Rocket Problems

[JoshBernstein]

I build a vox ac30 a couple of months back, but i was having some issues with a weird ring modulator like ghost note. I decided to gut it and make it more of a rocket ish build. So ive put it back together, into a very unorthodox rocket, using a dolid state rectifier and a 470 ohm resistor instead of a choke.
I replaced all resistors and capacitors on the board, as well as the filter caps, using rocket values , and a jj can cap instead of the traditional can cap. I put it into a new chassis, which i got from rj.
After a completer rebuild and replacement of all parts except for the transformers, jacks, screen grid resistors, and pots, im having the exact same issue as before. A weird synth like overtone on every note that sounds similar to a ring modulator. Just as before, chopsticking and wire placement seems to make no impact.
I have tried tube swaps, playing the amp through a different cab, and using different wall outlets, with no changes. Im starting to suspect my output transformer, which is pretty small for a rocket build, and is intended for a 40 watt fender. Could this cause my issue?

[sunnydaze]

It looks like your using pins 1 & 6 on the EL84 powertubes as tie/jumper points. The data sheet list those pins as "IC" (Internal connection). Not sure what the IC's are, but you may want to try wiring without using those pins.

Good luck.

Mike

[BLT]

I see Mike Z do this for his amps, and I've used it in one of my builds without a problem. But I think there are some EL84 type tubes that this can be a problem. It's been fine with JJs.

[JazzGuitarGimp]

As I was reading your post, I was thinking OT. Then I saw you suggested the OT as well. Do you another OT laying around that you could swap in to see?

[Littlewyan]

Sorry Josh, I got to your other thread a bit too late. That Fender OT is quite small for a Vox.

[JoshBernstein]

I dont have any others laying around, but ill probably just bite the bullet and buy a proper one. Even if it doesnt solve the issue, the amp will probably sound better with the correct size tranny.
Thank you for the responses, and any other suggestions are greatly appreciated.
Thanks again!

[Littlewyan]

Does the cut control remove the fizz? And have you tried a different guitar? Can you record the issue?

[JoshBernstein]

The cut control does not affect it, but as more high end is rolled off it becomes more evident. It does not change in volume or tone, it just becomes more "uncovered."
I have tried all 3 of my guitars, and both of my speaker cabinets. When i get home i may be able to get a crude recording using my phone, ill do my best.
I ordered a proper ac30 tranny from amp parts direct and ill see if it fixes the issue. Again, even if it doesnt it will probably be an overall tone-improver.
Thanks again!

[JoshBernstein]

Also, correct me if im wrong, but i believe that amp parts direct is in florida, only a few hours away from me so it should come pretty quickly. Ill report back in a couple of days.

[guitarmike2107]

You may have some severe ground loops on that layout using that cap can.

I am of the opinion that, long term, your build is not very safe, once you have this ringing thing sorted out you need rubber grommets fitted on the chassis penetrations, they cost cents are are not worth worrying over, if your chassis became live on a circuit that was not earthed you would be in trouble.

also that F&T cap needs supported, you can get clamps that will bolt to the chassis to secure it, or just use a cable tie, again cost pennies and may save you grief later on, you clearly took time to sort out the turret board layout, do the same for the rest ( I mean this as constructively as possible without being nasty, I hope it comes across that way)

I use the resistors on the sockets all the time with no issues when using new EL84's

I can't imagine the physical size of the OT would be the issue, only if is was faulty maybe...

[JoshBernstein]

Thank you for the help, i appreciate criticisms as they help to improve my skills/builds. I will do the things you've suggestet, but im wondering about how i should address the possible ground loop problem. I assume that the preamp and power amp should be grounded seperately, is this correct? If so, where should i ground each one? Also if that is correct, could i use the 20x20x20 part of the can for the preamp, leave the 40uf section unused, and add a separate 40 for the screen grids? Thank you again, its appreciated

[M Fowler]

Not sure why your using 82R bias resistor rather then 50R or 62R (cooler).

That OT surely would be suspect and need 4K 30watt OT at least of beefy size. I know there are small Fender type 35w 4k OT's but not the same.

Make sure speaker jacks are well grounded.

Mark

[JoshBernstein]

The 82r was to compensate for thr higher voltages from the solid state rectification. It was all i had on hand after having some pretty high dissipation using the stock 50r, i have a 62 and a couple of other values on order.

[Littlewyan]

Does the issue occur when you're playing clean or distorted?

With regards to grommets, definitely buy some to make the build a bit safer. An easy way I use to install them is to cut through one side, then you can fit it without unsoldering any wires.

[JoshBernstein]

The issue occurs at all volume levels, clean or distorted.
And will do in regards to the gromets