Problem related to Push-Pull or EL34?

@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.

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?

@

Yes, but the company doesn't excist anymore. I've heard that the guy who owned TT has left England for US (and are now working for Manley I think).

@jond 

I'm in Sweden. You mean he answered your mail? I would love to have the schematics over the Unisis Signature and have someone figure out how to bias it without the special bias meter TT made. Or even better he could tell me how many mV the tubes should have.

Do you know how to get in touch with him? Mail address?

@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.