Is img turned off?

[bcmatt]

Ok sweet. Thanks guys.

I'll be sure to check out the Aiken's grounding dissertation. I really appreciate those sorts of resources. You've already made aware about some grounding issues in some practical ways these last couple of days.

I have a question; are these hum balance pots for SE amps primarily, chokeless amps, or is this something that you do universally in all your amps?

[skyboltone]

Ok sweet. Thanks guys.

I'll be sure to check out the Aiken's grounding dissertation. I really appreciate those sorts of resources. You've already made aware about some grounding issues in some practical ways these last couple of days.

I have a question; are these hum balance pots for SE amps primarily, chokeless amps, or is this something that you do universally in all your amps?

I put them in everything. Most don't but I've found that they help if your environment is noisy. Like neon and flourescent.

[bcmatt]

Well, I stared and read and searched, but I am still unsure if I have clued in on how to do the hum balance pot wiring and grounding at that point.
I'll submit my latest pic and perhaps you can tell me if I've gone astray again.
If it's starting to look close, I may try to order all the caps and resisters and pots I need to try and convert this from my vibrochamp clone. I'm pretty keen on this hum balance idea. I could see it as something that I really stick to and incorporate into everything.
Thanks for the education guys.

[skyboltone]

The hum balance pot is correct. It will look way better when you have wire to work with instead of a mouse and curser.

Build it!

Dan

[bcmatt]

It will look way better when you have wire to work with instead of a mouse and curser.

Build it!

Haha! You are definitely correct on that one sir! Cheers! Thanks! Time to get a bit more hands on.

Matt

[bcmatt]

Ok, I used my Vibro Champ for the last time last weekend. I transformed it into this layout this week. I just finished.
I followed the schematic closely, and I used a layout pretty close to what I drew.
Anyways, I just finished this morning and fired it up. However, it takes pretty much cranked volume to get a barely audible whisper. The Master Volume pot provides some scratchiness at some decent volume when played with.

So, is my incredible lack of volume due to using a different power transformer than what Allen Amplification would use? Mine provides a 320V tap as per the Vibro Champ.

So, what is it that I need to do to fix this? Is it even possible using this transformer?
Should I be measuring my plate voltages and putting in larger plate resistors? I am completely new to this real amp building stuff where you actually pay attention to voltages.. but I would like to learn.

[skyboltone]

The number one rule on trouble shooting help is........Photos!

Take a bunch and post them, then we'll get you going.

[Phil_S]

Loose those 100ohm resistors between the heater pins and the cathode of the power tube. One frequently sees 100ohm balance resistors between heater leads and GROUND but never that way.

I really don't understand this business of running the 100z resistors into the cathode. Over at 18watt.com, they seem to swear by that "elevate the heaters" trick. I didn't bother with my 18W and, really, it works fine; no hum. Hum is probably 98% paying attention to where you spot the grounds.

I only mention this because if you hang out at the 18W forum, you wouldn't say "never". There, it is more like "frequently".

[bcmatt]

The number one rule on trouble shooting help is........Photos!

Take a bunch and post them, then we'll get you going.

Ok, I was afraid you would say that. I don't mind taking them, I just worry about them making sense. On some, I drew and wrote what was happening underneath the eyelet board. Because this is a transformation from a vibrochamp and I couldn't easily get a new eyelet board, it's not the neatest thing. OK, here we go:
[/img]

[bcmatt]

As a hypothetical question, if my wiring was exactly correct to the schematic, could it have this effect from having different transformers than the amp requires? Will my ceriatone vibrochamp transformers work for this? Could it be that the PT that the Schem is made for puts out a different voltage than my BF VC Clone PT, and therefore causes this problem? Or, is the only possiblilt that it must be faulty wiring?

[skyboltone]

As a hypothetical question, if my wiring was exactly correct to the schematic, could it have this effect from having different transformers than the amp requires? Will my ceriatone vibrochamp transformers work for this? Could it be that the PT that the Schem is made for puts out a different voltage than my BF VC Clone PT, and therefore causes this problem? Or, is the only possiblilt that it must be faulty wiring?

Refresh my memory. What tube worked in your vibrochamp and what tube do you have in there now?

It's almost certainly your wiring. Sorry. And it is hard to see because we're used to looking at two princepal amps here and can spot stuff instantly. But, I'll look these over and see what I see. In the meantime there is enormous talent here and somebody will catch the culprit even if I don't.

Thing is, this thread started out as a test thread and took off. Maybe wait for a reply and if nothing is forthcoming. Start a new thread in the technical section with pictures and arrows etc and youll get more envolved.

Dan

[bcmatt]

Refresh my memory. What tube worked in your vibrochamp and what tube do you have in there now?

It was a 6V6 that was in my vibrochamp and the same tube remains. The vibrochamp worked on monday before I started in on this, so the tubes should be fine.

Ok, thanks for the tips. I'll keep going over my wiring. I may update my layout document too, to coincide better with what I did. (Just a couple locations changed a bit,...and I noticed the ground wire on the mid pot was missing on my layout as well).

Yes, I may get much more organized with this soon and move it to a new thread in the technical discussion forum. That's probably a good idea.

[skyboltone]

OK, first close look, I don't spot anything glaring. The white center tap of the high voltage winding I assume is lead under the green wire and lands with it to the chassis. Did you scrub the paint off when you made all the connections to chassis? These sorts of things frequently resolve to grounding issues.

Work up the layout like you said, give us pin by pin voltages through the entire tube lineup and check all grounds. I'll bet you find it while doing that.

Oh, it's got nothing to do with you transformers. Trust me. It may have someting to do with the connection of wires under the tape. I hope you soldered those. Google "western union splice".

Dan

[bcmatt]

OK, first close look, I don't spot anything glaring. The white center tap of the high voltage winding I assume is lead under the green wire and lands with it to the chassis. Did you scrub the paint off when you made all the connections to chassis? These sorts of things frequently resolve to grounding issues.

Work up the layout like you said, give us pin by pin voltages through the entire tube lineup and check all grounds. I'll bet you find it while doing that.

Oh, it's got nothing to do with you transformers. Trust me. It may have someting to do with the connection of wires under the tape. I hope you soldered those. Google "western union splice".

Dan

Yup, the paint at the ground points is well scraped away.

Under all the taped wires I used a simple pigtail splice and always solder them. From now on I will likely use the Western Union Splice. Thanks for the suggestion.

So, this thing about checking voltages is kind of new to me. I'm embarrassed that I am about to ask this: Am I actually just simply checking the voltage, or am I supposed to use a resistor to really be finding out current like when I bias tubes?
So here is my really stupid question:
Do I just take my DMM and set it to the 600 Volts reading and then connect one lead to the chassis ground and the other to a pin and take a reading? (I know to be careful not to touch any others at the same time)

[skyboltone]

OK, first close look, I don't spot anything glaring. The white center tap of the high voltage winding I assume is lead under the green wire and lands with it to the chassis. Did you scrub the paint off when you made all the connections to chassis? These sorts of things frequently resolve to grounding issues.

Work up the layout like you said, give us pin by pin voltages through the entire tube lineup and check all grounds. I'll bet you find it while doing that.

Oh, it's got nothing to do with you transformers. Trust me. It may have someting to do with the connection of wires under the tape. I hope you soldered those. Google "western union splice".

Dan

Yup, the paint at the ground points is well scraped away.

Under all the taped wires I used a simple pigtail splice and always solder them. From now on I will likely use the Western Union Splice. Thanks for the suggestion.

So, this thing about checking voltages is kind of new to me. I'm embarrassed that I am about to ask this: Am I actually just simply checking the voltage, or am I supposed to use a resistor to really be finding out current like when I bias tubes?
So here is my really stupid question:
Do I just take my DMM and set it to the 600 Volts reading and then connect one lead to the chassis ground and the other to a pin and take a reading? (I know to be careful not to touch any others at the same time)

That's what you do. You'll find that some pins will cause the amp to let out a big grunt or shriek, but in your case that's not a bad thing right? If you start by checking the output tube plate voltage and it doesn't make a big THUNK when you touch the plate with the DMM probe you maybe got something amis with the OT wiring, or there's no voltage on the plate. Either way you learn something.