Peavey 3120 output troubles, please help

[cryptic Kitten]

First time user of this site. I recently traded a spider ii amp for a peavey 3120 that had some issues. Only one of the stereo outputs works and it buzzes when I use a distorted channel. I'm not sure what could cause this so I stopped using the amp. Could somebody please share their knowledge and help me out? Could it be a fuse, tube, output transformer?

This is my first tube amp, btw. I recieved it in this condition.



Also, my cabinet is is a 4x12 with 16 ohm speakers but it's wired parallel, making each side 8 ohms. The amp says using both outputs creates a parallel connection. Does that mean I need to have it on the 8 or 4 ohm switch? I'm not sure if the switch takes into account the parallel from the amp. If I only use one output on the amp, I assume I would run it at 8 ohms and that would be fine? Sorry if I am confusing.

[xtian]

First, your cab is 8ohm, so use the 8ohm out from the amp.

If your clean channel works OK but distortion channel does not, then it's likely a preamp tube. Not a fuse, since a blown fuse would cause the amp to not work at all.

If this is your amp:

http://www.zikinf.com/_gfx/matos/dyn/la ... 3120_2.jpg

it is NOT stereo out. Just mono. Just plug one cable from output to your cabinet. And if only one of the mono jacks works on the amp, I'd just it's just dirty and needs to be cleaned.

[cryptic Kitten]

But.. Each speaker is 16 ohm and each side is parallel so that's 8 ohm. Left and right halves of the cabinet aren't wired but if they were wouldn't that make two 8 ohms load 4 altogether?

16 16
+ +
16 16

It's a line 6 cab.

What kind of Y cable would you suggest.

I tried to take out a couple of tubes and neither the pre amp nor the power tubes want to budge. Like if I pull any harder they are going to shatter.

I could wire them together paraller or series to just one jack, I believe. What should I do? Still not understanding how my cab could be 8 ohms if it's two 8 ohm loads.

[NickC]

SPEAKER OUTPUTS
These paralleled 1/4” mono (TS) jacks are provided for the connection of speaker enclosure(s). Again, minimum speaker impedance is 4 ohms. The CABINET IMPEDANCE SWITCH (23) should be set to match the load of the speaker cabinet(s).

Owners Manual PDF
http://www.peavey.com/assets/literature ... 0_7703.pdf


The two 8-ohm speaker pairs (2 @ 16ohm in parallel) internally paralleled together through the two speaker jacks on the back of the amp present a 4 ohm load for the output stage of the amplifier.

[cryptic Kitten]

The two 8-ohm speaker pairs (2 @ 16ohm in parallel) internally paralleled together through the two speaker jacks on the back of the amp present a 4 ohm load for the output stage of the amplifier.

Thanks for the clarification. Will any old Y cable work? I tried using a Y cable before for another amp and it didn't work properly. I'm not sure if it was a bad idea to begin with or if the cable was bad.

[NickC]

The two 8-ohm speaker pairs (2 @ 16ohm in parallel) internally paralleled together through the two speaker jacks on the back of the amp present a 4 ohm load for the output stage of the amplifier.

Thanks for the clarification. Will any old Y cable work? I tried using a Y cable before for another amp and it didn't work properly. I'm not sure if it was a bad idea to begin with or if the cable was bad.

Do not use a store-bought Y-cable. Those are made for inserting outboard FX in/outs to a mixing desk. The wire inside those cables is far too light to use as speaker cable.

Use standard speaker cables (the longer the run, the heavier the gauge). Connect one cable from the back of the amp (speaker jack) to one side of the speaker cab (with 2 @ 16 ohm speakers in parallel). Connect another speaker cable from the back of the amp (speaker jack) to the other 2 @ 16 ohm speakers in parallel in the cab.

If you prefer, you could rewire the cab to series/parallel for a 4 ohm load and then you'd only need to hook up one speaker cable. Leaving it as is provides some flexibility. The impedance load works out the same either way.

[Reeltarded]

The cabinet is a stereo only cabinet? A Y is typically a series cable..

The cab should be 16 ohms s/p. amp set 16 and use one output.

[NickC]

The cabinet is a stereo only cabinet? A Y is typically a series cable..

The cab should be 16 ohms s/p. amp set 16 and use one output.

The way I read the OP was a stereo only cab. 2 @ 16ohm = 8 ohm for each side.

The amp speaker output(s) is a standard paralleled pair of 1/4" TS jacks. However, there is an impedance switch to control them.

That cab could be rewired a couple ways:

2 @ 16 ohm series wired in parallel with 2 @ 16 ohm series = 16 ohms total load

2 @ 16 ohm parallel wired in series with 2 @ 16 ohm in parallel = 4 ohms total load

[cryptic Kitten]

Okay, how am I supposed to do it that way? Do you have a link to a pic? I don't understand how I could plug a speaker cable into the other side when the jack for the other side would already be connected to the amp. Wouldn't series parallel equal a 16 ohm load?

edit: you were quicker than me.

[NickC]

Okay, how am I supposed to do it that way? Do you have a link to a pic? I don't understand how I could plug a speaker cable into the other side when the jack for the other side would already be connected to the amp. Wouldn't series parallel equal a 16 ohm load?

How many jacks are there on the speaker cabinet? Are there any switches?

[Reeltarded]

What cabinet os this!!? haha 3 clowns in a car, all back seat.

HONKA!

[cryptic Kitten]

Nothing besides left and right input. It's a cheapo line 6 cab. It sounds okay, with the celestion seventy 80's.

I guess it wouldn't be to hard to mod it. Could do a series AND a parallel jack. Would be nice if they just made a cable to save me time though.

[Reeltarded]

That cabinet has one mono jack for mono and one stereo jack that switches it to dual mono? I think so. I don't know of a stereo only cab that hasn't been a mussed up rewire or for a special use.

Have a meter? Set it to ohms and check each jack on the cab. I bet on jack is 8, other is 16, and if you are plugged into both they are both 8.

The 16 ohm jack is the one you run your amp to all speakers with at 16.

Check it and know. Don't take my word. If it is a rewire you could be surprised.

[cryptic Kitten]

That cabinet has one mono jack for mono and one stereo jack that switches it to dual mono? I think so. I don't know of a stereo only cab that hasn't been a mussed up rewire or for a special use.

Have a meter? Set it to ohms and check each jack on the cab. I bet on jack is 8, other is 16, and if you are plugged into both they are both 8.

The 16 ohm jack is the one you run your amp to all speakers with at 16.

Check it and know. Don't take my word. If it is a rewire you could be surprised.

I've already taken the thing apart. Both sides are completely separate, and each side is the same.

[NickC]

From Peavey amp owners manual (link posted above):

CABINET IMPEDANCE SWITCH
This three-position switch allows appropriate selection of speaker cabinet impedance. If two enclosures of equal impedance are used, the switch should be set to half the individual value. For example, two 16-ohm enclosures necessitate an 8-Ohm setting, while two 8-ohm enclosures would require a 4-ohm setting. Minimum speaker impedance is 4 ohms.