problems with TNT130 - worth fixing?

[ack1961]

Hello,

I've got a older (probably 10-15 years old) Peavey TNT130 (1x15) combo amp that we use for practice in my home.  It's developed quite a rattle at anything louder than 30% (sounds akin to when stereo speakers need to be re-coned).  Having never taken apart an amp, I was just wondering if it's worth diving into myself...I'm no electrician, however, I can take stuff apart and solder with the best of em.

I mean, it's not about the money invested.  It's an OK amp that I bought used for about $100 and we've used it for several years.  My son has done some small gigs with it. We're in the habit of giving away basses & amps that we don't use very much to friends with children who want to learn.  This amp is a candidate, but I wouldn't give it away without it being in good order.  It may not make any sense to most people, but I would sell it broken on CL before I gave it away broken.

Are there basic tests I can conduct here to verify if the speaker is "blown" and needs a replacement, or if it needs to be re-coned, or if I've got some other terminal problem with it.

Sorry for such basic questions, but I don't want to soak any more money than I need to into this thing.

Thanks,
Steve

[patman]

Push gently on the speaker cone and listen/feel for the voice coil rubbing...if you hear or feel anything, it's toast.  At least, this is the way I check for a cooked speaker.

Somebody may come up with something more scientific here in a moment.

Pat

[Highlander]

That works for me...

PBG will probably have the answer, but to me, if it is for home use, and it works for you, look for a budget speaker of the same ohmage value as the original and with a small spanner/screwdriver and a few minutes work with the soldering iron... job done...

Is it going to be worth the cost of getting a speaker re-coned if it is not a vintage item - ie no intrinsic value...

[patman]

I'd fix it if there's a problem.  I actually like old Peavey stuff.  YMMV.

[Psycho Bass Guy]

Take it apart and make sure that is is the speaker you're jearing and not something loose inside the amp.  If you determine that is in in the fact the speaker, Peavey makes replacement basket assemblies for a lot of their drivers that you screw onto the magnet, bascially DIY re-cone kits. One of those will be cheaper than the cost of a new speaker.

[Big_Stu]

Most cheap combo amps don't have any headroom built into them. I have a Laney 30w bass combo; never use it anymore but I still have it. It blew very soon after buying it years ago & I found that it had a speaker rated at 30w in it       I switched it for a Celestion 10" 60w & it's been good as new ever since.

Is it safe to assume when you say it rattles that you've picked it up & given it a shake to check there's nothing loose in it that louder vols. are rattling about in the cabinet?
Also that you don't get it with headphones plugged in, or through the headphone? Also assuming here that it has a headphone jack?

[ack1961]

Most cheap combo amps don't have any headroom built into them. I have a Laney 30w bass combo; never use it anymore but I still have it. It blew very soon after buying it years ago & I found that it had a speaker rated at 30w in it       I switched it for a Celestion 10" 60w & it's been good as new ever since.

Is it safe to assume when you say it rattles that you've picked it up & given it a shake to check there's nothing loose in it that louder vols. are rattling about in the cabinet?
Also that you don't get it with headphones plugged in, or through the headphone? Also assuming here that it has a headphone jack?

Nope. No headphone jack.  Good idea though.
I also don't hear anything rattling around inside when I shake it. This thing weighs a ton, so actually picking it up and shaking it is out of the question.
I don't ever want to mess with the guy who can pick this up and shake it, that's for sure.

The following observations might aid someone helping me isolate the problem:
I earlier described the problem as "rattling" - I probably should have used the word "buzzing". At times, it's a more accurate description of the problem.
- The Amp has 2 Inputs (Low Gain & High Gain) - the buzzing is more prevalent when using the High Gain Input
- If I activate the Post PreGain (Punch), even at 30% volume, I start to hear the buzzing. The Pre PreGain (Bright) doesn't ever seem to affect the sound.
- Equalization - the Low Frequencies seem to activate the buzzing.
- I always use an MXR M80 DI prior to the amp - I've removed it on occasions just to ensure that the problem still persists.  It does. 

THIS MIGHT HELP SOME:
- This amp has a Crossover section with 1/4" "High Out" and "Low Out" jacks, which should allow me to bi-amp
- This amp also has a Patch section with 1/4" "PreAmp Out" & "PowerAmp In" jacks (probably useless in this test)

Honestly, I don't know enough about this bi-amp stuff, but I'd imagine that I can use the Crossover outputs to connect another cabinet (or another combo amp).
I would never do this without being reassured that I'm not going to blow up more equipment.  I've read the specs on my amp, and the description of the Crossover Section does not give me enough confidence to try this myself.

I have a few smaller combo amps available (SWR LA12-60W & a Behringer 180W combo) to test with.  I'd hate to damage the SWR.
I also have a 300W powered monitor that I could use.
I do not have a cabinet at home.

Any suggestions before I disassemble the amp?

Thanks,
Steve

[Psycho Bass Guy]

It sounds like it's the lows that are bothering it, and that is is more than likely the speaker. The one that's in it right now is a Black Widow 1502-4 (Four ohm 100 watt 15") and would use a replacement basket #00560050.

[ack1961]

It sounds like it's the lows that are bothering it, and that is is more than likely the speaker. The one that's in it right now is a Black Widow 1502-4 (Four ohm 100 watt 15") and would use a replacement basket #00560050.

Thanks...that helps take the nightmare of ordering the correct part out of the way.
I'm actually looking fwd to opening this thing up.

[Highlander]

Dante's Inferno time...

[Big_Stu]

THIS MIGHT HELP SOME:
- This amp has a Crossover section with 1/4" "High Out" and "Low Out" jacks, which should allow me to bi-amp
- This amp also has a Patch section with 1/4" "PreAmp Out" & "PowerAmp In" jacks (probably useless in this test)

Honestly, I don't know enough about this bi-amp stuff, but I'd imagine that I can use the Crossover outputs to connect another cabinet (or another combo amp).
I would never do this without being reassured that I'm not going to blow up more equipment.  I've read the specs on my amp, and the description of the Crossover Section does not give me enough confidence to try this myself.

Did an ebay serach cos that's helped me in the past with other stuff & found this
http://cgi.ebay.com/PEAVEY-TNT-130-BASS-AMPLIFIER-VGC-VINTAGE-TNT130-15-BW-/270554959943?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3efe551047

I assume this is like yours? there's another on there which still has the grill. But this auction specifically mentions an extension cab. A third auction also has one with an 18" speaker!

[Nighttrain1127]

I had a Peavey Combo 300 and it was buzzing like an angry hornet with anything even remotely low Removed the amp amd speaker and reglued the baffel and seamsI(corners and every cab joint) let it set up for a couple days and no more buzz just the cost of some wood glue.

[Grog]

I have a TNT 150,  about a 1991 model, with a Black Widow speaker. It works well with the "Hobbit", but my '67 EB-2 made the cabinet buzz. I always assumed that the little triangular port, on the bottom, left hand corner, wasn't big enough to handle the BIG BALLS of the Mudbucker. I also have a 215 Black Widow cabinet with a Mark VIII head, from about the same era. That cabinet always handled anything I pumped into it without buzzing. It has a much bigger port. 

[Psycho Bass Guy]

The irony is that a larger port has a HIGHER frequency rolloff.  The speaker isn't buzzing because it is acoustically unloaded.

[Pilgrim]

Thanks...that helps take the nightmare of ordering the correct part out of the way.
I'm actually looking fwd to opening this thing up.

I've changed the "basket" on a Peavey Scorpion 15".  You pull out the speaker, and the replacement part is the entire speaker assy minus the magnet.  You remove three bolts, pull the magnet off, move it to the new "basket" and bolt it on, then re-install the speaker.  30 minutes tops.