It looks like there are not so many people that ended up buying the Fostex FX120, despite there seems to be a widespread good opinion about this driver. WEll, I guess I will now confirm what I basically wrote a couple of years ago.
PROS:
The FX 120 is defintely a great fullrange driver. Even in a cardboard box, it's in my opinion better than RS 40-1197, FE83 (unfair comparison, I know) and most bookshelf 2-way commercial speakers.
So far I tried only 12lt. BR in two very different enclosures with simialr results. It has a great and full midrange, including the lower end of voice frequencies, which is what most small speakers totally lack. Mids and higher freq. are never harsh tough or unbalanced. You never get that cheap-whizzer-cone feeling. I imagine someone may want a super-tweeter, but...not the readers of this forum section, I guess ! 😀
CONS:
that boomy (and slow, somehow) bass you get from a BR is just not good. It does not match the great great job the driver is doing above 100Hz!
Now, I know, I know, it's a 5" fullrange and it not supposed to go down to 20Hz and I was too lazy to try a TQWT, but this speaker needs help in the lowest freq. range.
Another so-to-say disappointing feature is that it took FOREVER to break in. Weeks of listening and then one day the magic happens. Not talking about a small difference either!😱
THE PROJECT :
I recently bought "by chance" two RS 40-1301A 15" woofers for a few dollars 😀 and was thinking about a design like linkwitz's orion. Open baffle FX120 (unfiltered of course) + RS 15" woofer in BR or sealed. The requirement for these woofer is ultimately to fill a little gap, I don't need to get every last Hz out of them. Unfortunately I don't have any datasheet about these RS drivers.
Can anyone help ? What are the critical parts of such a design ?
thanks,
Lorenzo
P.S. attached RS 40-1301a pic
PROS:
The FX 120 is defintely a great fullrange driver. Even in a cardboard box, it's in my opinion better than RS 40-1197, FE83 (unfair comparison, I know) and most bookshelf 2-way commercial speakers.
So far I tried only 12lt. BR in two very different enclosures with simialr results. It has a great and full midrange, including the lower end of voice frequencies, which is what most small speakers totally lack. Mids and higher freq. are never harsh tough or unbalanced. You never get that cheap-whizzer-cone feeling. I imagine someone may want a super-tweeter, but...not the readers of this forum section, I guess ! 😀
CONS:
that boomy (and slow, somehow) bass you get from a BR is just not good. It does not match the great great job the driver is doing above 100Hz!
Now, I know, I know, it's a 5" fullrange and it not supposed to go down to 20Hz and I was too lazy to try a TQWT, but this speaker needs help in the lowest freq. range.
Another so-to-say disappointing feature is that it took FOREVER to break in. Weeks of listening and then one day the magic happens. Not talking about a small difference either!😱
THE PROJECT :
I recently bought "by chance" two RS 40-1301A 15" woofers for a few dollars 😀 and was thinking about a design like linkwitz's orion. Open baffle FX120 (unfiltered of course) + RS 15" woofer in BR or sealed. The requirement for these woofer is ultimately to fill a little gap, I don't need to get every last Hz out of them. Unfortunately I don't have any datasheet about these RS drivers.
Can anyone help ? What are the critical parts of such a design ?
thanks,
Lorenzo
P.S. attached RS 40-1301a pic
Attachments
FX120
Hi,
I have had the FX120 in a sealed 6,5liter volume. It is a grat driver but you need a sub/bass under it. But I would use a 8" bass. A 15" is tooo big. It will not match with the sound of the Fostex.
Hi,
I have had the FX120 in a sealed 6,5liter volume. It is a grat driver but you need a sub/bass under it. But I would use a 8" bass. A 15" is tooo big. It will not match with the sound of the Fostex.
Re: FX120
Yes. I've built other speakers before and would agree 8" can do almost anything you want, but I don't want to buy new drivers if I don't have to. I'm sure I can get the 15" to work in the right way, my concerns would be more on directivity and speed... these thing have a small magnet and a big plastic cone.
I also must say I love the sound of big PAPER cones.
However I found this and may soon change my project:
http://jamo.com/Default.aspx?ID=2250&M=Shop&PID=15707&ProductID=17723
and can't get it out of my mind 😀 !
what do you think ? are 4 eminence alpha worth a shot ?
L.
Roemhild said:
Yes. I've built other speakers before and would agree 8" can do almost anything you want, but I don't want to buy new drivers if I don't have to. I'm sure I can get the 15" to work in the right way, my concerns would be more on directivity and speed... these thing have a small magnet and a big plastic cone.
I also must say I love the sound of big PAPER cones.
However I found this and may soon change my project:
http://jamo.com/Default.aspx?ID=2250&M=Shop&PID=15707&ProductID=17723
and can't get it out of my mind 😀 !
what do you think ? are 4 eminence alpha worth a shot ?
L.
OB all the way!
Hi Lorenzo,
The Jamo configuration is very close to how I plan to use my FX120's, although I will use a wider baffle and without a tweeter. I have several cheap 15" subwoofer drivers for that project. I have done several speaker projects using fullrangers or widerangers on OB sitting on BR boxes, and they worked out nicely, but I still like dipolar bass better.
My FX120 drivers are still new in boxes. Nevertheless, I once helped a friend put together a pair of OB speakers, each of which used the FX120 from about 250Hz up, a 12" driver from about 250 to 100Hz, and a Dayton IB 15" woofer for the lower bass. All the drivers were mounted on a simple open baffle. Active crossover and EQ for the dipolar bass was used. Even though the system was quickly slapped together, the sound was very nice and showed a lot of potential. He moved away shortly after that so I do not know how that system sounds now. A two-way system using the FX120 on OB augmented by a woofer for dipolar bass will be simpler to build, and I'm pretty sure that such a system will sound very good. I have pretty high hope for my FX120+Woofers OB system, and would expect that system to sound quite natural and neutral.
Without knowing the parameters of your RS woofers, it is hard to tell whether they will be suitable for the OB application, but it is worth a try, although more likely than not you'll need to EQ the bass. Also, as ScottMoose said, you may want to consider using an active crossover, which will reduce the excursion of the FX120 and may make driver integration easier.
Ciao,
Kurt
Hi Lorenzo,
The Jamo configuration is very close to how I plan to use my FX120's, although I will use a wider baffle and without a tweeter. I have several cheap 15" subwoofer drivers for that project. I have done several speaker projects using fullrangers or widerangers on OB sitting on BR boxes, and they worked out nicely, but I still like dipolar bass better.
My FX120 drivers are still new in boxes. Nevertheless, I once helped a friend put together a pair of OB speakers, each of which used the FX120 from about 250Hz up, a 12" driver from about 250 to 100Hz, and a Dayton IB 15" woofer for the lower bass. All the drivers were mounted on a simple open baffle. Active crossover and EQ for the dipolar bass was used. Even though the system was quickly slapped together, the sound was very nice and showed a lot of potential. He moved away shortly after that so I do not know how that system sounds now. A two-way system using the FX120 on OB augmented by a woofer for dipolar bass will be simpler to build, and I'm pretty sure that such a system will sound very good. I have pretty high hope for my FX120+Woofers OB system, and would expect that system to sound quite natural and neutral.
Without knowing the parameters of your RS woofers, it is hard to tell whether they will be suitable for the OB application, but it is worth a try, although more likely than not you'll need to EQ the bass. Also, as ScottMoose said, you may want to consider using an active crossover, which will reduce the excursion of the FX120 and may make driver integration easier.
Ciao,
Kurt
its tough...
I tried the fx 120 in BIB horns (see other forum) and the results were great. the bass speed of the fx120 is not the best though. I tend to prefer the effect of low qts on bass in general. it got quantity, but not that last air of refinement present in the midrange of the driver. so the sound in the end was less coherent than I desired. I am splitting hairs here though. none of my freinds ever knew the difference. all they thought was "geez, all that bass out of a 2.5 inch cone?" my favourite midrange out of the 120 so far was when it was in an open baffle. pretty quick but very even frequency wize
I would use a nice active EQ at 100- 130 or so hz, 9-12db roll off with a cheap 10 inch pro sound (emminence) woofer from parts express. you could run the fx120 full range (better sound) or EQed (more volume). the pro sound woofers (i think it is emminence alpha) are cheap, and the qts of the woofer is suited to OB I think. the speeds should match OK. the sound should be real big.
I saw a project to this effect a little while back on an american website. I forget the name though. shoulda wrote it down.
well, good luck.
Clark
I tried the fx 120 in BIB horns (see other forum) and the results were great. the bass speed of the fx120 is not the best though. I tend to prefer the effect of low qts on bass in general. it got quantity, but not that last air of refinement present in the midrange of the driver. so the sound in the end was less coherent than I desired. I am splitting hairs here though. none of my freinds ever knew the difference. all they thought was "geez, all that bass out of a 2.5 inch cone?" my favourite midrange out of the 120 so far was when it was in an open baffle. pretty quick but very even frequency wize
I would use a nice active EQ at 100- 130 or so hz, 9-12db roll off with a cheap 10 inch pro sound (emminence) woofer from parts express. you could run the fx120 full range (better sound) or EQed (more volume). the pro sound woofers (i think it is emminence alpha) are cheap, and the qts of the woofer is suited to OB I think. the speeds should match OK. the sound should be real big.
I saw a project to this effect a little while back on an american website. I forget the name though. shoulda wrote it down.
well, good luck.
Clark
Re: its tough...
Yes, I have to measure the parameters. I don't have all the equipment yet and it looks like it will be hard to get any info from radioshack.
I may sell them on ebay 🙂 e save for eminence woofers, which have the high qts I need.
What is the difference in an OB between 2 and 4 woofers, in your opinion ? A great improvement?
Well, same question for you : 1 or 2 woofers per channel ? They;re not that expensive....
thanks
L.
KCHANG said:
Yes, I have to measure the parameters. I don't have all the equipment yet and it looks like it will be hard to get any info from radioshack.
I may sell them on ebay 🙂 e save for eminence woofers, which have the high qts I need.
What is the difference in an OB between 2 and 4 woofers, in your opinion ? A great improvement?
blumenco said:
Well, same question for you : 1 or 2 woofers per channel ? They;re not that expensive....
thanks
L.
Go for 8!
Hi L.:
If you have the space on the OB and are willing to spend the money on the drivers, I'd recommend using at least two woofers per side. Using two woofers instead of one would significantly reduce the excursion of each woofer, which is an important consideration for dipolar operation. It may also be an important factor when you use cheaper drivers that normally do not have much excursion capability. Also, the enhanced coupling to air at the longer wavelengths provided by the increased moving surface area may also reduce the bass boost needed.
In my main speaker system, which uses 75" line-source drivers from 180Hz up, I have four 18" woofers on OB on each side for dipolar bass. The 8 woofers together provide a large total moving surface area, and the drivers are barely visibly moving even when playing japanese drum music at a floor-shaking level.
As to the Eminence Alpha drivers, if you are referring to the 15" one, I'd not choose it for OB, mainly because of its highish Fs. This may not be a problem for you, however, if you intend to use a separate subwoofer for the deep bass. Its Xmax is not very impressive, but might be OK if you use two or more drivers. Also, its Qts is quite hight. I don't like high-Q drivers in general, and prefer to use a driver of a lower Qts (but >0.4) and EQ it to get the bass right. You may want to consider the Dayton IB 385-8 15" woofer (PE295-455), which is great for OB, with its Fs of 20.8Hz, Qts of 0.65, and Xmax of 14.3mm, and a price of $110 each when you buy 4. One of this driver will equal 3 or 4 of the Eminence Alpha 15" in terms of excursion and will give almost one octave more bass extension.
Kurt
Hi L.:
If you have the space on the OB and are willing to spend the money on the drivers, I'd recommend using at least two woofers per side. Using two woofers instead of one would significantly reduce the excursion of each woofer, which is an important consideration for dipolar operation. It may also be an important factor when you use cheaper drivers that normally do not have much excursion capability. Also, the enhanced coupling to air at the longer wavelengths provided by the increased moving surface area may also reduce the bass boost needed.
In my main speaker system, which uses 75" line-source drivers from 180Hz up, I have four 18" woofers on OB on each side for dipolar bass. The 8 woofers together provide a large total moving surface area, and the drivers are barely visibly moving even when playing japanese drum music at a floor-shaking level.
As to the Eminence Alpha drivers, if you are referring to the 15" one, I'd not choose it for OB, mainly because of its highish Fs. This may not be a problem for you, however, if you intend to use a separate subwoofer for the deep bass. Its Xmax is not very impressive, but might be OK if you use two or more drivers. Also, its Qts is quite hight. I don't like high-Q drivers in general, and prefer to use a driver of a lower Qts (but >0.4) and EQ it to get the bass right. You may want to consider the Dayton IB 385-8 15" woofer (PE295-455), which is great for OB, with its Fs of 20.8Hz, Qts of 0.65, and Xmax of 14.3mm, and a price of $110 each when you buy 4. One of this driver will equal 3 or 4 of the Eminence Alpha 15" in terms of excursion and will give almost one octave more bass extension.
Kurt
geez,
well, kchang, it sounds like you have a very seriously dynamic system... that is awesome. I have a few horn subs with 18s in them. they will rock a partay.
I was only referring to the 10 inch alpha. it is like 40 bucks or so. i guess you could use two per side. i personally would be happy with just one per side though. i guess it depends on room/ preference.
clark
well, kchang, it sounds like you have a very seriously dynamic system... that is awesome. I have a few horn subs with 18s in them. they will rock a partay.
I was only referring to the 10 inch alpha. it is like 40 bucks or so. i guess you could use two per side. i personally would be happy with just one per side though. i guess it depends on room/ preference.
clark
Horn subs!
Hi Clark,
What's the design of your horn subs with18 inchers? How low do they go? I bought four Eminence LAB-12 drivers with the intent to build two LAB horns, but those drivers have been sitting there gathering dust for almost 3 years. Too many projects, too many drivers too try, and too little time!
I've heard Dr. Edgar's Titan system several times, and I think the ability of the eight 18" dipolar woofers to move air is close to that of the Seismic sub. Don't know about the dynamics. To me, if a flute sounds like a flute through the system, I'm happy. How often do people say: "Boy, that flute sounds so dynamic!"? 😉
Kurt
Hi Clark,
What's the design of your horn subs with18 inchers? How low do they go? I bought four Eminence LAB-12 drivers with the intent to build two LAB horns, but those drivers have been sitting there gathering dust for almost 3 years. Too many projects, too many drivers too try, and too little time!
I've heard Dr. Edgar's Titan system several times, and I think the ability of the eight 18" dipolar woofers to move air is close to that of the Seismic sub. Don't know about the dynamics. To me, if a flute sounds like a flute through the system, I'm happy. How often do people say: "Boy, that flute sounds so dynamic!"? 😉
Kurt
Re: Go for 8!
Ok, I still need to read more about the optimal paramenters for my OB, but there are definitely some problems right away :
- price (what a horrible person am I ? first thing in my mind is money! ) eminence 15" are something like 60$ each, shipped; 12"inches, which still have intersting parameters [Qts: .77 * Xmax: 2.4 mm] are10$ less.
4x18" or even 4x15" per channel are an overkill. unless...read on.
- bass extension & quality, two different things. I really don't need a earthquake at home and never believed in high-excursion drivers. I always had the feeling that yes, you get down to 10Hz but it's a big slow rumble that takes over the whole soundscene. Not my thing.
I prefer the sound of big and fast paper cones that maybe don't go that far low in terms of frequencies, but they keep up with the speed of the other speakers.
I had a Ciare 18" in a huge selaed box long ago [my attempt to clone B&W 801!] and I remember that speaker was hard as a rock, but drums would sound so alive...
My only doubt is now : will two 15" in an OB give me roughly the bass extension of a 10-12" in a box? Granted, without all the problems of the sealed enclosure and with an overall better dynamic
thanks
L.
KCHANG said:
Ok, I still need to read more about the optimal paramenters for my OB, but there are definitely some problems right away :
- price (what a horrible person am I ? first thing in my mind is money! ) eminence 15" are something like 60$ each, shipped; 12"inches, which still have intersting parameters [Qts: .77 * Xmax: 2.4 mm] are10$ less.
4x18" or even 4x15" per channel are an overkill. unless...read on.
- bass extension & quality, two different things. I really don't need a earthquake at home and never believed in high-excursion drivers. I always had the feeling that yes, you get down to 10Hz but it's a big slow rumble that takes over the whole soundscene. Not my thing.
I prefer the sound of big and fast paper cones that maybe don't go that far low in terms of frequencies, but they keep up with the speed of the other speakers.
I had a Ciare 18" in a huge selaed box long ago [my attempt to clone B&W 801!] and I remember that speaker was hard as a rock, but drums would sound so alive...
My only doubt is now : will two 15" in an OB give me roughly the bass extension of a 10-12" in a box? Granted, without all the problems of the sealed enclosure and with an overall better dynamic
thanks
L.
Dual 15" OB v. 10-12" in a box
Hi L.:
Without knowing the parameters for the 15" and the 10-12" drivers, there is of course not enough information to compare the bass extension of the two. Nevertheless, since you used the word "roughly," I'd say that two 15" in an OB have a good chance of out-performing a 10-12" in a box in terms of overall bass quality, and can have as good or better extension if the Fs of the 15" driver is lower than that of the smaller driver. With a woofer on an OB, you can get the bass extension roughly down to the Fs, with some EQ if necessary. As to "bass quality," especially the "dynamic" aspect, I suspect it has a lot to do with the efficiency of the woofer's coupling to the air, and that's perhaps why many people like the "quality" of the bass generated by a bass horn. Two 15" have 3-4 times the surface area of that of a 10-12", so I'd expect them to do pretty well, as long as the frequency response is not too lumpy or irregular.
Have fun,
Kurt
Hi L.:
Without knowing the parameters for the 15" and the 10-12" drivers, there is of course not enough information to compare the bass extension of the two. Nevertheless, since you used the word "roughly," I'd say that two 15" in an OB have a good chance of out-performing a 10-12" in a box in terms of overall bass quality, and can have as good or better extension if the Fs of the 15" driver is lower than that of the smaller driver. With a woofer on an OB, you can get the bass extension roughly down to the Fs, with some EQ if necessary. As to "bass quality," especially the "dynamic" aspect, I suspect it has a lot to do with the efficiency of the woofer's coupling to the air, and that's perhaps why many people like the "quality" of the bass generated by a bass horn. Two 15" have 3-4 times the surface area of that of a 10-12", so I'd expect them to do pretty well, as long as the frequency response is not too lumpy or irregular.
Have fun,
Kurt
Re: Dual 15" OB v. 10-12" in a box
I was basically sticking to the idea of eminence woofers, alpha series to cut on the cost. I guess the 15" should do well in an OB. Look at the specs below. You mentioned air coupling, a great concept, it would require a forum section on its own 🙂
I always had he feeling it's quite an unpredictable thing, expecially on cheap speakers; but from large paper cones, I'd expect a good, fast performance in the mid-bass range.
eminence A 10" :
Fs 50Hz qts 0.59 vas 82.2lt. thanks, but no, thanks.
eminence A 15":
Fs 41Hz qts 1.25 vas 260lt
Btw, 41Hz is really fine with me. I have to figure out the effects of this impressive qts now...perhaps sell my NADs and get a few gainclones and go wild with EQ!
thanks all
L.
KCHANG said:
I was basically sticking to the idea of eminence woofers, alpha series to cut on the cost. I guess the 15" should do well in an OB. Look at the specs below. You mentioned air coupling, a great concept, it would require a forum section on its own 🙂
I always had he feeling it's quite an unpredictable thing, expecially on cheap speakers; but from large paper cones, I'd expect a good, fast performance in the mid-bass range.
eminence A 10" :
Fs 50Hz qts 0.59 vas 82.2lt. thanks, but no, thanks.
eminence A 15":
Fs 41Hz qts 1.25 vas 260lt
Btw, 41Hz is really fine with me. I have to figure out the effects of this impressive qts now...perhaps sell my NADs and get a few gainclones and go wild with EQ!
thanks all
L.
By the way, reminding that FX120 is a 90db driver....I think a quality 12" hifi woofer in closed box will do very nicely
I'm presently thinking of trying the FX120 with a pdn.2450 (slot loaded) in a OB configuration, hoping that the slot will eq the response of the pdn.2450 (the raise in response with frequency) and sensitivity match it using series resistance.
Crazy ?
Crazy ?
Not necessarily, although it's a trifle left-field. Depends on implementation as to how well it will work out, and you are really the only one who can comment on that. 😉 For what it's worth, I see no insurmountable problems / objections, so it should be possible with a bit of jiggery, and if you will, pokery.
- Status
- Not open for further replies.