Balanced Low Power Tube Monoblocks?

There's always autoformers. On the M-60s the Speltz Zeros are not entirely sonically neutral (a bit more neutral on the higher wattage A-S amps) but the small trade off might be an alternate route. On the other hand, I've always liked Mike Sanders gear (still have a pair of the original 8417 monos).

Tim
 

I tried Speltz Zeroformers with the M-60 amps. I didn't care for the sound.

Thanks everyone for some excellent suggestions.

At this point, I'm going to wait a few months and revisit a speaker change
before purchasing a different amp.

Tvad, You might be surprised at how apparently powerful the Dehavillands are. My Alon V's supposedly recommend 200w/channel according to the manual, but I was impressed hearing Nolas & Dehavillands @ CES a few years ago, called Kara, who agreed that it was a great match. I don't listen at ear-splitting levels, but they go pretty loud >95db without running out of gas. These are 4ohm loads we are talking about, too. I think you would be fine, certainly on an interim basis. You might consider calling Kara Chafee; very helpful and not at all salesy. Good luck and keep us posted,
Spencer

Tvad, FWIW, a 'dip' to 4 ohms is not a problem for the M-60! OTOH, having the bass frequencies be 4 ohms (while the mids and highs are 8) is, and is a problem for **any** zero feedback tube amplifier.

When you see speakers that are 4 ohms in the bass and 8 ohms in the mids and highs, quite often the speaker designer is using woofers that are 3 db less efficient, and expecting that the amplifier will double power with the 4 ohm load. This brings the woofer output up to the level that the mids and highs operate at, but you need transistors to do that properly.

No tube amp will sound right with a load like that since no tube amp can double power as you cut the impedance in half! You can make a speaker like that work (sort of) if the tube amp has lots of feedback in its design. The problem is that the negative feedback will foreshorten the soundstage and impart a sheen to the mids and highs- IOW it will not sound natural.

That is why our amps have little or no feedback- why bother try to drive a speaker that will always sound electronic? I agree it has limited our market, but limited to the speakers that can sound like music (work properly with tubes), and that is not a bad thing :)

When you see speakers that are 4 ohms in the bass and 8 ohms in the mids and highs, quite often the speaker designer is using woofers that are 3 db less efficient, and expecting that the amplifier will double power with the 4 ohm load. This brings the woofer output up to the level that the mids and highs operate at, but you need transistors to do that properly.

Ralph,

This may seem like a matter of semantics, but I want to raise an issue in connection with this statement because I think it has been a point of confusion in some other recent threads.

A speaker that has say a 4 ohm impedance in the lows, and an 8 ohm impedance in the mids and highs, and that may have woofers that are 3db less efficient than the other elements, will, as you say, generally be best suited for a solid state amplifier that can double power into 4 ohms.

BUT, as long as the amplifier has an output impedance which is negligibly small in relation to 4 ohms, and as long as the volume levels it is called upon to deliver are within the limitations of both its voltage swing capability and its ability to deliver current, then a flat frequency response will result. It is not the ability to double power into 4 ohms per se which results in flat frequency response into such a speaker, but rather it is the ability of the amp to act essentially as a voltage source, up to some maximum volume level.

In other words, to cite an example, a solid state amp having low output impedance, which is capable of 200W into 8 ohms but only 300W into 4 ohms, will deliver just as flat a frequency response into such a speaker as an amp which is capable of 200W into 8 ohms and 400W into 4 ohms, IF it is not called upon to generate more volume than its relatively limited current capability can support.

Do you agree?

Regards,
-- Al