Mod chips. Old and new

Jordan Beyer · From: Ohio, USA

I recently got mod chips from Ken fox. I have an 84, peavey, Nashville 400. The old speaker was replaced with a 1501. I took apart the amp and found all the chips besides u7and u5had been replaced, or appeared to be with, OPA2604AP 57AEHR7. And I wonder, does this already have the chips? The new chips have a different number on them ( I didn't get them down, but they are the recent ones from Ken fox) i got the chips in and notice a difference for the better, but not really very much at all. And i do not know if I an thinking about it too much or what. If these are mod chips, what's the difference between them. One thing I have noticed is when I shut it off it doesn't make the slight pff sound that it had done before. Anyone have any ideas. Thanks, JB ( btw, I recently set up a pre amp in my rig. The pre amp addition made my tone sound better, but now, it only sounds thin and weak and cannot get it to sound good. Another thing, I can turn the bass all the way up where before it got, "wooffy" at about 3 to 4 ockock)

Jack Stoner · From: Kansas City, MO

The 2604's were used in early mods. They were replaced with the "better" sounding 2134's. The 2604 is a general purpose op-amp, the 2134 is an "audio" op-amp.

I had a factory modded Nashville 400 and replaced the op-amps with 2604's and didn't really notice any difference.

I modded a Nashville 112 with the 2604's and hated it as it sounded sort of "sterile". I later used the 2134's and it was a big improvement in sound over the stock op-amps. Same way I replaced the stock op-amps in a Nashville 1000 with the 2134's and a noticeable improvement.

Ken Fox · From: Nashville GA USA

I would suggest that you pull the chassis out and do a bit of cleaning and maintenance:

1- insert a jack into input one, spray cleaner on the now open contact. Then unplug and plugin several times to clean the grounding contact. An open or partial open jack will cause turn off noises. Repeat for jack #2. Does this as well for the power amp input Jack at the rear panel..

2- check the speaker connect at the chassis. The older ones used a Molex connector. Be sure to check the female pins and tighten by inserting a small jewelers screwdriver between the pin and the wall of the plastic connector. Later models had the wires soldered directly to the pins on the circuit board.

3- Check the Molex connector on the reverb wire harness that plugs into the chassis, tighten the female pins and apply cleaner to it and the pins inside the chassis that is plugs into.

4- clean all pots. Be sure the get the mid pot good and clean, it can cause a lot of problems when it is dirty

Hope that helps

Ken

Jordan Beyer · From: Ohio, USA

Oh no Ken. They do not sound bad at all, in fact, as I said, I can turn the bass up higher now, as where before I could not. I was just confused on what is the difference between the new BB chips and the old ones. Very Happy

Jordan Beyer · From: Ohio, USA

I guess That confused you was my pre amp thing, I was just saying how before it sounded better, but now it sound better without the preamp, sorry for any confusions

Ken Fox · From: Nashville GA USA

Not a problem. Been meaning to post the typical Peavey amp maintenance that I do on any amp that I work on. As a matter of fact it's standard procedure for any amp I work on.

Got a Crate amp, stereo chorus in the other day. The young fellow at the local music store told my friend it was not worth repairing. After ten minutes on the bench and doing the typical cleaning I mentioned above the amp was as good as new again. The stereo power amp input jack was the primary culprit. He also brought in a Peavey bass head that was popping, cracking and generally being an audio nightmare. Same procedure brought it back to life, good as new.

Jordan Beyer · From: Ohio, USA

Thanks for the info. Im going to do that them. Will electrical contact clener from the autoparts store do the trick? Should I worry about getiing excess on the board?

Ken Fox · From: Nashville GA USA

Not sure what they sell. Mojotone is where I get my cleaners and lubricant from, Lube is for the pots. You night ask on the forum and see what others are using. Radio Shach used to sell a good contact cleaner. Not sure if any of them are still in business

Jordan Beyer · From: Ohio, USA

Thanks!!

Jack Stoner · From: Kansas City, MO

I use Caig Deoxit D5 contact cleaner.
Peavey has "Funk Out" and from the container looks to be the Caig product with a Peavey label over the original.

Kevin Mincke · From: Farmington, MN (Twin Cities-South Metro) USA

I use Caig D5 for overall cleaner and also F-5 for the pots as it maintains a lubricant with the cleaner and seems to do quite well.

Jim Pitman · From: Waterbury Ctr. VT 05677 USA

Dito on the Ken Fox maintenance. I can't tell you how many amps I've fixed that have had just bad jacks or switches in jacks, generally any electro-mechanical connection is suspect. Don't discount the jacks that are PCB mounted rather than the ones that wire discretely down to the printed circuit board too. It's not uncommon for the solder joint to split open from the repeating force of the plug being plugged in and out. I also had one of those PCB mounted ones with an internal (not visible) switch contact get bent beyond its' compliance and not come back.
Second after this is cold solder joints - especially early 90s gear when the industry first switched to RHOS solder. (lead works really well albeit dangerous). Then comes dried out electrolytic capacitors. After checking all that, then you can suspect other components. Tube amps can have faulty tube sockets - sprung contacts.

Gary Leggett · From: Space Coast, FL

I've used the Peavey "funk out" for years. I know it's one of the Caig products but I've seen it do incredible things compared to other cleaners. It cleans very well.

pots that are hard to locate because no one makes the leg configuration any more, etc. It brought them back to life.

And most important on some of the newer low end boards, rack gear, even keyboards, sometimes standard cleaners will dissolve the graphite strip in the pot because they are being made so cheaply now for lack of a better word.

Funk Out never hurt anything sensitive like this and would clean very well at the same time.

Jack Stoner · From: Kansas City, MO

I peeled the Peavey wrapper off the Funk Out can and its Caig Deoxit D5. Looking further, the fine print on the Peavey label says its Caig Deoxit D5.

Jerry Overstreet · From: Louisville Ky

Anybody know what chips John LeMay used? I had him mod one of my NV400's sometime in the mid 90's. It has been wonderful for all these years and still sounds great, but I'm wondering if it might be time for some maintenance and upgrades?

Jack Stoner · From: Kansas City, MO

The Lemay mods had chips that were painted over or the part number obliterated, however I would suspect the same chips that Peavey used. The Peavey mod changed the same components as the Lemay except for one capacitor. The OPA 2134 chips were not used in either mod.

Jerry Overstreet · From: Louisville Ky

Thanks Jack. I've had the chassis out several times but never paid any attention to the chips. I may consider re-doing it down the road, but it sounds so good, I'm not sure I want to mess with it yet.

Steve Sycamore · From: Sweden

My NV400 has the LeMay mod and I'm quite certain that high performance opamps were added. But I don't remember if I chose to do that myself or if they were included in the LeMay package.

The NV400 has become cranky lately probably due to bad connections or jacks. I'll try to pull it apart this weekend and see what opamps are there. I remember they had high slew rate capabilities. I'm extremely happy with it's tone but it also has a JBL D140R with original cone which makes all the difference in the world.

Jack Stoner · From: Kansas City, MO

I've done one NV400 Lemay mod. That one, the identifying data on the Op-Amps was obliterated. Later we (the user and I) updated the op-amps to OPA2604's and didn't hear any difference. However, my NV400 was modified by Peavey when I ordered it and did not have "high performance" op-amps. I put 2604's in it and didn't notice any difference either.

If we would have known about the 2134 op-amps (that Ken Fox came across several years later) that may have made a difference. I tried the 2604's in a Nashville 112 and it made the sound "sterile" or "brittle", however the 2134's cleaned it up nicely.

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