Tube amp for "difficult" speakers,,,

Asa, FWIW any Atma-Sphere product that gets updated to the latest level gets warranty reactivation. In addition, the warranty is transferable. This helps with the resale value on amps like the MA-1, which don't tend to hang on audiogon all that long.

Acoustat 2+2s are easily driven with a set of M-60s and a set of ZEROs. They are not a power-hungry speaker.

Hey Ralph, didn't mean to talk down the resale marketability of your OTL's. Hyperbole is a bitch, but then again it is a thread, right? On you MA-1's: I agree, nice amps, great amps, actually. And, yes, they always find a good home, in relatively good time, to the right guy. Hey, maybe it was too much pouring through audiomart newsletters (remember that, Crewe, VA?!), or maybe I've been permanently scared by my Jadis Defy 7 resale experience twenty years ago? Could be...

BTW, I had a friend with the MP-1 and I loved it too, almost bought it; one could swim all day in that luxurious phono. And I like that you are still around, like today, proud of your work.

But, like I said, lots of tubes. It's a psychological fact that, when advising on system evolution, that moving a guy from SS straight into a gazillion tubes may not be the most wise thing to do. I've done it with people asking for help and have seen the faces later. A few more interim steps is sometimes advised. Or maybe not. Like I said, I'd have to know O holter personally to make that decision; mine was a context dependent answer in the middle of a probability analysis...

Basically, I see your MA-1's as a product that is fairly sophisticated; not necessarily in operation, but who ends up there. Please take that as a compliment. With that said, I think that guys who think that they may want to move from 600W SS amps and go SET with a 83db load, might need an interim step. Its the context dependent thing again.

On the 2+2's, we will have to agree to disagree. Granted,I have no experience with the M-60's on the Acoustats, and its been a while since I've heard either on their own, but when I say, take a hold, I don't mean it in a quantitative sense, as in, will it drive the speaker. I was thinking more in the sense, does the speaker speak with its best voice. My comrade had his Acoustats with MA1's and then a Berning and I preferred the MA-1's by a mile(the luxurious part...), so I'm all for the MA-1's with just about anything, including a 83db load. Incidentally, he moved to the Berning because of all of the tubes. But, at the end of the day, I think he might still be tube-rolling the inputs on the Berning looking for that harmonic complexity thing. If you say back, no, the M-60's will drive 2+2's no problemo with dynamic authority and no loss of harmonic nuance throughout the spectrum, then I will defer to you there.

I met you once, Ralph. You won't remember; at a couple of CES's when I was reviewing, and then later at a Chi audiophile club meeting. A while ago now, but what I remember is that you stayed around after the meeting and talked to anyone who wanted to pick your brain. That was nice. More of that in audioland.

Mark Bucksath (Asa)

Hi Mark, the trick to driving Accoustats is being able to deal with the load. A friend of mine had them- wicked low impedance- but we ran them with a set of M-60s and a set of our Z-Music autoformers to deal with the load. They sounded fabulous and could play any reasonable volume- we never ran the system out of power. He had an ARC too; it needed the autoformer as well!

These days you get a set of ZEROs (we don't make the Z-Music anymore) and a set of M-60s will do the job. You would need them even if you had MA-1s; Accoustats are a 'difficult' load, and the ZEROs can be looked at as a great problem solver for things like that. IOW a great way to get a tube amp to drive a problem load.

People often ask if there is a degradation, which is a sort of Red Herring; obviously if the amp can't drive the load 'without', and it does it great 'with', then the answer is 'no, it works great!'

Yep, its the load, impedance-wise on the 2+2's. I should have been clearer. When I talk here about driving a speaker, I tend to talk about impedance/sensitivity together, until I'm absolutely forced to talk about technicals. BTW, I still liked the MA-1s on them. Then again, I'm an SET guy these days, so dynamic compression doesn't bother me as much as most. What are those Dynaudios we are talking about here - 4 ohm load? That sounds familiar in my head.

I've got a second system with 88db (or, 89, I can't remember) sensitive LS3/5A's, but they are 15 ohms, so I can run them quite well with an Air Tight 300B 10W amp. You wouldn't think so, but its works quite well. No head-banging, but its not meant to be that way, can't be.

Anyway, 83db/4ohm speakers I think are going to suck up some serious real estate. To be honest, I think someone you wants those types of speakers should go for a Pass 200 watter and be happy that that's as close as he's going to get to SET, or OTL, mids, spacial rendition and harmonics.

I assume the sans-ZERO MA-1s could do the job, but, then again, he's coming off of 600W of Krell...

Hey, o Holter, what do you say about some big OTL's? Ralph Karsten is here and he's the man...OK, I'm changing my mind...anyone who has Krell on a 83db speaker and wants to go SET MUST be willing to get into the deep end, right?

Ralph, I hope I just helped you with a sale!

I am on holiday and not able to follow this thread so often, so this is just to say, thanks for more advice and suggestions, and also: I use the Aesthetix Io, so I am not exactly new to tubes.