2 Hole Octal 6V6s Rocket with Verb

[surfsup]

EDITED for 6V6s...Okay so I am starting to order parts (ordered tubes, sockets, etc. the other day). I am looking at PT/OT choices:

-four 12ax7s (three plus 1 for verb) = 20mA draw
-two JJ-6V6s = 100mA draw
-one 5Y3 tube recto

-So I think I need a 120mA at least
-300V with 5Y3 will yield ~330VDC after recto (can use a dropping R to lower it a tad)
-I need 6.3V (3A) and 5V filaments (2A)

*This one has enough if I never want to add 2 more octals:
XPWR061-120
Power transformer for a 120V, 60Hz. line to 600V (300-0-300) at 120mA center tapped, 6.3V (3.15-0-3.15) at 3A center tapped and 5V at 2A.

**If I predrill 2 6V6s sockets for 4 total Ptubes, will 200mA be enough?
XPWR008-120
Power transformer for a 120V, 60Hz. line to 600V (300-0-300) at 200mA center tapped, 6.3V at 4A and 5V at 3A.

XPWR172-120/220
Power transformer for a 120V or 220V, 50/60Hz. line to 600V (300-0-300) at 200mA center tapped, 6.3V at 6A and 5V at 3A.

***If I want a lower voltage switch and stick with 2-6V6s, is the 240 too low?
XPWR145-120
Power transformer for a 120V, 60Hz. line to 600V and 480V (300-240-0-240-300) at 120mA center tapped, 6.3V (3.15-0-3.15) at 3A center tapped and 5V at 2A.

Should I be looking at other brands of PTs for the Rocket besides Edcor?

[Zippy]

Just go with the standard trannie set from our AmpGarage parts/kits buddies and switch one pair of tubes in/out. You know you will want to try the two vs four tube setup to hear the difference.

You seem to have a gift for making things seem difficult.

Enjoy the Rocket - and don't forget the MID knob!

You'll probably want to build the octal Rocket next... That's where it really starts to Happen.

[M Fowler]

For a two hole EL84 I would use 280v or 290v at 120mA to 140mA.

Also I would go with Heyboer or Edcor that has already been tried and used. rjguitar has them but are higher mA.

Dartanion has a nice tranny set that I used for mine that works out well.

Magnetic Components has the standup 18w Marshall tranny set now at Triode or another source as well, can't remember the site?.

Turretboards.com has a stand up Marshall 18w set used for the Spitfire and Marshall lite IIB set.

Mark

[surfsup]

You'll probably want to build the octal Rocket next... That's where it really starts to Happen

I'm an idiot. I am building this with two JJ6V6s, sorry! ARGH. My other amp is a 2-El84. The mA range should be appx the same though. I had EL84 on the brain. The "matched pair" I got says 29mA on the side but still looking at (0.8*14W)/320V = 35mA +10mA for screen =~50mA (100mA for two). I guess if I want to swap to EL34s I would want higher current (+10mA each maybe)...

Just go with the standard trannie set from our AmpGarage parts/kits buddies

I know RJ and Allyn have them, I am already talking to RJ. I don't have allyn's info, I should search. I'll talk to dartanion as well (thx mark) but I'm leaning toward RJ because I am getting the SupreEagle from him as well (three builds at once, whoa) so it will save on shipping costs if he has them in "stock".

I already have a 16x8x2 chassis so I hope that size is ok.

[Zippy]

You'll probably want to build the octal Rocket next... That's where it really starts to Happen

I'm an idiot. I am building this with two JJ6V6s, sorry! ARGH...

Hah! Have you read up on the KT-66 Rockster?

Yummy...

[RJ Guitars]

Surfsup - Zippy is actually the true father of the "Rockster" amp. It is basically a Trainwreck Rocket Preamp into a cathode biased octal output section. It's actually very close to the older Fender Bassman circuits than anything else. FWIW - This would imply that the AC-30 and thus the Rocket probably borrowed their preamp circuit from a Bassman - Your Opinion May Vary (YOMV).

Zippy and I had talked about the idea of using Octal output tubes in the Rocket (actually I think Normster did this before we did) and finally Zippy encouraged me until i finally built one. It was immediately a cool amp, but Zippy offered me the use of a set of KT-66's that were collecting dust in his collection... someday I'll give them back to him (not likely).

The KT-66's sounded very similar to the EL-84's of the Rocket, but seemed to have more of everything good concerning volume and tone. I went on to try 5881's - very awesome creamy distortion tone, and then El-34's - again awesome sounding. there are several good options.

One thing taken from the Trainwreck builds this amp was based on was the use of "Big Iron". That is a constant in Trainwreck amps and generally a good idea. This allows you to try almost any output tube compliment save maybe the KT-88's or KT-90's. I prefer Edcor transformers for these amps but any of the common Wreck trannies will give you good results... most combinations of them have been used along the way. The Edcor I use offers 250mA of current and I wouldn't go with anything less. The outputs are rated at 35 watts and that is conservatively rated...noticeably bigger than a 50 watt Fender output tranny.

At one point Rawnster built one of these and added reverb (Normster was first with that idea too). Reverb works out well in these amps and they take pedals extremely well.

Lots of precedent to follow and a really friendly amp to dial in and enjoy.

rj

[surfsup]

Thanks RJ, okay I'll leave the PT/OT/Choke choice to rest

Have you read up on the KT-66 Rockster?

No but I think now I have to. KT66s? Damn....I just bought the 6v6's! You guys are killing me. This amp is expensive enough in parts...maybe later after its built and I've got it running for a while.

I found this:

https://tubeamparchive.com/viewtopic.php?t=12420
https://tubeamparchive.com/viewtopic.php?t=7300

[M Fowler]

I would rather go with 325v on a 6V6 and get the plate voltage up.

Tthe same with with the Rocket 6L6 and EL34 instead of using TW iron at 300v or less.

What do you say about that guys

[RJ Guitars]

Have you read up on the KT-66 Rockster?

No but I think now I have to. KT66s? Damn....I just bought the 6v6's! You guys are killing me. This amp is expensive enough in parts...maybe later after its built and I've got it running for a while.

Hey, what an opportunity. Now that you have the tubes you could actually just a build another amp for them...

Seriously though, I think the 6V6's will work well and you want to hear them before you give up on the idea of a 6V6 Rocket.

One item that matters (maybe) - I built the original Rockster using an Express chassis. This works out oK for 6V6's and EL-34's but there isn't really much space in between the tube sockets for a pair of KT-66's...

rj

[RJ Guitars]

I would rather go with 325v on a 6V6 and get the plate voltage up.

Tthe same with with the Rocket 6L6 and EL34 instead of using TW iron at 300v or less.

What do you say about that guys

Blaspheme!

[Structo]

I threw together a 6V6 Rocket a while back.
It was one of those deals of using what was on hand type things.

In the end I liked it quite a lot.

I think I would like it with higher output tubes such as 5881 or the KT66.

No reverb but I did put a passive loop in it so I could run my Dumbleator and my effects through it.

This is pretty close to what I ended up with.

I didn't use the stack O caps but instead used a JJ cap can that was already in the chassis.

And of course the bias setup depends on your plate voltage so the cathode resistor may not be the same.

Oh, and I put the cathode bypass cap on V1a (C4) on a footswitch for a boost.

[Ian444]

Has anyone done a Rockster with fixed bias? Just wondering...

[RJ Guitars]

Has anyone done a Rockster with fixed bias? Just wondering...

Great thought! Something I call the "Road Rocker"... there is just no staying ahead of the great minds on a forum like this. I drew this up a couple years ago thinking that I'd put it into the building queue. I think I was anticipating that the cathode biasing wouldn't sound that good on the Rockster so I was planning ahead... I never built it. If somebody does, I'd love to have a report. As you can see, I again avoided the "Stack O Caps" and put the power supply filtering on a board. I have since modified that PS board design and created the design for an 80 watt version... with master volume. I haven't built that one either but I have all the parts and even had faceplates made up. So many amps to build and so little time...

Caution - This is an untested layout and it's probable that there will be plenty of corrections that are needed before this actually works.

With fixed biasing it becomes extremely Fenderish... if we use Dr. Fowlers suggestion of more volts on the B+ (also referred to as Blaspheme) then we have just about invented the 59' Bassman all over again.

Of course I am just kidding Mark - I would be interested in hearing why you like the higher B+?

rj

[Ian444]

Road Rocker, that's a good name. I was wondering what the next/another one might be called. If we could get even more blasphemous, it is not that difficult to put in a DPDT switch to switch between Fenderish and Marshallish, by switching in the unused half tube in a Marshall 2203/4 cct fashion. This is the direction I am thinking of going, and with fixed bias, I have a TW clone chassis but am wondering if this is just stretching it too far and I should keep the TW chassis for a more realistic TW clone. I think so. Can post a basic schem if you want to see. You could get 2 classic designs in the one amp. Surely someone has done that already too? That XP-80 face plate would work great, with that Bad 1 and Bad 2 switch right at the input

[dave g]

Honestly sounds like Mark Huss' 6V6 plexi to me.

I always thought it would be cool to add an extra input jack that goes to the grid of the unused triode, which feeds an extra 1MA pot on the front, the wiper of which then goes to the shorting lug of the "regular" input jack. So it's basically like a plexi with the cascade mod. Or you could just use the DPDT switch coming off the input jack. But in either case I think the extra gain control is a good idea.