Looking for a new amp to build

[rutledj]

I'd like to build a low wattage amp and I'm hoping some of you could offer some suggestions. I built a Princeton clone but was less than thrilled with the tone. I'm leaning toward a Dr. Z Mini although I've never heard one in person, just the youtube clips.

Any suggestions?

Thanks,
rut

[j-po]

Since you are looking for a low wattage amp I suppose you want PA distortion. Take your favorite classic amp that relies on PA distortion for its sound but use smaller output tubes like EL95, EL91, ECL86 or whatever, you may want to select tubes that have a similar power dissipation ratio between plates/screens as your original amp. Anyway, make sure you don't hit the grids with too high PI output or it will not sound much like the original. Compare bias voltages. If the original is biased at say 40v and yours is running at 10v you want only a quarter drive from the PI. Increase the tail resistor and/or split the plates.

You can use a strings of zeners going to the screens and OT center tap to lower the power tube voltage while preserving preamp voltages. The smaller tubes can't take your regular 500v.
The speaker may not sound quite the same as when driven to the max by a more powerful amp. Still a couple of watts will be loud enough to damage your hearing. Good luck.

[harryk]

If you are after power tube distortion, you can build a little bigger tube amp and add a VVR (Variable Voltage Regulator/Reducer) to it. VVR is pretty simple to add to a cathode biased amp. If you do not want to build it yourself, you can buy a VVR kit from Dana Hall alias UR12 here in forum. I have assembled many VVR kits to different tube amps with success. With a VVR you can reduce noise level to a bedroom level if wanted and still get power tube distortion. I think that Dana`s webpages are www.hallamplification.com. My friend just built a Matchless Lightning with a VVR and it sounds cool with it. Harry

[10thTx]

I built a 7-9 watt 56T which is my version of DaGeezer's HoSo56 which is loosely modeled after a SoHo65.

However, I use 6BM8 pentode (only) in my amp and added reverb. It sounds excellent to me. With 9 watts and VVR, you can get some pretty remarkable overdrive at low volumes. There is a sound sample here:

http://www.soundclick.com/player/single ... i&newref=1

http://www.soundclick.com/player/single ... i&newref=1

(you may get a pop up asking if you want the window to close, if you hit
"no" - it should play) The recording was done at a very low volume using the VVR less than TV listening volume. No effects pedals used and only some delay added to the mix.

You can find a schematic and layout here:
http://s28.photobucket.com/albums/c216/ ... 56TVVR.gif

There is a picture of the amp here but I changed the controls after wiring the amp into the 56T.

http://s28.photobucket.com/albums/c216/ ... mbopic.jpg

With respect, 10thtx

[rutledj]

Thanks. Unfortunately I already have a small combo cab that I wanted to use that will only contain circuitry for about a 5w amp. It currently has a tube rectifier, 12ax7, and 6v6. Volume,Tone knob and 10" weber blue dog alnico spkr and is built quite a lot like your cab (mahogany).

I'd like to reuse this if possible. I also have the vvr board but have never used it in anything.

Rut

[tubeswell]

What is the PT rated for? Have you thought about running a different output tube and rectumfrier in there (just for the sake of experiment) before you pull it to bits? (I say now's the time to let loose with some 'mods' before you undo it)

[10thTx]

Well, that info changes the options.

What about something like this:

https://tubeamparchive.com/viewtopic.php?t=9958

If you did not want the overdrive just build the clean channel.

With respect, 10thtx

[rutledj]

What is the PT rated for? Have you thought about running a different output tube and rectumfrier in there (just for the sake of experiment) before you pull it to bits? (I say now's the time to let loose with some 'mods' before you undo it)

It uses a Hammond 270ex PT and Hammond 125ese OT. Ckt is basically a princeton 5d2 ckt http://www.ampwares.com/schematics/princeton_5d2.pdf

I don't really get any dirt with the ckt. Looking for something with more character that will fit in the 6 x 10 enclosure I have.

Rut

[ChrisM]

http://www.geofex.com/FX_images/humfree2.gif

Perfect ABY box for switching between two amps.

[M Fowler]

Well to keep with what you already have how about the Super Champs or the two I attached.

Mark

[tubeswell]

What is the PT rated for? Have you thought about running a different output tube and rectumfrier in there (just for the sake of experiment) before you pull it to bits? (I say now's the time to let loose with some 'mods' before you undo it)

It uses a Hammond 270ex PT and Hammond 125ese OT. Ckt is basically a princeton 5d2 ckt http://www.ampwares.com/schematics/princeton_5d2.pdf

That PT is 275-0-275, and it has plenty of current capability, but even with a 5AR4 rectifier you'll only get to 350B+, which should be fine for driving a 6V6. However, you could drive a 6L6 at about 390V B+ if you used SS rectification and a ~120mA choke (in place of teh 470R resistor) in a CLC filter (i.e.; instead of the CRC filter). The OT would handle that, and it would saturate better, and have less noise floor. And that would boost the power to about 8-9W for minimal extra outlay. 2CW

Another option might be to try a 5AR4 in there with your 6V6 running at about 360V, and using a 40-50mA choke (in place of the 470R resistor) in a CLC filter, and going up to 60uF on the reservoir cap (instead of 8uF).

[azatplayer]

Well to keep with what you already have how about the Super Champs or the two I attached.

Mark

I built this champ ultra circuit, and it is pretty darn nice. The trem is great. Definitely worth trying first, you may love it. You can get some dirt from it too easily enough if needed.