Amp screeching

[lamb_of_gods]

Crawling back looking for help.
When plugged into the krank head, a very loud high pitched squeal of feedback comes through. When notes are played it stops but if im not playing it screams. Ive tired 3 different guitars through it and all do the same. The peavey did the same thing when I ran a pedal into it. What am I doing wrong. And how do I fix it. It seems to happen more if I've got the gain high and if I get close to the amp . I googled it, but couldn't find anything.
On a side note, it doesn't happen with lower wattage amps, ie, vox valtonix 15 or my partners new lil night train combo ( what a sweet little beast that beauty is, makes me want to sell the krank and get a orange tiny terror. Creamy overdrive. tubes at bedroom level is nirvana. But that's another topic.)

[bornannoying]

Crawling back looking for help.

Oh yeah? Well fuck you!

How loud are you playing? My first thought is that it's just what you say it is: feedback. If you're up loud, using a distorted tone, and standing close to the amp, you're likely to get feedback. If you're getting it when on the clean channel, with the gain backed off to more of an overdriven tone, or at bedroom levels, then it's something else.

That it happened with the Peavey is interesting. Could it be that an effect pedal is causing it, or have you tried going in direct and still got the problem? With a tube amp, a high pitched squeal can often be a screwed preamp valve, but that's ruled out if your Peavey was doing it too. Is it happening when using the Kolbe, or without it?

In short, we need more info. Try plugging your guitar directly into the head – no pedals, no Kolbe preamp – try all channels, and let us know what you hear.

[lamb_of_gods]

Plugging straight in, on the clean channel, everything is fine. All knobs at 12 o'clock. Switching to krank channel, volume low, all knobs at 12, it sounds fine but the sound is clean, edging the volume up to break up the cleans and get a nice distortion is when then screech starts, movin the volume back down doesn't stop it. The peavey only did it when I had the infamously bad death medal pedal plugged in to the clean channel.
I assumed it was to much gain until the krank head did it without any pedals.

[bornannoying]

Sounds like a fucked preamp tube to me. Tube amps often have a spare pre tube clamped to the inside of the casing. If there isn't one, and you don't have any, buy a few: they're worth having around and don't cost much. They're almost certainly 12AX7s, but do check your amp's manual, or the product details on the manufacturer's website.

If you bought it used, it's probably a good idea to just change the whole set. In fact, fuck it. Replace the whole set to be sure they're all good. The pre-tubes are the small, roughly thumb sized (slightly shorter) ones; usually at the front of the amp, so looking at the back of the amp, they'll be behind the power tubes (which are larger than pre tubes).

For the love of fuck, be careful poking around in there: there are lethal levels of juice going through your amp. Turn it off and unplug before you do anything, and don't touch anything other than the tubes. You can get a potentially lethal shock even when it's off: anything other than a tube change is a job for a tech. Also, when handling tubes, it's an idea to handle them by wrapping a cloth around them. It keeps finger grease off them (apparently causes problems) and, more to the point, if you happen to fracture one, you stand a chance of not having a fist full of broken glass.

They can be tough to pull out. Just gently wiggle the tube from side to side while pulling up (don't grip too tight and crush it), and it should come free. When you put the new ones in, make sure to push them fully into their sockets.

Oh, and, check the precise part number for the tubes your amp uses. 12AX7 is a generic type; there are specific varieties that some manufactures recommend for specific positions. My VHT uses 2 or 3 different types of 12AX7, and the manual tells you which one should go where. Sometimes they're obscure and hard to source, in which case just go with the nearest equivalent.

[lamb_of_gods]

Cheers, I might take it into the shop and get them to look it over, and change the tubes. I don't want to stuff anything up. I don't know if it will have any affect but it's a soild state tube amp. So no little pre-amp tubes.

[bornannoying]

Ah, well, forget everything I just said then. It's all completely irrelevant to SS. I guess you could have mentioned that earlier.

[lamb_of_gods]

Sorry should have mentioned in my first post , my mistake. It's a hybrid bastard child. It's got a tube pre amp and a solid state amp. Thanks for the help anyways. Very prompt on the replies, cheers

BTW fuck you too I'm not kissing ass I just think your pretty

[bornannoying]

Jesus… in that case, then, it could be a knackered preamp valve. And, being a hybrid, it's a piece of piss (and entails less risk) to swap it out yourself. Save yourself some hassle and $.

You think I'm pretty? You're only human.

[lamb_of_gods]

Found the problem, karmas a bitch. Plugged in tonight and it's dead. Tried different wall outlets, different plugs. Nothing, it won't even turn on on. No light show of sparks, nothing, what a let down, I atleast wanted some fireworks. Go out with a bang you pussy. Less than two months old, probably had 6 hours use at most.It was soothed over by a email about a package I ordered months ago from the dita's website that read in it's entirety " that was sent out months ago, must have got lost in the post. Thanks". Well fuck you karma and fuck you Dita I hope you know I ripped all your posters off the wall (of the hotties thread).

[bornannoying]

I take it you've checked and, if necessary, changed the various fuses?

[lamb_of_gods]

I haven't looked under the hood properly, as I don't want to stuff around with something I have no idea about. We have a pretty clued up jack of all things electronic at work, I'm going to take it in to him and get it looked over. Fingers crossed it's a easy fix. I dont want to tinker with the internals, thus avoiding any warranty i may have? After goggling, im worried that even it is just fuse, it's not something more serious causing it. Ive kept it unplugged when not in use and it worked fine yesterday. Im a under the assumption it commited suicide after putting a all tube amp near it yesterday. Can't blame it, if you can't compete, why race

[lowmantotempole]

Please for the love of god... Sell me that GP1 before you f_ck that up too!!!

[lamb_of_gods]

Please for the love of god... Sell me that GP1 before you f_ck that up too!!!

I loled so hard at this, im making it my sig.
The GP1 is being very well looked after, dont worry. Its being babied.
Turns out it was just a fuse. Easy fix, apart from the travelling to 12 stores which didnt have the right size in stock.

[lowmantotempole]

Nice.

Well I actually spoke to Mr. Kolbe last night for about half an hour. I'm moving to NJ in July. So he invited me up to his shop in NYC once I get settled. It's only about a 90 minute drive. So I'm sure I'll get ball rolling on something good.

He also mentioned something about designing a new version of the GP-1 and building it late fall this year.

Good stuff!!!

Cheers.

[lamb_of_gods]

That's awesome news. Fingers crossed he builds the new pre amps, the GP1 is amazing. Ill have to start saving for this. Also as you know, he did/does amp mods, maybe see if he can mod your amp instead of getting a pre-amp. It will probably cost less, you'll get a custom product suited to you and it will fetch a hefty price on the second hand market, if you decided too sell it down the track. If the horror stories are to be believed, don't pay for anything upfront.