KT66 Rocket Build

[tweedeluxe]

Just finished my first Trainwreck inspired build - a KT66 Rocket.

I have spent very little time playing it thus far - but it sounds heavenly - I really can't imagine a better clean tone. I WILL post clips soon. Many thanks to everyone on the forum, especially those who posted about their own octal Rocket type builds.

I got most of the parts from RJ, who has been a big help.

I did change a few things:
-Split the KT66 cathodes (per data sheet instructions).
-5k6 grid stoppers
-220 ohm screen grid Rs
-25k mid control
-Single/parallel V1 switch (split cathodes 1k5/22u, 1k5/1u, shared 100k Ra)
-2nd stage bypass cap toggle (no cap, 1u, or 10u)

The Edcor xfrmrs came from RJ. I used the 5k2 tap on the OT.

I wrote down the operating voltages but I don't have the sheet with me. If I remember correctly, B+ was around 315V, and the plates on V1 were 95V. I forgot everything in between - but will post them later.

More reports coming soon. Pictures below. Comments and suggestions are welcome!

[Zippy]

-2nd stage bypass cap toggle (no cap, 1u, or 10u)

Cool build! Those KT66s are NOT going to fall out!

Can you swap tubes with the chassis in the cabinet?

Regarding the bypass cap toggle: Did you need the wrap on those leads to suppress noise? I wouldn't expect any difference since you are already so close to ground.

I'm curious because there are so many other similar cool opportunities to tweak in this platform.

[tweedeluxe]

Hey Zippy,

Yep there is just enough room to remove the KT66s - pretty tight though!

I'm sure that I didn't need to wrap the bypass cap toggle leads. I just did it because there was already a ground wire going to the switch - so I wrapped it around the other leads. I figure it couldn't hurt.

This amp will get most of its use in an extremely noisy environment, so I tried to take every precaution.

The bypass cap toggle is a really useful modficiation to this amp.

[Zippy]

Thanks.

I'm curious to learn what position on that bypass switch you find most preferable.

... and please tell us what guitars you find most pleasing with this amp.

[M Fowler]

I like your build and your data on this build thanks. The black cab with that wood face plate is very nice.

Mark

[tweedeluxe]

Ok, was just out with the future owner of the amp. We tested out a strat, tele, and gretsch jet into a 1965 bassman cab with 2x12" Jensens.

I personally liked the strat and tele the best, but I'm not much of a humbucker guy.

Honestly, there is not a bad tone to be found in any of the toggle positions.

The parallel switch adds a bit of volume and hair, and the bypass cap on the 2nd stage gives the amp a "fuller" sound, and of course decreases the headroom. The 1uf is just a little more "tight" when compared to the 10u. The 1k5/1u corner frequency should be about the same as the 2k7/.68 marshall combo.

Both switches up gives the amp quite a bit more drive.

With both switches down (stock), it stays pretty clean until about 1:00 on the volume.

Going to try some different tubes out tonight.

[Zippy]

Excellent notes. Thanks.

Anything that the amp doesn't deliver, things that you'd like to get from it?

[Kregg]

Nice amp dude. I like an amp with 66's ... have any clips?

[RJ Guitars]

Just finished my first Trainwreck inspired build - a KT66 Rocket.

I have spent very little time playing it thus far - but it sounds heavenly - I really can't imagine a better clean tone. I WILL post clips soon. Many thanks to everyone on the forum, especially those who posted about their own octal Rocket type builds. ...

I did change a few things:
-Split the KT66 cathodes (per data sheet instructions).
-5k6 grid stoppers
-220 ohm screen grid Rs
-25k mid control
-Single/parallel V1 switch (split cathodes 1k5/22u, 1k5/1u, shared 100k Ra)
-2nd stage bypass cap toggle (no cap, 1u, or 10u)

Most Excellent TD! I learn a little bit more every time somebody puts up a good thorough post like this... I'm interested in the voltages when you get to that part... but play it for a while and enjoy what you've done.

Sounds like everything matched up nicely with that output transformer. It's great to have a data point for a guitar amp with an Edcor output tranny.

I've been waiting for that info on the single/parallel switch on the first gain stage. You beat me to the punch on putting in switch so i could get an A/B result. Now I'm wishing I had an extra hole for a switch in my existing builds.

Good job, can't wait to hear some clips...

rj

[M Fowler]

rj,

I should have recognised that blue transfor, Edcor? Are all your Edcors going to be blue? Cause I like black.

Mark

[RJ Guitars]

rj,

I should have recognised that blue transfor, Edcor? Are all your Edcors going to be blue? Cause I like black.

Mark

Mark,

The Edcor standard is Blue. They have a Black core though.

In the very early prototypes, they had a black coat over the Blue.... yours might actually be one of them that will show the Blue if you rub through the Black. From now on, they will all be Blue and will have the Edcor Logo on them.

Edcor does a very clean job on the assembly and there is no varnish runs on them so the bells come off clean and easy if everything else suits you and you prefer to paint them.

So far, both the price and quality have been very good and they have very accommodating... a really great company!

rj

[M Fowler]

The transformers are the only thing keeping me from my planned amp builds, but I must agree the prices from people like you and others on this forum are very reasonable and high quality. I might have to start selling my amp builds.

Mark

[RJ Guitars]

Mark - let me know when you need a tranny and I'll do a custom paint job for you so that nothing stands in your way toward that next build... just kidding but of course it's always possible.

TweedDeluxe - can you share your capacitor selection with us? I recognize the orange drops and the Tech-Cap filter caps, what are those others?

Thanks,

rj

[Blind Lemon]

I got some of the blue Edcores, from RJ, for a rocket build (EL84s) I'm working on now. I'll probably be able to fire it up this weekend.

BL

[skyboltone]

Ditto on the great experiment. I like KT-66s.