| Author |
Topic: Web 6-14e schematic question - little help? |
Scott Hay
From:
Portland, OR / Yucca Valley, CA USA
|
Posted 2 Oct 2011 3:43 pm |
|
Hey folks,
Couple questions....
1) anyone have the schematic for an older webb 6-14e? I think mine's a late 70's / early 80's one.
2) I've noticed on my amp, the volume knob is really touchy. It's basically on 10 once it hits 1, which is not my first preference when trying to fine tune levels in a band.
I had a reputable amp tech here in Portland look at it and he pointed out that the volume pot was a "reverse audio" pot , 50k I believe, and thought that was a bit odd that it was "reverse audio". (the meaning of which is beyond my achieved nerd-dom)
Any insight on this from other or former owners of older Webb's?
If that was the intent in design and it serves a sonic purpose I'll probably live with it, as the amp sounds killer.
Thanks in advance!
- Scott |
|
|
 |
Jay Ganz
From:
Out Behind The Barn
|
Posted 3 Oct 2011 5:05 am
|
|
What??? That sounds pretty strange. I started sending out schematics years ago to a few forum members and they have also been sending them around.
This sounds like just a bad control though. You shouldn't need a schematic for that. Just another control or possibly contact cleaner. |
|
|
|
Steve Lipsey
From:
Portland, Oregon, USA
|
Posted 3 Oct 2011 8:18 am
|
|
Scott-
I'm guessing that someone broke the original pot (easy to snap off a shaft if you bang it) and replaced it with whatever they had in their parts bin - it is highly unlikely to have been what was used originally. Easy to change it to an audio taper pot: I could do it, or you could take it to any amp repair place - if the Webb isn't constructed with it buried behind a lot of stuff, it is easy to do...
Here's the story, if you are interested:
"In a potentiometer, taper refers to how the resistance varies as the pot's armature is rotated
For a pot with a linear taper, the resistance varies linearly as the wiper moves.
For a pot with a logarithmic (log) taper, the resistance varies logarithmically with the wiper's motion. When used in an amplifier circuit, the output varies slowly as the pot is operated at the low end and varies more and more rapidly as the pot is operated toward the high end.
This is also called an audio taper because it is most commonly used for audio volume controls. The ear responds logarithmically (each doubling in signal is perceived as an equal step in volume). The ear is more sensitive to changes at lower volumes, so an audio volume control varies the signal slowly at lower settings and more rapidly at higher settings. The net effect is that the sound seems to vary smoothly through the pot's range.
An antilog or reverse audio taper pot is quite uncommon, but used to be used for left-right balance controls using a dual gang pot. It is described mainly for its interest value, but they are generally an historical component now. |
|
|
|
Scott Hay
From:
Portland, OR / Yucca Valley, CA USA
|
Posted 3 Oct 2011 12:21 pm
|
|
Dudes, thanks for the feedback.
Jay, any chance I could get a PDF / jpg of the schematic? I know I don't need it to change a pot, but would dig having it for reference should I need it down the line. This is all under the pretext that it's not troublesome for you to do so.
Steve, thanks for the offer for help and for the Tech tips too! I love learning new things.
The Webb is bit hairy under the hood, as in kind of hard to get to. I may just have my bud do it. See you around Portland! |
|
|
|
Ken Fox
From:
Nashville GA USA
|
Posted 3 Oct 2011 12:48 pm
|
|
In Tom Bradshaw's new schematics it is shown as a 50K audio taperpot. It is shown also as a custom CTS pot made for Tom. You might get in touch with him.
The old 614E schematic (drawn by George Moore) shows all controls are 50K linear taper pots. That schematic dates to the very early models. There were changes in the reverb drive section of the 80's models, about he only changes I have seen on the many Webb's that have come thru my shop. |
|
|
|
Jay Ganz
From:
Out Behind The Barn
|
Posted 3 Oct 2011 12:59 pm
|
|
Yeah, back in '78 George sent me the original schematics. He said in his letter that they were the first ones ever he drew up.
Scott: send me a message with your email address if you want. |
|
|
|
