rocket build advice

[pancho510]

I'm sure ill need a lot of advice for this build so let me start with cap choices
for the power supply I wanted to buy Sprague Atom not sure why. F &T caps are cheaper . what s a good cap choice and why?
I use OD 715 on last build for pre amp should I use these or try Malloy or something else.

[Blackburn]

Go with F&Ts for the filter supply caps. Cheaper and better quality (IMO) than new Spragues. Go with orange caps to be similar to originals or Mallories for some different flavor. 716Ps are good polypropylenes and cheap, as are 6PS, only polyester.

[telentubes]

I've been happy with F&T e-caps, and have used Mallory 150s on the last couple of Rockets with good results. I've used PEC pots, which are great, but expensive. I'm sure you would have favorable results with less expensive pots, a good place to save a chunk of money.

[pancho510]

thanks for the advice. this will be my second high voltage amp and i have built few guitars I have always used average or cheap pots. There are only 4 pots maybe I should try some better pots. Can I get some more advice on some pots and a good source where to purchase.

[KellyBass]

I use PEC pots every chance I get, and recommend them often as an upgrade. They are especially nice on 4 knob amps as they are pricey. Recently, i've been purchasing them from Amplified Parts. Great prices and service and a nice selection of electrolytics. I would really encourage anyone starting a rocket build to check out RJguitars. RJ is a member here. He has great parts, a wealth of knowledge, and is a great guy to boot.

[pancho510]

any recommendation on Tube selection? pre amp and power

[M Fowler]

I've had problems with PEC but they seem to be built very well not sure if it is a supplier problem or just me.

The PEC pots are sealed so I use CTS for mojotone and Alpha for Mojotone.

[ampmike]

Guys ,I Had some pec sealed pots go scratchy,poopy on me.Is there a way to fix that,Sorry dont want to hijack the threat.It was on my RJ rocket kit.I second how what a nice man rj is to deal with.He has got real nice kits for the wrecks,topshelf parts. Mikey

[Zippy]

Guys ,I Had some pec sealed pots go scratchy,poopy on me.Is there a way to fix that,Sorry dont want to hijack the threat.

The first thing to look for regarding scratchy pots, is to check the upstream capacitor to see if it is passing DC - the "scratchy pot" problem is often a failed cap rather than a failed pot.

[martin manning]

Zippy has a good advice. PEC pot failures of this type are not unknown though, so look for DC on them and please do report back.

[Blackburn]

Every PEC pot I've ever used in an amp has eventually developed a scratch. I doubt there's any DC on them and they're probably just dirty. Alphas are almost a tenth cheaper and can be sprayed easily. The only way to clean a PEC is to pry the casing off after removing it from the amp.

[Zippy]

Even with a bad personal history with PEC pots, it takes only a little time to troubleshoot the cause, rather than remove/rebuild the pot, only to find there is a bad cap. If it is not a bad cap, you haven't lost much time on the bench, and you've eliminated the cause of rebuilding the next pot that isn't a problem.

Good troubleshooting skills are worth the time to develop.

[cbass]

I wondering being seald and all with a plastic element.How do them things get durty?

[martin manning]

Must be they're self-soiling.

[Zippy]

Must be they're self-soiling.

I like that.

Making a WAG here...

I'd guess that it is oxidation/corrosion between the wiper and track, rather than the introduction of Stuff.

I've never bothered to look into it before, but maybe it'd be worthwhile to dissect some "bad" pots, and examine the traces and wipers under a microscope.