Who has a really LOW wattage tube amp?

The little ~1W cigarette pack amps will drive a 4x12 quite nicely.

The sensitivity ratings for speakers are derived by driving the speaker with a 1W pure sine wave signal and measuring the SPL with a calibrated microphone mounted 1M in front of the speaker mounted in a baffle, on the center line of the speaker. Considering that the sensitivity levels for guitar amp speakers run from about 92 to 104 dB, that 1W can make a good bit of sound.

As for low power amp kits and designs, look here: http://ax84.com/?pg=projects

Under "Legacy Projects" you'll find the Firefly.

Under "Core Projects," they now have the AX-84 amps split up into modular preamp and power amp designs. Under power amps there's a 2W push-pull one.

Thanks for that, Rico. I didn't know the sensitivity ratings were based on a 1w signal. That's interesting, and helpful. So a 2w amp through a fairly efficient speaker might be ... loud!

Yes, the Doberman kits (from AX84.com projects) are ones that I've seen. Also looking at Guytronix, who has one that's supposed to be more Vox-like, which is something I'd like. (And he's local. :D )

I have a 1W Hughes & Kettner Cream Machine (driven by 12AX7 tube). It's more than enough to give good bedroom volume and a healthy lot of distortion (depending on the 12A?7 tube that is in the preamp stage) - I'm using a 12AT7 (pre) and a 12AX7 ("power").
There's some nice 1/2W stuff from Z-Vex, if I'm not mistaken.

AC/DC AM table radios of the miniature "All American Five" tube variety, with a 50C5 output tube, put out about 150 mW if I'm not mistaken. They usually have a dinky little speaker in the 3-4" range, and still can get pretty loud.

Nope, my memory's failing. I looked it up. Typical operation figures for output range from 1.9 to 2.3W for a 50C5 running on 110-120V. Pretty loud anyway, with those dinky inefficient little speakers.

Maybe one of these days I'll get around to building a little guitar amp (not AC/DC, due to the "hot chassis" issues) with the output stage modeled on that. I'm sure it's been done.

I think that might be the tube used in the Silvertone amp-in-case models.

Running an EL84 on a low plate and screen voltage around 110V would give similar results. Those tubes are still in production, a big advantage, though 50C5s are still common.

The problem with that little Z-vex amp is the subminiature tube it uses, which is out of production and not all that common.

I have a 1W Hughes & Kettner Cream Machine (driven by 12AX7 tube). It's more than enough to give good bedroom volume and a healthy lot of distortion (depending on the 12A?7 tube that is in the preamp stage) - I'm using a 12AT7 (pre) and a 12AX7 ("power").

How do you like it? I sometimes see these or some of the other small H&K amps like the Blues Master for sale at a not too large price. Worth it is a small practice amp? How about as a booster / overdrive?

Thanks.

Greybeard: how is the clean tone on the H&K?

Rico: yeah tearing apart a tube radio and making a guitar amp would be fun if I had any idea what I was doing. :wink: A prefab unit, or a kit with very specific instructions is more up my alley.

Looked up the Z-Vex and that tube situation scares me; the company has a whole web page devoted to changing the tubes. Looks like work.

Also the smaller Guytronix has an odd 6N1P tube in the power stage. Anyone familiar with it?

6N1P info: http://en.wikipedia.org/wiki/6N1P

Hi Mitch,

Probably you know this site: http://www.amptone.com/#lowwattamps

I have a bumbox (there's supposed to be an umlaut over the u, pronounce it "boombox") Lead 1 that is a 1W amp that's supposed to have a Marshall-ish sound. To me it sounds fairly along the lines of a JCM900. It uses the aforementioned 6n1p for the power tube. I play it through a 12" cab, and even at 1W, it can be pretty loud. Clean tones aren't anything to brag about though, but it does a pretty nice AC/DC crunch.

TZ

Thanks for the help guys!

LOL at "bumbox." That does look very cool though.

Probably leaning toward the Guytronix with the 1/2-watt to 2 watt converter. A little Voxkiller.

Now I need to think about the right speaker to match it to... Maybe the Weber Blue Pup if I use my little 10" cab ... or maybe something bigger ... :)

Lovepedal makes a 1/2 Watt amp in low gain and ultra high gain versions.

I've had it tied up to a 12" Fane speaker (the real, built in Barnsley Fane) and the clean is pretty good. I took out the 12AX7 from the pre-amp stage, because there was too little clean for me, the 12AT7 is better, but could be improved even more with a 12AU7 or 12AY7.

There is still a good amount of everdrive/distortion, even with the 12AT7.

For home practice it's ideal.

My lil Vox DA5 goes down to .5w, but is SS.

I have a Bumbox "Sally", a 1w amp that uses a 12AX7 as it's output tube. The guy who makes Bumbox amps doesn't do these anymore, his lineup has changed since I got mine. I run it through a 10" speaker and it's pretty loud but can be kept down to reasonable levels.

It's a good little amp but a real one trick pony. Does a great '70's lead crunch. No clean tone to speak of.