Peavey, Vegas 400 Mod

Dennis Manuel · Post by **Dennis Manuel** » 28 Apr 2001 5:42 am

Just wondering if anyone has the Peavey, Vegas 400 Modification (not Lemay mod)installed in their Vegas 400 amp and if so how do you like it?
Last night I installed the Peavey modification in my Vegas 400 and it is much louder, however, so is all the inherent noise.
Please respond and let me know if you have had the same results.[This message was edited by Dennis Manuel on 28 April 2001 at 08:46 AM.]

Jack Stoner · Post by **Jack Stoner** » 29 Apr 2001 2:45 am

The mods for the two different amps can't be compared. You have to compare two of the same type.

The Peavey factory mod for the Nashville 400 has the opposite affect - makes it quieter as they went to a lower noise op-amp.

My suggestion is to go back over the mod and make sure everything was installed correctly and all the solder joints are good, no solder splashed on an adjacent land, etc. Also check any internal Molex connectors to make sure they are connected properly. Then see what it does.

I've heard several Nashvilles with the factory mod and they are not noisy. I installed a Lemay "mod" in an older Session 400 for a customer and it perked it back up.

As far as the differences between the Lemay mods and the Peavey factory mods, both do about the same thing with about the same components.

If you wind up with more noise, after doing either the Lemay or Peavey factory mod on any amp, there is either a component installed incorrectly, a bad component or something unrelated to the mod causing the problem or the last thing the noise is normal and because of component deterioration over the years the noise level wasn't noticed until the parts were "renewed".

Dennis Manuel · Post by **Dennis Manuel** » 29 Apr 2001 5:43 pm

Thanks for the reply everyone.
With respect to the components they are definitely installed correctly and there is no solder bridges. The molex connectors have been cleaned and they are making good, tight connections. This amp was comparable to any other amp when it comes to the inherent hum and hiss that is heard when any amp is simply turned on. However, after the kit installation the noise that was noticed in a wide open setting is now noticed at approximately 1/2 settings and the amp is simply not as quiet as it was. Also, this amp has less than 50 hrs. playing on it and although its possible I do not think the components would be deteriorated.
There is no distortion in the amp it's just noisier than I think it should be and I think its because of the higher gain.
Please respond.[This message was edited by Dennis Manuel on 29 April 2001 at 06:44 PM.]

Jack Stoner · Post by **Jack Stoner** » 30 Apr 2001 3:17 am

Try changing, one at a time, the IC's that were changed in the mod with a new type with an IC (same part number) in a different location. It may be one of the op amps is noiser than the others and in a different circuit it may not be noticeable.

Or, you could take one of the old IC's use it as a 'test' op-amp to try and find which one is the noisy one. The Vegas is similar to the Nashville 400 and in that one U1-U5 was changed from 4558 to either TL072 or the newer OPA op amp. Try those one at a time and see if the noise quiets down.

Bill Crook · Post by **Bill Crook** » 30 Apr 2001 4:29 am

There is no distortion in the amp it's just noisier

I think you may have found your own problem.....

After you installed the mod,the new and improved op-amps,different capicitors brought out the inheritant noises of the pre-amp section. While this is NOT a bad or defective pre-amp,the transisit noises (this could get deep,but we won't go there) have always been there. And also you are now hearing other and new(to you) freqs picked up by the P/U's on your axe.

Bill Terry · Post by **Bill Terry** » 30 Apr 2001 7:01 am

I just did the Peavey mod on a fellow forumites Vegas and I didn't notice any change in noise. This amp has certainly been 'broken in', I'd guess it's at least 10 years old, and appears to have all original parts other than the mod kit.

I'd suspect what Jack suggested, a bad op-amp.

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Glenn Austin · Post by **Glenn Austin** » 30 Apr 2001 7:13 am

Dennis, I put the Lemay mod in my Vegas, and my amp is much noiser, especially the reverb.
It does sound sweeter though! From what I can gather the increased noise is part and parcel of changing the gain structure in the circuit.

Fred Murphy · Post by **Fred Murphy** » 30 Apr 2001 7:21 am

I recently installed the Lemay mod kit in four Nashville 400's and two Session 500's and there was no increase in noise or hum.

Glenn Austin · Post by **Glenn Austin** » 30 Apr 2001 11:10 am

Maybe it's because we're Canadian Eh!

Gary Walker · Post by **Gary Walker** » 30 Apr 2001 12:05 pm

I put the LeMay mod in my 500 and not only is it not noisier but WOW, what a whoopee sound, smoother, more range, more volume. It has that velvet tone that can come alive and bite. Most awesome amp I have ever used, Gary
84 black P/P
76 black P/P
Mullen D-11
Session 2000, PX300, RC2000
Session 500
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Jack Stoner · Post by **Jack Stoner** » 30 Apr 2001 12:38 pm

I don't think being Canadian has anything to do with it. All the Canadian snowbirds I see down here in Florida in the wintertime look just like us.

Glenn Austin · Post by **Glenn Austin** » 1 May 2001 5:28 am

Except their money is worth half as much and their amps are noisy.

Dennis Manuel · Post by **Dennis Manuel** » 1 May 2001 2:34 pm

Thanks again for all the replies. Bill the amp is noisier and this is with no guitar plugged in.