Low Wattage Fire fly type amps

[jojokeo]

Well, that's the million-dollar question. Possibly nothing at couple-watt levels will truly sound/feel like playing at 30-100w levels. Hopefully it sounds good-enough to be workable.

I've built a number of various lo-watt amps and it sort of depends what actual wattage is right for which kind of amp you have in mind. My firecracker (baby Marshall/firefly-ish) sounds, plays, and feels not so good using a weak little 12au7 (just not enough zip) but put a 12bh7 in there and it's perfect at about 2watts. With an ECC99 it's a bit louder at 3 or 31/2watts but still with everything else still being right. You don't have to play it full-up utilizing the entire 2 to 3 watts either to get the mojo factor going. (Maybe using a 12au7 needs to have only a 6" speaker to be the ticket for something that low/small?) If not making a higher gainer like the Firefly and you like that power tube crunchiness at a lower level then I'd suggest using a pentode preamp tube w/ a gain control and you can use a variety of "power tubes" such as 1.2w 6ak6, 1.3w 6an5, 1.4w 6am5 types. But they just aren't quite enough to get your juices flowing if using "cleaner Fender or Vox-ish type" preamps - I have to play it pretty much all the way up to get things ok but still isn't quite there. So in another low watt class "cleaner-type" amp and using preamp triodes I like these for "power tubes"; a 3w el95/6dl5, 3.5w 6ar5, or 4.5w 6aq5/6005 and this amp sounds great which ever is in there AND you don't have to turn it up fully to get things sounding, playing, and feeling right. But you need those extra few watts for a reasonable level cleaner tone and feel. I normally just use the 6aq5 and play it about half way up or so.

Hope this helps and gives you some ideas to consider-


Edit- I moved this from HBP's thread on 2x12" cab in speakers topic.   Brad Willabe

[Willabe]

What OT did you use with what Z primary with what tubes?

Do you try some, most, all these tubes?

And what different speaker(s) did you try with these amps? 1x8", 1x10", 1x12", 2x10"?


                  Brad     
 

[Jack_Hester]

There's been discussion over on the Harmony site, from time to time, about modifying small Harmony amps, to do a little something more than clean.  Your Firecracker may be one such mod that can be made.  Most of the little Harmony amps are point-to-point, and the discussion is mostly about building from scratch.  Have you posted your Firecracker at any time?  I've seen the FireFly.  How close is yours to that?  Thanks.
 
Jack

[Ritchie200]

I've built several iterations of the Firefly/Firecracker and other single ended amps.  One of the big complaints about these amps is the single ended fizz these tubes seem to generate when pushed.  I would have to agree that I am not a fan and the conjunctive filters just take too much life out of the end result.  You mentioned going smaller with the speakers to drive them harder.  I've found the opposite to be true.  A Firefly through a low wattage 15" sounds quite nice.  I even built one in an old Crate bass amp with the original 12" bass speaker rated for 100w and that sounded good too.  I have not tried some of the tubes you mentioned, but maybe try a larger speaker, you may be surprised.

JMHO
Jim

[jazbo8]

+1 Small amp + big speakers is the way to go, I tried 8" (unknown brand), 10" (Raging Cajun) and 12" (Jensen) with my 3Watter, the 12" definitely sounded better, next up 2 x 12" 


Check out this demo, JTM1 with 2 x 12".

Marshall JTM1 demo

[jojokeo]

Wow, my bad for not seeing this sooner. I play mine with an 8" Vox bulldog speaker but have used others too. No real good reason other than I only have so much space and the chassis fits the cab more proportionally, not because it sounds the best this way. Under it I usually plug into a 10" Celestion Vintage 30 or 60w? which sounds fine and I have used 12" speakers many times with it too. Yes, bigger speakers usually sound better with smaller powered amps or rather they help the smaller amp to sound larger & fuller. It doesn't seem to have the hash Jim speaks of? I used the suggested and expensive Hammond universal OT 125A I think is the model number if memory serves? It's wired up at around 20k-24k primary z. I straight sub the 12bh7a & ECC99 and don't really use 12au7s in it but can straight sub that one in too. I can also slightly modify the cathode resistor to bias the ECC99 a bit more but it's really not all that necessary.
Hmm, we used to have a tab where we could post our amp porn err builds but I can't seem to find it now since the site's changed? Not sure if I posted it, but I thought I did maybe even with a sound sample?