Hurricane Day- Time for another amp...

[DougH]

With a free day off thanks to Fay, I thought it was time to build another amp... It's not as ambitious as it sounds. When I built the Dragonfly, I initially prototyped it using my old Firefly chassis and transformer set. I figured it was time to button it back up since the Dragonfly is done. So I figured what the heck, let's have some fun, and I did this:

http://www.aronnelson.com/gallery/main.php/v/DougH/amp/chime/

The photo is just the old Firefly photo. New photos and clips to come (especially if I get tomorrow off too! )

[drk]

looking forward to it 

btw, hurricanes?? i dont have that here 

[petemoore]

  That looks beautiful, you have a 220k between B3 and V1a.
  Small blurb here about the output tube:
 
  http://thetubestore.com/teslaecc99.html
  Data sheet link...interesting tube, cool application Doug !
  I love a nicely tweeked out [as opposed to just 'up'] amplifier, especially the dinky tube ones, that way you can actually 'use' the tubes.
  V1 in basically all my amps has been a swap from stock 12ax7 / shown resistor values, to reduced V1 gain.

[DougH]

btw, hurricanes?? i dont have that here

Actually it's just a tropical storm. Thanks for the comments.

That looks beautiful, you have a 220k between B3 and V1a.

Thanks Pete! I was genuinely surprised how good it sounded when I first plugged in. It's a nice complement to the Dragonfly, which is more of a "mini TW Rocket" kind of thing. That sucker has so much gain and is a great lead amp,  but this one has so much headroom and the cleans are really nice. Yes, it has the 220k like a typical Top Boost preamp. But you got me thinking... I may try a 100K there (and double up the 500p coupling cap) to give it even more headroom, given that it's such a nice "clean machine". This amp is going to get a lot of gig time- it's the perfect volume for mic-ing and low stage volume. And I've plugged my pedal board in and it works great with lots of "augmentation" too.

[John Lyons]

Look cool doug. Is it pretty much clean to mild break up all the way with that one?
Did you ever post the Dragonfly schematic?


john

[Ben N]

I like the mosfet follower. Since RG posted the Heresy article, I think that is the first posted design that I saw it incorporated in. I think thisis a must-build. The Firefly was a little too "intense" for me.

[DougH]

I added a clip in the layout folder. There's also a clip of it with the phase 90 in my phaser folder.

[Ben N]

Real nice! I think your Vox fascination is a good thing for all, Doug.

[fpaul]

Oh, great.  I was getting ready to build a Firefly, NOW I have to decide if I'd rather build THIS!  That's the problem with our society, too many choices.

Just kidding, Thanks for sharing.

[DougH]

Real nice! I think your Vox fascination is a good thing for all, Doug.

Thanks!

The other day I was thinking I'd like a cleaner amp. My tube amps are fairly gainy in a vintage way. I like Fender cleans but the mid scoop drives me nuts sometimes. What I like about the Vox clean sound is there is still some midrange which helps it in a mix. And the highs sound kind of "airy" to me, for lack of a better word. For whatever reason I've always favored the Vox/Marshall sound over the Fender and others.

[DougH]

Oh, great.  I was getting ready to build a Firefly, NOW I have to decide if I'd rather build THIS! 

Some of the ax84 folks are using ECC99's for the power stage. It's a much better sounding tube, the 12au7 sounds like toy in comparison. It's a direct sub and if you like it you can bias it hotter than a 12au7 too.

[DougH]

I just uploaded a new schematic.There were some typos in the output stage that I corrected.

There are a couple little tweaks I'm finalizing right now- stay tuned...

[Dragonfly]

When I built the Dragonfly....

I always thought I was found under a rock in the woods, like a normal boy....now you're telling me that I'm an android ??!?!?!?!? 

[DougH]

Bwahahaha!

[DougH]

Just uploaded a schematic update. This should be it (I put it back together and it's off my bench... haha... ).

I changed 2 things:

1) Added a Zobel network to the output transformer secondary to kill some of the high freq harshness of the 125a. This may not be needed with a better transformer.

2) Reduced the phase inverter tail resistor from 47k to 15k. This keeps the PI from clipping as soon, reducing PI compression and it hits the output stage with a hotter signal for slightly more volume and a "bigger" sound.

I'll do some more clips when I get a chance.