2. amps-preamps
  3. 127327-23130

Tube Power Amp Suggestions

I have been looking for a tube power amp. Ideally I want to have about 40 to 70 watts output power, with sound qualities as close to a delicate SET amp as possible, with lots of details, fast, good tone (a tiny bit on the warm side) and imaging, yet with good bass and dynamic. Budget is about 10,000. Second-hand is fine. I know I am asking really too much and will probably get negative response because of this. I just want to get the best within my budget.    
      
My initial considerations are EAR 890 or EAR 861. What do you think?      
    
I heard people saying that push-pull amp can be better than SET if it is implemented well, but push-pull is more difficult to make than a SET amp.    
      
My speakers are measured 91db sensitivity, but it needs power to perform well. I have tried both a SET 300B XLS output at 13W and a push-pull EL34 at about 35W. My impression is as follow:            
      
- SET 300B XLS output at 13W: more delicate and smooth, better resolution and density, lack bass and dynamic       
- Push-pull EL34 at 35W: much more bass and dynamic, sounds a bit coarse, less 3-dimensional and delicate     
    
Thank you in advance for your input. 
   

bigdish

Showing 3 responses by atmasphere

atmasphere's avatar
atmasphere
12,088 posts
 
@bigdish if you really plan to keep with those speakers, the problem you are up against is that the speakers are designed for an amp than can act like a voltage source. Most of the amps suggest so far (including ours) are Power sources.

The difference will be on this speaker that a power source will play the woofer section 3 db down from where the designer intended.

There is a reason people are suggesting amps that behave as Power Sources though- in tube amps in particular, they tend to sound more natural.

More here:
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php
atmasphere's avatar
atmasphere
12,088 posts
 
@bigdish You say your speakers are 91 db; do you know the impedance? What speakers are they?
atmasphere's avatar
atmasphere
12,088 posts
 
Its impedance is rather flat at 6 ohm.

They are not very easy to drive IMO.
Its easy to see why when you look at the pdf. The speaker has 4 ohm impedance in the bass frequencies and rises to the 8 ohm impedance of the Festerex at 550Hz. I would call this a 4 ohm speaker and no mistake. Its not what I would call 6 ohms. The design suggests an amplifier with ’voltage source’ characteristics should be used, which means that most of the amps suggested so far won’t sound right on this speaker without the help of a set of ZEROs (www.zeroimpedance.com).

The kind of amp needed to drive this will be a tube amp with lots of feedback or a solid state amp. However, you can assume from many of the posts here that most of the people on this thread prefer amps with little or no feedback.

If you wanted this speaker to work easily with a tube amp, the best solution would be to put the woofers in series and redesign the crossover (creating a 16 ohm loudspeaker). I expect the Festerex is considerably more efficient than the woofers; its likely that after such redesign the speaker would also be more efficient.
More to discover