A good sounding EL34 PP sch please - Page 2

vinylkid58 · 26th August 2011, 09:09 PM

Quote:

Originally Posted by woodturner-fran

toroidal output iron is the kind..... and I don't have other spec's than the fact that they were used for EL34s. I suppose I could also put in KT66s or maybe even KT88, but I thought KT88 would need a bit higher B+ (+ more heater)

Maybe give one of the KT88 PP blocks a try. It's a big thread thou:

"Mullard 5-20 KT88 PP blocks!

jeff

tinitus · 26th August 2011, 09:25 PM

Quote:

Originally Posted by woodturner-fran

I've got about 500V of B+ to play with, .....

Fran

from what I have read, some older EL34, and it equivalents, takes the higher voltage better than new ones
and also better than KT88
don't much about tho

Bas Horneman · 26th August 2011, 09:41 PM

How about PP2C? Designed by the late Allen Wright. He used to mail (the schematic) it to everyone who asked him for it.

Or the PP1C which uses EL34. Later on Allen added as CCS in the output stages as well. Apperently with positive results.

woodturner-fran · 26th August 2011, 11:55 PM

The PP2C looks interesting indeed.... I've gone back to ask about the impedance of the OPT, but given as it was made especially for a PP EL34, I'm guessing that the impedance should be about right.

Many thanks for all the suggestions so far!! Is there a thread somewhere about the PP2C? - a search didn't throw up anything...

Fran

planet10 · 27th August 2011, 12:21 AM

PP2C was originally developed for an ST70 donor. Issues may be providing sufficient heater current (but this amp really deserves an indendent heater supply) and a shunt reg is mandatory on top of the cascode LTP.

My buddy is building one of these and i am gathering parts for an EL84 derivative.

dave

cjkpkg · 27th August 2011, 11:25 AM

Here is another one from tubecad journal

I have built the PPEL84 circuit in this post and it is a terrific amp...I have plans to build this EL34 amp someday....

woodturner-fran · 27th August 2011, 12:04 PM

Hi cjkpkg,

I can't believe you posted that!! I also built that EL84 amp - its a stunning amp!! Thats the one I'll build - nice winter project!

Thanks a mill for the heads up and everyones suggestions!

Fran

cjkpkg · 01:14 PM

Yes indeed...the EL84 amp is quite a nice little setup. I may start collecting my iron for this one as well. I have been wanting to build a higher power tube power amp in a more contemporary enclosure chassis. Like a HiFi2000 3U if it could fit or maybe a 4U if height dictates. The P2P + EL34 height will dictate that. A hammond 10X12 bottom plate should work nicely with a few bends in it....

Power Xformer
OPT's

cjkpkg · 27th August 2011, 02:16 PM

I would also like to experiment with an LED bias scheme for the first triode input in lieu of the cathode resistor. This worked wonders on the EL84 amp.

Another interesting approach would be a CCS on the EL34's. I am running 80mA per channel on an LM317 on the EL84 as well.

boywonder · 27th August 2011, 02:17 PM

There's also Poinz' 6GK5/EL34 Music Machine. Triode, Fixed bias, CCS under the LTP, very straightforward design...about 12-14W or so.

The power supply in my MM is a fairly conventional CLC.....

Required OT impendance is 5K.

27th August 2011, 12:21 AM	#15
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5	PP2C was originally developed for an ST70 donor. Issues may be providing sufficient heater current (but this amp really deserves an indendent heater supply) and a shunt reg is mandatory on top of the cascode LTP. My buddy is building one of these and i am gathering parts for an EL84 derivative. dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

27th August 2011, 01:09 PM	#18
cjkpkg diyAudio Member Join Date: Aug 2008 Location: Roswell GA	Yes indeed...the EL84 amp is quite a nice little setup. I may start collecting my iron for this one as well. I have been wanting to build a higher power tube power amp in a more contemporary enclosure chassis. Like a HiFi2000 3U if it could fit or maybe a 4U if height dictates. The P2P + EL34 height will dictate that. A hammond 10X12 bottom plate should work nicely with a few bends in it.... Power Xformer OPT's Last edited by cjkpkg; 27th August 2011 at 01:14 PM.

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26th August 2011, 11:55 PM	#14
woodturner-fran diyAudio Member Join Date: Jan 2006 Location: Ireland	The PP2C looks interesting indeed.... I've gone back to ask about the impedance of the OPT, but given as it was made especially for a PP EL34, I'm guessing that the impedance should be about right. Many thanks for all the suggestions so far!! Is there a thread somewhere about the PP2C? - a search didn't throw up anything... Fran

27th August 2011, 11:25 AM	#16
cjkpkg diyAudio Member Join Date: Aug 2008 Location: Roswell GA	Here is another one from tubecad journal I have built the PPEL84 circuit in this post and it is a terrific amp...I have plans to build this EL34 amp someday....

27th August 2011, 12:04 PM	#17
woodturner-fran diyAudio Member Join Date: Jan 2006 Location: Ireland	Hi cjkpkg, I can't believe you posted that!! I also built that EL84 amp - its a stunning amp!! Thats the one I'll build - nice winter project! Thanks a mill for the heads up and everyones suggestions! Fran

27th August 2011, 02:16 PM	#19
cjkpkg diyAudio Member Join Date: Aug 2008 Location: Roswell GA	I would also like to experiment with an LED bias scheme for the first triode input in lieu of the cathode resistor. This worked wonders on the EL84 amp. Another interesting approach would be a CCS on the EL34's. I am running 80mA per channel on an LM317 on the EL84 as well.