Peavey TNT100 Bass Combo Amp

Re-acquisition: Peavey TNT100 Bass Combo Amp

For years, I played an old Peavey TNT100 bass combo, 45W RMS, 1x15". I sold it just before moving from Houston to Austin, mainly just to keep from having to move it. I've regretted that decision ever since.
Even though this amp isn't powerful, or modern, or even all that great an amp as compared to what's out there these days, it had a character all its own, and a good punchy tone that I always liked. At only 45W RMS, it's still loud enough to get along with a small venue just fine.

Peavey TNT100 Bass Combo Amp Features

  • 1x15" driver in a slot-ported cabinet (24"W X 27"T X 12"D)
  • Hi & Lo sensitivity inputs
  • Preamp Gain, Bass, Mid (with 'shift' control), Treble, and Master Volume controls
  • One speaker output to internal speaker
  • Preamp Out (not on this one, though...I found out from Peavey Tech Support that this amp was made in the first year of production, and they didn't put the preamp outputs on them until their second production year)

    This is a BIG amp for only 45W, and pretty heavy, but with added casters, it's not a problem to move around.

    As I said, I've regretted ever selling that ol' amp, but there's some good news. I just made a Craigslist swap for another one! I traded a cheapy Epiphone SG Special with a transplanted neck, and one of my beloved 15W guitar practice amps (the Crate GX-15R) for it. The guy thought I was out of my mind for wanting to trade a guitar and a small amp for this unit, but little did he know how infrequently I played that guitar, nor how much that ol' Peavey bass amp had meant to me. So we both came away quite happy with the trade, and that's all that counts, right?

    This amp, though, has a couple of differences from the other one I had. For one, I think it may actually be older than the other one, but in generally great shape...except for the mud-dauber nest in the port slot. And the speaker is different. The first one had a pretty generic Peavey 15" bass driver, whose edge suspension was the same paper as the cone, but corrugated and rubberized. It was punchy enough...for a 15"...but still a little slow on the response. The recently-acquired amp has a very different driver that is really quick to respond and doesn't have that typical 15" 'mush'. The edge suspension on this driver is a treated cloth, kind of orangey-brown in color, and seems much more flexible than the other, giving it a really quick and lively response. This driver also seems to have better high frequencies than I remember the other one having...Bonus! The Tolex on this amp is in great condition, just dirty, and the chrome corners and chassis-mount straps could use replacement because they're pretty rusty. Someone at some point added casters to the bottom of the cabinet, but kept the original chromed steel 'glides' that were on the bottom, having attached them to the sides of the cabinet at the bottom....I suppose just to keep them with the amp. It's missing the big 'Peavey' logo off the grille, and I'll want to find another to replace it, for sure. The knobs are aluminum and had colored inserts in the caps, but those inserts are long gone, leaving only the contact cement. The indicators on those knobs are almost invisible little tiny lines, so I may just replace them entirely with some cool red 'chicken head' knobs... because those let you see the settings at a glance. I love them ol' chicken-head knobs!

    All in all, this amp sounds a good deal better than I remember the other one sounding, I think because of the different speaker in it. I had thought about adding a piezo tweeter (there's plenty of room on the speaker baffle), but after playing it for a while, even slappin' & poppin' thru it sounds just fine without a tweeter. The jury is still out on that, though. I also thought about building it all into a much smaller tuned/ported cabinet with a 10" driver for better portability, but since the original cabinet is in good shape, what the heck? It's got 'vintage mojo' as it is, so I think I'll leave it alone.

    Craigslist trades rawk! Sometimes you see something on there that you really, really want, and you just happen to have something that the lister really, really wants, and it all aligns just perfectly for a really good swap. This was one of those.

    Peavey TNT100 Bass Combo Amp More...

    As I mentioned, this amp must have been sitting in a garage or storage shed at some point, because there were mud-dauber nests in it..and I discovered a couple more when I took the driver out to install some fiberglass inside the speaker chamber (more about the fiberglas shortly). So I chiseled them out and cleaned the mud residue off all the surfaces. The speaker baffle, port shelf, and top panel of the speaker chamber, I found, are particle board, while the rest of the cabinet seems to be Birch plywood. There had apparently been some exposure to humidity, enough to very slightly affect all those particle board pieces and loosen up their 'structural integrity' some. The baffle itself had some places where the paint had actually flaked off, leaving the wood color showing, so I got some flat black paint to repaint it and hopefully seal it up against futher weakening. The baffle appeared to be simply stapled into the top panel of the speaker chamber, and I could actually pull a little space between the two. Perhaps there had been glue there at one time, but that it had loosened over the years. So I drilled and countersunk a couple of pilot holes for wood screws and fastened it down tightly before I painted the baffle panel. Then I installed 2" fiberglass batting inside the speaker chamber, as it had no damping material at all in there. I don't understand why amp manufacturers seem rarely to think about that! It eliminates or greatly reduces standing waves between parallel panels, and also any tendency for the rear-radiating sound coming off the speaker cone from reflecting off the back panel and back out thru the speaker cone itself, causing distortions and phase cancellations (response peaks & dips). Once I had installed this insulation, the low bass response improved a good deal, and became very smooth, without pronounced peaks or dips. It sounds at least 50% better than it did....which wasn't bad to begin with.

    So the ol' guy is indeed showing its age in a few places, and might one day have to be re-cabbed, but for now, I think I've shored it up enough for another good ten years. I though about building it out into a head cab and a separate speaker cab with two 10' I typically don't like 15's much. But this particular 15 is really quick and snappy, as I mentioned before, and as long as it lasts, it'll stay in this amp. I've finally got the ol' thing pretty cleaned up and spiffy so that it actually looks pretty good now, and I look forward to keeping it around until it just rolls over & dies...which I don't anticipate happening soon. After all, it's a Peavey, and those things'll outlive the cockroaches. They may not sound as good as an Ampeg or a David Eden or a Markbass amp, but I'll bet it'll still be around when those have burned themselves out.

    Peavey TNT100 Bass Combo Amp Even More...

    I had a nasty (physical) rattle develop in this amp, and it drove me nuts for a couple of weeks. On certain notes, most notably E, there was this rattling going on inside the amp somwhere that I thought had to be the cabinetry. I ran glue into cracks, I drove screws thru the back panel into the back panel brace...stilll, the rattle went on rattling. I discovered that when I tilted tha cabinet back some, it went away until I turned the volume up more. What's kinda funny is that as the note died out, the rattle would become more and more sporadic until it, too finally died away. Still convinced that it had to be in the cabinetry, I was finally out of ideas and was thinking again about re-cabbing the whole thing. Then one day I removed the amp chassis from the cab, one more time, to try to figure out where that damnable buzzing was coming from. While I had the chassis out, I accidentally bumped it into the corner of the amp cabinet, and heard that rattle, coming from the amp chassis! I had already gone thru the chassis and tightened down every screw, even replacing a missing one on the circuit board. But as i was examining the chassis, I noticed that there was a small transformer built right onto the board, which, when I touched it, the coil would move a tiny, tiny amount within the frame. When i wiggled it back and forth, guess what happened? Ah-HA!!!! There was my rattle. The varnish on that coil most likely had shrunk enough over the years that it created that very tiny amount of slack between the coil and its frame, such that when a note was played that just happened to coincide with the natural resonance of that coil sitting in its frame, it would rattle back and forth making that horrible buzzing noise. And the explanation for the fact that tilting the amp back would eliminate the rattle (at least at low volumes), is that the coil would then gravitate to the low-side of the frame and come to rest there. But when sitting straight up, it was free to rattle around.

    So, because the amp functioned perfectly otherwise, I didn't even think about replacing that transformer. Instead, I whipped out my trusty ol' tube of RTV silicone rubber sealant, and applied it all around the interface of the coil and its frame, pushing it as far as I could into the space between the two, and...problem solved! No more hellish buzzing on the 'E' note...or any other.

    Now, if that ain't 'DIY' (or rather 'shade tree mechanic'), I don't know what is.

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