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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
simna OP
165 posts
 

When comparing these two tube amplifiers everything else is the same except for the amplifiers. I have just switched between the amplifiers. I have tried both the 8 ohms tap and the 4 ohms tap.

I’m grateful for your posts but I wonder how I will know when the "damping factor" of a tube amp is problematic and how do I know what the "damping factor" of this amplifier is?

roberjerman wrote:

"Tube amps with output impedances greater than 1 ohm will not have a flat response into a speaker’s varying impedance. They will act as tone controls! So, choose your tube amp/speakers with this consideration in mind!"
This may be right, but how do I, an ordinary music lover, not a technician, know what to look for? What should I look for in specs for the tube amp and the speakers?

The LM34IA has 40W and my old EL84 amp (without boomines) has 35W so it can’t be due to lack of power. Speaker sensitivity is 89dB (Tannoy Eaton Legacy).

I have heard another possible explanation why I get this boomines. The LM34IA is slow and the capacitors should be replaced with "ultrafast capacitors". This maybe why I don’t have boomy sound from my old EL84 amp (Tube Technology Unisis Signature) which has "ultrafast capacitors".

So as I see it there are only two things that can cause this problem; the tubes (solution: try another brand with tighter bass) and/or the capacitors (solution: replace the capacitor to faster).
Maybe also this "damping factor" that I don’t understand what to do/look for to exclude.

Or am I totally lost in my conclusions?

lowrider57's avatar
lowrider57
5,417 posts
 
I’m not an EE, but I’ve never heard of a case where troubleshooting starts with changing out the caps.
If a tube amp/speaker sounds slow and boomy it could be the rectification of the amp.

I would not worry about damping factor.
It could be as simple as the tubes. Maybe you are hearing bass bloat.
What power tubes are installed?

https://www.line-magnetic.eu/en/products-line-magnetic-en/integrated-tube-amplifier-line-magnetic-en...

The Tannoy Eaton Legacy seems like an easy load to drive, but room placement is important and will affect results.

http://www.audiodrom.net/en/component/element/detail/29-stand-mount-monitors/576-tannoy-legacy-eaton



simna OP
165 posts
 

@lowrider57 

Yes, I'm gonna change the tubes, but I really wanna know the brand of the stock tubes before I do that. They are just labeled "Line Magnetic". If this dosen't do the trick I will have the capacitors replaced.

Yes, the speakers are easy to drive, and as I wrote, with my old EL84 amp there's no problem with boomines. Or, to be honest, there's a faint hint of boomines. And yes, I know there's a problem somewhere around 46-50Hz.

jond's avatar
jond
5,853 posts
 
I have no idea what I have no idea what constitutes an "ultra-fast capacitor" but it's unlikely caps are the issue as stated by others above. Also you don't actually need to understand damping factor, just the different output taps and use the one that sounds better. lowrider gives you good advice on trying better tubes likely the LM branded tubes are a cost effective option from China, better tubes are out there.


Curious about your Tube Technology Unisis Signature amp, I used to own the Tube Technology Fusion CD64 cd player and absolutely loved it. Sadly it died but based on that listen your "old" amp may in fact be a better amp that the LM amp you're considering.

Last thing did you try moving the speakers around to compensate for that boominess?
simna OP
165 posts
 
@jond
Yes, maybe my old TT is a better. But I have had problems with it or maybe I have had bad luck with the two last quads EL84 tubes. I’ve had trouble with elaking tubes and the bias not being stable and I’m not even sure if I have the right information of how to adjust the bias. A friend of mine said I should adjust the tubes to120mV. I don’t know if it’s to high or not and I can’t find any information anywhere.
TT once sold a meter for the bias adjustment and when that meter showed 3.0 the bias was spot on. But 3.0 what? How do I translate that to mV?
So, the reason for a new amp is that I’m tried of all this hassle.
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