Measuring 604 D TS parameters

**charly1944** · February 24th, 2012, 06:32 AM

Hi,
I finally measured my speakers with a tester woofer 2.
The closed box method gave the following results:
Speaker 1: RE:10.93 ohms;Fs:27.68 Hz;Zmax :285.17 ohms;Qes:0.31;Qms:7.9131;Qts:0.30;Le:1.4841 mH at 1kHz;Vas:527.5 L;Sensitivity:97.2 dB @1w/1m.
Speaker 2: RE:10.62 ohms;Fs:27.83 Hz;Zmax :268.78 ohms;Qes:0.31;Qms:7.5351;Qts:0.30;Le:1.4841 mH at 1kHz;Vas:519.7 L;Sensitivity:97.3 dB@ 1w/1m.
It looks to me that they are pretty well matched but that the Qts are relatively high compared to the specs.Is it important and if yes are they ways to get those Qts down by further burning in the loudspeakers at low frequencies?
Charles.

**charly1944** · February 26th, 2012, 03:53 AM

HI,
No answer so far regarding the results of my Altec 604 D TS.Those have been reconed by GPA and the QTS are respectively at 0.29 and 0.30 when they should be around 0.21.(Altec 604 E specs) despite 2 weeks of burning in with all kind of music.Is this difference in QTs important and is there a way to fix it?
Thanks for your reply.
Charles.

GM · February 26th, 2012, 04:43 AM

FWIW, I've accumulated quite a few sets of measured specs from all but the original duplex and none have been close to having a 0.21 Qts except the 617-8A ceiling speaker. That said, the E series have averaged ~0.33 with the K-L ~0.27, so apparently the re-cone kits are for the newer series and your old magnets either weren't, or couldn't be, re-magnetized enough to drop Qes/Qts any lower.

Regardless, unless you couple them to a matching impedance, they are plenty low enough for excellent performance and matched closer than many modern drivers.

GM