Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Madison on May 23, 2010, 01:41:29 am

Title: Anybody built a "Two Stroke" amp?
Post by: Madison on May 23, 2010, 01:41:29 am

Or something similar with an 8" plus a 10" or 12"?
I have a couple of 8" speaker sitting and thinking of building something different.
Not sure about the Two Stroke's 2x6v6 SE idea though.
Maybe just a single octal would be sufficient?

Title: Re: Anybody built a "Two Stroke" amp?
Post by: alexandru_voicu on May 23, 2010, 04:39:10 am

Hi,

I have built one. This was my first build, actually. I built it with one 6L6 tube. After learning more about tube amps, I reverted it to a "standard" 5F2-A circuit. I also re-did the grounding, now resulting in a better sounding and almost hum-free amp.

My observations:

Stick to one power tube (6V6 or 6L6)
Improve the grounding of Hunter's layout (check other layouts for inspiration or study the Hoffman grounding layout)
The voltages with a 330/0/330 transformer are way too high. Go for 300/0/300 or less, preferably 280/0/280.

If you want to make it cheaper, go for a 250/0/250 PT with solid state rectification. Also, you can try the soviet 6N2P-EV tubes in V1. I absolutely love them for this kind of amp.

Alex

Title: Re: Anybody built a "Two Stroke" amp?
Post by: Danskman on May 23, 2010, 10:30:46 am

I built one with 2x6V6, Hammond SE 15W OT, a 12" and a 12AX7.
Revert to 1x6V6, as the 2nd 6V6 doesn't improve the loudness so much.
Tried 6L6GS, KT66 and even an EL34, but the 6V6 (TungSol RI) is better to my ears.
Tried it with a 1x8" + 1x10", but the 12" is so cool that I made a new cab for it.
I added a choke (5F2) as the amp was humming to much for my taste, but it was my 2nd build (1st was a 5F6A, really good sounding) and was not too much experienced at the time. I built other 5F2 / "2 strokes" amps and they were better built than the 1st, for sure!

Title: Re: Anybody built a "Two Stroke" amp?
Post by: tubeswell on May 23, 2010, 02:25:32 pm

A 5F2A with a 12" Goodman speaker in a Tweed deluxe style/sized cab was also the first thing I built. I put an NFB lift switch in, and it did a really mean stairway solo when cranked

Title: Re: Anybody built a "Two Stroke" amp?
Post by: Madison on May 23, 2010, 07:53:02 pm

Thanks for all the input.
Okay so if I do something like this looks like I'll go for a 5f2-a.
I personally like 12" speakers too so there is another hitch.
More though needed.
Thanks again.

Title: Re: Anybody built a "Two Stroke" amp?
Post by: topbrent on May 23, 2010, 08:26:00 pm

Here is some Two-Stroke info I found surfing google for 5 minutes.  Compare it to the 5f2a.
http://www.tonecentral.net/gearpics/homebrew/twostroke/

(http://www.kbapps.com/audio/schematics/tubeamps/fender/images/princeton5f2a.gif)

Two-Stroke
(http://www.tonecentral.net/gearpics/homebrew/twostroke/Hunter_Two-Stroke_Schematic_Axeplyr_First_Amp_sm.JPG)
(http://www.tonecentral.net/gearpics/homebrew/twostroke/Hunter_Two_Stroke_Layout-180.JPG)

Title: Re: Anybody built a "Two Stroke" amp?
Post by: sluckey on May 23, 2010, 09:36:37 pm

There's a big error in that 2 stroke schematic. The 5vac rectifier filament cannot be connected to ground. And the HT CT is missing. The layout looks OK.

Title: Re: Anybody built a "Two Stroke" amp?
Post by: FYL on May 24, 2010, 05:32:28 am

Quote

The layout looks OK.

The layo is a scan from Hunter's book.

Title: Re: Anybody built a "Two Stroke" amp?
Post by: tubeswell on May 24, 2010, 05:38:19 am

FWIW I see Angela has put the 2 x 6V6 SE article back on-line

http://angela.com/angelasupersingle-ended6v6guitarampproject.aspx