Help with rocket weird noise......

[Richie]

From way back as far as i can remember, i always used a piece of foam for the amp to sit on top of the cab. Combos can be much worse to keep the noise down on. One thing you can do,is have someone else play the amp while you use a small dowel stick to hold or touch componets. mostly caps or wires. But don't overlook things like handles,or backboards,vents or any other hardware.
Sometimes it can be more than one causeing it. Then you can use silicone or similar to dab it and keep it from vibrating.
Other things, the board itself. if you have metal standoffs these can cause lots of vibration to the board. You can use some rubber washers that can help keep the vibrations down and not so solid of a contact to the chassis.
Putting the small heat shrink on componet leads, or other types of spagatti over the leads help cure vibration problems.
I had one fender combo that had a good buzz on certian notes,it was one of the tone caps. laying or bent to 45 degress it buzzed, stand it straight up it was quiet. So, it don't take much sometimes.

Some amps pick up chassis noises easier. Any rattles and so on, like unused tube pins can be picked up by the tube. You can put small pieces of heat shrink over them to help keep them from rattling or buzzing. I always tried to use something besides ceramic sockets too,they seem to transfer these noises easier. Or maybe thats just me. I try not to use them on some amps or combos.
Even your output tubes. Good tubes should not be noisey. Older or tubes with some wear can be microphonic too, they can rumble pick up noise from those spring retainers and all kinds of things can happen when playing loud.

Like checking any tube a light tapping on the chassis or tube you might find its quiet,or it is microphonic. Seems as output tubes wear the parts inside start to sound like they are very loose.
Just a few things to look for that might help someone.

[redshark]

Thanks for all the comments, No matter that the rocket is very quiet when is not on top of the speaker cab I think I will try to find what causes the rattle. Will try to go through all my connections. Specially on the rocket with the resistors soldered directly to the pins of the power tube sockets that could be the problem. If is the tubes there's not much to do but replace them but I had found some NOS mullards that sound sweet and make the amp sound swirly and nice.

I corrected it in my previous post, my cabinet is pine, not maple...

[Cliff Schecht]

My 6aq5 rocket still has a weird harshness on the open string high notes, especially the g and d, even when set to super clean. I'm still scratching my head trying to figure out what is causing it. Happens at all volumes (MV installed) but is especially bad at higher volumes. This is an open chassis with no head and its set a good distance away from the closed 1x12 cab. It's something in the very high end, sort of a scratchiness or harshness riding on top of the notes. Any thoughts?

Also, why does the volume dip for a second when I turn the bass pot quickly?

[amplifiednation]

I thought my rocket was making all this rattling distortion last night and tried a couple diff cabs and couldnt get it to stop. I walked around playing bass notes and found a drawer of metal shelving that I had forgotten about rattling like crazy.

Funny how concerned you get with noise from an amp you put together. Its like being convinced it must be something you did wrong even though it could be a bunch of trash in a drawer in your basement you tried to hide instead of throwing away!

[bandade]

I had a slight buzzy distortion on certain notes of my last amp I built. I swore I had a bad tube, speaker, or component somewhere. I pulled my hair out and chased it for over a month before I found out that it was being caused by my engraved logo tag right above the speaker. I had not drove one of the tacks in hard enough and had a 1/10 mm or so gap between the logo and the tolex which was vibrating a certain frequencies.

I would check your cab construction.

Goodluck!

[Cliff Schecht]

It doesn't seem like a cab issue, I use this cab for everything and the amp does the same thing on other speaker cabs, open or closed back. I'm suspecting something goofy in the power supply because smacking all of the amp components with a chopstick yields no strangeness. Just the g and d strings make a harsh sound in the background that fades as the signal does. Could the cathode follower be causing this?

[Richie]

I was looking back at the pics you posted of the amp builds. A couple things you might look at. Those black oil caps. I'd swap those for regular film caps. Alot of these are bad or leaky.
And what did you use to solder to the backs of the PEC pot/s Those can be soldered to,but you have to use some special stuff to make it work. Might be easier to tie those grounds to a ground lug.

Also check voltages on the cap of the preamp section And voltages on the tube pins B+. Measure with the tube in the socket. then remove the tube and remeasure. Sometimes a cap will charge up to what looks to be a close voltage. remove the tube and you have the same voltage weather its in or out. Can be tricky. but that can cause the buzz or noise like that.

[Cliff Schecht]

I plugged in my real Rocket build and noticed the same harshness when the amp is set clean. It's predominantly the b string with this amp but there is definitely some hash that can be heard on top of the open string notes. Maybe its the maple fretboard guitars I use not agreeing with the amp.. I'm still suspecting the cathode follower is adding some unwanted crud but only time and tweaking will tell.

[redshark]

Since I started this thread I will say the reason of the noise in my built which is fixed now is that I had 2 cold solder joints and the vibration made the noise. I just fixed those 2 connections and noise is gone!!. Still I think is a good idea to have a piece of foam between the cab and the head.
The connections that were bad is R2 to the input jack, that turret was bad and also R5 had a cold solder joint in the grounding buss...how did I know? hitting every turret with a chopstick with the amp on and the volume at least at noon. Nothing plugged in....

[Zippy]

The connections that were bad is R2 to the input jack, that turret was bad and also R5 had a cold solder joint in the grounding buss...how did I know? hitting every turret with a chopstick with the amp on and the volume at least at noon. Nothing plugged in....

"that turret was bad" - do you mean that the joint at that turret was bad? I don't see how a turret being loose could cause noise.

[redshark]

Ha! yes, u r right Zippy, the connection at that turret was bad, everytime I hit with the chopstick I got noise...so I fixed that and Voila!! no more noise....sorry for not writing correctly

[Cliff Schecht]

It's not a loose connection, I've tapped every joint in both amps and they don't have any issues there. I need to try these amps out with darker guitars and see if the problem really is with just maple fretboard Fender style guitars. The noise is in both of my Rocket builds and is a nasty harshness in the open string notes, especially the B-string. This is one of those things that until you notice the problem it doesn't bug you, but once you hear it you can't unhear it! Does nobody else hear a certain hash in the open high-string notes on their Rocket builds?

[redshark]

Not really, and just 2 days ago I played a danocaster tele with a maple neck that sounded fabulous in the rocket...I've never heard that harshness u talk about in my rocket. Very smooth.