Reply
 
Thread Tools Display Modes
  #1   Report Post  
Jim Stewart
 
Posts: n/a
Default "matched" tubes on ebay

This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?
  #2   Report Post  
arizona cowboy
 
Posts: n/a
Default

tube matching is the source of a lot of controversy

you can match tubes on transconductance, plate current, or several other
factors

there are even well respected experts who feel that the best sound comes
from tube pairs that are somewhat un-matched (R.G. Keen, for example)

JJ/Tesla tubes are a best buy, but I would also say that SED "winged C"
sound as good or better, and are just as good of a buy, perhaps even a
better choice.

I recommend you test the tubes you already have on a calibrated
transconductance tube tester i.e. Hickok, TV-7D/U, etc.

the ones already in there may be better made and better sounding than
anything you can buy new, if they are not worn out

don't worry if they are not "matched", or of different manufacture, as long
as they are similar in their transconductance characteristics and condition,
they will be great

tube "matching" is way overrated

tube biasing is what you want to worry about!
now that IS important!

PS - examine the tubes carefully, the best tubes typically have welded
(soldered) plates, and opposed to stapled plates
if you can determine the original country of origin, that is another good
indicator
my order of preference - britain, germany, russia, czech republic,
yugoslavia (avoid usa and chinese EL34)


"Jim Stewart" wrote in message
...
This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?



  #3   Report Post  
Chris Hornbeck
 
Posts: n/a
Default

On Mon, 25 Oct 2004 17:40:45 -0400, "arizona cowboy"
wrote:

lots of solid advice snipped for bandwidth

(avoid usa and chinese EL34)


The Chinese part is obvious, but the USA part may seem
strange. But it's good advice for use in lots of antique
amplifiers. The American 6CA7's seem to motorboat in
bone stock, up to speed, all good stock values, machines.
FWIW.

Chris Hornbeck
  #4   Report Post  
Lord Valve
 
Posts: n/a
Default



Jim Stewart wrote:

This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?



I have what you need.


Lord Valve
Tone Chaperone

VISIT MY WEBSITE: http://www.nebsnow.com/LordValve
I specialize in top quality HAND SELECTED NOS and
current-production vacuum tubes for guitar and
bass amps. Good prices, fast service.
QSC amps, RNC compressors, lots of other good stuff!

Partial Client List: * Derek Trucks/Allman Brothers Band *
* Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling *
* Rob Hyckys (guitarist for Commander Cody) * Waky Amps *
* Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Dale Bruning *
* Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps *
* Jim Kelley * Balls Amplification * Roccaforte Amplifiers *
* Gerhart Amplification * Aiken Amplification * The Right Half of AGA *
* Lots More *

NBS Electronics, 230 South Broadway, Denver, CO 80209-1510
Phone orders/tech support after 1:30 PM Denver time at 303-778-1156

- Our 23rd Year -

VISA - MASTERCARD - PAYPAL

Philo T. Farnsworth sez, "Vacuum tubes kick major ass.
Be a MAN...and buy some TODAY!"

  #5   Report Post  
Fabio Berutti
 
Posts: n/a
Default

Tubes need to be matched only when used in push-pull pairs as in the Dyna;
ideally, they should have same characteristics in terms of both

- quiescent current at the working point, in order to balance DC flow
through the output transformer, thus reducing iron core saturation and
improving bandwidth
- transconductance (gain), because each tube amplifies only half wave,
therefore, should one have higher gain, the resulting amplified wave would
have one half "bigger" than the other - distortion is produced.

In real world, the first issue is not a problem at least within +/- 10%
because OPTs are designed to handle some DC unbalance without problems and
the second is neither too IF the amp has some feedback (like the Dyna) and
the 2 tubes are not widely different.
Ordinary "shop matched" tubes, sold by any reputable supplier, are usually
tested on a good, tuned transconductance tube tester and sorted to much
closer tolerances than it was done 40 years ago, when the Dyna was
produced., therefore they will work perfectly (provided that they're
correctly biased, ie. the amp's circuitry is properly working).
Get a quartet of JJs or Svetlanas "winged C" as You prefer, they both
provide top quality @ fair price.

Ciao

Fabio


"Jim Stewart" ha scritto nel messaggio
...
This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?





  #6   Report Post  
Lou deGonzague
 
Posts: n/a
Default

LV, I didn't see any links to what you offer or pricing? Or do you email for
a price and availability?
"Lord Valve" wrote in message
...


Jim Stewart wrote:

This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?



I have what you need.


Lord Valve
Tone Chaperone

VISIT MY WEBSITE: http://www.nebsnow.com/LordValve
I specialize in top quality HAND SELECTED NOS and
current-production vacuum tubes for guitar and
bass amps. Good prices, fast service.
QSC amps, RNC compressors, lots of other good stuff!

Partial Client List: * Derek Trucks/Allman Brothers Band *
* Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling *
* Rob Hyckys (guitarist for Commander Cody) * Waky Amps *
* Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Dale Bruning *
* Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps *
* Jim Kelley * Balls Amplification * Roccaforte Amplifiers *
* Gerhart Amplification * Aiken Amplification * The Right Half of AGA *
* Lots More *

NBS Electronics, 230 South Broadway, Denver, CO 80209-1510
Phone orders/tech support after 1:30 PM Denver time at 303-778-1156

- Our 23rd Year -

VISA - MASTERCARD - PAYPAL

Philo T. Farnsworth sez, "Vacuum tubes kick major ass.
Be a MAN...and buy some TODAY!"



  #7   Report Post  
Jim Stewart
 
Posts: n/a
Default

Lord Valve wrote:

Jim Stewart wrote:


This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?




I have what you need.


Maybe you could tell us what equipment you use
and how you match your tubes and how much they
cost.

Lord Valve


Massive sigvertizement snipped..
  #8   Report Post  
arizona cowboy
 
Posts: n/a
Default


"Lou deGonzague" wrote in message
...
LV, I didn't see any links to what you offer or pricing? Or do you email
for
a price and availability?



be very careful of this Lord Valve person, while he knows a fair amount from
a technical standpoint, he also has a checkered past of steering folks into
the brands of tubes that have the highest profit margin for him, rather than
the tubes that have the best tone for the same amount of dough.

my recommendation for a source would be Ned Carlson, of Triode Electronics,
same tubes that Lord Valve has available, a bit cheaper than LV, and far
more important, Ned will recommend tubes based on sound, and not let greed
cloud his objectivity. He is also a hilarious, beer swilling, crazy
mexican-food-chompin real Chicago old-school guy, reminds me of John Belushi
a little bit. And no one has been selling tubes and Dynaco upgrades longer,
that I can think of.

here is the link to Ned's Triode Electronics site (one of America's largest
tube stores and a treasure trove of free technical info)
http://store.yahoo.com/triodeel/index.html


  #9   Report Post  
Lord Valve
 
Posts: n/a
Default

Yeah, I'll send you a catalog if you request it. (6 catalogs, actually...
one for power tubes, one for rectifier tubes, one for preamp tubes,
one for parts, one for Caig Labs doctor juices, and one for QSC amps.)

LV



Lou deGonzague wrote:

LV, I didn't see any links to what you offer or pricing? Or do you email for
a price and availability?
"Lord Valve" wrote in message
...


Jim Stewart wrote:

This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?



I have what you need.


Lord Valve
Tone Chaperone

VISIT MY WEBSITE: http://www.nebsnow.com/LordValve
I specialize in top quality HAND SELECTED NOS and
current-production vacuum tubes for guitar and
bass amps. Good prices, fast service.
QSC amps, RNC compressors, lots of other good stuff!

Partial Client List: * Derek Trucks/Allman Brothers Band *
* Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling *
* Rob Hyckys (guitarist for Commander Cody) * Waky Amps *
* Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Dale Bruning *
* Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps *
* Jim Kelley * Balls Amplification * Roccaforte Amplifiers *
* Gerhart Amplification * Aiken Amplification * The Right Half of AGA *
* Lots More *

NBS Electronics, 230 South Broadway, Denver, CO 80209-1510
Phone orders/tech support after 1:30 PM Denver time at 303-778-1156

- Our 23rd Year -

VISA - MASTERCARD - PAYPAL

Philo T. Farnsworth sez, "Vacuum tubes kick major ass.
Be a MAN...and buy some TODAY!"




  #10   Report Post  
Lord Valve
 
Posts: n/a
Default



Jim Stewart wrote:

Lord Valve wrote:

Jim Stewart wrote:


This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?




I have what you need.


Maybe you could tell us what equipment you use


I built all of it myself.

and how you match your tubes


Really friggin' close.

and how much they
cost.


Not all that much.

Those folks listed in my sigfile know how good they are.
If you'd like to hear for yourself, just listen to the radio...
there'll be some of mine on in a bit.

LV




  #11   Report Post  
Lord Valve
 
Posts: n/a
Default



arizona cowboy wrote:

"Lou deGonzague" wrote in message
...
LV, I didn't see any links to what you offer or pricing? Or do you email
for
a price and availability?


be very careful of this Lord Valve person, while he knows a fair amount from
a technical standpoint, he also has a checkered past of steering folks into
the brands of tubes that have the highest profit margin for him, rather than
the tubes that have the best tone for the same amount of dough.


You're a liar. In fact, let's see you prove *anything* you've said..

These folks -

Partial Client List: * Derek Trucks/Allman Brothers Band *
* Meatloaf * Catherine Wheel * Yo La Tengo * Let's Go Bowling *
* Fleetwood Mac * Tyrin Benoit * Eugene Fodor * Roccaforte Amplifiers *
*Rob Hykys (guitarist for Commander Cody)
* Komet Amplification * Dr. Z * Maven Peal * Blockhead Amps *
* Jim Kelley * Balls Amplification * Dale Bruning *
* Gerhart Amplfiers * The Right Half of AGA * Lots More *

....would be fairly hard to fool. You, sir, are a dumpster-diver and
a know-nothing. Go hustle your moldy **** on e-bay and leave
the real stuff to the pros.

Lord Valve
Expert





  #12   Report Post  
Patrick Turner
 
Posts: n/a
Default



Wbittle wrote:

Hi,
I have used Sovtek, Tesla, and Svetlana and all work well. The
problem with matched sets is how long they were 'burned in' prior to the
final testing stage for matching. What you really want in an ST70 to
preserve sonic balance channel to channel is a matched quartet of
EL34's. Personally, I'd read the seller's feedback and see what others
think of his items. If the seller has mostly all excellent feedback,
then chances are he is a pretty square shooter. But if you see a lot of
neutrals or negatives, be careful. Also, if this amp was recovered from
a dumpster chances are it is in need of an electronic restoration before
it will ever sound correct or be reliable. ST70's are great power amps.
I have one myself. But my amp is totally refurbished. You would not
believe the difference in sound when you change out certain old
components which have drifted in value.
There is no way to know for sure that tubes balanced with a tester
will in fact perform as a matched set in an actual circuit. So, although
the set you buy could have been picked, tested and packed as a matched
set. That is no guarantee that they will remain that way. I have a set
of four EL84's in a Scott 222C that I matched out of 12 tubes and they
have remained close for over three years. I have a set of Sovtek 7591's
that remained matched for about 3 months of use then drifted apart in
value. I had to remove them and recheck them then do my best to pair
them off in reasonably matched pairs. There is no way the seller could
have known this would happen.
BIll B.



All tubes drift apart after they have been supplied matched.
But the ones that were not matched stay well apart forever,
or they only drift together accidently.

In the last pair of Quad II amps which I re-furbished, the thd in signal
at listening levels could be drastically reduced by swapping the
positions of the output tubes and input EF86 around for the lowest measured
thd.
In one position, thd could be 15 dB higher than the other, mainly 2H.
The tubes involved in the samples I refurbished were probably not well
matched.

With guitar amps, I doubt matching the tubes for the same signal
transconductance
at the same idle current would make much difference, and I doubt you'd
notice it when listening
to the radio, as Mr Valve suggests.
I haven't a clue how Mr Valve matches his valves, and although he is quick
to say he does a great job,
he leaves me completely uninformed about how he does it,
and I remain very unlikely to go to him for matched tubes.
Sure there are lots of musos who like his services, but musos mostly know
sweet ****
all about technical aspects of their amplifiers, so any muso recommendations

can only mean sfa to me.

What may be more important for guitar amp tubes is that they have equal idle
currents
at a given grid voltage. Having equal transconductance does not always mean
an equal
grid bias voltage will produce the same idle current.

A small number of tubes would need the same bias voltage applied, *and* have
the same
transconductance with signal.
If this is the case, these tubes are truly matched.

In amps with more than two output tubes, the tubes can be swapped around so
the
transconductance, Gm, of each 1/2 of the tubes on each side of the PP
circuit
do total to give very nearly equal Gm for each 1/2, and the thd will then be
lowest
when the tubes re biased individually for equal idle current.

To set up for lowest thd at listening levels for hi-fi amps takes time and
patience,
and a thd meter and volt meter. Sorry, but its all rather fiddly and
difficult.

95% of musos just buy tubes, plug them in and use them. Some bother to
adjust the bias,
or *balance* the bias via the pot at the back of their amps,
and this minimises the hum caused unequal bias currents in a pair of output
tubes
fed from a PS where there is a lot of hum at the CT, which is a feature of
so many guitar amps;
they have attrociously noisy PS compared to hi-fi amps.
And it was compounded somewhat by the practice of Fender et all to supply
export
model amps without the LC filter following the resevoir capacitor.
But the extra dirty growl caused by the supply hum intermodulating with the
guitar
notes is all musical to most musos in the world of pop.

Musos are rarely if ever satisfied with their amps unless they sound
pleasantly
distorted, so 10% of mainly 2H and 3H is normal at even low levels,
with 40% on strong overdrives, where the signal is mainly a square wave,
and the type of tubes don't make much difference.
You could have an EL34 and a 6L6 in a PP circuit, and not hear
anything spectacularly better or worse during serious over drives.
The heavy metal bands, and now dark metal types can only
survive on 40% Dn for most of the time, and tube matching is a silly concept

of no value whatsoever.

But to listen seriously to an old Italian cello being played by a master,
better you have well matched tubes, lest the cello sound worse than
if you were at the venue where it was recorded.

Patrick Turner.



  #13   Report Post  
Wbittle
 
Posts: n/a
Default

Hi,
I have used Sovtek, Tesla, and Svetlana and all work well. The
problem with matched sets is how long they were 'burned in' prior to the
final testing stage for matching. What you really want in an ST70 to
preserve sonic balance channel to channel is a matched quartet of
EL34's. Personally, I'd read the seller's feedback and see what others
think of his items. If the seller has mostly all excellent feedback,
then chances are he is a pretty square shooter. But if you see a lot of
neutrals or negatives, be careful. Also, if this amp was recovered from
a dumpster chances are it is in need of an electronic restoration before
it will ever sound correct or be reliable. ST70's are great power amps.
I have one myself. But my amp is totally refurbished. You would not
believe the difference in sound when you change out certain old
components which have drifted in value.
There is no way to know for sure that tubes balanced with a tester
will in fact perform as a matched set in an actual circuit. So, although
the set you buy could have been picked, tested and packed as a matched
set. That is no guarantee that they will remain that way. I have a set
of four EL84's in a Scott 222C that I matched out of 12 tubes and they
have remained close for over three years. I have a set of Sovtek 7591's
that remained matched for about 3 months of use then drifted apart in
value. I had to remove them and recheck them then do my best to pair
them off in reasonably matched pairs. There is no way the seller could
have known this would happen.
BIll B.

Jim Stewart wrote:

This weekend I rescued a beautiful old Dynaco
Stereo 70 amplifier from the dumpster at the
recycling center. It's in good shape, but the
output EL34's are of all different manufacture.

I'd like to get 2 sets of matching pairs for
replacement. I take a look on ebay and there's
a zillion people selling matched pair EL34's.

How do I know that they are truly matched?
There's never any statements about how they are
matched. For all I know, "matched" means the
same manufacturer.

On one website I looked at, the writer suggested
matched Tesla EL34's for good performance at a
reasonable cost. Any opinions on this? Where
can I get two pairs?



  #14   Report Post  
Chad Wahls
 
Posts: n/a
Default


"arizona cowboy" wrote in message
...

"Lou deGonzague" wrote in message
...
LV, I didn't see any links to what you offer or pricing? Or do you email
for
a price and availability?



be very careful of this Lord Valve person, while he knows a fair amount
from a technical standpoint,


More than a fair amount, I regard him as a valuable resourse to me when I
have a problem I can't figure out. I have used his brain once, he helped me
immensly. I certainly owe him some sugar free Red-Bull's!

he also has a checkered past of steering folks into
the brands of tubes that have the highest profit margin for him, rather
than the tubes that have the best tone for the same amount of dough.


Fisrt off he can balance tone and longevity, these amps get the hell beat
out of them, I've repaired my fair share of geetar amps in my time as a
bench tech. I am 100% with him on his reccomendations on RELIABLE tubes.

Profit margin..... I like my profit margin too, believe it or not; this fat
boy's gotta eat, pay mortgage, run a shop, and buy toys. Have you lost your
knowledge of American commerce? It's Walmart/internet assholes of the world
that ruin face to face trade and customer service. If I buy a ****load of
tubes because I got a deal do you think I'm giving you a discount? Hell No!
It's my ability to buy a ****load that allows me to make money off of you.
If you want a deal, go get a dealer account, tax number, etc and buy your
own ****load and let the unused rot away. I don't care because there are of
plenty of geetar players who do buy them off the internet, "repair" them
theirselves, screw them up worse, and bring them to me. Wola I just made
more money and sold another set of tubes because the dip**** doesn't know
what a bias resistor is.

my recommendation for a source would be Ned Carlson, of Triode
Electronics,


Yep he'e a great guy, close to me geographicaly.

same tubes that Lord Valve has available, a bit cheaper than LV, and far
more important, Ned will recommend tubes based on sound, and not let greed
cloud his objectivity.


How 'bout ones that sound good and can get slammed in and out of a
entend-o-van nightly and still fire up 5 min before showtime, Remember some
of our customers make money off the reliablility of their gear, our
reputation of reliability allows us to make more money because the customer
is buying "insurance".

He is also a hilarious, beer swilling, crazy
mexican-food-chompin real Chicago old-school guy, reminds me of John
Belushi a little bit. And no one has been selling tubes and Dynaco
upgrades longer, that I can think of.


I would imagine there are more people out there making money off their
Ampegs, Marshalls, Leslies, and Fenders than for Dynaco owners. I enjoyed
the rare Dynaco in the shop. But my bread and butter was from the
PROFESSIONALS.

here is the link to Ned's Triode Electronics site (one of America's
largest tube stores and a treasure trove of free technical info)
http://store.yahoo.com/triodeel/index.html



I'm not putting Ned down, BUT there is no reason to put LV down due to his
business practices. They are legit and I would feel very comfortable (I
have) using his advice and BUYING from him after I got the advice! I have
referred many of my touring customers to him in times of need.

Chad


Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Some tube history about 6L6. Patrick Turner Vacuum Tubes 10 August 28th 04 06:24 PM
Lots Of Great Tubes For Sale Jim McShane Marketplace 0 April 14th 04 02:22 PM
Lots Of Great Tubes For Sale Jim McShane Marketplace 0 April 14th 04 02:22 PM
Lots Of Great Audio Tubes For Sale! Jim McShane Marketplace 0 November 21st 03 03:05 PM
F.A. RCA 6L6/5881 power output tubes (matched) S. White Marketplace 0 November 10th 03 06:02 AM


All times are GMT +1. The time now is 10:24 AM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"