The Amp Garage

Cool! Let me know how it works out. If you've already got the space for the extra pot, you can have 2 MVs, one being for solo volume. You switch out the wipers, and grounds if you are concerned with loading. That AND the mid boost on the same rlay would be quite a kick. Then, if you had both MVs se...

Thanks Smokebreak, this is very timely (weird how that happens) I have a build in the tweaking stage that the customer requested a lead boost. Wanting to make it variable I put a boost pot wired as a variable resistor "under" the volume pot, to ground. Well... that didn't give me what I was looking ...

what are the origins of that 10n , 150K boost circuit on the treble pot? I don't recall seeing that before. Is that a boost in the form of increased mids?

I use cheap 2" brushes with the wood handle from the home centers for $1 ea. In between coats I put them in a jar with mineral spirits that keeps them from hardening. Prior to the next coat I wipe the excess mineral spirits off with a paper towel, and then take a wire brush to it for about 15 second...

memphis032 wrote:I assume two 1M pots in parallel, switching between the wipers?

Correct!

Smokebreak wrote: Triggered MVs linked to each channel would be fun.

That's what I did, and it is (fun).
Two relays triggered together, a DPDT for the channel and a SPDT for the MV. I used a DPDT for both.

[double post]

Yeah, it depends on the plate voltage the PT will give you. The Marshall 50W replacement PTs that Magnetic Components sells are rated at 150mA with 345-0-345 secondaries.
http://www.classictone.net/40-18023.pdf
But I always feel better putting something rated 200mA+ in amps of that sort.

I don't think this issue is related to 6L6 vs. 5881. The tweed bassman 5F6A is a common example of an amp "designed for 5881s" that folks routinely run 6L6s in. You should be able to bias a little hotter than 35mA w/ 6L6s, but I don't think that has anything to do with the issue you're describing. S...

This "Journey to the Center of a Tube" might help:
http://youtu.be/WnZRJjmOZb8

have you shopped locally? I can get a 4' x 8' sheet of .060" here for just under $100.

A few have mentioned tips not lasting... a few years ago I read a tip to use only distilled water on the sponge, that this would help tip longevity. ...something about the minerals in most tap water. I made the switch and I definitely think it makes a difference.

Inspired my cbass and FusionBear's recent Naylor Superdrive builds in this thread: http://ampgarage.com/forum/viewtopic.php?t=24344 I decided to gut an old 2x5881 build that never went anywhere and has been gathering dust for the past three years, an fill it with some superdrive goodness. This OT fo...

Your numbers look good. You are correct that since your probe is 10:1, 2v peak to peak on the scope is equal to 20v peak to peak at the probe tip. Now, as far as the filament supply measurement goes, your meter is showing the AC RMS voltage, but your scope is showing you peak to peak voltage. To co...

Thanks for the tips. I did have an issue with the way my probe was assembled. Under the spring-loaded clip piece there was a small sleeve that I think was preventing good contact. I removed that and I'm getting a much better trace. I connected the probe to a new 9V battery that measures 9.8V with my...