Vegas Lemay mod.

Justin Mills · From: South Carolina, USA

Picked up a super clean Vegas 400 the other day. As I was searching online for the manual and schematics to print out for reference, I noticed there is a lot of talk about a Lemay mod. What exactly is it and what do I need to do? I have an Electronics shop here so I have lots of capacitors and resistors on hand. I know I did an IC upgrade to a kb300 I have here as directed by a forum member and it worked just fine. Is this similar? I'm just trying to find out exactly what needs to be changed so I can give it a shot As It Seems all of the folks who have had this mod done seems to think it was worth it.
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Danny Letz · From: Old Glory,Texas, USA 79540

The Lemay mod was a mod done by John Lemay. I don’t know if it was ever made available in kit or schematic form. I had one done by John & liked it. I remember that the pilot light was blue instead of red when I got it back.

George Webb · From: Mississauga, Ont, CAN

Justin,

There was a kit available in the 90's. I bought it and did my Vegas.
The kit is very easy to follow ... it had schematic and component layout diagrams.
The resistors and caps were standard stuff, but the IC's were unmarked. I've never seen a description of what they were.
I used that amp on weekend gigs for 18 years and loved it.
Recently I swapped the IC's for the Burr 2134's and couldn't hear a difference. But my ears are 79 now and have lost a lot of high frequency.

George Webb

Jerry Overstreet · From: Louisville Ky

Yes, John Lemay built the first Peavey amp mod that I knew of. It was for the NV400 and may have included the Vegas, I don't know. Initially, the chassis were sent to him for service.

This was done due to the design of circuits on the amps following the Session/LTD and their use of the 1501-4 speaker v. the 1502. It included some method of boosting the low end frequency of the Nashville/Vegas series amps.

Later on, he did offer kits but they were somewhat limited from the mod he did in house.

I don't think he ever disclosed everything he did. I'm quite sure it included replacing the ICs.

Ken Fox also had, or maybe still has, a kit. He is a member here and he may have posted a schematic...can't say for sure...

The Peavey company also marketed a mod kit in later years.

I don't know any way to reach John, if he is still with us.

You might search around here and the 'net for diagrams of which ICs might be involved, but I doubt anyone is going to divulge all the components and service done to fully modify these amps. Why would they? Then everybody could be doing it themselves taking away the work from them.

I never asked...I played a Lemay modded NV400 for over 30 yrs...I just enjoyed it...never caring what was done.

Pat Chong · From: New Mexico, USA

Hi Justin,

Check your amp out, it may already have been "modded". The original ic chips were 4558's. Pull your amp chassis, and if those are the chips you see, then it has not been altered.

What has been mentioned is part of it: replacing the 4558's with Burr 2134's. Texas Instruments now sells the OPA2134PA chips, available at Mouser Electronics. Just replacing the chips is a noticable improvement. Be careful of buying those chips on Ebay, some sell fakes.

I have modified my NV400 by replacing the 4558's. The work also included replacing capacitors in the tone control circuits and various resistors here and there, but I don't know if this applies to the Vegas 400, too.

I got the mod instructions for my NV400 from Peavey, and would suppose you can get the Vegas instructions from them, also. If you do get it, make sure you also get the parts placement page, too, as none of the components are labeled on the pc board (R1, C12, etc.), and some of the capacitors look suspisiously like resistors!

Luck on your work..........Pat.

By the way, Bob Metzger (a member) sells a mod for the reverb circuit (NV400) that may also apply to the Vegas amp.

Jerry Overstreet · From: Louisville Ky

I believe I omitted some info...it's been a while...The earliest Nashville 400 and Vegas 400 with the 1502-4 alum dome speakers did not need any mods. It was only after Peavey, somewhere early or mid 80s, re-designed the circuits for those amps and changed the speaker model that folks like Lemay and other users like me didn't like the anemic tone and midrange honk that developed following the new circuit design.

One way to tell if your Vegas amp has the more desirable circuit is by the hardware. Those amps had chrome corners while the later ones were black. Also in combination with the 1502-4 ribbed cone speaker.

Of course any of those things might have been changed but maybe the product label on the amp can shed some light as the serial numbers can be decoded to find the year of build.

Justin Mills · From: South Carolina, USA

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Justin...you just got the amp??? Then forget about modifying it! Don't do anything until you've experimented with what you have. Play it for at least 6 months, have others try it or listen to it. Then, after all that, you can think about mods (or just trading it for another amp) if you're not happy with the sound.

The LeMay mods were created to reduce the midrange and boost the bass response. (The bass response was reduced in the factory design to reduce speaker failures.) Along with the IC change, the LeMay kits included several capacitors that were changed, and that was actually the most significant part of the mod.

Pat Chong · From: New Mexico, USA

Hi Justin,

The chips that Peavey put out in their update mod was the TLO72 ic. That may be the one you labeled "unobtainium". The OPA2134PA chip is better than the TLO72's, anyway. And No, not all chips are replaced, just the 4558's. And probably not ic "U10", because that is part of the "comp" circuit.

I have seen a schematic on the web, just look up "Peavey Vegas 400 schematic".

Donny's sugjestion to wait, is valid. However, by the same token, I would not have known about the NV400 mod if I hadn't read about it, and probably would have been satisfied with how that amp sounded, because those amps were the popular choice. Anyway, the changes DID make it sound better.

Were you able to get the instructions and parts placement papers specific to the Vegas amp? That way, if the parts aren't available through Peavey, at least you can get the stated parts through other sources.

.......Pat.

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