The Steel Guitar Forum

Over in Buy and Sell, there is a thread on a modified Nashville 400 (see http://steelguitarforum.com/Forum3/HTML/008782.html). Of course, the discussion came up regarding the subjective value of modifying stock amplifiers. What I'd like to know is.... what is the modification, and what does it do to the amplifier's sound in technical terms?

For example, does it replace the input DC blocking capacitor with a larger value cap or with one made of different material? Does it play with the tone control section and increase or decrease the gain in certain frequency band(s)? Does anybody have a frequency plot of an amplifier before and after the modification? Or measurements of total harmonic distortion before and after?

I'm an engineer in an audio amplifier company by trade, so such things interest me. I'm not trying to copy this or take away anybody's business, I'm just curious.

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<font size=-1>Bill (steel not out of the woodshed) | MSA Classic U12 | Email | My music | Steeler birthdays | Over 50?</font><FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Bill Llewellyn on 13 December 2001 at 09:02 AM.]</p></FONT>

I believe the LaMay mod to the Nashville 400 is just about the same as the mod kit that you can get from Peavey (the parts list and schematic of changes is available on their website). It does two things: First, it replaces the 4558 opamps with high slewrate, low noise ones. Second, the frequencies for the tone controls are moved around a bit. If I remember, on a stock 400 the two higher frequency controls seemed to be too close together. In the mod they are farther apart.

John Fabian of Carter Steel Guitars http://www.steelguitar.com called me up and gave me a rundown of the basic changes involved in the modification in technical terms. Now I get it! Thanks, John... what a great guy.

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<font size=-1>Bill (steel not out of the woodshed) | MSA Classic U12 | Email | My music | Steeler birthdays | Over 50?</font>

Bill,

Good topic. Wondered the same thing myself.
Still do...

Enlighten us (unless, of course, you're under oath.)

Regards,
Tom

Bill, Don't leave us hanging.

I've been curious about this, too.

I won't give exact details (I don't have them all, anyway) since that may be inappropriate. Also, there are two mods available, a LaMay and a Peavey mod, which are apparently very close. Generally speaking, from what I've been told by a few different folks, the modification improves low frequency coupling between preamp stages, re-voices the tone circuit a bit (separates the mid and high center frequencies), addresses a "midrange bump", and replaces some stock opamps with lower noise, higher slew rate versions. All of these are good things in principal, so I can see why there would be a difference in sound (though I've not actually heard a demonstration of it.) <FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Bill Llewellyn on 14 December 2001 at 10:58 AM.]</p></FONT>

I agree with Jim above . . . it 'opens' the mid range tone circuit, and in the course of it, makes a 400 a usuable amp. I had one for years as a spare that I didn't play 'cause I could not stand the tone (my 'regular amp was a Webb); however, with the [Peavey] mod in it, I now use it for most outdoor gigs and all "jams."

I modded my Vegas 400 with the Lemay mod. While the amp sounds better, the reverb doesn't work as good anymore, kind of lower in level with more hiss. Has anybody noticed this too?

I thought that I would "hold off" on replying to this post until a few users of both kits had a chance to provide their point of view and "reviews".

Anyway, I have had the opportunity to compare the Peavey mod kits to the Miracle Audio kits early on. The main difference in the kits is the PRICE. However, we did extend the low end response, but we also made the decision to allow the amp to do this SAFELY without bordering on the line of possible speaker failure. Remember, the amplifiers in question are open back and too much low frequency can result in speaker failure. Guess who was responsible for covering the failed speakers on modified amps???????????

Also, most all players want that low frequency response in a SMALL CABINET. This is really where we had to be cautious because we are the manufacturer of the speakers. Third party companies are not so concerned with the warranty of failed speakers.

Our kits boost the low end response, smoothes out the midrange frequencies which also effects the high frequency end of the spectrum. There is no magic in mod kits.

Check out our kits on our website at;
http://www.peavey.com/guitaramps/steelguitars.html
<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Mike Brown on 14 December 2001 at 02:06 PM.]</p></FONT>

Keep in mind this mod only affects the preamp. If you are using a ProFex into the power amp input, you are not gaining anything with the mod, don't look for a change in your sound! It is a super mod for guys who use the built in preamp. I've done quite a few of the Peavey mods, all the guys are really pleased with their amps now! I had one friend who was using a Session 500 on the job and the Nashville 400 only as a practice amp. After the mod he decided to start using the Nashville on the job instead!

Ken, good point! Thanks.

I bought and installed John Lemay's Mod Kit,
and noticed a much brighter and presence of
sound thru a Vegas 400.

I also have an Evans FET[?] 500.

I wish John Lemay would come out with a 'mod'
kit for the Evans. Lord knows there must be plenty of Evans amps out there [like Peavey]
that steelers are using. What I'm getting at is John would probably find it worth his effort to make up these Evans kits.

After many years of denial, I finally have to admit that, altho the Peavey and Evans amps are really excellent steel amps, I just
do not care for either's reverb. And I know I'm thinking Fender here, but Peavey & Evans
do not have that Fender real depth and smoothness. They sound harsh.

I've been playing just thru the Peavey for the past 3-4 months without any reverb or effects. The John Lemay kit really did change
the sound quality, and so it's now like I don't miss the crummy reverb. Playing/practicing thru a 'colorless' amp forces you to pay more attention to what you're doing, and I think, is a good way to
go. By doing this, there now is no other conveyance to maybe cover up blips and mistakes. You are on your own. It's humbling.
Even reverb can hide "bad" playing. 'FUZZ' is probably the best.

FWIW...ChipsAhoy

10 years ago I had a 'long' reverb tank installed in my Evans FET 500 and it made a huge difference.

Chas,
I posed a question about reverb tanks [specifically the Fender Twin tank, or the one today that is the replacement for it]not
too long ago in ELECTRONICS.

I was thinking of getting one and 'simply' installing it in one or both of the amps.

Well the unanimous reply from everyone was that to get that unmistakable Fender reverb sound, you would have to put the tank in a Fender amp only. It's the internal circuitry,
as well, that works with the tank to produce that sound. You won't get it using a non-Fender amp.

Anyway, FWIW...ChipsAhoy<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by CHIP FOSSA on 16 December 2001 at 04:20 AM.]</p></FONT>

Hi - To Glen Austin - I was told the lemay mod and the peavey mod were the same - except for price - I installed the Peavey mod in mine - Love the tone, but experienced the same thing with the reverb. Makes me think they must be almost the same!!

I installed the Peavey mod in my N400 and it made a tremendous difference in the sound of the amp. It sounds (even) cleaner, the highs sparkle more; the lows and highs just sound better. The un-modded amp seemed to have too much midrange type tone that was hard to get away from--great for a particular kind of classic steel tone, but I wanted more high end sparkle and deeper bass. I used a Fender Twin for a long time before I got the 400 because of this, but found that the 400 had better attack/punch in the low end. Now it has everything! The Peavey mod was inexpensive & came with good instructions. Plus Mike Brown and the people at Peavey were very helpful. The company is great with customer service. Ed

I just sold my session 400 and profex11 and got me a nashville 1000 now when it came to the house i never even turned it on or hooked it up my family thought I was nuts for not even tring it out. well it sit here for 4 days ontil the night I went out to play. now in my mind I thought I was getting the same amp I had before thats why i never tried it but when i turned that thing on I could not believe the difference in sound. now i may be wrong about this because im going by what someone else told me, but maybe mike can fix this for me.
isnt the mod kits and the nashville 1000 sit up on the same electronics? again going by someone elses brain waves lol. merry xmas

There's quite a difference between a Session 400 and the Nashville 1000 (or the Session 500 and Nashville 400). The EQ on the Nashville400/1000 and Session 500 use the Parametric EQ system. The Session 400 uses a different active EQ system. There is quite a difference between the two. The power amp is different in the 1000 than the other amps too.

You can't equate a modified Session 400 to the other amps either, because of the different preamp/EQ design.