Hi All

Can anyone direct me towards a good, tried and tested EL84 PP schematic for
my stereo project. I'd like the newsgroups opinion and consider all options
before I warm up my soldering bolt.

Thnx
John McNairn

http://www.quadesl.com/schematics.shtml

Scroll down to the heading "Fisher SA-16 Amp". You're there.

Jim

Fox wrote:
Hi All

Can anyone direct me towards a good, tried and tested EL84 PP schematic for
my stereo project. I'd like the newsgroups opinion and consider all options
before I warm up my soldering bolt.

Thnx
John McNairn

I've always liked the Dynaco ST35 circuit (see
http://www.triodeel.com/dynast35.gif). Simple as a hammer. You can
substitute 12AX7s and 12AU7s for the 7247s.

Pete Reese

The reprinted GEC and Philips books offered by reprint vendors contain
nice ones and companies like Sowter make the specified OPTs. However
you may want to rethink the EL84 as a hi-fi amplifier tube. They are
NOT usually hi-fi, precisely why they work great for guitar amps.

EL84 may not be the best tube for hi-fi, but I will never forget the
night about 10 years ago when I broke out my 1968 vintage SCA35 and
subbed it for my transistor amp. The sound was so good I thought I
had gone mad. Any serious listening since has involved glass. (Makes
it kind of hard to listen to the Bose systems built into my Corvette.)

Pete Reese

"Fox" wrote in message
...
Hi All

Can anyone direct me towards a good, tried and tested EL84 PP
schematic for
my stereo project. I'd like the newsgroups opinion and consider all
options
before I warm up my soldering bolt.

Thnx
John McNairn


Take a look at the "Mullard 5-10" design from the 1960's. I built two
of them (both UL versions.) Here's a URL:
http://www.bonavolta.ch/hobby/en/audio/el84_7.htm
Cheers,
Roger

Thnx for all responses, much appreciated :-)

cheers
Fox

wrote:

EL84 may not be the best tube for hi-fi, but I will never forget the
night about 10 years ago when I broke out my 1968 vintage SCA35 and
subbed it for my transistor amp. The sound was so good I thought I
had gone mad. Any serious listening since has involved glass. (Makes
it kind of hard to listen to the Bose systems built into my Corvette.)

Pete Reese

A pair of EL84 can only make about 9 watts of class A pentode
audio, and so due to the miserly amount of power,
how could such be clasified as hi-fi when used with modern speakers?
And the Dn is all odd order.

Usually, 20 dB of NFB will make the pentode amp
much more acceptable, and in class AB1, with 700v on the anode,
350v on the screens, 36 watts is available, mostly class B.
I measured this in a Musical Reference amp 3 years ago, during a service,
and it was classed as a hi-fi amp, with a lotta FB.
There is a 200mA fuse from the CT of the CFB winding to ground,
just in case there is bias failure.
The amp had been running fine for 7 years until some clown
place a 2 amp fuse in there and maladjusted the bias.


Baird get 60 watts from a six pack of EL84, UL, fixed bias,
and it is hi-fi, definately.
Leak get about 12 watts class AB1 in the Leak 20, and these are also
regarded as hi-fi,
or at least certainly were when most speakers of 1960 were designed to make

a huge amount of sound from only one lousy watt.

Anyway, I like the 6BQ5/EL84 used as a hi-fi tube;
it sure qualifies as one afaiac; just use enough of them,
and preferably in UL, or even better with CFB like Quad II.
A quad of EL84 with CFB make a very nice 20 watts......

Patrick Turner.

Hi

The EL84 was my choice of tube mainly because I have a dozen or so kicking
around and I've always wanted to use the EL84s in a hifi. My first repair
job on an EL84 circuit was an old VOX AC30 bass amp (strangely enuff it had
a top boost circuit), once it was revamped it sounded great. I actually made
a guitar amp using a quartet of EL84 but I only had a 420 volt OT, this
stressed the tubes too much and I had to switch to EL34s; the tubes have sat
in a drawer ever since. Also I dont need a high powered amp, 10 watts will
be more than enuff :-)
I'm looking forward to the sound. thnx for your input :-)

Cheers
Fox

"Patrick Turner" wrote in message
...


wrote:

EL84 may not be the best tube for hi-fi, but I will never forget the
night about 10 years ago when I broke out my 1968 vintage SCA35 and
subbed it for my transistor amp. The sound was so good I thought I
had gone mad. Any serious listening since has involved glass. (Makes
it kind of hard to listen to the Bose systems built into my Corvette.)

Pete Reese

A pair of EL84 can only make about 9 watts of class A pentode
audio, and so due to the miserly amount of power,
how could such be clasified as hi-fi when used with modern speakers?
And the Dn is all odd order.

Usually, 20 dB of NFB will make the pentode amp
much more acceptable, and in class AB1, with 700v on the anode,
350v on the screens, 36 watts is available, mostly class B.
I measured this in a Musical Reference amp 3 years ago, during a service,
and it was classed as a hi-fi amp, with a lotta FB.
There is a 200mA fuse from the CT of the CFB winding to ground,
just in case there is bias failure.
The amp had been running fine for 7 years until some clown
place a 2 amp fuse in there and maladjusted the bias.


Baird get 60 watts from a six pack of EL84, UL, fixed bias,
and it is hi-fi, definately.
Leak get about 12 watts class AB1 in the Leak 20, and these are also
regarded as hi-fi,
or at least certainly were when most speakers of 1960 were designed to
make

a huge amount of sound from only one lousy watt.

Anyway, I like the 6BQ5/EL84 used as a hi-fi tube;
it sure qualifies as one afaiac; just use enough of them,
and preferably in UL, or even better with CFB like Quad II.
A quad of EL84 with CFB make a very nice 20 watts......

Patrick Turner.

On Thu, 10 Mar 2005 21:11:07 +0000, Fox wrote:

Hi All

Can anyone direct me towards a good, tried and tested EL84 PP schematic
for my stereo project. I'd like the newsgroups opinion and consider all
options before I warm up my soldering bolt.


If you fancy something a bit different, this looks interesting:
http://diyparadise.com/simpleel84.html
Might be worth an experiment.


--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk