matched?

79 Transam · Post by **79 Transam** » Tue Oct 18, 2005 1:40 am

Pardon the rookie question, but what is considered 'matched'. Is there a small variation?
Just what is measured when matching tubes.
Thanks in advance.

rjgtr · Post by **rjgtr** » Tue Oct 18, 2005 6:14 pm

It should be exact or within a couple ma. But many vendors consider a difference as high as 5 ma matched. On the other hand slightly unmatched tubes can sound richer than closely matched tubes.

Necrovore · Post by **Necrovore** » Tue Oct 18, 2005 8:37 pm

rjgtr wrote:It should be exact or within a couple ma. But many vendors consider a difference as high as 5 ma matched. On the other hand slightly unmatched tubes can sound richer than closely matched tubes.

Just as long as the tubes can be biased and not have one fail like my recent experience with a set of "Matched" EH EL34's.

Guest · Post by **Guest** » Fri Nov 25, 2005 9:50 pm

Hello and hope you are doing well,

The "matching" of power tubes is a process that ensures that the push/pull (class A/B circut) effect on either side of the power tubes are equivicated precisley on both ends to facilitate and promote an even response in the circut cycle.

Best regards to all,
Dave

Mass · Post by **Mass** » Fri Nov 25, 2005 9:51 pm

Hello and hope you are doing well,

The "matching" of power tubes is a process that ensures that the push/pull (class A/B circut) effect on either side of the power tubes are equivicated precisley on both ends to facilitate and promote an even response in the circut cycle.

Best regards to all,
Dave

P.S. An amazing site to visit concerning circutries:

http://www.allaboutcircuits.com/vol_3/chpt_13/3.html

Billy Batz · Post by **Billy Batz** » Sat Nov 26, 2005 10:33 am

Which also isnt to say that it sounds better. Matching was apparently only a HiFi thing until more recently, like Dave said to get a more even and linear responce, but mostly a hifi tueb audio thing and back in the 60s and 70s noone bought matched tubes for guitar amps and with that you can bet your ass part of the tone they got was from the coloring of mismatched tubes. A lot of people prefer mismatched tubes as long as its not so far out its problematic. I am definitely one. Or Ill put it this way. I buy matched sets but I dont sweat it if they are loosely matched at best. I prefer them that way and the tube manufacturers being what they are these days dont usually let me down

There is a safe limit though. I definitely dont want to have 3 around 35mA then have one cooking at 48mA!

Flames1950 · Post by **Flames1950** » Sat Nov 26, 2005 12:18 pm

I don't mind a spread of between 4 and 7 mA between the tubes of a set......

MSML · Post by **MSML** » Wed Nov 30, 2005 4:22 pm

In Kevin O'Connor's books he makes the point that with most of the parts in the circuit path of the tubes having tolerances as wide as 20%, closely matching pairs of tubes may be undone by big variations in component values in the circuit. For him, the solution is just to have bias trimmers for each tube.

I'm curious what your take on this is.

Mike