Newbie needs help on Audio Research and DynAudio Quality

Mapman, if you download the "manuals" (they’re actually nicely detailed spec sheets) at the following link, for your Contour 1.3 MkII and the OP’s Contour 1.8 MkII, you’ll see that the impedance characteristics of his speakers are much more benign than yours. And in fact their impedance magnitude is remarkably flat compared to most speakers, with impedance phase angles being benign as well.

https://www.dynaudio.com/support/manuals

Also, based on the Classic 120’s specified damping factor of 45 and its use of a relatively large amount of feedback (21 db), it seems certain that the Classic 120 has VERY low output impedance for a tube amp, approaching solid state territory in that respect. So the amp **will** double power into halved load impedances, to a very close approximation, as long as it is not asked to exceed its maximum power capability.

So on paper, at least, it seems like the Classic 120 should be a suitable match for the Contour 1.8 MkII, assuming its maximum power capability is adequate for his purposes (which I would expect it to be under most circumstances). Also, based on the numbers in the spec sheet it seems very likely that the 4 ohm taps of the amps would be the best match for these speakers. If one of the other taps is being used the 4 ohm tap should certainly be tried.

Finally, one thing I note in the spec sheet for the speaker is that its crossover uses "high quality polypropylene capacitors." Poly capacitors can require lengthy breakin periods, IME, with the speaker actually playing music for dozens if not hundreds of hours before they will sound their best. And I suppose it is conceivable that they could have lost that breakin during the four years of non-use. And perhaps the drivers need to loosen up as well. I mention these points because in reading the initial post I’m not completely certain if the solid state equipment that was mentioned was tried with the Dynaudio speakers, or if it was just used with the JBLs.

Best regards,
-- Al

Almarg how would you reconcile the manual indicating same power into 4 8 and 16 ohm with doubling down power into the same? It is a hybrid design so that would bode well in terms of having low output impedance for a tube based amp.

Those amps were introduced in 1990 and not used for several years. It's  possible they are not operating up to spec.

I suspected the larger models would be an easier drive but did not check the specs. Good catch! Dynaudios in general seem to get the rap of being towards the power and current hungry end of things.

Almarg how would you reconcile the manual indicating same power into 4 8 and 16 ohm with doubling down power into the same?

Tube amps providing multiple output taps typically have the same or similar **maximum** power rating when a 4 ohm load is connected to the 4 ohm tap as when an 8 ohm load is connected to the 8 ohm tap, and likewise for a 16 ohm tap if one is provided (as it is here).

However as long as the amp is operated within the limits of that maximum power capability, how much power is delivered as a function of the speaker’s impedance vs. frequency variations depends on the relation between the impedance of the speaker at each frequency and the output impedance of the amp. It does NOT depend on the amp’s **maximum** power capability, as long as that capability is not exceeded. That’s a point which is often not recognized. And as I mentioned the output impedance of this amp comes very close to being in solid state territory, and to being almost negligible in relation to the impedance of the speaker at all frequencies.

Best regards,
-- Al

Yes the multiple outputs for various impedance levels does cover that.

The speaker specs indicate bass range impedance down to 3.8 ohm. Not natural turf for a tube amp. The speaker specs are fairly detailed for a product manual but specs still leave grey areas. Plus the current operating condition is not clear. It is very hard to say without actually being able to hear what the op hears. I’d give the Luxman a shot for comparison if not done already. Perhaps the ARC amps just need a tune up. They look pretty beefy like they should be reasonably up to the task. Still 4 ohm and less in the bass region and most tube amps are not a natural match from a low distortion perspective.

When I had Dyns they did not sound good at all with tubes. That was with a Cayin A100T with kt120s. They sounded great with high current ss amps.