The Eagle Supre - Big SE Amp

[RJ Guitars]

mrvfr - I sent an email note out to you earlier this evening - punching an extra hole is easy enough if you want to go with the side by side swap option. I've also made up octal to 9-pin adapter plugs that work well. Part of the coolness of the single ended cathode biased output section is that you have a lot of tube options... add EL84 and or parallel and that would give you just about all the 31 flavors.

[mrvfr]

Thanks guys - I gotta read my "tube amps 101" and practice soldering a bit before the kit arrives first.

[Berger]

mrvfr - glad to see someone else getting ready for the kit. Also VERY cool idea about having it use a el84 tube


A couple updates from me. I finally dug out merlin's preamp book and my datasheets and did the appropriate load lines for the 6ac10 tube. I hooked up the tube with the extra triode after the tone stack, and just got a bunch of blocking distortion and oscillations. So I tore everything apart...

Last night I thought about having the extra triode first. So I re-wired it and put a 1M pot in between it and the second stage. At certain points in the pots turn I still got blocking distortion,etc But for most of it. I got a really nice distortion out of it. I comparing it to the normal 12ax7 I really like the changes.

So now I'm debating of removing the pot and just putting in resistors as fixed values...I also may try some of the tricks to remove the blocking distortion if possible...

Added is a post f my "flying" potentiometer its seeting on the rubber foot and then electrical taped to it so it can turn.

Aaron

[rogb]

You could punch the EL84 power tube socket and wire it so you can switch between 6V6 or EL84 or (both parallel power tubes).

Interesting, I know the little Cornford has an octal/noval switch.
In my 86 Special I am forever swapping EL84 and 6V6 in and out. Have you got a switch layout that could be used for this at all? I have looked before but found nothing. Thanks.

edit: I found this on the web which looks interesting. You would need to go to standby first of course before switching!

[Berger]

Interesting rogb, thanks for finding that!

I might look at that as well. having a el84 would be a great option!

[M Fowler]

Or the blend control like in the Egnator Rebel amps which uses a four gang pot, to mix the output tubes. But you would only need a dual gang pot.

[Berger]

Or the blend control like in the Egnator Rebel amps which uses a four gang pot, to mix the output tubes. But you would only need a dual gang pot.

Any idea what the watt rating would have to be on the pot?

Also in the above image the el84 is missing its cathode resistor is it not?

[ChrisM]

Or the blend control like in the Egnator Rebel amps which uses a four gang pot, to mix the output tubes. But you would only need a dual gang pot.

Any idea what the watt rating would have to be on the pot?

Also in the above image the el84 is missing its cathode resistor is it not?

Pot power rating does not matter in this situation. It's just handling the signal levels not a DC voltage or a HV for that matter.

[rogb]

Or the blend control like in the Egnator Rebel amps which uses a four gang pot, to mix the output tubes. But you would only need a dual gang pot.

Any idea what the watt rating would have to be on the pot?

Also in the above image the el84 is missing its cathode resistor is it not?

Don't think that matters as the schematic only highlights the switching of the grid and the plate on each tube.

[rogb]

Or the blend control like in the Egnator Rebel amps which uses a four gang pot, to mix the output tubes. But you would only need a dual gang pot.

Does the Rebel blend the grid and plates in the same way as the switch shows? I can't find a schematic for it.

[ChrisM]

Or the blend control like in the Egnator Rebel amps which uses a four gang pot, to mix the output tubes. But you would only need a dual gang pot.

Does the Rebel blend the grid and plates in the same way as the switch shows? I can't find a schematic for it.

Just the grids

It's basically two MV's acting in opposite to each other.

[rogb]

Or the blend control like in the Egnator Rebel amps which uses a four gang pot, to mix the output tubes. But you would only need a dual gang pot.

Does the Rebel blend the grid and plates in the same way as the switch shows? I can't find a schematic for it.

Just the grids

It's basically two MV's acting in opposite to each other.

Ahh thanks Chris, I can picture that perfectly now.

[rogb]

You could punch the EL84 power tube socket and wire it so you can switch between 6V6 or EL84 or (both parallel power tubes).

Interesting, I know the little Cornford has an octal/noval switch.
In my 86 Special I am forever swapping EL84 and 6V6 in and out. Have you got a switch layout that could be used for this at all? I have looked before but found nothing. Thanks.

edit: I found this on the web which looks interesting. You would need to go to standby first of course before switching!

I have just fitted the grid/plate changeover switch and it has been working fine for an hour, changing over from el84 to JJ6v6 every now and again. Trannys are running cool and even with 160mA HT and mains fusing, no problems so far. I'm happy with this mod

[Berger]

You could punch the EL84 power tube socket and wire it so you can switch between 6V6 or EL84 or (both parallel power tubes).

Interesting, I know the little Cornford has an octal/noval switch.
In my 86 Special I am forever swapping EL84 and 6V6 in and out. Have you got a switch layout that could be used for this at all? I have looked before but found nothing. Thanks.

edit: I found this on the web which looks interesting. You would need to go to standby first of course before switching!

I have just fitted the grid/plate changeover switch and it has been working fine for an hour, changing over from el84 to JJ6v6 every now and again. Trannys are running cool and even with 160mA HT and mains fusing, no problems so far. I'm happy with this mod

Sweet! Could you post of pic of it wired up? I'm interesting in seeing it.

Aaron

[rogb]

Interesting, I know the little Cornford has an octal/noval switch.
In my 86 Special I am forever swapping EL84 and 6V6 in and out. Have you got a switch layout that could be used for this at all? I have looked before but found nothing. Thanks.

edit: I found this on the web which looks interesting. You would need to go to standby first of course before switching!

I have just fitted the grid/plate changeover switch and it has been working fine for an hour, changing over from el84 to JJ6v6 every now and again. Trannys are running cool and even with 160mA HT and mains fusing, no problems so far. I'm happy with this mod

Sweet! Could you post of pic of it wired up? I'm interesting in seeing it.

Aaron

I could but the switch is right underneath the rear panel switches mounted next to and forward of the el84 socket in a very tight build, heater wires overhead too.
It would be hard to see anything constructive. On this little baby 12" chassis, I have MV, VVR, pre-amp volume, HRM, PAB, mid-boost, to name a few
To say it is crowded is an understatement, it only fitted in because I removed a bias pot and test points that were there unused.
I can describe the wiring exactly for you on the DPDT switch:

Center poles: the wire to the OT and the wire to pin 2 of the el84 from the plate of v1b or v2 via 280K resistor.

EL84 poles: pin 2 and 7
6V6 poles: pin 5 and 3

It's as easy as that, just make sure you have enough juice in your PT for the extra tube's heater etc