[NSD] Jensen P10/40 BB a.k.a Blackbird 10 AlNiCo

[Gitterbug]

Anyone else tried this new speaker yet? I got my first sample around 1.00 pm yesterday, built a TOOB 10S around it in record time and was on the air at 4.30 pm. It was love from the first chord! It's hard to improve on a standard 10" Tornado, but the good people in Trecastelli have really nailed it. This was confirmed by today's band rehearsals. I hope to land a player a few leagues above mine to do a jazz demo. This speaker speaks jazz and blues.

[nevershouldhavesoldit]

Interesting! Some of the operating parameters are quite different from those of the Tornado. It weighs the same (3.75 lbs) as a neo Tornado 10 and the sensitivity is almost exactly the same, but the similarities end there. The total Q is about twice as high (0.94 vs 0.58 for the 8 Ohm versions) with significantly higher mechanical and electrical damping, the flux density is higher, voice coil is copper vs aluminum etc. Jensen does describe the Blackbird 10's bass as being tight and the Tornado's as fat. Did it take any tweaking of the Toob or was the improvement just a serendipitous drop-in, Markku?

[Gitterbug]

Just a drop-in, given the time squeeze. The Qt values of the BB AlNiCos are quite high, but I'm not sure how literally one should take the recommendations you often quote. I will definitely try the 10" BB 40 in an open or half-open cab. Whether this results in a TOOB 10J or a even 10/12J Mk II remains to be seen. Prototypes exist; if only there were quality time to spend with them.

I've said this before and say it again: 10" makes more sense than 12" as a reference jazz speaker caliber. I may not see the day when the change of mind happens, but given the recent popularity of 8", even 6.5" cabs, it's nearing. And, "blooze" is not too far from jazz in this regard.

[nevershouldhavesoldit]

The Qt values of the BB AlNiCos are quite high, but I'm not sure how literally one should take the recommendations you often quote.

I consider those admonitions to be guidelines rather than recommendations. It makes perfect sense that a speaker with a lot of mechanical and electrical damping (i.e. a very low Qts) will tighten up excessively if stuffed into a sealed box and would yield mo' better bass in a vented or ported enclosure by exciting low frequency cabinet and port resonances. But I've never quite figured out why a high Qts is supposed to favor an open back. This seems counterintuitive, since there's absolutely no "air spring" to add control to the extremes of excursion in an open back enclosure, leaving the cone / coil assembly undamped or underdamped at low frequencies and high SPLs. My understanding has always been that this was a common reason in the old days for blown speakers in small, open back tube amps pushed to their limits. Low amplifier damping factor, high harmonic distortion levels, and poor mechanical control of the cone led to ripping - and this was a bigger problem with underpowered amps than overpowered ones because of the destructive energy exerted on the speaker's moving parts by high odd order harmonic distortion.

Conceptually, the free air resonant frequency is the frequency at which the mass of the moving components in the speaker is exactly offset by the force of its suspension components. And if I remember correctly, the Qs are measured at the free air resonance of the speaker. So the main effect of interaction between the Q and the enclosure design would be at or near that frequency and would not exert much effect on sound quality at frequencies above it.

But there are so many examples of great amps and speakers whose design parameters fall outside the usually stated TS parameters that these are obviously imperfect.