Help with rocket weird noise......

[redshark]

After running fine for a couple months my rocket started having a noise on top of the note once is breaking up. In the beggining I though it was tubes but I replaced all of them and still there, then I reflowed all the joints that I though were suspicious and now the noise only happens between the E and F note and only in the 6th and 5th string when volume on guitar open.
What could be making that distorted noise? I know it is not tubes, is like a overly distorted noise only in that frequency...any ideas?

[M Fowler]

What brand of filter caps did you use? I had some F&T that sounded like that in a Liverpool.

[redshark]

Mallory TC series, but I'm more suspicious about cathode cap...220mu @ 100 v

[dartanion]

Have you tried a different speaker or cab? Also, Mallory TCs are not what they used to be. Did you measure them all before using them? They could be fakes too as that has been happening for while.

[redshark]

Found the problem, cold solder joint in the resistor(R9) connected from the bass pot to ground, I guess it wasn't making a good mechanical connection and it started acting up whenever it was loud and with more frequencies more than others. I also replaced that bias cap C13 just in case but now is back to normal, thanks!!
The Mallory TC caps were bought from allied dartanion, even that supplier has had fake ones?

Yes, in this build I measured EVERYTHING before putting on the circuit.

[redshark]

NOOOOOOOOOO the noise is back!!!!!!!!! is like it distorts on the E to F, and also the F. I know it's not microphonics cause I replaced the tubes. Any ideas? It wasn't the cathode resistor and cap. What else could that be?

[dartanion]

Fake electronic components have bitten the whole industry. Fake Intel CPUs. Fake MOSFETs. Fake caps. You name it. And this not isolated to small suppliers.

To the issue at hand. Have you tried different speakers or a different speaker cab? I have seen a few cabs/speaker combinations that work fine with some amps and ghost with others. One recent example was a THD 212 (Billion81's cab) that was loaded with Emi Delta Pros. Weird ghosting all over the fret board. Swapped in some Medusa 150s and the ghosting was gone.

[Cliff Schecht]

My 6AQ5 Rocket clone does this on the low notes of the g string and I haven't been able to figure out why either. I tried clipping out the cathode bypass cap on the second stage to cut down the gain in an attempt to fix this and it did help a bit, but it didn't completely fix the problem. Does it have something to do with the cathode follower?

FWIW the guy I fix amps for was telling me about the Allen Old Flame and how he heard this issue with these amps. He told his friend that owned two of them (and loved them) about the problem, which I guess the guy never noticed before, and the guy ended up dumping both amps.

[Richie]

Vibrating compnets can cause the buzz on some notes. And it can be a head if its still sitting on a cab. or if it is anywhere near it. Loose connections can also cause it. I'd also look into the recto tube. The low notes and so on.
You may not see a problem as muchat lower volumes, as when the amp is cranked or turned up more. if possible lower the filtering if using a tube recto. Having too much can cause buzzes and things happening.

[redshark]

Well, I'm using a 1x12 pine built cab with a celestion gold. I figured it out. Once I got the head off the cab and moved it 2 feet away no more noise. I guess the pine is a very resonant and vibrating wood and even the rocket that doesn't have lots of gain caused all those noises. I can't imagine if I put the express on top of it!!!! No wonder Ken wrote in his trainwreck manuals that placing the head on top of the cab wasn't recommended. Mistery solved I guess.

[Gibsonman63]

I have seen some odd things with vibration. My amp is fine on a keyboard stand. On a speaker cabinet, it goes microphonic. I have two 4 x 12 cabinets. If I plug into one and set the head on the other, it moves the speakers enough to create enough vibration to cause a little ringing at the end of my notes.

Try to isolate it completely from your speaker cabinet and see what happens.

[Big Jim]

Well, I'm using a 1x12 maple built cab with a celestion gold. I figured it out. Once I got the head off the cab and moved it 2 feet away no more noise. I guess the maple is a very resonant and vibrating wood and even the rocket that doesn't have lots of gain caused all those noises. I can't imagine if I put the express on top of it!!!! No wonder Ken wrote in his trainwreck manuals that placing the head on top of the cab wasn't recommended. Mistery solved I guess.

And I thought it was just my build I think I'm gonna try one of those Gramma foam bases for my cab.

[M Fowler]

Just go out to the gardening center and pickup those rectangle kneeling pads and place that between your speaker cabinet and head cab.

[Big Jim]

Just go out to the gardening center and pickup those rectangle kneeling pads and place that between your speaker cabinet and head cab.

That's a fine Idea Mark. LOTS cheaper I'd imagine.

[M Fowler]

Yeah and they come with a built in handle on one end