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In Reply to: RE: well dang....... posted by vinnie2 on June 19, 2017 at 13:23:48
Get for an OPT one with screen taps around 20%. Hook the LTP plate loads to the g2 taps for plate-to-grid around the finals. Try B+ around 280V, and g2 of the input tubes around 100V with 8k plate loads. Idle current for the LTP around 35 mA or so. By pass their g2 to the cathode node, not ground.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Follow Ups:
I appreciate the effort, but I am a schematic kind of guy. That is all over my head without one.
You've built a few amps by now. Time to take a dive into design. You can do it!
Sketch what Pak Protector described and use the basic layout of the CCS from Eli's El Cheapo. The power supply won't be much different from other supplies you've built, at least not in overall principles. Throw the sketch up for us to see and we can help you in the next phase to make it work.
Go for it, Vinnie!
here it is, done for 6AU6's. Circuit topology is the same, and I will help you with values...:)
http://audiokarma.org/forums/index.php?threads/e-linear-from-a-dynaco-st-70.647808/
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Thanks for the schematic. I am currently breadboarding another I found this afternoon using a 12at7 to drive the 6bq5's, so I will see how that goes and go from there. Thanks again.
I have another simple one channel design that I just found I will try first. If that doesn't work I will give your suggestion a try. I just want to see if I can hear a difference between PP & SE with using like tubes. I am actually more into breadboarding and listening to different designs than doing the designing myself. There are about a gazillion designs out there already, and most of them are most likely better than anything I am likely to come up with. Thanks for the tip.
vinnie,
are you prepared to build a CCS for the tail of your EL84 phase splitter?
No, not really.
you are going to get poor balance without one. you may as well hang up the idea if you aren't willing to work with a CCS.....the inbalance will color the sound to much and not give a good representation of PP vs SE.
I don't think there is a cookie cutter EL84 driving EL84 push pull schematic out there for you... you may get away with an EL84 driver into an inter stage transformer.
While am proponent of Ccs ... A transformer phase splitter walks.all over it.
The Mind has No Firewall~ U.S. Army War College.
IDK about that...LOL As a matter of fact I come to the opposite conclusion. What TX's in particular are you using? I might have to try them.
Cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Magnequest... Cheap won't do in this position.
I don't like interstages but perhaps that mantra is correct "good ones won't do... You need great ones"
The Mind has No Firewall~ U.S. Army War College.
err...not just whose, but which one?
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
EXO 173... That was it's only real purpose. Phase splitter... With 180 degrees and er , no phase shift.
The Mind has No Firewall~ U.S. Army War College.
That one I am intimately familiar with. While I discovered it can test well, I was not fond of its sonics( in any of implementation ), especially in favour of a LTP riding a CCS.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Understood, preferences are as multi-faceted as light through a prism.
A very close friend has owned Wilson Watt 7's for years and I never liked them as much as normal Khorns. Polite, clean, accurate.
No jump factor.
The Mind has No Firewall~ U.S. Army War College.
Guys, keep firmly in mind the fact that an interstage trafo inside a NFB loop is a prescription for trouble.
Eli D.
I have grid chokes in the last two 'ground up' E-Linear builds...:)
Have to get some for the next time I go playing with my W6m's too, along with a lower voltage power trans. Going to take B+ beneath 400V on that one.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
I am breadboarding a 12at7 driving el84's in PP right now just to see how the PP compares to the SE. No CCS required. I may not go any further than that with the PP design. Depends on what I hear.
Edits: 06/20/17 06/20/17
what circuit vinnie? are you able to take distortion measurements?
At this point I am just trying to get it up and running and listen to it a bit.
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