Fostex FF125K 4.5" speaker
I am going to be building some transmission line stereo cabinets soon and I am looking for advice on some mid range speakers. The crossover points will be 160 HZ and 3,000 HZ. I have a budget that I am working with and do not want to spend more than about $40 to $45 for each mid range unit. I have seen in the Madisound catalog that there is a nice Fostex speaker, model
number FF125K. It is a 4.5" unit that is 8 ohms, has a 92 db spl,
and is rated at 50 watts (peak, I think). It has a free air resonance of 72 HZ. The freq graph looks pretty flat from 150 HZ
to 3,500 HZ. This is a full range speaker, but it fits into my price range and I like the freq graph for the crossover points that I will be using.
Does anybody have any suggestions for other mid range units that I could use that are within my design and price limits ?
Thanks ! !
I am going to be building some transmission line stereo cabinets soon and I am looking for advice on some mid range speakers. The crossover points will be 160 HZ and 3,000 HZ. I have a budget that I am working with and do not want to spend more than about $40 to $45 for each mid range unit. I have seen in the Madisound catalog that there is a nice Fostex speaker, model
number FF125K. It is a 4.5" unit that is 8 ohms, has a 92 db spl,
and is rated at 50 watts (peak, I think). It has a free air resonance of 72 HZ. The freq graph looks pretty flat from 150 HZ
to 3,500 HZ. This is a full range speaker, but it fits into my price range and I like the freq graph for the crossover points that I will be using.
Does anybody have any suggestions for other mid range units that I could use that are within my design and price limits ?
Thanks ! !
I had a pair of the older made in japan FF125. They make very good high resolution midranges in a 3 way, and are one of the best bangs for bucks in the fostex line IMO. I think i like the mids a bit more in the FE108EZ, but the freq extremes might actually be a bit better with the cheaper FF. Both are sweet and musical. It'd sound harsh with SS probably.
HOWEVER, this is a horn driver, and as such it has rising response that you will need to deal with. My lowpass ended up looking more like 3rd order with a damping resistor on the shunt. It's not going to be 92db all the way down to 150hz unless horn loaded. I would actually cross it higher and use a clean midbass/woofer for maximum efficiency. I ended up using a 3500 crossover point, but for best integration I glued a felt disk over the metal dustcap. It was also very good run stock, with a piezo supertweeter crossed in very high. Makes a good full range too, with a cheap highish DCR small gauge aircore choke to flatten the response.
GB
HOWEVER, this is a horn driver, and as such it has rising response that you will need to deal with. My lowpass ended up looking more like 3rd order with a damping resistor on the shunt. It's not going to be 92db all the way down to 150hz unless horn loaded. I would actually cross it higher and use a clean midbass/woofer for maximum efficiency. I ended up using a 3500 crossover point, but for best integration I glued a felt disk over the metal dustcap. It was also very good run stock, with a piezo supertweeter crossed in very high. Makes a good full range too, with a cheap highish DCR small gauge aircore choke to flatten the response.
GB
Thank you for your thoughts and ideas. I have a pair of titanium tweeters that I bought at MCM Electronics, part number 53-530.
I will also consider the Dayton planar tweeter that costs about
$29 in the Parts Express catalog. I will cross the tweeters over at 3 or 3.5 K using a 12 or 18 db unit. I will build a separate box for the mid range, tweeter and crossover, so that I can experiment a bit.
The woofer is a 10" unit. I am lacking on the thiel parameters for the unit. About all that I know is, it is 8 ohms, has a free air res
of about 35 or 40 HZ, has a 2" voice coil, big magnet, and is rated to handle 370 watts peak power. It has a treated accordian cloth suspension, and the cone is ribbed. The spyder is a large diameter type. It has a cast aluminum basket. The unit is made in Guangzhou, China, by the Ming Hua Mfg. Co. I bought it in 2003 during a visit to Shenzhen.
After more thought, research and advice, I will build a pair of transmission line cabinets for the woofers. The quarter wave line length of a 38 -40 HZ wave should be about 7.5 feet. The classical design is what I am leaning toward, with a tapered line and a slot at the end. I may experiment using a block of wood to seal the slot, and also place a bass reflex tube in the block of wood, to try and fine tune the enclosure. I will only let the woofer go up to about 150 or 160 HZ, and then cross it over to the Fostex FF125 K unit. I am hoping that the TL line will go down to 30 HZ accurately and cleanly, perhaps lower.
Back in 1980 I actually built two pair of TL cabinets for my stereo system. The first pair used 10" woofers with a slot at the end. The second pair used 12" woofers and passive radiators at the end of the line. Both were pretty good considering the era back then. And considering that I had not the slightest idea what I was doing. However, I am pretty good at working with wood, as I have built many cabinets in the past for my electric guitar and various stereo setups.
Another question is this: Is MDF really sonically better than 3/4 inch marine plywood ? Almost all of the cabinets that I have built in the past have been with high grade plywood. Perhaps the TL cabinets should be MDF ? Your thoughts and ideas please.
Any thoughts and ideas regarding the classic TL would be appreciated, thanks.
I will also consider the Dayton planar tweeter that costs about
$29 in the Parts Express catalog. I will cross the tweeters over at 3 or 3.5 K using a 12 or 18 db unit. I will build a separate box for the mid range, tweeter and crossover, so that I can experiment a bit.
The woofer is a 10" unit. I am lacking on the thiel parameters for the unit. About all that I know is, it is 8 ohms, has a free air res
of about 35 or 40 HZ, has a 2" voice coil, big magnet, and is rated to handle 370 watts peak power. It has a treated accordian cloth suspension, and the cone is ribbed. The spyder is a large diameter type. It has a cast aluminum basket. The unit is made in Guangzhou, China, by the Ming Hua Mfg. Co. I bought it in 2003 during a visit to Shenzhen.
After more thought, research and advice, I will build a pair of transmission line cabinets for the woofers. The quarter wave line length of a 38 -40 HZ wave should be about 7.5 feet. The classical design is what I am leaning toward, with a tapered line and a slot at the end. I may experiment using a block of wood to seal the slot, and also place a bass reflex tube in the block of wood, to try and fine tune the enclosure. I will only let the woofer go up to about 150 or 160 HZ, and then cross it over to the Fostex FF125 K unit. I am hoping that the TL line will go down to 30 HZ accurately and cleanly, perhaps lower.
Back in 1980 I actually built two pair of TL cabinets for my stereo system. The first pair used 10" woofers with a slot at the end. The second pair used 12" woofers and passive radiators at the end of the line. Both were pretty good considering the era back then. And considering that I had not the slightest idea what I was doing. However, I am pretty good at working with wood, as I have built many cabinets in the past for my electric guitar and various stereo setups.
Another question is this: Is MDF really sonically better than 3/4 inch marine plywood ? Almost all of the cabinets that I have built in the past have been with high grade plywood. Perhaps the TL cabinets should be MDF ? Your thoughts and ideas please.
Any thoughts and ideas regarding the classic TL would be appreciated, thanks.
barth2102 said:
Classic lines are more often than not, less than optimal... measuring the T/S of your bass drivers would give you a real edge on getting the most out of them. If you do just wing it, start the line at, say, 3 Sd, and offset the driver (the ratio in the MJK tables would be what i'd choose)
dave
That's for sure. There is no point in torturing yourself anymore with ROT cut and try methods for TL design IMO. See Martin King's website and read everything would be my advice. If you must, a moderate Qts driver will typically work OK in a classic TL, though it's better to have a bit higher Qms than is normal for sealed box type drivers. Just a warning - I cut up lots of failed TLs in the bad old days.
Those drivers may be OK, but I wouldn't hesitate to use the fostex can hold it's own with much more expensive types. It may be better sounding without a tweeter. The TL's I built using the FF125 as a mid used a focal 10W something for the woofer. I crossed the mid at about 650 and 3600hz first order (acoustically).
Between the crossover and winging it on the TL, this project may be a bit of a challenge.
GB
Those drivers may be OK, but I wouldn't hesitate to use the fostex can hold it's own with much more expensive types. It may be better sounding without a tweeter. The TL's I built using the FF125 as a mid used a focal 10W something for the woofer. I crossed the mid at about 650 and 3600hz first order (acoustically).
Between the crossover and winging it on the TL, this project may be a bit of a challenge.
GB
I want to thank you all for your thoughts and ideas. Okay, so I need to measure the woofer to get the thiel parameters. I have no test equipment and no knowledge of how to do this. Please recommend a good starting point for this, such as reading material and perhaps test equipment. I am within a few hours drive of Seattle. Is there any place that I can go in Seattle to have this test done ?
I think that the 10" woofer that I may use is a pro sound unit, not really intended for hi-fi use. But if it has decent spl and will go to 30 HZ cleanly, I would like to use it. I also have some aluminum cone 10" woofers from MCM. They have a fs of 34 HZ, and I do have all the thiel parameter specs on them. If both pair of units are at all close in the specs, I would like to experiment with them
to see which pair sound best.
If a classic TL is not optimum, can anyone suggest a more efficient TL design ?
In my next reply, I will try to attach a picture of the 10" pro driver from China. I have a bunch of other drivers from China, with aluminum magnesium cones like the hi-vi units, but I have no thiel
specs on these units either .
thanks again everyone !
I think that the 10" woofer that I may use is a pro sound unit, not really intended for hi-fi use. But if it has decent spl and will go to 30 HZ cleanly, I would like to use it. I also have some aluminum cone 10" woofers from MCM. They have a fs of 34 HZ, and I do have all the thiel parameter specs on them. If both pair of units are at all close in the specs, I would like to experiment with them
to see which pair sound best.
If a classic TL is not optimum, can anyone suggest a more efficient TL design ?
In my next reply, I will try to attach a picture of the 10" pro driver from China. I have a bunch of other drivers from China, with aluminum magnesium cones like the hi-vi units, but I have no thiel
specs on these units either .
thanks again everyone !
It's actually a lot easier to test T/S parameters than you might think. I know there's an online tutorial or two somewhere. Perhaps someone will chime in. All you really need is a multimeter and a couple resistors. You can use your computer for a signal generator.
Which MCM drivers do you have? The cheap MI drivers they sell are fairly well suited to 'classic' TLs.
GB
Which MCM drivers do you have? The cheap MI drivers they sell are fairly well suited to 'classic' TLs.
GB
Here is the technique i use (but hopefully not for long -- FuzzMeasure should have T/S generation really soon now).
http://www.diysubwoofers.org/measure.htm
dave
http://www.diysubwoofers.org/measure.htm
dave
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 .
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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