MBL 101 (~1990) - amp suggestions.


Does anybody have experience with those speakers:
Designation was MBL 101, or MBL 101a/b/c (letters may designate colour).
They have _no_ cone drivers, only three 'Radialstrahler' units, the same size units as in later/current MBL 101 range, but lower crossover points. Subwoofers (MBL 201) were optional, I do not have them.
So far I have tried the following amps:
Pass Aleph 4: almost there, but feels like lacking authority. Also, female vocals seem to suffer (males fare better).
300B SET (glasshouse/hificollective): they make sound, even loud if pushed (circuit allows 300B to go A2), yet the match is poor, orchestra becomes a mess.
Moderate power SS AB amp ("INnovative Audio Ultrapath"): pointless. Sounds flat and gutless, worse than Aleph 4 or SET.
Mark Levinson 23: the best match so far. Controlled and effortless; merciless at times (poorer recordings are exposed for what they are).
-- Do you think I can [substantially] improve over ML 23?

inefficient
The non-Evo Antileon even today is a good choice.
Yes all model Gryphon's are good.
These MBL's are only "tested" at 81db!!!, so amp around 150w or more is needed.
But also they have epdr resistance of around 2ohms in the low bass, and need an amp with BIG current to deal with this, if the owner of the speakers wants to get the very best out of the bass.

Cheers George    
Looked up 'EPDR resistance' -- thanks for the tip!
Stereophile has a good article in their archive, that clarifies a lot, among other things sets in perspective use of tubes (300B with a 6 Ohm tap really did not work too well, in 2 Ohm 'epdr' resistance they should not).
Also explains why Aleph 4 was not happy, it can live with 4 Ohm, but not with 2 Ohm.
So ML 23 is a decent match, and an amp doubling output down to 1 Ohm could be worth a try.
Thinking of 'eprd', McIntosh with their autoformers are on to something.
Gryphons seem rather costly.
Dear @inneficient :  The 20.6's double its power ( 100 watts at 8ohms. ) from 8ohms to 1 ohm, goes from 100 to 800w and 400 at 2ohms.

Do it a favor and don't put in the signal " road " transformers7autoformers and the like: can't improve that music signal.

This is other great alternative:

https://www.audiogon.com/listings/lis9cid4-spectral-dma-360-ref-solid-state

R.

Not that this is helpful for the OP, but...

I own MBL 121 monitors, which have essentially the same tough-to-drive specs as the big models.

And yet my CJ premier 12 140w tube amps seem to drive them great and even more wild, probably my favorite pairing has been my old Eico HF-81, 14W tube integrated.   They sound glorious driven by that Eico!

(I don't listen very loud, but even when I do crank it up, it still sounds great).
Also explains why Aleph 4 was not happy, it can live with 4 Ohm, but not with 2 Ohm.
So ML 23 is a decent match, and an amp doubling output down to 1 Ohm could be worth a try.
What is important is that the amp be able to act as a voltage source. It does not need to double power at 1 or even 2 ohms to do that.