[ErinH]

Full report attached via PDF.

Driver:
Tang Band W6-1721

Tang Band W6-1721 6-1/2" Underhung Midbass Driver 264-874

Photo:
(stock)

Impedance and T/S Parameters:

• Re = 3.5805 ohms
• Fs = 45.2438 Hz
• Zmax = 25.9420 ohms
• Qes = 0.5976
• Qms = 3.7321
• Qts = 0.5151
• Le = 0.2889 mH (at 1 kHz)
• Diam = 127.7620 mm ( 5.0300 in )
• Sd =12820.1563 mm^2( 19.8713 in^2)
• Vas = 13.8331 L ( 0.4885 ft^3)
• BL = 5.9644 N/A
• Mms = 20.8859 g
• Cms = 592.4734 uM/N
• Kms = 1687.8396 N/M
• Rms = 1.5909 R mechanical
• Efficiency = 0.2014 %
• Sensitivity= 85.0595 dB @1W/1m
• Sensitivity= 88.5510 dB @2.83Vrms/1m

Klippel 10% Distortion based Xmax:

• X Bl @ Bl min=82% >7.7 mm *
• X C @ C min=75% 4.0 mm

* I pounded on this speaker (took the protection parameter on Cmin as low as I could @ 20%) and could not get Bl to resolve at all. Regardless, you're suspension limited but I still like to resolve all the parameters I can when possible.

Sample Klippel Data:

 

[SSSnake]

Lots of stuff to talk about on this one. The Bl symmetry range looks horrible. I assume this affected by not being able to resolve the BL curve. Thoughts?

The distortion analysis looks great accept for the suspension. I wonder how these things would look with a better suspension design. All the money that went into this monster of an underhung motor with an inadequate suspension is really disappointing. This thing could have been in scan territory with the right suspension (Le not as good but still).

 

[ErinH]

The distortion analysis looks great accept for the suspension. I wonder how these things would look with a better suspension design. All the money that went into this monster of an underhung motor with an inadequate suspension is really disappointing. This thing could have been in scan territory with the right suspension (Le not as good but still).

That's the first thing I thought. It just seems odd to me a company would put SO MUCH effort in to such a large motor when it's so terribly suspension limited in terms of these results. It just seems like a waste in this regard.

 

[cvjoint]

Wow, what a motor. If properly optimized this thing would be a beast! I wish TB got a Klippel and worked on their centering and suspensions. It has the potential to be a Scan killer for sure, but falls very short in this state of affairs.

Safe to say the offset in BL is 2.5mm or so. The variance is quite low for the estimate even without the BL resolved. This motor has the potential for 12mm one way linear Xmax for the prescribed 10% distortion limits. Quite possibly the most linear motor for a 7" if polished a little.

 

[thehatedguy]

Polishing or good QC?

 

[SSSnake]

Both. As I'm sure you know, a great design that can't be consistently implemented is no better than a medicore design that can be implemented consistently (and sometimes is even worse). We used to give the IEs (Industrial Engineers) hell in school but truth be told some of the most significant problems involved with getting an outstanding product to market are in the design/optimization of the production systems.

 

[soongsc]

I kind of suspect the test signal polarity is reversed. Inductance should be higher for the coil in direction and the typical BL curve for an under hung motor would have the higher BL side on the coil in direction.

 

[Hillbilly SQ]

I as well as several others in the deep south had an encounter with these monsters in Blakes toaster. They were in kicks that stuck out a mile to accommodate the big underhung motor. I really liked the sound they had to offer. Actually, it was at Erins house I heard them. They were teamed with the Tang ceramic tweet...which was a pretty good tweeter when crossed at or above about 3500. I wonder if Tang has a woofer with a more reasonable mounting depth that can compare in sound to this underhung beast?