Chandler Tube Driver...Any chance to build one?

[jsleep]

I haven't gotten the noise down to what I would consider acceptable yet, but I'm not too worried. I think when I box it up most of the noise will disappear.  Also I could shield the auido wiring, but I hate to break my perfect record of never having used shielded wire in any of my stompboxes :lol:  Anyone see anything inherently wrong with the layout?

I tried tapping of the dc voltage for the heaters, but I couldn't get it to work, so I'm not sure what I did wrong there.

It really sounds good to me other than the background hum that I'm getting.  I twisted the heater wires and got them away from the other wiring, like an amp, but that didn't help much.

JD

[Doug H]

I haven't gotten the noise down to what I would consider acceptable yet, but I'm not too worried. I think when I box it up most of the noise will disappear.  Also I could shield the auido wiring, but I hate to break my perfect record of never having used shielded wire in any of my stompboxes :lol:  Anyone see anything inherently wrong with the layout?

I tried tapping of the dc voltage for the heaters, but I couldn't get it to work, so I'm not sure what I did wrong there.
JD

The problem there is that the heater pulls so much current it really makes the "v+" voltage drop. You will have a hard time doing that with an unregulated pwr supply like this.

It really sounds good to me other than the background hum that I'm getting.  I twisted the heater wires and got them away from the other wiring, like an amp, but that didn't help much.

JD

I suspect what is going on is that with the one side of the heater essentially grounded, you are getting AC noise from the heater circuit on the ground bus.  I haven't looked that closely at your PCB (or mine for the pentode driver, for that matter ) but I suspect a star-grounding scheme might help: one star for the Pwr supply/heater circuit, and one star for all the signal grounds. Then connect the stars with a wire. (Not sure what that does to your PCB layout .:wink: ) The main thing is to give the signal current a local return path where it doesn't have to go through the noisy pwr supply and AC heater stuff. (The thing is, I think I essentially did that with the Pentode Driver because I have a completely separate pwr supply board...)

Another thing you might try is insulating the input jack, so it does not get grounded through the chassis. The input will be sensitive to noise. Just thinking out loud but it might work better to let the output jack provide the ground "shield" connection for the box.

I went through similar "hum" frustrations as you have described with my Pentode Driver. I ended up just living with it.  I really think a better way of doing these starved plate tube pedals is to dump that bi-polar supply to begin with. Connect the "v-" points on the tube circuit to ground, use a divider for a Vref for the op-amp, use a 30v wall-wart for the tube/op-amp power and use a voltage regulator to get a DC heater voltage for that. But you know that drill, JD.  

Doug

[jsleep]

Thanks  for all the tips Doug!

Yeah, I was hoping to keep it "original", even though my layout is anything but original.  But yeah, I've had a concern about the ps for this thing since I first saw JG's hand-drawn schematic.  I've considered updating the ps part of the circuit, but decided to try it first as-is.

I'll try the star grounds, that won't be hard to do. I may even move the ps off the board and see if that helps, that shouldn't be too hard either.  I'll keep posting here (might start a new thread) after I do some more heavy duty experimenting.

JD

[zonta]

please do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it do it....



thanks btw.

[Doug H]

I think useing DC voltage for the filmament heaters can improve the noise - and maybe the use of shielded cables.

6.3VAC would be okay too, since you would use the heater center tap and wire the 12ax7 in "humbucking" mode (like with most amps). Can't do that with this PS, but anyway... In any case, the 12.6VAC heater is going to be a noisy affair.

Doug

[Doug H]

Big T:  

I debated the pcb mount tube, but in the end I decided that it would be better off-board.  The more I think about it the more I think I was wrong ;-)  JD

IMO, off-board is a better way to go. I have no experience with PCB-mount tube sockets but I sure hate the idea of putting that kind of mechanical pressure on a PCB. Tubes/sockets can really be a tight fit. The wiring of a PCB-mount is much simpler, if you can point everyone to use the same socket part# so the spacing will match the drill pattern on your PCB. But it's a tradeoff, I guess...

Doug

[Mike Nichting]

here is a pic of my Tube Driver board with off board tube socket before I wired the pots and such.
I still haven't wired up the transformer yet but have a look anyway.

 let me know if the PS needs to be off board before I finish this. Click on "my photos" and it's all the way to the right.

thanks all~!!
Mike N.
http://f1.pg.photos.yahoo.com/imwrekt

[zonta]

Jsleep it is weekend and i don't see any tubedriver pcb on the page.

[BillyJ]

Hey Mike,

I don't know if you have to but I recently had to replace a PS for one and indeed the transformer was out of the box.

[rx5]

guys,

Ive heard bout those tubes producing hiss or hum... there are ways to eliminate it....

1> DC voltage 12.6VDC to the filament.wire them in series so each filament gets 6.3VDC....
2> I dunno how much the supply to the plate is...but aim for +45VDC to +100VDC...use a voltage multiplier or a "reversed" connection transformer......
3> shield all connections, including the pots... I mean SHIELD those conecting wires to pots, not just the pot body....
4> If it has hiss, it means that the the TUBE is oscillating....that how it oscliiates...unlike semiconductors that "squeEll" when they oscillate....
5> If hum, it just needs shielding... as stated in #3
6> carbon comp resistorr are noisy when used in tubes... carbon film are best...
or search google for "real mctube II" so you get more info but 12AX7 tubeand other helphfull stuff....

regards

-Ralph

[Ansil]

wicked cool idea to carry i may have to check that out.

[jsleep]

Zonta,

Are you looking at the right site?

http://www.generalguitargadgets.com

http://www.generalguitargadgets.com/v2/index.php?option=displaypage&Itemid=117&op=page&SubMenu=

This stuff has been out there for several weeks.

JD

[zonta]

lol dude.

i mean the pcb for online sale.

[jsleep]

Zonta,

Now it may be another 2 or 3 weeks.  I'm working on the noise problem, but now Anubics has posted a Chandler Tube Driver Schematic, so I need to factor that into this project as well, thus the hold up.  When this is done, it will be good, but we must have patience.  Sorry it didn't work out as soon as I thought it would, but it will be worth the extra wait.

I plan on experimenting with several different power supplies and also try out the slight variation in the tone controls on that new schematic.

JD

[analogguru]

jsleep, you also should have a look at the kampo 901 schematic.

it seems to be a tubeworks 901 copy.

greetings, analogguru

[zonta]

ok. i may wait for a couple of weeks for sounding like david gilmour. i have waited 15 years already so a few weeks more is nothing.