Strange issue with my amp head

Question

I'm a relative noob. So please excuse me if my information is insufficient.

Amp head: Peavey 6505 mini, Cab: Orange PPC 112, Guitar: Yamaha Pacifica 510v,

I get almost no sound from this setup(1% say) UNLESS I have my BOSS NS-2 noise suppressor connected. Even under the latter, there is no distortion and I must have the volume on my guitar turned up fully to even reach what was previously a low volume output. Without the noise suppressor, and even at only 1% vol, I can detect much distortion (vol at max level).

The guitar and leads have been tested on a spare amp and everything works correctly.

The setup had been working just fine previously.

What could be the issue? The amp head and cab are < 1 month old.

Answer 1

From what you've written the most likely problem seems to be something wrong with the input to the Peavey head. If your spare amp has a preamp out and the Peavey has a power amp in (or effects loop send and return, respectively), then a good test would be to plug the guitar into the input of the spare amp, then connect the pre out/effect send from the spare amp to the power amp in/effects return on the Peavey and see if you get noise from the Peavey through the Orange cab.

If you do get sound that way, then most likely there's a problem with the Peavey preamp. If it's a tube amp, then you could try replacing the preamp tubes and see if that helps at all. If it doesn't help or it's not a tube amp, you might have to take it to a tech.

If you don't get sound with the above test, then you could reverse the test and see what happens. Run the guitar into the input on the Peavey, come out of the preamp out from the Peavey into the power amp in on the spare amp, and see if you get sound. If you do, then and the Peavey is a tube amp, you could replace the power tubes and the phase inverter tube (which will look like one of the preamp tubes - the manual should specify which tube it is). You also should check that you are using a speaker cable, not an instrument cable, between the amp head and the speaker cabinet. And you should check that the nominal impedance of the speaker cabinet (should be written on the back or available online - the "ohms") is equal to or greater than the rated output impedance of the Peavey (again, written near the speaker out or available online).

Amps can be really hard to DIY on, and usually dangerous, since very high voltages can be present. If none of the above works, you pretty much have to take it to a tech.

Answer 2

The footswitch controls whether or not the effects loop is engaged. If the loop is engaged and nothing is plugged into it, you will get no sound. Or run a patch cable between the send/return on the amp effect loop. Then plug straight into the amp input and try it.

https://assets.peavey.com/literature/manuals/118738_30842.pdf

Also, this is not the right signal chain. "NS output -> amp input. effects send -> NS return. guitar -> NS input. NS send -> effects loop return –"

Use this: Guitar > NS Input > NS Output > Amp Input > Effects Loop Send > Additional Effects pedals > Effect Loop Return > Speaker Out > Speaker

Answer 3

It sounds to me like you may have blown your speakers and they're not quite dead yet. you can check them with a multi-meter set on ohms. at any rate, if that's what's happening, it's a bad idea to try and make it work with any amplifier. they just don't like a shorted load.