The Eagle Supre - Big SE Amp

[M Fowler]

That just switches secondary HT 250v or 290v to the tube rectifier socket. Run hard or soft.

Mark

[statorvane]

Is there a technical reason like system noise or other technical strategy to isolate the IEC socket all to itself?

Well, that is the safety ground point for the entire amplifier. I have read where the recommended method to minimize safety ground failure is to dedicate a single attachment point specifically for the safety ground, very close to the IEC socket. Ref here: http://www.aikenamps.com/StarGround.html

The rest of the ground reference points can then be attached as required and will not affect the safety ground.

BTW, I forgot to add that is a great sounding amp there RJ. Sounds a lot more ballsy than my P1 eX.

[HTH]

btw, that switch on the Dr.Z is likely to be a split-load plate switch on the second stage since it's a 'wreck-inspired amp (like the switch on the Komet)

To what post are you responding???

the OP mentions the fast/gradual switch on the Dr.Z 'wreck' earlier in the thread - should've quoted the post I suppose, would've made more sense.

[Zippy]

Ah, I see... Here it is:

I was watching a Dr. Z amp demo where he switches the amp between the "Speed" and "Comfort" settings. The difference is apparently a change in the plate voltage, I suspect accomplished by switching the power tranny secondary windings. I've had folks ask for this option on our Supre amp and it seems so easy to do that I decided to look into it.

about 5 minutes into the video -- http://www.youtube.com/watch?v=TeXVHhN2I-U

"Fast/Gradual" - Komet

"Speed/Comfort" - Dr. Z

Not necessarily the same thing - Mark responded with his take on it. I suspect that may be based on something "known".

Thanks, tho', for helping clear this up. I get very distracted by Stuff. Hmmm, compulsive or obsessive? I dunno. I guess I'll have to get that cleared up as well.

Cheers!

[RJ Guitars]

Is there a technical reason like system noise or other technical strategy to isolate the IEC socket all to itself?

Well, that is the safety ground point for the entire amplifier. I have read where the recommended method to minimize safety ground failure is to dedicate a single attachment point specifically for the safety ground, very close to the IEC socket. Ref here: http://www.aikenamps.com/StarGround.html

The rest of the ground reference points can then be attached as required and will not affect the safety ground.

BTW, I forgot to add that is a great sounding amp there RJ. Sounds a lot more ballsy than my P1 eX.

Thanks Strato. I recently tried an old stock Syvania EL34 and it really brought my Stratocaster to life. That is definitely one of the cool things about these amps, you can play with a wide variety of tubes and hear the differences, some of which are really huge.

I have decided to follow the convention and establish it for myself on the safety ground. One dedicated post for it and tie nothing else to that point.

Even though I was pleased that I was able to get all the hum out of the amp, I have drawn the latest layout using a more pure form of the Merlin ground system, maybe the same as the Aiken system. In this scheme all the components that are fed from a certain B+ node are brought back to ground with the filter cap from that same node. I haven't built it this way so if it's noisy, retreat to layout 1.2, subtle difference.

I started shipping the Supre's out on Saturday and everything should be out to the builders before the end of this next week.

Schematics and layouts are updated on page one.

enjoy!

rj

[RJ Guitars]

Ah, I see... Here it is:

I was watching a Dr. Z amp demo where he switches the amp between the "Speed" and "Comfort" settings. The difference is apparently a change in the plate voltage, I suspect accomplished by switching the power tranny secondary windings. I've had folks ask for this option on our Supre amp and it seems so easy to do that I decided to look into it.

about 5 minutes into the video -- http://www.youtube.com/watch?v=TeXVHhN2I-U

"Fast/Gradual" - Komet

"Speed/Comfort" - Dr. Z

Not necessarily the same thing - Mark responded with his take on it. I suspect that may be based on something "known".

Thanks, tho', for helping clear this up. I get very distracted by Stuff. Hmmm, compulsive or obsessive? I dunno. I guess I'll have to get that cleared up as well.

Cheers!

After the first few of these are done, somebody tell me they can hear a difference in the two settings. I can almost hear it but it seems like it should be huge. Looking forward to a few reports.

rj

[M Fowler]

I have done this switching in two amps and am not going to install in my other builds, not work it to me. Can't hear that much of a change when switching the voltage.

[surfsup]

Something looks familiar! After removing half of the insulation from RJ's house (well packed!) the Eagle Supre has landed near Ohare Airport.

[img600]http://chicagocadcam.com/ChrisHahn/schem/box.jpg[/img]

[surfsup]

ChrisM wrote:
Interesting indeed. I see you have your IEC ground point sharing with some other grounds though.

Chris, I was going to move the system grounds to another lug, but once the amp got quiet I really didn't want to make changes. I know that we refer to the IEC ground is the safety ground for obvious reasons. Is there a technical reason like system noise or other technical strategy to isolate the IEC socket all to itself?

I think I am going to drill a hole for a dedicated IEC right under the jack, I'll leave all the other grounds the way you have them. Might also drill another hole for two more triodes, as gain or maybe a send loop with a couple jack holes on the back. Why not? Rather do it upfront than with stuff in the chassis.

[RJ Guitars]

Something looks familiar! After removing half of the insulation from RJ's house (well packed!) the Eagle Supre has landed near Ohare Airport.

Pleased it made it to you. Look that parts list over and make sure it all got there. There has been a gremlin plaguing my packer lately. I think that old geezer is loosing it... works at half the speed he used to and after all those years of experience he still makes mistakes. He must have a really patient wife!

rj

[M Fowler]

I'd fire him rj,

oh crap you can't fire yourself can you!

Do you even pay the old F**ker '

Mark

[Zippy]

I think I am going to drill a hole for a dedicated IEC right under the jack, I'll leave all the other grounds the way you have them. Might also drill another hole for two more triodes, as gain or maybe a send loop with a couple jack holes on the back. Why not? Rather do it upfront than with stuff in the chassis.

My Supre #2 sprouted another hole in the back panel for a 250K pot wired in series between R10 (NFB resistor) and the output jack. 10K seems to low there and I've never seen a discussion on dialing in the value of that component - seem like this is the place for me to exercise that.

Check also the values of VR1 and VR2 - I think those are switched.

Regarding "more gain" - my Supre #1 is going to be built per schematic, Supre #2 is going to be more tweedy (less tone stack, mo' gain). I'm going to implement a tone "stack" ala 5F3 with the option to lift it's ground with a switch "5F1/5F3".

[RJ Guitars]

Check also the values of VR1 and VR2 - I think those are switched.

I just put the most recent schematic and layout on page one of this thread. The schematic has the pots according to my plan, but that may or not be the final answer.

I was planning 1 Meg for Volume and Treble pots and 250K for Bass, although it is a plan and not an implementation so far.

I don't like the way the Bass control works yet and still prefer the tonestack bypass to any settings with the tone controls. Maybe what your telling me is that the treble pot affects the amount of bass I get and it is the treble pot I should change?

What were your thoughts?

rj

[Zippy]

Check also the values of VR1 and VR2 - I think those are switched.

I was planning 1 Meg for Volume and Treble pots and 250K for Bass, although it is a plan and not an implementation so far.

I don't like the way the Bass control works yet and still prefer the tonestack bypass to any settings with the tone controls. Maybe what your telling me is that the treble pot affects the amount of bass I get and it is the treble pot I should change?

What were your thoughts?

rj

Hmmm, that's a big "Dunno" for me - I don't recall seeing (and you know I'm a schematic junkie) or using that arrangement before. If you don't like what it's doing, I'd suggest swapping them.

[RJ Guitars]

I started with everything at 1 Meg., didn't especially like that. Next I'll try the 250K for the Bass pot... see what happens there. The treble response and volume control are both agreeable to me, just feel like the Bass control leaves a lot of signal behind compared to the bypass tone. It's not entirely clear that I have created the perfect tone stack schematically and also not even guaranteed that I built it like I drew it up... I'll check into that as well.

At risk of repeating myself repeatedly, the best tone for me from this amp is with the tonestack bypassed...

rj