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Re: Blown PT?

Posted: Sun 06/23/19 4:50 pm
by crgfrench

Re: Blown PT?

Posted: Sun 06/23/19 5:36 pm
by Riffmonster
crgfrench wrote: Paul Ruby has a good startup guide:
https://paulrubyamps.com/info.html#FirstPowerUp

Rob Robinette too:
https://robrobinette.com/Tube_Amp_Startup.htm
These are great resources, thanks. Chopsticking the cap does not alter the noise at all though...

Re: Blown PT?

Posted: Mon 06/24/19 9:21 am
by JMPGuitars
Riffmonster wrote:
Sun 06/23/19 5:36 pm
Chopsticking the cap does not alter the noise at all though...
No, tap the caps with the chopstick. It won't alter the noise, but it may give you a clue as to whether or not any are defective.

Re: Blown PT?

Posted: Tue 06/25/19 5:32 am
by Riffmonster
JMPGuitars wrote: No, tap the caps with the chopstick. It won't alter the noise, but it may give you a clue as to whether or not any are defective.
Yes, that’s what I did but I couldn’t detect anything. I am starting to think, that it is the power supply in my room. I borrowed two other amps and they both make a lot of noise in my room. The room is super small too.

As a side note, the lite2b seems to be louder than a 50watt JMP haha...

Re: Blown PT?

Posted: Wed 06/26/19 12:56 am
by Daviedawg
Going back to listen to your video it may be that you are suffering from external electrical interference. My soldering station causes noise similar to that. More common sources used to be fluorescence lights. But they are less common now. You could try a simple test of switching everything else off including adjacent room. But my feeling is that you would hear it all the time not just with the guitar.

Dd

Re: Blown PT?

Posted: Thu 07/04/19 8:15 am
by Riffmonster
Thanks Dd for the input! The noise is a bit less with the lights and soldering station turned off.
Since I got tired of troubleshooting, I decided to order new parts (resistors, caps and filter caps) and try building it up again. I will use the same chassis, turret board, tubes and transformers so the costs are manageable. I will keep you updated!

Re: Blown PT?

Posted: Thu 07/04/19 10:30 am
by colossal
Are you using a shield plate to cover the chassis while testing?

Re: Blown PT?

Posted: Thu 07/04/19 10:33 am
by Riffmonster
No I don't. I actually do not have one available here at the moment.

Re: Blown PT?

Posted: Thu 07/04/19 12:15 pm
by colossal
Riffmonster wrote:
Thu 07/04/19 10:33 am
No I don't. I actually do not have one available here at the moment.
It's very possible your amp is just picking up the room noise, as has been previously mentioned. Usually, a test of any amp is to be able to dime the controls and have no oscillation, even without a shield plate. However, if the environment is dirty, this can easily couple to the amp, inducing noise. A shield plate can be very effective. It must couple to the chassis to create a faraday cage.

If you have some metal foil tape, such as what is used for furnace ducting, you could place some strips on a piece of light plywood or masonite (or whatever you might have...cereal box would be a good candidate) and use that as a temporary shield plate. It might be tempting to use a piece of aluminum foil but you can kill yourself if collapses into the live amp. Use something rigid. You could use some spray adhesive on a piece of foam core or cereal box cardboard and lay out a piece of aluminum foil on it and smooth with a pencil.

If you've already gutted the amp, great. No need to test anything, but you probably need a plate the next time you are up and running in that room. But, to hedge against radio or line noise in the first place, nothing beats a good layout, good lead dress, and a solid ground scheme.

Re: Blown PT?

Posted: Thu 08/01/19 10:11 am
by Riffmonster
Hey guys,

sorry for the long silence, I have been quite busy!
I have rebuilt the amp and the noise is very acceptable now and it sounds awesome!
However, when I tried to record some samples with my two notes captor, i noticed that at full drive the sound includes something like a phaser sound if I let a chord ring. I attach a file for you to listen. I am unsure if it is from the captor or some kind of blocking distortion. What do you think?
Cheers!
Lite2bPhase.mp3

Re: Blown PT?

Posted: Fri 08/02/19 2:20 am
by Daviedawg
Always hard to be totally definitive on recordings, but that sounds like "fizz" to me. It is not too hard to rectify. A search will find a number of references to fizz and what to do about it.

There is a specific fix called the Paul Ruby fix. But I cannot remember how it went.

Dd

Edit. There is a whole sticky on the topic up at the top of this section.
Edit 2. storage/18-watter_buzz_info_311.pdf. This includes a diagram of the fix Paul adopted which has been used successfully by others.

Re: Blown PT?

Posted: Fri 08/02/19 6:45 am
by Riffmonster
Thanks man, that looks like an easy (to try) fix! I will order some diodes and tell you about the results.
Cheers!