1W woes - anyone spent time on this before?

[johnnyreece]

If you want a clean triode amp that isn't real loud, try something like this. Preamp of your choice, just not high gain. You might want to back down the PT voltage a bit. I've got mine running on the edge of 450V, the max for 6SN7. I'm thinking 400-ish B+ would be good. I built this because I wanted to find a use the that 460-460 PT I had on the bone pile.

I'm attempting a similar project, although I'm thinking of using the second triode of the 6SL7. Thank for posting this!

[Phil_S]

If you want a clean triode amp that isn't real loud, try something like this. Preamp of your choice, just not high gain. You might want to back down the PT voltage a bit. I've got mine running on the edge of 450V, the max for 6SN7. I'm thinking 400-ish B+ would be good. I built this because I wanted to find a use the that 460-460 PT I had on the bone pile.

I'm attempting a similar project, although I'm thinking of using the second triode of the 6SL7. Thank for posting this!

Don't waste a dual triode for the concertina. I actually built it with a 6AQ7, which is a tube you can probably buy for $3 or less.

Apologies to the OP for the minor hijack.

[Tillydog]

Did you try the Ruby zener clamp?

Yes, I did, and it helped, but not enough that I was happy with it (and I experimented with different zener voltages).

[johnnyreece]

If you want a clean triode amp that isn't real loud, try something like this. Preamp of your choice, just not high gain. You might want to back down the PT voltage a bit. I've got mine running on the edge of 450V, the max for 6SN7. I'm thinking 400-ish B+ would be good. I built this because I wanted to find a use the that 460-460 PT I had on the bone pile.

I'm attempting a similar project, although I'm thinking of using the second triode of the 6SL7. Thank for posting this!

Don't waste a dual triode for the concertina. I actually built it with a 6AQ7, which is a tube you can probably buy for $3 or less.

Apologies to the OP for the minor hijack.

Hah, sorry...it's similar mostly with power section. The preamp is going to be something of an 18W Lite style, with dual 6SL7's. Hopefully.

Thanks for the tube tip, though! Being budget-minded never hurts!

[Milkmansound]

after another few days of futzing I think I am finally narrowing in on a design

first of all - I gave up on getting a thick distortion from the dual triode. Just never going to sound good. I tried a few different OTs, voltages, bias settings… the best thing sound wise was to keep it conservative and let the amp remain mostly clean with just a *slight* breakup on 10.

second thing I did was stick to a single triode preamp design with a cathode follower before the output tube. This really helps the amp handle pedals better. With a boost pedal and my trusty old Blues Driver I can get a really great distortion tone from the mini amp

third - if you don't have an efficient speaker, this is not going to be loud enough for you! An 8ohm Jensen MOD ate most of the power while my Jupiter C12 large magnet just brings the whole thing to life.

I ended up jacking the voltages back up to 350 and sticking to 12AX7s for both stages. The amp seems to sound best that way. This means 250VCT into a bridge rectifier with no center tap.

The last thing I did was add a "buffered" line output on a switched jack between the gain stage and the output tube (pre EQ). This way the amp can be used as a preamp, boost, or whatever if the 1W output is not necessary.

I will draw up a schematic and share it when I am sure this will work for me

[Cantplay]

Have you considered using 6922 or 6n1p as power tube?

John

[Milkmansound]

Here is where I am at now

The amp has become something pretty useful and cool - the CF helped. I changed it over to an AC coupled CF to take advantage of the volume and treble for preamp functionality

This is great fun with pedals - the amp will breakup on its own but just barely - not enough to make it too fizzy sounding. Also, the buffered output can be used to drive long cables or as a preamp. My goal is to make this thing as useful as possible - here is a very quick and hopefully not too wrong schematic:

[IMG768]http://i896.photobucket.com/albums/ac167/milkmansound/c96b82e2-653f-404a-a1e8-4c7b6cc83f74_zpsa6a77247.jpg[/img]

For someone with a lot of pedals, this can be used either at the back end as a practice amp or at the front end as a driver.

[andrew]

This looks fun
http://www.solorb.com/elect/musiccirc/f ... index.html

[johnnyreece]

Sorry to pull this out of the past, but I finished my low-watt amp yesterday, and have the same fizzy action on my distortion as well. I had the Ruby Zener trick mentioned to me as a potential fix: http://www.paulamps.com/18watterbuzz.ht ... Distortion

I've not picked up any parts yet, but I know you were fighting this, as well. Hope it helps (if you're still interested)!

[stephenl]

I've been meaning to try out this low watt approach for a while. I think its about 1/2 watt max output. It's from Richard Keuhnal's Ampbook site.

[stephenl]

I've been meaning to try out this low watt approach for a while. I think its about 1/2 watt max output. It's from Richard Keuhnal's Ampbook site.

[stephenl]

I've been meaning to try out this low watt approach for a while. I think its about 1/2 watt max output. It's from Richard Keuhnal's Ampbook site.

[stephenl]

From Richard Keuhnal's Ampbook site. 1/2 watt max output. I haven't gotten around to building it yet.

[billc]

A couple of thoughts on the distortion and design....I had a similar weird distortion on an amp I built and it turned out to be a cold solder joint, FWIW I had recently reached an age where I needed reading glasses and had built without them so I did not spot the bad joint
On the output stage it might be worth experimenting with a grid stopper resistor on one (or maybe both?) of the output triodes, I recently built a GA-9 and it has a 470 ohm resistor on one of the parallel 6V6 grids. I don't entirely understand the theory but there is a good page on it at http://www.valvewizard.co.uk/gridstopper.html