The Eagle Supre - Big SE Amp

[RJ Guitars]

Hello TAG members,

From a previous effort http://ampgarage.com/forum/viewtopic.php?t=13407 we have evolved a project with the involvement of several contributors to build a large single ended amp. It is still evolving so many of the specifics remain to be nailed down and many of them won't ever be static. We started with the old champ 5F1 schematic but have added a tonestack so it's probably closer to one of the later iterations. It is a combo as drawn but could be built as a head for those with that inclination.

I will try to keep the schematic and layout documentation here on page one to make it easy to find them. I won't try too hard to keep up on all the variations and iterations that other folks come up with but they can post them up as we go.

I verified with the machine shop today that we are in the queue for the CNC machine starting tomorrow. Hopefully we'll have chassis ready to go soon. I also got a note from Edcor indicating the transformers have shipped. There will be a mix of Edcor and Heyboer transformers available from me and always the option of sourcing them elsewhere.

Thanks for all the encouragement on this project. We are just about ready to get going here and it should be fun,

rj

[mcrracer]

Thanks ...subscribed

[gktamps]

Thanks to RJ and to all who have been contributing to this project - you are awesome!
Cheers,
GKT

[patrick620]

I will enjoy seeing how this evolves.

[showsii]

I'm in.

I read through the other posts of the other thread and as a new comer I am excited to join everyone in this build!

Ian

[dartanion]

Are you sure you're going to have enough gain in the preamp for a TB tone stack? Also, I think NFB on a switch or pot would be a good idea. Otherwise this is just an EL34 Champ, which is cool. I have built a couple of these and the non NFB ones were my favorites. A tweed princeton tone controls works well with this circuit.

Another source for transformers for this project would be from Allen Amps. TP25 PT and TO11C OT. His are all made by Heyboer.

Have fun with the project.

[Alexo]

Might you want to up the cathode bypass cap on the power tube to a 50-volter?

[RJ Guitars]

Thanks for the notes. I think many of these things will be implemented and you'll see several iterations. In the case of undersized components, they will definitely be changed.

I picked up the chassis yesterday. I have nine of them in this first batch. If that isn't enough, we'll make more.

I was thinking about ordering a KT-90 tube. If anyone wants one of these, let me know and I'll order a couple extra and pass them on at cost... I think they are almost $40 each.

rj

[mcrracer]

Has anyone built this one yet? How did the tone stack work out? Enough gain?
Thanks

[RJ Guitars]

MC - I haven't built this yet but it is really getting close to the Blackface Champ at this point so it should be a reasonable expectation for the tone stack to work well. One thing I will probably do is reduce the dropping string resistance to something closer to the Blackface specs. that should give it a little extra punch. Also, I might advocate the use of a 12BZ7 over the 12AX7. This might give you that little extra if you are looking for it. There is also room for another preamp tube if the single tube is just not enough. Could go with a cathode follower or maybe do some tube paralleling.

On another note - Half of the Edcor trannies arrived today, they look great and they are quite beefy as well. They fit the chassis holes correctly so I am pleased.

rj

[ToneMerc]

Thanks for the notes. I think many of these things will be implemented and you'll see several iterations.

rj

I like your big Heyboer 25W OT, I think it will be the ticket for JJ 6V6's. I think I 'm going to do a Supre Eagle harp tuned with parallel 6v6's and dual cathodes.

TM

[RJ Guitars]

... I think I 'm going to do a Supre Eagle harp tuned with parallel 6v6's and dual cathodes.

TM

This will be interesting to follow. Will you use different cathode resistor and capacitor values on each 6V6? This might also leave the option open to chose a EL-34 or different Octal output tube in the 2nd hole for added complex flavor.

Have you mentioned your power tranny specifications? Looks like a stout unit for sure.

rj

[ToneMerc]

... I think I 'm going to do a Supre Eagle harp tuned with parallel 6v6's and dual cathodes.

TM

This will be interesting to follow. Will you use different cathode resistor and capacitor values on each 6V6? This might also leave the option open to chose a EL-34 or different Octal output tube in the 2nd hole for added complex flavor.

Have you mentioned your power tranny specifications? Looks like a stout unit for sure.

rj

RJ,
no plans for different cathodes resistor/cap combinations, although that might be kind of cool.

It's one I had Heyboer make me I my quest to get 150mA HT on a Champ PT frame. Obviously, it didn't happen. Alden said he had a frame that could work with just about anything I needed. I ordered this one wrong, as I should have ordered as 250mA instead of 150mA. So, it's a bit heavy on the filament winding for couple small bulb tubes.

360@150mA
5V@ 3.5A
6.3@ 4.5A

TM

[ToneMerc]

... I think I 'm going to do a Supre Eagle harp tuned with parallel 6v6's and dual cathodes.

TM

This will be interesting to follow. Will you use different cathode resistor and capacitor values on each 6V6?

rj

RJ, it will be a modified version of this layout, most like with adjustable cathode bias.

TM

[RJ Guitars]

Edit - April 22 - I reverse imaged the layout and posted drawings that agree with the "as built" unit.

Things have begun to take shape a bit more. I just sent the cabinet specs to my cabinet guy for an estimate. I'm not going to try to make the reverse image this time, that was really a pain for such a small number of amps. In this case, the chassis and the head cabinet is identical for either tubes up or tubes down orientation. I went ultra simple on cabinet design and I can share the design specs with you if they aren't already obvious. I have ask the cab guy to create the cabs as DIY parts out of pine. Everything will be cut and prepped for the complete build, you supply the glue, clamps, precision, and elbow grease to finish them up. The combo has a cutout for a single 12 and I did not do any calculations so keep you expectations low and you won't be disappointed.

looking forward to the the upcoming festivities.

rj

PS - there hasn't been a huge interest in the cabinets but I'll tell you all more about them anyway. I talked with the cabinet builder today about having these available as a drop ship item. That avoids me as the middle man in the shipping process adding unwanted extra shipping costs to the equations. The combo cabinet in the DIY format is $99 which includes all the cleats and is ready for you to clamp and glue. The combo in the glued and assembled ready to sand and finish state is $120. For the head cabinet it will be $72 for the DIY version made up of 3/4" pine box parts, dove tailed; backs & cleats or head cabinet is $90 ready to sand and finish. the cab builder is a pro and makes first class stuff.