Help with my Divided by 13 SJT 10/20

I just got my 10/20 head and it rocks! Looks great, too. However, I'm having two issues and I'm hoping somebody out there can help me (I've already spoken to Fredric, and he's offered to do an overhaul if I ship it back to him, but I'd prefer to see if anyone else has some thoughts first).

First, it broadcasts radio stations. Not when I turn it on. Not when I turn up the volume. But as soon as I plug in an instrument cable, voila! I have Tejano coming loud and clear through the speaker. This, of course, is amplified by any sort of gain. When I spoke to Fredric, he said certain locations around the country were prone to this issue -- that the cable was acting as an antenna for certain super high frequencies. He suggested I try different cables. I have. George L's, Whirlwind, old cheap-o curly cue cables. Even a 6" effects patch cable. All result in perfect broadcasts of unwanted radio. Now I have not tried Evidence Audio, yet, which Fredric suggested. That is next on my list. I have also tried lifting the ground plug and changing speaker cables. To no avail. Just for further information, once I start playing, you can't hear the radio. But as soon as I pause, or palm mute, or hold a note just a little too long, back it comes.

Second, it hisses quite a bit. Now I'm no amp guru, and truth be told, this is the first non-ss rectified amp I've owned (I've played plenty, just never bought one until now), but there is a significant difference in hiss between my 10/20 and any of my other amps (Fargen DC, Marshall DSL-401, Fender Blues Junior and even my ZVex Nano Amp). Hiss definitely increases with the 5879 channel and with volume. Again, once I start playing, you cannot hear it, except at low volume clean settings. However, as soon as I pause, palm mute, etc., there it is, loud and clear. Could this be a tube issue? Perhaps break in? The amp is only 1 week old. I have noticed that if you use an attenuator and set it at more than 1/2 way on the attenuation level, both the radio and hiss disappear. I am guessing this is because the attenuator is cutting out the high frequencies?

Any help y'all could offer would be greatly appreciated. Thanks much.

John

 

Thanks, Tom. I will give the dampening switch a go. How did you like your 10/20 when you got it back from Fredric? Did you hear a noticeable difference after the mod? As I said, he's offered to do the same for me. I'm just trying any home remedies anyone has first.

John

P.S. Are your clips with the 10/20 up on your band's website? I'd love to hear them.

 

Thanks, Ken. Much appreciated. I plan on spending some time trying to work on these issues this weekend. I'll let y'all know what happens.

John

 

Thanks Bob. By "filtered power outlet" do you mean like a Furman power conditioner? Or do you just mean like a power strip? Please forgive my ignorance.

UPDATE: So I took my rig over to a buddy's house this morning to jam for a couple of hours. I set up exactly as I do in my place (same speaker cable, same instrument cable, same power cable, etc.). Flipped on power, then flipped on standby and guess what? No radio whatsoever. Even dimed. Not a blip. Fredric did tell me that it could be location, but I didn't think it could be that simple. But I guess it is. That said, as soon as I got back to my apartment and plugged in, it was back. Very frustrating. But a relief to know that my 10/20 is not to blame.

Also, not sure if my amp is "breaking in" or what, but the hiss seemed greatly diminished at my buddy's place, too. He was playing a Victoria tweed and both amps made about the same amount of noise. I can say that for about 3 hours today, he and I were all smiles. Sam Evans told me to just keep playing, that it got better with time. So far, he's dead on right! Thanks, Sam.

John