MFB's with valves/tubes?

No, never heard about it. On the other side, i'm very curious how an MFB-speaker would sound, connected to a superb valve-pre-amp... Anyone experience with this?

Hello!
Haven't used anything more than my Quad 44.
There are valve-powered active speakers, Klein+Hummel have made some in the 60s, but not with the MFB-principle...
tom

Klein+Hummel... already heard some positive things about it... That the brand should be reckoned -together with Philips MFB- as one of the better SMALL speakers. Do you have at the moment such speakers, Tom? Or what kind of speakers are you using at the moment with your (nice) Quad 44?

Hello!
I am using my Quad 44 with a pair of Quad II valve amps that drive Tannoy SGM-10B's.

But I have a pair of old Dux 544s in the closet and they are good for rocky stuff, although I want to change the tweeter the first thing I do...when I take them out, that is...and you can always connect several MFB's should your neighbours not hear the music 🙂

I was wondering because I like the valve sound and it wouldn't be too hard for the technically inclined to make a control circuit for the feedback 😉
I have heard K+H's in the eaarly 80's as the little sound enginering company I worked for as a young guy imported K+H speakers and stuff and Schopes microphones.
The K+H's I remember, sounded very good for the small size.

I would refrain from trying to make the low note amp a tube based one because the mfb principle requires a relatively high damping factor for the final stage which by nature isn't something tubes can deliver on due to the mandatory output transformer. There might however be some huge gain in making the mid-high section tube driven, specially with some nifty class A design.

It would be nice to try and combine the best of both worlds, something like a hybrid amp using a classD design for the low note together with a switching power supply that at the same time provides the high voltage for the mid-high tube amps.

It will cost though....

cheers - cc

Wow..!

"with a switching power supply that at the same time provides the high voltage for the mid-high tube amps."

Are u kiddin'?
This is quite hard to believe...Switching power supplies are fine for PC's and TV's but certainly not for audio! When using tubes, keep it simple. A conventional tube rectifier + LC circuit works fine...

And it is possible to use a tube amp with a very high damping factor to drive the low section. Using the OTL (Output Transformer Less) principle gets rid of all the output transformer cons! It is costly however...

Anyway, I think that combining tube technology with MFB's is a challenge, but due to the relatively low sensitivity and 70ies qualities of the speaker units, it might not bring out all the benefits of tube technology.

Regards,

Gijs.