Fostex FF125K 4.5" speaker - Page 2 - diyAudio
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Old 24th April 2005, 06:21 AM   #11
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Join Date: Apr 2005
Location: Washington state
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Thanks for the help with the websites for driver measurements.
I have also been studing the TS parameter definitions and hope to gain some good knowledge that I can apply in the near future.
I have plenty of drivers that I bought in China that I have no specs for, so I have much work ahead of me.

Today I finished a new pair of bass reflex cabinets for my stereo.
The old speakers were, a pair of tweeters from Norway, the OLD
OLD style Jordan aluminum cone drivers from the 70's for the mid
range, and the Dayton 6 & 1/2" woofer that Partsexpress sells that seems to be so popular. The ancient crossovers were from a place called McGee Electronics.

I removed the woofer from the .98 cu. ft. box and went to work with the saber saw using the scroll to cut out a larger hole for a new 8" aluminum cone woofer from MCM. It has a FS of 45 HZ.
Using the port calculator at a few websites I came up with a decent figure for the tube length. The 8" woofer is far better suited for the .98 cu ft cabinet compared to the smaller woofer. It has much more output, sounds cleaner and goes lower. I used minimal stuffing at the base of the cabinet.

I built a separate box for the midrange, tweeter and crossover. The midrange unit has an aluminum-magnesium cone, is about 4.5 inches in diameter, and has a rubber suspension. By the looks of it I would guess the FS to be about 90 - 110 HZ. The tweeter is a soft dome unit. Both the mid and tweeter are made in Shanghai, China. The company name is T & T. They are both English designs. Crossover points are 375 HZ and 3,000 HZ and the crossover is the Partsexpress unit.

I would like to reduce the output of the mid and tweeter just a little. The woofer is rated at 86 db spl. The mid and tweeter are rated at 89 db spl. I need advice on the resistor value that I should use to reduce the mid and tweeter by about 1 or 2 db.
One ohm ? Two ohms? .5 ohm ? And where should I put the resistors? In series with the positive terminal of the drivers ? I am hoping not to do any mods to the crossovers, just to cut the output of the mid and tweet a bit .

I am hoping to build some classic TL lines in the future, and that is what part of this thread is about. I have a nice pair of 10" woofers that I purchased in Shenzhen in 2003. Big magnets, 2"
v.c. , ribbed cone with treated cloth suspension, large diameter spyder, aluminum basket. I am guessing maybe a high BL figure and low QMS figure. So maybe good for a TL cabinet . I will try to purchase a multimeter, signal generator, and the other things needed to obtain the TS parameters. I have heard about the q-wave website , but I have much to learn.

I have tried to attach a picture of the woofer, but it has too much info, so I will have to do this later on.

Thank you everyone for your thought and ideas .
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