7 can be used with good results...

[trad3mark]

ok, so i'm starting to get somewhere.

Regenadrain, i'm more or less working off your VC vero with the tone dial. The only difference i made to it is that i added a line at the top, where i have all my grounds running to. It's just to simplify that in case i miss a ground. I've noticed one mistake since i took the pictures below, and that's that pin 5 was not grounded. I fixed that and it's giving the valve that old familiar orange glow. HOWEVER, i still have no fun overdrive. I don't think it's an issue with the jacks, cos i'm getting true bypass cleans like. Here's a load of pics anyway. I feel i'm close like... I've included a bunch of pics. It's easier to help with tonnes of pics, right?

1. Start off on a good note. the gental glow of a tube.
http://i43.tinypic.com/aorl75.jpg

2. Topside of the board. The black line at the top is my "Ground line". There's also a spacer line between that and the top of Regenadrain's vero, so it might be easier to check it by working from the bottom upwards.
http://i39.tinypic.com/1t5vo9.jpg

3. Tube wiring. A bit of a blurry pic, but for reference to the board.
http://i44.tinypic.com/2qw2338.jpg

4. The 1uF cap between board and Tone 1, which then goes to ground. I put it on a tiny bit of board for convenience.
http://i42.tinypic.com/2lo54i9.jpg

5. The 10nF cap between vol 3 and tone 2
http://i39.tinypic.com/2u6g4er.jpg

6. The 10nF and Vol pot. The purple wire goes to the correct pin on the switch for output.
http://i42.tinypic.com/2sbmzqq.jpg

7. The gain pot. 1 Goes to ground on board and 2 is coming from pin 3 on the tube.
http://i39.tinypic.com/10cvi13.jpg

8. And finally, the obligitory shot of the board underbelly, with the mystical magical ground line at the top.
http://i43.tinypic.com/5noncy.jpg

Again, i reiterate that pin 5 is now connected to ground (my mistake!). I have buzz/hum when i touch certain points of the whole scheme too, apart from the obvious ones like the hot input jack wire etc.

[Renegadrian]

Ok, looked at this one http://i39.tinypic.com/1t5vo9.jpg and http://i43.tinypic.com/5noncy.jpg

two things I'd like to point out.
1) the 47nF cap that lays horizontal (to the copper tracks) must have a break between its pins/legs.
The pic is not clear enough so I can't say there is that break in the track.
2) Also the res. placements is not so clear...Let's try to explain their positions with words...
Starting from the left
* 470k - pin7 and one part of the other 47nF <----> ground | It should be ok
* 1M - pin2 and the output of the first 47nF  <----> ground | I cannot understand wheter it's correctly connected to ground...
* 220k - pin1 and one part of the other 47nF <----> 12V | that seems correct.
* 100k -  pin6 <----> 12V | that seems correct.

So I believe the problem is where that 1M res is connected...It should go to ground together with the 470k, but my eyes don't seem to get that...

[Renegadrian]

PS try to write my name correctly or I won't help you anymore!!! 
(kidding...)

[trad3mark]

sorry Renegadrian

yeah i had a little look there this morning, and noticed a few mistakes. Here's a pic to update:
http://i42.tinypic.com/2vx24k5.jpg

So just to clear some things up:
1. There is a cut between that 47nF horizontal cap.
2. The resistors:
a. The 470k is going from (at the bottom) Pin 7/47nCap 2 TO Pin 4/Ground/1M (At top, and to 1M via jumper)
b. The 1M is going from (at the bottom) 47nCap1/Pin 2 TO Pin4/Ground/470k (At top, and to 470k via jumper)
c. The 220k is going from Pin 1/47nCap2 TO Pin 5/9V+/100k
d. The 100k is going from 9V+ to Pin 6

Which all seems correct, right?

[Renegadrian]

Yeah, it seems correct...I'd advise you to run it at 12V.

[trad3mark]

not much point doing that though if i've no output at 9V, right?

[trad3mark]

Just to verify, if i had a problem with one of the jacks i wouldn't get any signal on true bypass, right? and if it was an issue with the lug with the -ve, the tube wouldn't light up, right?

[mcelek]

Hi boys!
I read this topic for a year, but I couldn't register here. Why? I don't know... 
I was searching for a tube preamp. I build a guitar amp for myself and I wanted a tube preamp.
Do you know The Hood? It's the best low-voltage preamp, I think.
http://www.pdfelectronics.com/the_hood_a_custom_pre_amp_design.htm
It has a very good working tone stack. Boost and clean/dirty switch...
It has warm and very detailed sound. From the clean sound to hard overdive... Great!
I'm using it with stable +24V power (7824), because the power amp has a +-26V supply.
(How can I insert image?)

Attila

[Ripthorn]

Chris, the guy who developed the Hood is quite active with tube stuff here.  He's a good guy with great designs.  Welcome to the forum.

[trad3mark]

Hmmm...

anyone got some Voltage Refs for the 9v version, preferably Renegadarian's Vero version with tone?

[frequencycentral]

Hmmm...

anyone got some Voltage Refs for the 9v version, preferably Renegadarian's Vero version with tone?

The only voltages in this entire 65 page thread are the ones I've posted a few times, taken at 12 volts. Yours at 9 volts will just be 75% of mine. Post up your own voltages and we'll detect what's amiss.

[trad3mark]

so where should i check? (this is my first go of my new multimeter, and my first set of voltage refs! )

[frequencycentral]

so where should i check? (this is my first go of my new multimeter, and my first set of voltage refs! )

Set the Gain, Tone and Volume to maximum. Hook up the black probe of your DMM to ground and use the red probe to take readings from each of the tube's 9 pins.

Here's mine:

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

[trad3mark]

Great. Thanks FC. I've to take the dog out for a walk really quickly, i'll check it all when i get back.

[trad3mark]

Right, not sure if i'm doing this right:
Black lead is connected to COM on DMM. DMM is set to 20V, Black Probe to Ground on Output, 9v Battery connected, input jack connected, and i put the red probe on the pins giving these readings:

1. 6.47
2. -0.02
3. 0.00
4. 0.00
5. 7.83
6. 7.09
7. -0.02
8. 0.00
9. 3.86

is that done correctly?

[frequencycentral]

Firstly, your battery is only reading 7.83 volts, that's probably not enough, as the heater requires 12 volts. I personally feel that 9 volts isn't enough for the heater really. Valvecasters eat batteries for breakfast. Consider using a regulated wallwart, preferably a 12 volt one.

Secondly, your voltage at pin 1 is way too high. Double check the value of the resistor connected to pin 1, it should be 220K. Your pin 6 voltage is a little high too, but solving the issue at pin 1 is the key right now.

[trad3mark]

i checked that resistor. it's 220k, definitely. I checked the voltage at both ends, and there's a drop, so it's soldered correctly too.