Rocket Problems

Express, Liverpool, Rocket, Dirty Little Monster, etc.

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Littlewyan
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Re: Rocket Problems

Post by Littlewyan »

Well in that case unless the OT is faulty it does rule that out. Smaller OTs wil generally affect the low frequency response I believe so keeping that OT (assuming its good) will mean you won't get as much low end.

When you say you've tried different valves do you mean you've tried replacing both the Output and Pre Amp Valves?

Also have you tried playing the amp in a different room? I've had it before where something in the room has been making a noise.

Also also can you make this happen with any notes on the guitar or just certain notes? Is it a low pitch ring or a high pitch ring?
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

I have tried several different preamp and power amp tubes, as well as moving it to different rooms. The ring is synth like, is lower than the note being played, and it occurs on all notes. It becomes more evident as the actual note fades away.
I have tried different speakers and cabs as well. Ill do my best to get a recording of it later.
Thanks again
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

My first thought on this was that the amp was oscillating, but no amount of lead dress/chopsticking has helped anything, and ive poked around in it for hours. So im reasonably confident that it's not that. I figured it must be a bad part so i replaced pretty close to everything, but the noise remains.
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Littlewyan
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Re: Rocket Problems

Post by Littlewyan »

Does the volume of this ringing change with the volume control? Is it definitely coming from the speakers?
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

It seems to increase a bit with more volume, and 100% sure its coming from the speakers.
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Littlewyan
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Re: Rocket Problems

Post by Littlewyan »

Only a bit? So it doesn't increase in sync with the volume control then? If you have the volume turned right down to say, 1, does it still occur?
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

With the volume on 1, it is most noticable. As the volume increases, the noise increases more gradually, but is covered up more by the actual note being played. Ive also noticed that if i play a note and then palm mute it, the fizzy type not continues ringing out
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Littlewyan
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Re: Rocket Problems

Post by Littlewyan »

Then that says to me that the issue is later on in the circuit.

You say when you palm mute the noise continues to ring out? Have you managed to get a recording of it?
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

I have not, i didnt get home from work til very late last night and i didn't want to wake up the neighbors. Ill give it another shot tonight
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

I was able to get a couple of videos with my phone in between school in work. Some of what's being heard is the mic clipping, but the noise is audible in the clips. The first one is just a few single notes that make the sound really evident, and the second is just some noodling.
Sorry for the poor quality and the sub par playing (i was in a rush)
Also in the first clip i went through all the controls, showing how they have little to no effect on the issue. I couldnt crank it as my family is home.
Playing through my 1x12 test cab which i ruled out as the problem by playing another amp through it.

https://youtu.be/riGaI2S0vMI

https://youtu.be/m2cymkkovso
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Littlewyan
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Re: Rocket Problems

Post by Littlewyan »

I can hear it in the first clip. I wonder if its the ground scheme used. I've not come across that kind of issue before but I wonder if its signal leaking into a later stage via the ground.

It looks like your preamp grounds connect to the power amp grounds via that red wire at the moment. I'd say connect it to your input jack but it looks like your input jack is grounded on the board? Where is the 1Meg Grid Leak resistor?
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

The 1 meg grid leak is directly on the jack. Ill try moving the preamp ground to the input jack and see if anything changes.
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Littlewyan
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Re: Rocket Problems

Post by Littlewyan »

Cool ok.

Few things I can't work out which I've highlighted in the photo attached.

1. Where does the wire go that the arrow is pointing to?

2. The circled part. Looks like the resistor and capacitor for the EL84 Cathodes. Why is there two capacitors in parallel? And why are so many turrets joined up that aren't used? You don't want all that extra connectivity as its going to act as an antenna. You only want to connect turrets that are required.

I'm assuming the red wire on the left hand side of the cap and resistor goes to a ground by the big cap on the left? Black wire should be used for grounding, not red. You really want clear distinction between live and ground leads in amplifiers. A) For Safety B) For easy troubleshooting
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

The 2 capacitors in parallel are 2 100uf, as i didnt have a 220 on hand that i was sure was good. The red wire with the arrow is going to the potentiometer grounds. I will reduce the amount unnecessary wires that are connected to empty turrets, and will change my ground wire colors. Should i ground the pots with the preamp bus at the input jack?
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JoshBernstein
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Re: Rocket Problems

Post by JoshBernstein »

Ive also just noticed that my volume pot is miswired, probably wont fix the problem but ill get thay straightened out anyway
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