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well dang.......

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Posted on June 19, 2017 at 07:18:29
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 Want to try a push pull design to continue my look into Sakuma's idea of using like tubes to drive like tubes, but so far have not been able to find a PP design that uses 6bq5's for driver and output tubes. Does anyone know if one? I don't think using some other tubes to drive the 6bq5 PP pair would be the same thing.

 

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RE: well dang......., posted on June 19, 2017 at 11:36:57
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 You asked for it. ;>D

Each channel takes 4X EL84/6BQ5 tubes. Pentode LTP feeding PP "finals". Don't forget the CCS load in the LTP's tail.


Eli D.

 

RE: well dang......., posted on June 19, 2017 at 13:23:48
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 Did you include a link Eli? If you did I don't see it.

 

Sure - 4p1L driving 4P1L, posted on June 19, 2017 at 15:15:53
andy evans
Audiophile

Posts: 4378
Joined: October 20, 2000
 You can parallel up the outputs. All filament bias. See Bsrtola Valves website.

 

RE: Sure - 4p1L driving 4P1L, posted on June 19, 2017 at 16:02:13
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 I think you must own stock in the 4P1L tube factory Andy! Got anything for the 6bq5?

 

RE: well dang......., posted on June 19, 2017 at 17:29:41
PakProtector
Audiophile

Posts: 12360
Joined: May 14, 2002
 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.

 

Haven't used indirectly heated tubes for 8 years., posted on June 20, 2017 at 00:39:52
andy evans
Audiophile

Posts: 4378
Joined: October 20, 2000
 I'm strictly DHT. Nothing else does the clarity and timbre for me. So no 6BQ5 - that's history.

 

RE: well dang......., posted on June 20, 2017 at 06:20:16
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 I appreciate the effort, but I am a schematic kind of guy. That is all over my head without one.

 

RE: well dang......., posted on June 20, 2017 at 07:24:00
jyourison
Audiophile

Posts: 279
Location: Wisconsin
Joined: June 20, 2006
 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!

 

RE: well dang......., posted on June 20, 2017 at 09:00:03
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 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.

 

RE: well dang......., posted on June 20, 2017 at 10:40:25
rage
Audiophile

Posts: 792
Joined: December 17, 2010
 vinnie,

are you prepared to build a CCS for the tail of your EL84 phase splitter?

 

RE: well dang......., posted on June 20, 2017 at 12:32:54
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 No, not really.

 

RE: well dang......., posted on June 20, 2017 at 12:42:32
rage
Audiophile

Posts: 792
Joined: December 17, 2010
 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.

 

RE: well dang......., posted on June 20, 2017 at 13:24:54
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 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.

 

RE: well dang......., posted on June 20, 2017 at 14:20:53
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 While am proponent of Ccs ... A transformer phase splitter walks.all over it.
The Mind has No Firewall~ U.S. Army War College.

 

RE: well dang......., posted on June 20, 2017 at 14:22:49
rage
Audiophile

Posts: 792
Joined: December 17, 2010
 what circuit vinnie? are you able to take distortion measurements?

 

RE: well dang......., posted on June 20, 2017 at 14:40:48
PakProtector
Audiophile

Posts: 12360
Joined: May 14, 2002
 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.

 

RE: well dang......., posted on June 20, 2017 at 14:45:55
PakProtector
Audiophile

Posts: 12360
Joined: May 14, 2002
 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.

 

RE: well dang......., posted on June 20, 2017 at 16:49:58
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 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.

 

RE: well dang......., posted on June 20, 2017 at 16:55:41
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 Guys, keep firmly in mind the fact that an interstage trafo inside a NFB loop is a prescription for trouble.


Eli D.

 

RE: well dang......., posted on June 20, 2017 at 17:01:42
PakProtector
Audiophile

Posts: 12360
Joined: May 14, 2002
 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.

 

RE: well dang......., posted on June 20, 2017 at 17:23:13
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 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.

 

RE: well dang......., posted on June 20, 2017 at 18:02:20
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 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.

 

RE: well dang......., posted on June 20, 2017 at 18:05:13
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 At this point I am just trying to get it up and running and listen to it a bit.

 

RE: well dang......., posted on June 21, 2017 at 01:30:11
PakProtector
Audiophile

Posts: 12360
Joined: May 14, 2002
 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.

 

RE: well dang......., posted on June 21, 2017 at 01:53:12
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 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.

 

RE: well dang......., posted on June 21, 2017 at 03:13:59
amnesiac
Audiophile

Posts: 717
Joined: August 21, 2002
 vin he dont use like tubes just likes big tubes and likes to mix them up to taste.

Thorsten's never use any tube twice is something to think about. a little flaw doubled is a bigger flaw.

like Sakuma ,use what you have to hand and try and hear what works.

and be sure you brush paint some real rough art on the front of the case when your done.

personally I get my baby girl to do mine.

oh and mount your paper oil ps caps terminals up. teaches your kids not to touch...

 

RE: well dang......., posted on June 21, 2017 at 03:53:43
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 Not so. Take a look at some of his designs on the web.

 

RE: well dang......., posted on June 21, 2017 at 07:28:17
PakProtector
Audiophile

Posts: 12360
Joined: May 14, 2002
 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.

 

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