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Problem related to Push-Pull or EL34?

Hej

I have compared my EL84 amp with an EL34 amp and what strikes me is that the EL34 amp is boomy. I know that my room has a problem in the bass region and it’s like the E34 amp makes this worse. So why is that? Both are Push-Pull, but my EL84 amp has got the original capacitors replaced to “ultrafast” capacitors. So this makes me wonder if there is any truth in what I've heard: 

  1. ...the Push-Pull design in itself increases the bass and makes the sound a little boomy.

  2. ...you can counteract this by replacing capacitors to “ultrafast” capacitors.

  3. ...EL34 tubes by design emphasis bass frequencies.

This makes me very frustrated because I really like this EL34 amp (LM EL34IA) except for this bass problem. The amp is in my budget range and I need the 40W it gives (which means Push-Pull).

Any thoughts?

simna
jond's avatar
jond
5,853 posts
 
@simna Yes he answered my email this was some time ago maybe about 4-5 years ago. I have since changed my email and don’t have the correspondence any longer but it was the Tube Technology contact email; contact@tubetechnology.co.uk so I don’t know if it’s still active but worth a try.

Also I was just reading the owners manual of your amp online and this statement jumped out at me:

If your dealer cannot offer this re-tubing service it is possible to fit a replacement tube andadjust the bias yourself with the aid of a custom TT Bias Meter available from anauthorised Tube Technology dealer.


Does an everyday bias meter work on the amp or do you need this custom unit? Are you able to bias at all?
simna OP
165 posts
 

@jond 

Actually to bias is not the big problem. There's a 8-pin connector on one side of the amp where this special TT Bias Meter is supposed to be connected. I have figured out which pin goes to which tube and then I use a multimeter to measure the tubes mV. But I don't know if 120mV is too much or too little. And then I have another problem. If I adjust the tubes one day to 120mV, next day some of the them measures 122 - 128mV.  The guy who bought these tubes for me (russian no-name) says that it's OK for a tube to change from one day to the other within 10%. But I don't know if this is true.

lowrider57's avatar
lowrider57
5,417 posts
 
The measurement of tube voltage will change every day and at different times during the day. It’s caused by the fluctuation of line voltage coming into the dwelling and the mains.

The measurements you stated are acceptable.


jond's avatar
jond
5,853 posts
 
@lowrider is correct those measurements are totally fine and if you think your amp sounds better than LM I would say keep it and be happy.
truman
167 posts
 
Pleased that OP has tangentially, but nonetheless, highlighted how good E-84's can sound. One of my favorite output tubes that "doesn't get the press it deserves". And, yes, it does have nice rich bass that often warrants a "double take".
EL-34's offer a lighter style, more "finesse" like a Lafite Wine... it seems to me. -Though I know the circuit is at least as important.
See if you can't listen to an EL-84 amp sometime.
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