I have a Pioneer SM-83 power amp and it's a beauty!
I've heard that you can replace the E84L/6BQ5 with 6V6 tubes. Is that true?
If so... for what? What do you get/don't get? What's the difference?
Thanks

ComoEstasAmigo wrote:

I have a Pioneer SM-83 power amp and it's a beauty!
I've heard that you can replace the E84L/6BQ5 with 6V6 tubes. Is that true?
If so... for what? What do you get/don't get? What's the difference?
Thanks

The two tubes are similar in power and load requirements,
and little is to be gained by changing from 6BQ5 to 6V6.
The 6V6 need octal sockets, which are larger and difficult to fit into a
chassis
with holes fitted with small 9 pin sockets.

I'd leave the amp alone, grab a beer from the fridge, sit back
and enjoy the music.

Patrick Turner.

ComoEstasAmigo wrote in message ...
I have a Pioneer SM-83 power amp and it's a beauty!
I've heard that you can replace the E84L/6BQ5 with 6V6 tubes. Is that true?
If so... for what? What do you get/don't get? What's the difference?
Thanks

If you go to Duncan's Tube Amp Pages at

http://tdsl.duncanamps.com/

You can download a great program that will give you tube
substitutions. But to answer yr question, no. Try a 6P15 or CV8069.

For 6V6's you can sub a 5871 or a 6AY5, among others. As it turns out,
6V6's are cheaper than most of the substitute tubes.

Different tubes -- as well as different brands of tubes -- will give
you different performance/sounds. Do google searches on the tubes and
you'll likely pull up dozens of postings offering various opinions on
the matter.

By the way, it's EL84. The E84L is also a tube, with slightly
different specs than the EL84.

Chris Grier wrote:

By the way, it's EL84. The E84L is also a tube, with slightly
different specs than the EL84.

The EL84 and E84L are the same basic tube. The difference is the
E84L is a "premium" tube. It uses more pure materials, gold plated
pins, and is supposed to last longer. Every E84L I have found in
old equipment was dead or dying, so I can't really comment on the
longer life thing.

The same numbering convention exists with all of the European numbered
tubes. For example:

ECC83 is the regular tube, E83CC is the premium tube.

This is not to say that there is always a premium version of each
tube.

In the US numbering method, the premium tubes got a 6000's series
number, and were known as 10,000 hour tubes, or something like that.

-Chuck

OBTW,

"E" means 6V
"C" means triode
"CC" means triode,triode
"L" means beam power tube, or pentode
....

The numbers are a sequence number indicating order of registration.

Say you have an EL84 PP amp - plenty about (I have one) As we've said, 6V6 is
octal so we don't want to drill out the chassis. The cute question is
therefore, is there a noval triode that uses about 45mA and gives you more than
a trioded EL84 itself? I haven't found one. Plenty of lower power options -
6EW7 and all the dissimilar triodes, 12B4 etc etc. My christmas present would
be a nine pin triode that gives me even 8 watts per channel in PP!

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Andy Evans wrote:

Say you have an EL84 PP amp - plenty about (I have one) As we've said, 6V6 is
octal so we don't want to drill out the chassis. The cute question is
therefore, is there a noval triode that uses about 45mA and gives you more than
a trioded EL84 itself? I haven't found one. Plenty of lower power options -
6EW7 and all the dissimilar triodes, 12B4 etc etc. My christmas present would
be a nine pin triode that gives me even 8 watts per channel in PP!

The problem is going to be idle dissipation limits.
6BQ5 in pentode or UL can be set up with 12 watts of Pd
in each tube, from which 8.4 watts of pure class A can be had.
maybe 15 watts of class AB are doable, but the Pd needs to be kept
at around 9 watts per tube.
The class efficiency is 35%, and class AB up to 65%,
but for triode you about halve the figures, anf 5 watts from 6BQ5
is all you'll get.

There are no ninepin minis that do any better than a 6BQ5,
and I'd suggest just optimising the topology would work better
than replacing the tubes to get more PO.

But I once bought some OPTs suited to ECL86/6GW8,
and I used 6CM5 with the same plate current, but in triode,
with the same Ia as the maximum that would have been used for 6GW8.
I get 8 watts class A, with 22 watts class AB max.
6FW5 are the same tube, but these are octals.
Leak 20 could sustain the same mod, to get better performance.

Patrick Turner.



=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

I used 6CM5 with the same plate current, but in triode,with the same Ia as the
maximum that would have been used for 6GW8.I get 8 watts class A, with 22 watts
class AB max. 6FW5 are the same tube, but these are octals.

These are all octals, I think. Bigger bases are a different game. Surely
there's no noval triodes? I'm mainly thinking damping factor since I have zero
global feedack in my Leak, as you know. Cheers, Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Andy Evans wrote:

I used 6CM5 with the same plate current, but in triode,with the same Ia as the
maximum that would have been used for 6GW8.I get 8 watts class A, with 22 watts
class AB max. 6FW5 are the same tube, but these are octals.

These are all octals, I think. Bigger bases are a different game. Surely
there's no noval triodes? I'm mainly thinking damping factor since I have zero
global feedack in my Leak, as you know. Cheers, Andy

Maybe there are triodes which might fit, but they may not suit the loads.
To get 10 watts in triode from EL84, use a quad of tubes.
There is a Manley amp which makes 25 watts from a quad I think, but
it uses very high Ea, and is mainly class B.

For 10 watts class A triode, you need to dissipate 40 watts
of power at idle, and there is no escape from this rule.

6CM5/6FW5 have triode efficiency higher than many other triodes,
because the Ra is only 600 ohms along the Eg1 = 0v line,
and you get a decent voltage swing without using classAB2 operation.
And you only need 375v Ea plate voltage, but you will need
-60v fixed grid bias, and a decent driver stage.
The 6FW5 is little known, but identical to the 6CM5 but with no top cap.
Its a beautiful beam tetrode which is great in triode.
( I won't charge you for this secret info, and don't you tell anyone, you hear )

My "junkbox" triode amp is at
http://www.turneraudio.com.au/webpic...ab400w317h.jpg

Patrick Turner.



=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

On Thu, 18 Dec 2003 22:02:06 +1100, the highly esteemed ComoEstasAmigo
enlightened us with these pearls of wisdom:

I have a Pioneer SM-83 power amp and it's a beauty! I've heard that you
can replace the E84L/6BQ5 with 6V6 tubes. Is that true? If so... for what?
What do you get/don't get? What's the difference? Thanks

Well, they will sound different. One substantial difference is the
sensitivity of the 6BQ5 vs. the 6V6. The 6V6 is less sensitive, having
1/2 to 1/3 the transconductance of the 6BQ5/EL84. This means it
will require more bias voltage (necessitating a change in the cathode
bias resistors), more drive voltage (the amp probably has more than
enough extra drive voltage available) and changes to the feedback
resistors (to maintain the same feedback with the lower gain of the
6V6 - you don't HAVE to do this though). The gain of the amplifier
will be lower than with the 6BQ5s.

I don't see anything to be gained by such a switch. I would reccomend
making sure it is in good shape (no leaky caps or off-spec components)
make sure it has good tubes and run it...
--
Greg

--The software said it requires Win2000 or better, so I installed Linux.

(Chris Grier) wrote in
om:

By the way, it's EL84. The E84L is also a tube, with slightly
different specs than the EL84.


Thanks for the info, but I assure you the tubes say quite clearly E84L
Siemens!

The 6FW5 is little known, but identical to the 6CM5 but with no top cap.
Its a beautiful beam tetrode which is great in triode.
( I won't charge you for this secret info, and don't you tell anyone, you hear
)


Patrick - on your advice I bought 16. you're right - I'm going to use them for
another amp with octal sockets. Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

In message , Andy Evans
writes
Say you have an EL84 PP amp - plenty about (I have one) As we've said, 6V6 is
octal so we don't want to drill out the chassis. The cute question is
therefore, is there a noval triode that uses about 45mA and gives you more than
a trioded EL84 itself? I haven't found one. Plenty of lower power options -
6EW7 and all the dissimilar triodes, 12B4 etc etc. My christmas present would
be a nine pin triode that gives me even 8 watts per channel in PP!

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

How about using a couple of 7233s ?

(Need a low Z output transformer though, and a B+ of about 160V.)
--
Chris Morriss

How about using a couple of 7233s ?

Nice idea for another project, but I'm stuck with my Leak ST20 right now -
wondered what would go in that! Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.