Help Tannoy XT6F with Primaluna

I had used a Japanese Triode integrated 300B amplifier with a pair of Tannoy DC 8's and that sounded really really good.

I had used a Japanese Triode integrated 300B amplifier with a pair of Tannoy DC 8's and that sounded really really good.

Ben, I agree with the earlier poster that additional breakin may very well help. However, although most Tannoy speakers that I am familiar with have tube friendly impedance characteristics, unfortunately I suspect that the root cause of the problem in this case is that yours do not.

I suspect that the impedance curve of your XT6F speakers is similar to the one shown for the XT8F in the graph at the very end of this review. As you'll see, the impedance of that speaker, despite its 8 ohm nominal rating, is around 3 ohms in much of the bass region, rising to around 10 ohms in the mid-range, followed by a sharp rise to more than 40 ohms at about 4 kHz, followed by a decrease to around 10 ohms in the upper treble.

As a zero feedback tube power amp, your PrimaLuna undoubtedly has a fairly high output impedance, corresponding to a very low damping factor, although neither parameter appears to be specified. The interaction of a high amplifier output impedance with the speaker impedance characteristic shown in the graph will result in EXACTLY what you have described -- weak bass and an over-emphasized upper mid-range.

If the sound continues to be unsatisfactory following additional breakin, I suspect that among tube amplifiers a much better choice for use with the XT6F would be a medium powered Audio Research model, if you can find one used at a suitable price point. ARC designs tend to have significantly lower output impedances/higher damping factors than many other tube amps, in part due to the use of moderate amounts of feedback. Also, they tend to have robust power supplies, which may also be helpful with respect to the low impedance of the speakers in the bass region.

Good luck. Regards,
-- Al

 Well I have been trying everything I know to try. I have let the speakers play for hours on end. I have tried Cables, room position, Toe in tow out tilting forward tilting back. I still can't seem to tame that harshness. Things that sound good sound really really good but the things sound bad sound horrible. The kefs seem to be able to make everything sound pretty good. I even tried hanging paper towels in front of the upper driver. It did tame the sound but then the things that sounded good now sounded dull. I'm going to try a McCormack power amp this weekend.  I'm hoping for something good. If not I guess I have to sell the speakers. 

By the way none of this has been with the prima Luna. It's all been with the Rotel solid-state power amp. The primaluna will absolutely not work with these speakers.