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Topic: my webb has a hiss: help?! |
Chris Erbacher
From:
Sausalito, California, USA
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Posted 25 May 2003 12:58 pm |
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| i just recently purchased a used webb, i believe was made in '81. i love the tone and flexibility of this amp, but it has a hiss that is driving me nuts. i have eliminated all effects etc... as being the problem, because nothing is plugged into it, and it still produces the hissing. it is not a hum, like is typical in places that have bad grounding, but a white noise like hiss. it will go away once i turn down the higher frequency knobs in the eq section and the treble knob, but that just eats my tone. i hve unplugged both sides of the reverb tank, and it still does this. has anyone out there had this problem with their webb, and if so, how did you fix it? any ideas? i talked with jimmie webb and he was telling me that the only time this happens is when someone has monkeyed around on the inside, but to my knowledge nobody has done this. i would just take it to him as he is only about an hour from where i live, but his tech won't be back for another month, so i decided to put a post up and see what comes in. any information that you can give me is greatly appreciated as i love this amplifier, but can't live with the hiss. |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 25 May 2003 6:27 pm
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| In solid-state amps, a leaky transistor, or cheap (or defective) op-amp can cause the hiss you're talking about. In tube amps, some hiss is a natural occurance, but it's usually reduced by changes in circuit design, such as negative feedback and special biasing circuits. (On rare occasions, I've seen faulty preamp tubes cause it, too.) In any case, a good tech can put a 'scope on it, and tell just where that hiss is coming from. If you're not familiar with electronics, I don't recommend poking around inside! |
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Chris Erbacher
From:
Sausalito, California, USA
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Posted 26 May 2003 12:16 am
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| thanks donny, i opened it up last night and just looked with a flashlight to see if by some strange reason i would see a wire loose or something, but i didn't touch anything because i know very little about the actual functioning of the individual parts inside an amplifier. i didn't see anything unusual, as if i would know if something was, so i just put it back together and decided to post this thread. i know without this hissing, my guitar's sound will make me grin from ear to ear, as it already sounds very nice, but everytime things get really quiet, there is this hissssssssss. thanks for the info, every bit helps. |
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John Bresler R.I.P.
From:
Thornton, Colorado
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Posted 26 May 2003 7:26 am
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Chris:
Does it hiss without the equalizer switched in?
I have an older webb 6-14-E that is quiet as a mouse until the equalizer is switched in. The hiss is not very loud, tho. If you're not next to the amp, you'll never hear it.
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Chris Erbacher
From:
Sausalito, California, USA
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Posted 26 May 2003 11:57 am
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| john, when i switch the eq on it is quieter than without it, but mostly because i can turn the knobs down in the upper frequency range. i can get it quiet, but i have to turn the selector knob to the green light, turn the treble way down, and all the upper frequency knobs in the eq way down, which doesn't help the overall tone, and this leads me to believe that whatever it is inside the amp that deals with the upper frequencies, is the culprit. thanks for your input john, if you have any more ideas, i'm all ears. |
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John Bresler R.I.P.
From:
Thornton, Colorado
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Posted 26 May 2003 2:24 pm
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| I don't have any test gear anymore since I'm retired. I'd suggest calling Jimmie Webb and asking him for a hint. I don't think you have an option except to get a good tech on it. The schematics are available here on the forum, but if you're not a tech you really don't need them. Sorry I can't help. If you get a tech, I'd suggest replacing the parts with the same high quality parts Jimmie Webb uses (close tolerences). |
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Chris Erbacher
From:
Sausalito, California, USA
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Posted 26 May 2003 4:59 pm
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| thanks again. i talked to jimmie about a week ago and he was baffled and it seemed a little defensive/embarrassed over the phone, sort of like this never happens to his amps, and that i was hearing things, or had my settings all wrong, but he is a very nice man and i can understand his position. he told me this is a rarity and that it is usually due to someone messing with the internals of the amp, and not knowing what they were doing, which i am not sure is the case here, and then told me that his tech won't be around for another month and to look around for someone closer to me,(he is about an hour from where i live), but the only guys i know close to me are tube guys, and i'm not sure if they know a lot about solid state stuff, i will hve to call them tomorrow and see. looks like i'm going to have to spend more money to get an amp that works like it should. thanks for your help |
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Kenny Dail
From:
Kinston, N.C. R.I.P.
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Posted 26 May 2003 7:44 pm
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Chris, I am no amp tech and I never have seen a Webb, but I had have some experience with "white noise" and I find that some amps and effects units that carry a "pre" gain
adjustment and a "post" gain adjustment and white noise usually develops when the POST level exceeds the PRE level. I use an ALESIS QUADRAVERB fx unit and when I max the post gain and use the pre gain for any adjustment of volume, I get white noise. I reversed the settings and ran the pre gain at about 3/4 volume and the post at the necessary level for the playing environment. This eliminated my white noise problem. You might check your settings on your outside fx as well as the settngs in the amp. If you have not tried this...uplug all you equipment and see if the HISS is still there, if it is, the amp is the problem. If the hiss goes away...it might just be your settings. Hope this helps...
kd...and the beat goes on...
[This message was edited by Kenny Dail on 26 May 2003 at 08:49 PM.] |
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Chris Erbacher
From:
Sausalito, California, USA
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Posted 27 May 2003 1:44 pm
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| thanks kenny. i have eliminated the outside effects because i don't use any, just a little reverb from the amp, and the noise is there when nothing is plugged into it, and the only thing i can do to get it to go away is to turn all the knobs that effect the higher frequencies, down or off. i appreciate your advice. |
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