The Steel Guitar Forum

I picked up an '85 Nashville 400 from a music store that has what I think would be the original 1502 BW speaker. Just being curious, I opened it up to see if the electronics were also original or if they were given either the Peavey mod or the Fox mod. I'm not completely sure what these mods do, I can only say that I found 6 chips that were marked "OPA2134PA" which I assume replaced older "4558" chips. There is still one "4558" on the board, along with a "70487478" which I looked up and found it to be a compressor chip for Peavey amps. I've uploaded some images of the amp showing the board layout. There's a tag on the handle that says "Rev 011". Also someone's initials written on the board. Maybe someone can tell by the pictures what's been done to it. I'm just the curious sort.
All this aside, to me the amp sounds great as it is right now. But it is pretty heavy, and if I could lighten the load with an EPS-15C speaker without changing the sound of this amp (much) I would definitely do it. I know that a few forum members have switched from the newer 1501's and love them. I'm not sure if anyone has swapped out an older 1502. If so, I would really appreciate their thoughts on it.

All that has been done is the Burr Brown audio chip upgrade. The other 4558 is not in the audio path. Works with compression circuit to light the LED for DDT compression when engaged


The EPC15c is very different in tone, more akin to the 1501-4BW. You will lose a lot of low end and a lot more high end with the EPC15C.

Aside from changing the speaker, I would suggest that the remainder of the "Ken Fox mods" would improve the amplifier. This is capacitor upgrades. Also, the "Metzger reverb mod" is a big help to this amp.

I made some changes to my Nashville 400 and I couldn’t be any happier. I added the Ken Fox chipset modification ( by the way, there’s not a nicer more helpful guy than Ken Fox ) and when I got to the speaker I chose the Telonics 15” and it made the perfect amp!
It’s a fantastic speaker as far as I’m concerned. The lows are tight and full but very clean. The ice pick highs no longer exist and it’s very balanced throughout the entire tonal range.
It has great tonal separation and I use it for lead guitar as well as steel. I’ve been very happy with this setup. And it’s much lighter with the Telonics speaker.

1502 is a bass speaker which were factory installed to keep the speaker from blowing. I switched the 1502 out with an Eminence 15c for our lead player. He loves the tone and less weight. The newer steel speakers will handle more wattage than the previous generation. I use two 15c's in separate cabinets with my rack gear. Fully satisfied with the results.

Thanks for all the input. I'm not sure I want to try any further electronics mods just yet. I'm pretty happy with the sound at present, so first off I'm just looking to take a few pounds out of it, hopefully without drastically changing the amp's overall sound. It sounds like the neo speaker might be worth a try, I can always switch back easily if it doesn't work out. Deep bass may not be a concern as I only have a single neck E9th...

Steven Paris wrote:Aside from changing the speaker, I would suggest that the remainder of the "Ken Fox mods" would improve the amplifier. This is capacitor upgrades. Also, the "Metzger reverb mod" is a big help to this amp.

Thanks Steven, once I'm past the speaker change, I'll be very interested in finding out more about these additional mods. To me, anything else that may improve overall sound is worth looking into. I would need to have an amp tech do them, as I don't pretend to know anything about that stuff. Thank you for letting me know about them, I'm definitely interested for later on.

David Graves wrote:I made some changes to my Nashville 400 and I couldn’t be any happier. I added the Ken Fox chipset modification ( by the way, there’s not a nicer more helpful guy than Ken Fox ) and when I got to the speaker I chose the Telonics 15” and it made the perfect amp!
It’s a fantastic speaker as far as I’m concerned. The lows are tight and full but very clean. The ice pick highs no longer exist and it’s very balanced throughout the entire tonal range.
It has great tonal separation and I use it for lead guitar as well as steel. I’ve been very happy with this setup. And it’s much lighter with the Telonics speaker.

David, I'm not having much luck finding a cost for the Telonics 15". The Eminence is $200, how does one compare to the other cost wise, and for performance are the two really much different?

The original NV400's, like the one you have, are voiced for the 1502 speaker - the EQ circuitry is customized for the "bass" speaker. Peavey later went to the 1501-4 speaker and lost the low end and had too many highs and thus the reason for the Lemay and later Peavey tone mod that "revoiced" the amp for the 1501-4. The Eminence EPS-15C and Telonics which is similar, is designed to be a direct replacement for the 1501-4 and thus you would as noted lose low end and increase the highs. I don't recommend the EPS-15C as a replacement.

Ken Fox used to sell SICA speakers for steel, which were "bass" speakers. If they are still available (elsewhere) that is an option. The SICA models he sold were neodymium magnet speakers and light weight.

There are no "mods" really needed for this version, compared to the later version. Possibly due to age, the power supply filter caps are suspect but that's all and that is not a "mod", just a maintenance item.

Makes me wonder why someone would have put in those 2134 OpAmps if the amp was voiced for the 1502 which was already in the amp to begin with. Shouldn't that speaker have sounded ok with the original electronics? Or does the 2134 improve the sound regardless of which speaker it has? Just trying to gain a better understanding before I make any changes.
Jack, I did find the SICA's available at $100 which is half of the EPS-15C cost. From what you wrote I gather that the SICA might be the best lightweight replacement for the 1502, is that correct?

The original Session 400 low frequency (bass control) was stacked at 60hz as was the early Nashville 400. The 1502 was replaced by the shallow basket 1501 around mid 1990. So, I don't know what was changed with the tone stack at that time? The high frequency stack was also the same. So? Maybe something changed with the power amp board other than more power? I could hear no difference with the tone of our lead player after I switched the 1502 for a 1501. Maybe he had to tweak his tone setting slightly to get his original tone? I'm guessing the 1502 required more power to push it? Plus having to turn up the treble since the 1502 was only good up to about 2000hz and dropped off? Tech guys would have the answers.

The original model NV400 with the 1502 speaker (which was sold by Peavey as a bass speaker) was "voiced" (as Mike Brown calls it) for the 1502. Since it was a bass speaker the low end did not need a boost and maybe even some low end removed because of the bass speaker. The high end needed to be boosted because the bass speaker didn't have the high end response a "regular" speaker would have. When they changed to the 1501-4 speaker (which was modeled after the JBL that was used in the original Session 400) which had a different frequency response. e.g. not as much low and more high frequency Peavey did not adjust the EQ circuits to compensate for the change in speaker response. Along came John Lemay who was working at a TV station in Nashville at the time and had a lot of interaction with the Nashville musicians. Musicians were complaining about "all highs" in the 1501-4 version Nashville 400. John Lemay developed the mod to "revoice" the NV400 and return the low end response and control the highs. Later Peavey picked up on the mod and offered their own mod which was identical to the Lemay mod except one capacitor. Initially an amp would have to be sent back to Peavey to have their mod installed but later they offered it as a kit. About the same time they offered it as a kit they did an engineering change and incorporated the mod into production (I think September 1996). I bought a NV400 in April or May (don't remember) of 96 and it had to be ordered from the factory as the music store did not have one in stock and I talked to Mike Brown about doing the mod before it was shipped to the store. Mike commented he was considering incorporating the mod into production and thus the next run of NV400's built (again around Sept 96) had the parts changed in production.

NV400's with S/N 08575482 and above have the mod incorporated in production.

Lemay mod parts list:
C1 with a 2.2 and reverses polarity. C5 and C6 are replaced with 22uf and
observes polarity.
C41 is replaced with a 22uf 35V
R3 is replaced with a 1 meg resistor.
C8 is replaced with a 2.2 Plus end facing rear of board
R10 is replaced with 100K resistor
C10 is replaced with a 682K
C14 and 15 are replaced a 473K (he recommends 563, but sends the 473K
C12 and C13 are replaced with a 472K
All IC's are replaced except U7 and U8.

PEAVEY NASHVILLE 400 TONE MOD
Same parts as Lemay except C41
U1 through U5 OPA2604 (original kits used TL072, P/N 040072)
U6 OPA2604

Dave Welch wrote: Or does the 2134 improve the sound regardless of which speaker it has?

EXACTLY.

That all makes sense and clears a few things up, Jack. Much appreciated!

Steven Paris wrote:

Dave Welch wrote: Or does the 2134 improve the sound regardless of which speaker it has?

EXACTLY.

I had a feeling that was the case. So now I feel fortunate to have gotten this amp with that already done to it.

Thanks Jack! Details from a tech!

Thinking back I think I'm wrong on when their kit was offered, I think it was later than 96.

As far as the op-amps, as the NV400 I had was an early mod version done by the factory it had the TL072 op-amps. Blake Hawkins had a NV400 that he did the Lemay mod to. I ordered 2604 op amps for both NV400's and we installed them. Neither of us heard any difference in sound. However, I suspect the 2134's do offer some improvement.

I had the same experience with a Session 400 Limited. They typically have a lot of treble and it's hard to dial in good tone unless the presence is full left and drastic cut to the high control. I replaced the IC's with upgrades and noticed no difference in tone.

Dennis Detweiler wrote: I replaced the IC's with upgrades and noticed no difference in tone.

WHICH ICs did you use for the upgrade?

Regarding the speaker, I put a 15c in my N400 and didn't really care for it. I'll bet the Travis Toy 15" would be a great speaker for that amp, or for that matter, any steel guitar amp.

Putting an Eminence EPS-15C or the Travis Toy 15 in the original model NV400 will present the same problem that the later 1501-4 BW NV400's ran into and I outlined in detail. It will have all highs and no lows.


Here are the published frequency response curves for the TT15 and EPS-15C. They are very close to each other.

EPS-15C


TT-15

I can shed a !little light on this in a week. I will be taking possession of a silver corner 400 next Saturday. It has an EV SRO 15" bass speaker in it. I have a TT-12 in a cabinet I will be trying next Sunday. I will post my opinion then. If it is too bright and I don't like the SRO, I guess my next move will be a 1502 speaker.

https://www.amplifiedparts.com/products ... w-aluminum

Closest speaker I found to original 1502-4. They still have a few they are closing out at the link above. Frequency response curve at link below

https://www.amplifiedparts.com/sites/de ... 15b25s.pdf

Would the Sica work well in a black corner NV 400?
Or could I use a TS-Neo 15 since it has the factory mod.

ZZ Sounds has 1502 DT speaker. Is this the same as the original 1502's that came in the early 400's? What does the DT mean?

The chrome corner 400 I am getting Saturday has an EV SRO bass speaker in it. Anybody tried this in a 400 and have an opinion?