Question About Early Webb 6-14E Amps

[Dave Grafe]

I recently acquired an early Webb 6-14E amp (S/N 832) in need of TLC. In the course of cataloging needed repairs I noticed a significant volume loss when engaging the extra 5-band EQ section. Upon further investigation each of the right four knobs clearly boosted and cut its respective frequency range, but the first, 50Hz knob did very little in comparison.

I have heard that others have noticed similar anomalies in the early Webb EQ, and noticed on the schematic that the transistor in this filter's circuit is not utilized in the same way as the same component is used in the other four.
Further digging revealed that this 50Hz section was re-designed to conform to the circuit flow of the other four when Tom Bradshaw began building them, which begs the question if this was simply a design flaw and not a failed component.

My question for those in the know is this: Is this loss of gain and ineffectual 50Hz knob a "normal" behavior of these amps or a sign of needed repair? I don't want to take it apart again if there is nothing to be gained, I already cuss too much as it is.

[Dave Grafe]

If it ain't broke we can fix that too

[Jon Light]

One thing that I'm trying to remember, Dave, (and not having a very successful go at) is .... when I first got the Webb, I think I settled in on my favorite sounds with the EQ IN. I do not recall a loss of dB or a loss of tone. The state where switching the EQ IN is simply a non-starter would seem to be a later condition. That is to say, I think I would remember if it had been like that years ago. But...I trust nothing....neither of my memory nor of my sense of sound 20 something years ago. I was easily impressed by wizbang stuff like a whole bunch of knobs and I possibly could have said 'this sounds great!' because of...a whole bunch of knobs.

[Jim Cooley]

Dave - I don't have my first generation Webb any more. However, it seems that there was a slight drop in volume when usung the EQ function. It was pretty minimal, though. It does seem that the 50 Hz knob had little, if any effect. I thought it was just my ears, but maybe not.

[Andy Gibson]

I own 2 614-E’s Both of them drop slightly in volume when the eq is turned on. I never use the eq anyway.

[Dave Grafe]

I possibly could have said 'this sounds great!' because of...a whole bunch of knobs.

It happens all the time

[David Wren]

Dave, I bought a very early Webb (no serial number)... in fact I was told it was Chuck's "prototype", not sure about any of that....but recently I contacted Tom Bradshaw and he sent me copies of schematics, and info sheets on all the various configurations of Webb amps... I think he wanted around $25 to put together that package and ship it.

You might want to contact Tom yourself.. he's a super nice guy to work with.

Contact info for him is on the forum home page under links.

Email if you need more info.

[Ken Fox]

http://foxvintageamps.com/classic_green_008.htm

Lot of info there

[Dave Grafe]

Thanks guys for the worthy suggestions and the library link, Tommy Cass gave me the the printed material, I'm just curious about actual user experiences. I have been in touch with Tom Bradshaw about parts as I have cleaned this old gurl up, but have not attempted to pick his brain further.

50Hz seems a curious choice, good only for controlling mechanical rumble but little to nothing in the bandwidth of the instrument. 50Hz is nearly an octave below the 80Hz of the low E on a bass guitar, the common 10 string drop to F on the C6 neck is slightly higher than that, and the common AC hum centers at 120Hz, so 50 Hz is just not an obvious center point for a filter. So much to learn so little time...