Nashville 112 With Telonics Speaker

Paul King · From: Gainesville, Texas, USA

I purchased a Telonics speaker and installed it in my Nashville 112. Sure is cleaner and brighter and will take a little time to tweak. On the original speaker I had a hum when I turned reverb on. With the Telonics speaker the hum is much worse. I only use the reverb at home for practice and use a reverb pedal when out playing. Anyone have any ideas why the reverb would hum on this amp?

mtulbert · From: Plano, Texas 75023

The Telonics speaker may be more efficient that the previous speaker or the hum frequency is enhanced by the speaker's frequency response. Just a guess.
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Paul King · From: Gainesville, Texas, USA

I am no electronics man by any means. The hum has been there for a long time with reverb on.

Jim Cooley · From: The 'Ville, Texas, USA

Paul,

1.) Have you checked to see if it is a ground loop problem?

Don't Nashville 112s have spring reverb tanks? If so:

2.) I'm not sure about Nashville 112s, but many Peavey amps have Molex connectors from the reverb tank to the underside of head. There's also a Molex reverb connector inside the head unit. Make sure these are tight.

3.) There are a few really small wires inside the reverb tank. One of them might be broken.

4.) Also inside the reverb tank, at one or both ends of the springs, you should see a couple of short metal looking posts. I don't remember what they are called. Make sure they are straight. Gently straighten any that look bent.

5.) It could be a bad filter cap.

I've found and fixed problems #2, #3, and #4 in various Peavey amps. They are generally rock solid amplifiers, but spring reverb units can be touchy.

Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

If the hum occurs just when the reverb is on and goes away when the reverb is off, then I would definitely check Jim's #2, 3, and 4 first. Yes, the NV 112 has a spring reverb pan. I suppose it could be a ground-loop hum, but that would normally be present with or without the reverb on.

I had a terrible but intermittent hum from my 12-year old NV 112. One minute it would be fine and the next, the hum was so loud you couldn't hear anything else. I pulled the chassis and carefully probed around with a chopstick and isolated it to one of the can electrolytic capacitors - not surprising since the hum was at 120 Hz. It turned out to be an intermittent connection of that electrolytic from a cold solder joint.

After pulling out the PC boards, I pulled out the various connectors inside the amp and sprayed/reseated them, as well as sprayed out pots and jacks. All this requires a moderately delicate touch to avoid breaking something - if you're not used to doing this kind of thing, probably best to have a tech go over it. Amp sounds like new now.

Jack Stoner · From: Kansas City, MO

The NV112 does not have a Molex connector for the reverb like the NV400 and earlier did. The new connector has not been a problem like the old Molex.

My NV112 (original)had some reverb hum if the control was above 5. I recall on some the reverb connections, at the reverb pan, had been reversed at the factory. But I don't know if it would even work with reversed connections.

Another "fix" (minimize hum) was to move the pan as far away from the speaker as possible (toward the back edge of the cabinet.

Another "fix" is to put aluminum foil over the open side of the reverb pan.

On a non reverb hum, mine developed that once. There are two Molex connectors internally associated with the power supply. One of those was my problem. I reseated (unplugged and plugged back in) both and it went away so I'm not sure which one it was.

George Kimery · From: Limestone, TN, USA

I bought a new 112 a few years ago. I couldn't turn the reverb past 4 without getting a hum I couldn't live with. I called Peavey and was told they had a run of them go out that had the reverb connector plugged in backwards.They told me to take it to my local dealer and have them pull the chassis and reverse the reverb plug. The dealer immediately placed it on the counter and did the reversal. End of problem. It was as quiet as a mouse peeing on a cotton ball after that. Under warranty, no charge.

Jack Stoner · From: Kansas City, MO

So it was the reverb plug and not the connections at the reverb pan, didn't remember.

However, you don't have to pull the chassis to unplug/plug in the connector. Maybe hard to reach for some but shouldn't be a problem for an amp tech.

Paul King · From: Gainesville, Texas, USA

What is the solution for a ground loop problem? My reverb unit has a plug that goes on the control board that can be taken off on the bottom of the chassis. I will check it and see if it could be backwards.

John Palumbo · From: Lansdale, PA.

I'm having the same problem with mine the cables that lead from the chassis to the reverb can not be removed from the chassis one and one lead is longer than the other one. The reverb pan is mounted at the bottom of the amp so that the connectors for the leads on the pan are facing front towards the speaker. The back of the reverb pan is labeled one for 'in' and one for 'out'. Beings the leads are two different lengths the shorter length lead is and can only reach to the 'out' socket of the reverb pan. This out is on the right hand side. The other longer lead is connected to the 'in' socket of the reverb pan. If I turn the amp on and take the reverb out of the amp and move it away from it there is no hump. But my issue is besides replacing the original speaker with the Telonics as Paul did I also I tried replacing the original reverb with a MOD P-RMOD-9E2G1B. I guess like they say, in my case anyway if it ain't broke don't fix it.

Paul King · From: Gainesville, Texas, USA

I checked mine again. You cannot get the plug on backwards since it has a tab to keep it in place.

Jack Stoner · From: Kansas City, MO

A "ground loop" is not the same as the reverb hum in the NV112.

A "ground loop" is when the ground in two AC power devices that are connected are at a different ground potential. for example you have an effect unit that is powered by an AC power supply (wall wart or whatever) and you have an amp that is AC powered. If connected together and the "AC power ground" is at a different potential (voltage) there can be hum. This is caused by the design of the device(s) and takes a "hum eliminator" device to safely get rid of the ground loop hum. On some isolating the AC ground lug on one device will get rid of the ground loop hum but this is really an unsafe or potentially unsafe condition. The proper way is with a device specifically designed to safely do it.

There can be a missing ground that causes hum such as a bad/missing ground on a guitar cord but that is a different situation is not really an AC ground loop.

Paul King · From: Gainesville, Texas, USA

Where can I find a hum eliminator device Jack?

Lee Baucum · From: McAllen, Texas (Extreme South) The Final Frontier

For A/C ground loop hum, the Hum X device works well:

Click Here
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Jack Stoner · From: Kansas City, MO

Exactly what kind of "ground loop hum" do you have?
From this thread the only thing I see if the reverb hum and that is not a "ground loop" hum.

Paul King · From: Gainesville, Texas, USA

I use a reverb and delay stomp box. I do get a small hum when using them but nothing like the reverb hum on the amp.

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