I ordered a pair of MCM 55-5670 8 inch woofers the other day. They look good on paper and they meet my design criteria. I tried to shoot some measurements with my DATS V3 but I keep getting this little bump at around 800hz. The impedance curve looks right. But the software considers this little bump the Fs and sometimes gives really high Q numbers and sometimes nothing for Q. Twice I've been able to get some realistic numbers. I played music through them for about 6 hours today and then tried measurements again and got the same results. Has anybody had this happen to them? Do I just need to break them in more? Or is there something wrong with these woofers?
I'm very interested in the numbers that you come up with for Qes,Qms,Qts and Vas. I've entered in to Winisd the TS Param for about 80% of the MCM drivers and thinking about buying a pair. A few people on forums stated that for certain models their measured Qts was double the manufacturers specs. Somewhat higher Qts is not unusual but double is a little hard to accept. I like the 7.5mm xmax of 55-5670. Cheers!
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A few people on forums stated that for certain models their measured Qts was double the manufacturers specs
I should have said "Double the Volume"
Fs 37.31, Qts 0.4656, Qes 0.6554, Qms 1.607, Vas 84L
With these numbers I get a 2db rise with 56L
I'm thinking sealed mid bass crossed low in a 4way, or 3way.
They look good on paper and they meet my design criteria. I tried to shoot some measurements with my DATS V3 but I keep getting this little bump at around 800hz.
No experience with DATs, but tall, relatively stiff [at least when new], rubber surrounds can create fairly strong eigenmodes with its odd harmonics being peaks = ~13543/3/800 = ~5.64", so is this ~the inside diameter of the surround?
GM
OK, the resonance will occur somewhere between the surround's base and top, so likely the reason.
Maybe better to do a current measurement: Read Research - Articles - Measuring Thiele-Small Parameters - Page 3
GM
Maybe better to do a current measurement: Read Research - Articles - Measuring Thiele-Small Parameters - Page 3
GM
After a healthy dose of nothing but low frequencies, yesterday and again today, I was hoping for some lower numbers. But the woofers measure the same. At least both woofers measure pretty close together in spec. The resonance at 800hz is still there but I've found if I have the driver at a slight angle, I can get a valid measurement
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