[mulletman]

Originally Posted by BillSPrestonEsq

shielding usually helps with noise. Is your guitar noisy with lower gain settings? If not, I sincerely doubt that its a noise issue from the guitar.

Is there a connection between the tone knob and the squeal? Little giants seemed to squeal on some of my guitars with the treble past 6. and the gain all the way...

Some modern amps have too much gain in the first few gain stages and reach a howling self oscilation as soon as you feed any signal in.

If the cord, with no guitar were to feedback, I would suggest that, (assuming that your cable is not contacting anything that makes a massive buzz) it might be a fundamental flaw with the first two gain stages.

It isn't really noisy at lower gain settings... The tone knob doesn't do anything as far as I can hear. The cable, with no guitar attached, does make the same noise.

Would there be a fix for what you're referring to?

[Major Tom]

Originally Posted by mulletman

Hmm. Would there be a fix for that?

Yeah, a lower gain tube, or a different value for the bias resistors. Or turning down the gain on the amp.

Let us know what happens with a new cable.

One other question - how loud is the squeal? Really loud, hurt your ears, like when someone points their mic at a monitor, or more like an annoying low level noise?

[mulletman]

Alright. When I get a new cable....

It behaves very much like someone pointing a mic at a monitor. When I turn the volume/gain knobs up, I can hear it start.. and then build, like feedback. At that point I generally roll the knobs back. But yes, it would get to ear-damaging levels if I let it.

[mulletman]

Here's an interesting twist....

It seems that the squealing noise seems to be progressing toward the lower volume levels... Now, with full gain, it starts to feedback at just below half volume....

[BillSPrestonEsq]

Originally Posted by mulletman

Here's an interesting twist....

It seems that the squealing noise seems to be progressing toward the lower volume levels... Now, with full gain, it starts to feedback at just below half volume....

That sounds like a preamp tube to me...

Do you have the original chinese tubes?

[mulletman]

That's what I was thinking... but it just seemed odd that it still happened after new tubes.

I do have them. I suppose I will probably end up messing with those a bit more...

I should have gotten a head/cab, instead of the combo. In order to get to the tubes, I have to tear the whole thing apart. It's a pain.

[mulletman]

Alright. So I pulled the amp out of the cab, and tried it again with the amp sitting on top of the cab. Significantly less squeal. I could turn both the volume and tone knobs all the way up, and I still got some high-frequency noise, but it didn't seem to build into squealing feedback. The only time it turned to feedback was when the volume, gain, and tone knobs were ALL turn all the way to the right. I'm waiting for the tubes to cool off, so I can mess with the original tubes....

Now I really wish I had gotten a head instead of a combo...

Edit: Results: I tried one of the stock Chinese tubes in the preamp spot closest to the input jack, and it seemed to be about the same. Perhaps a bit less noisy. I'm going to try the other one in a minute.

[mulletman]

Alright. Here's the deal. Apparently the Tung-Sol 12AX7's do not get along with this amp, for whatever reason. I'm guessing they're higher gain than the stock Chinese tubes. I tried all possible combinations, and here's what I came up with. I've currently got one Tung-Sol in it, along with the Chinese tube in the first preamp spot. I re-assembled, and ..... no squeal. I know a lot of the Orange guys have been using different preamp tubes with the Tiny Terror, in order to produce a bit less gain. I might try a 12AT7, 12AU7, or 5751 in the future... we'll see.

I'd still like to end up with a head/combo, though. Changing a tube takes forever with the current configuration.

[Major Tom]

I'd still like to end up with a head/combo, though. Changing a tube takes forever with the current configuration.

Would a mirror help? Guys say the same thing about the AC15CC, I just lay it on its front, put a piece of mirror in there, and reach in and change them.

For a lower gain tube I would try a 5751 first, experimenting with it in both positions - its lower in gain enough to make a difference for what you are trying to do, but not so dramatic that it will alter the amp's gain / feel like a 12AT7

How many 12AX7's are in there - 2 or 3?

[mulletman]

Originally Posted by Major Tom

Would a mirror help? Guys say the same thing about the AC15CC, I just lay it on its front, put a piece of mirror in there, and reach in and change them.

For a lower gain tube I would try a 5751 first, experimenting with it in both positions - its lower in gain enough to make a difference for what you are trying to do, but not so dramatic that it will alter the amp's gain / feel like a 12AT7

How many 12AX7's are in there - 2 or 3?

Heh, if you get a chance, you should take a look at the Tiny Terror combo some time. A mirror wouldn't really do anything.

The combo is basically constructed as head+box. Orange took a Tiny Terror head, turned it sideways, and bolted it into the box. Therefore, everything is enclosed in that same metal-lunchbox looking enclosure. 16 screws hold the amp in the box, along with half of the back of the cabinet. Then another 5 screws will get the cover off, once you have the amp out. From there, you can get at the tubes.

I'll take a look at the 5751, for sure. There are two 12AX7's, and two EL84's in there.

[Major Tom]

Bummer about its construction. Usually the ones with hard to get at tubes are like the AC15, they are out in the open, but pointing toward the front of the cab.

I'll take a look at the 5751, for sure. There are two 12AX7's, and two EL84's in there.

In that case, I would definitely not put a 12AT7 in V1. If you really wanted to clean the amp up, you might try one in V2 (closest to the power tubes), the phase inverter position, but that would be a pretty drastic change. The 5751 could go in either spot, but with only 2 preamp gain stages, it may be a bit disappointing. You might want to try finding some in depth comparison reviews or ratings of 12AX7 tubes; ones that rate the tubes for microphonics, tone, gain, and current. Some tubes that are rated for being among the best sounding, are rated low for microphonics, for example the Sovtek 12AX7LPS - they sound great, and also have a high current capacity, but the long plate spiral filament construction is more microphonic. Tubes really vary a lot for that, even within the same brand/model - you could buy 4 of the same ones and maybe find one that stands out as being better. I don't know how the Tung Sol "re-issues" fare in those categories.

For V1, you want one with low microphonics, good tonally, don't worry about the current.
For V2, again, low microphonics, don't worry as much about the tonal rating, and you want one that is rated for higher current (it needs that to drive the power tube section without farting out). The JJ 12AX7 would be a good choice for V2 I think.

If it were my amp, I would try some different things - like I said, maybe something to shield the tubes from the brunt of the soundwaves, like a piece of sheetmetal or thin plywood between them and the inside of the cab. It seems like there are some aftermarket tube vibration dampening products available - like tube holders or something. I'm wondering if that chassis + cage, or a part of it is getting vibrated and then ringing at its resonant frequency like a tuning fork, and then the tubes are picking that up. See if you can get it to squeal and try putting your hand on the metal chassis / cage, which would dampen any resonant frequency thing - does that eliminate it? If so, I would see if I could use something like weatherstripping between the cab and the chassis, and probably put some of that weatherstripping on the chassis / cage.

[mulletman]

Interesting ideas, all of them. And I keep that in mind as I look for tube options...

Thanks a lot for all of the help/info. I definitely appreciate it.