The Eagle Supre - Big SE Amp

[surfsup]

I plan for:
- another tube (loop or gain stage)
- NFB like you guys
- conjuntive filter
- Hi/Low voltage switch

ordered parts for if I do the loop already. Got the stuff from one of the latter designs in Merlin's preamp book, I trust it will work (hopefully) but I haven't even started building this amp yet. I will plan a layout and see if I can use the turretboard supplied with RJs kit.

I am still contemplating the tube recto. Wonder how it would work iwth the lower voltage option. I know you guys think its pointless. I have 4 recto tubes here though. I figure maybe I can do a P-P as an option later if i don't like it, but I would need 3novals if I were to keep the loop.

[RJ Guitars]

...I am still contemplating the tube recto. Wonder how it would work iwth the lower voltage option. I know you guys think its pointless. I have 4 recto tubes here though...

A single Ended project like this has several good things that come out of it. One primary driver in working up the original eagle builds was to give new builders a very fundamental build opportunity. Tube rectos don't serve that much purpose in light of the fact that a couple 8 cent diodes can replace them but it's entirely cool to consider how they work and somewhere along the way build at least one amp the old school way. So just for your own education it's probably worth doing.

My best guess is that you won't hear any difference unless it drops the voltage on the preamp tubes way below 90 volts or so. If you decide later to pull it out and recycle components then most of your major parts can be reused anyway.

Looking forward to the build reports...

rj

[Zippy]

- conjuntive filter

What do you hope to gain from that?

[surfsup]

Zippy, it made a big difference on my SE HO. Smoothed the distortion quite a bit. So I am "planning" it as an option but can remove it if it is not necessary.

RJ although I haven't gone through the box doing an inventory check I just want to say to you and anyone reading that you really put in the effort on this and offering up your hardwork at the cost it is available to strangers like me is really appreciated.

Just packaging all this stuff must have taken you forever...and knowing you drilled the chassis by hand that's just a crazy bargain! Thanks again. I look forward to the build as well.

[angelodp]

Hi, I just blew an old 12ax7 on this rig, at least it went very noisy and was picking up rf. Put in a new tube that cleaned up right away but as I check
some voltage readings... 6V6 tube in - 600v secondaries.



heaters 7v?? Merlin indicates up to 6.9v happily. Close enough I guess.

B1 333
B2 270
B3 250

Do these B+ seem ok.

I also discovered that the 100uf 25v is underpowered and it was making weird noises as I chopsticked it. I swapped out for a 47uf 50v which I had on hand and the noises there abated. Not a big change in tone, subtle.
I also ran a separate ground lead from the Power Cathode RC ( 470R/47uf) to ground, that eased a bit more hum out.

best A

[RJ Guitars]

Hi, I just blew an old 12ax7 on this rig, at least it went very noisy and was picking up rf. Put in a new tube that cleaned up right away but as I check
some voltage readings... 6V6 tube in - 600v secondaries.



heaters 7v?? Merlin indicates up to 6.9v happily. Close enough I guess.

B1 333
B2 270
B3 250

Do these B+ seem ok.

I also discovered that the 100uf 25v is underpowered and it was making weird noises as I chopsticked it. I swapped out for a 47uf 50v which I had on hand and the noises there abated. Not a big change in tone, subtle.
I also ran a separate ground lead from the Power Cathode RC ( 470R/47uf) to ground, that eased a bit more hum out.

best A

Ange,

Nothing strikes me as looking way off as far as those voltages. It occurs to me that I have not put together an Excel voltage table. That is something that would be useful. Let us know if it eats another tube, that shouldn't be a regular occurrence. I have pounded mine pretty hard and haven't had any parts failures yet. We are not operating in extreme range for any of the components so I am expecting you just hit a couple bad parts

When you get a chance, measure your voltages across those cathode resistors, that would be interesting to learn where we are on those.

rj

[angelodp]

Ok, my flub. I had a loose 22uf, sitting in the turret but not soldered so that was causing all sorts of guff. Its all good now. I get 14v across that cathode R. The 47uf in place of the 100uf seems fine maybe a bit tighter bass now? I will crank it tomorrow and get a better sense.

Alls well that....

A

[RJ Guitars]

Ok, my flub. I had a loose 22uf, sitting in the turret but not soldered so that was causing all sorts of guff. Its all good now. I get 14v across that cathode R. The 47uf in place of the 100uf seems fine maybe a bit tighter bass now? I will crank it tomorrow and get a better sense.

Alls well that....

A

Good work Ange. I am certain that every honest builder on the forum can relate to the experience. It's always a little easier on you when you find it yourself and it doesn't take too long.

Clips and maybe a photo/video of the finished unit in action when you have time if you can do it...

rj

[angelodp]

Good news. I have a 6L6 in the amp and added the 600v/stndby/480v switch. I also tried a 1M pot on the NFB loop. That 1M is working nicely to bring on some more raunch and drive. The 6L6 adds some headroom and punch. The 600v position is also a nice touch.

BTW hello ZZ top tones

A

[IMG842]http://i260.photobucket.com/albums/ii9/ ... co-NFB.jpg[/img]

[IMG:576:647]http://i260.photobucket.com/albums/ii9/ ... 1/Mcab.jpg[/img]

[angelodp]

Here is another idea. The 1M pot worked well to bring on the raunch, so I tried putting an additional 1M in series and found that drove the distortion and drive even more. So here is the idea, to use a DPDT switch to have the original 1M pot in line with the 10k and dial in what you like, or switch to a fixed 1M in addition to the 1M-10k arrangement.

[IMG1645]http://i260.photobucket.com/albums/ii9/ ... es-3-2.jpg[/img]

[RJ Guitars]

BTW hello ZZ top tones

a har har har...

you might be running some stiff competition with Mark Fowler for "Grampa of the year". I hope I am as cool as you guys when I get to be your age

[Zippy]

Here is another idea. The 1M pot worked well to bring on the raunch, so I tried putting an additional 1M in series and found that drove the distortion and drive even more. So here is the idea, to use a DPDT switch to have the original 1M pot in line with the 10k and dial in what you like, or switch to a fixed 1M in addition to the 1M-10k arrangement.

Now THAT's over the top!

Have you compared it to just opening the NFB loop?

5F1 had no tone stack at all - bypassing the tone stack will bring the next level of raunch. And with all that iron, you should expect to have plenty o' bottom to the sound.

What speaker(s) are you driving?

I've gotta negotiate some private time to finish up my Supre's...

[angelodp]

Yes it is more or less equivalent to the open loop. I am thinking a switch to take the loop out as an option.

I have a rather non-discript 8 ohm that I pulled out of a SS amp. It sounds ok. I have also tied it with a Jensen from my 5E3 which has more high end and sparkle. The best is driving a 4x12 full of Celestions.

The 6L6 is nice in there.

[Colossal]

The best is driving a 4x12 full of Celestions.

Yeah, it's amazing how huge SE amps can sound through a 4x12! What Celestions do you have in your 4x12 Ange?

[angelodp]

Its a pastiche .... 3 celestion 12k-85 ( peavey cab ) and 1 warehouse 65.

I know its not exactly a hero package, but it does crank pretty well.