well gentlemen! thank you for discuss.
but do you agree, ANY solution have to work? I have a lot of it. very differing, for any different tastes.
and now I want to bring about fullrange 2 way loudspeaker, including active part - 30-80 Hz.
dear Scottmoose, what should be with F200A into small sealed box? 25 litres. it's has Q<then 60. isn't it?
what's happening should I place 2 pcs F200A over there? Vas don't=2*Vas as well. do you agree. it's just add 1driver volume.
so, I'll get Q of this system about 0.5. what's it looks like? Bessel. acoutic filtre.
variovent just help me for tune it up. it's not realy sealed. see the difference.
1) What sort of music do you listen to? - basicaly modern jazz
2) How large is your room and what shape? - it's for not a small one.
3) Where are you intending to put the speakers? - close a corner's on front side
4) How loud do you like to listen? - ideal - the same like concert hall. 120 db enough
but do you agree, ANY solution have to work? I have a lot of it. very differing, for any different tastes.
and now I want to bring about fullrange 2 way loudspeaker, including active part - 30-80 Hz.
dear Scottmoose, what should be with F200A into small sealed box? 25 litres. it's has Q<then 60. isn't it?
what's happening should I place 2 pcs F200A over there? Vas don't=2*Vas as well. do you agree. it's just add 1driver volume.
so, I'll get Q of this system about 0.5. what's it looks like? Bessel. acoutic filtre.
variovent just help me for tune it up. it's not realy sealed. see the difference.
1) What sort of music do you listen to? - basicaly modern jazz
2) How large is your room and what shape? - it's for not a small one.
3) Where are you intending to put the speakers? - close a corner's on front side
4) How loud do you like to listen? - ideal - the same like concert hall. 120 db enough
Hi Yury
I know exactly what variovents are -I've used them in the past. What you create with them is an aperiodic enclosure, which is in practical terms a half-way point between a regular vented enclosure and a sealed box.
2 drivers in 1 enclosure? Nothing fancy about it. Sd doubles, Vas doubles, if you wire in parallel Re and Zvc halve, if you wire in series, Re and Zvc double. That's it. So if you want to use 2 drivers in an enclosure, it will need to be double the volume of an enclosure using a single driver.
Try this. 2 Fostex F200a mounted in bipolar configuration in a box of these internal dimensions: 20Cm wide x 20 cm deep x 62.5cm tall. Drivers 15.25cm down from the top, one on the front baffle, one on the rear. That'll get you down to around 80Hz, without baffle-step problems, and with circa 90db for 1w sensitivity. The subs you can sort out from there. You'll need to run them at the upper end of their range. Still not quite ideal, as you should really cross a sub over 20 db before the main drivers roll off, but it'll work. Let me reiterate though: DON'T try putting both drivers on the front panel, unless you are willing to add a small filter to one of them, just to roll it off above, say, 500Hz, which would not damage the sound quality.
Best
Scott
I know exactly what variovents are -I've used them in the past. What you create with them is an aperiodic enclosure, which is in practical terms a half-way point between a regular vented enclosure and a sealed box.
2 drivers in 1 enclosure? Nothing fancy about it. Sd doubles, Vas doubles, if you wire in parallel Re and Zvc halve, if you wire in series, Re and Zvc double. That's it. So if you want to use 2 drivers in an enclosure, it will need to be double the volume of an enclosure using a single driver.
Try this. 2 Fostex F200a mounted in bipolar configuration in a box of these internal dimensions: 20Cm wide x 20 cm deep x 62.5cm tall. Drivers 15.25cm down from the top, one on the front baffle, one on the rear. That'll get you down to around 80Hz, without baffle-step problems, and with circa 90db for 1w sensitivity. The subs you can sort out from there. You'll need to run them at the upper end of their range. Still not quite ideal, as you should really cross a sub over 20 db before the main drivers roll off, but it'll work. Let me reiterate though: DON'T try putting both drivers on the front panel, unless you are willing to add a small filter to one of them, just to roll it off above, say, 500Hz, which would not damage the sound quality.
Best
Scott
Sorry Yuri: it's not wrong.
If you choose not to believe me, then go to Martin J. king's site at www.quarter-wave.com and take a good long read of his article on modelling two drivers in one enclosure.
Also read the loudspeaker design cookbook, which details the exact same method. One which I and many others have used for quite some time, both in theory, modelling drivers in MathCad for various enclosure tyopes, sealed, vented, double-bass reflex and TLs of all their different kinds, and in practice, in building enclosures.
Scott
If you choose not to believe me, then go to Martin J. king's site at www.quarter-wave.com and take a good long read of his article on modelling two drivers in one enclosure.
Also read the loudspeaker design cookbook, which details the exact same method. One which I and many others have used for quite some time, both in theory, modelling drivers in MathCad for various enclosure tyopes, sealed, vented, double-bass reflex and TLs of all their different kinds, and in practice, in building enclosures.
Scott
I would like to recommend the FF225k. It has a relatively laid back sound without the upper midrange peak of the whizzer-coned Fostexes. It does not quite get up to 20kHz, but to me that is not a big deal.
I don't see any problem using these in a small box designed to roll of around 60Hz, but I'm not sure you need 2 of them per channel. This will give you more efficiency, less cone movement, but I don;t think you will need it, and you will be sacrificing the imaging of a singla speaker. And you will have a 4 ohm load, which has it's own drawbacks.
jsn
I don't see any problem using these in a small box designed to roll of around 60Hz, but I'm not sure you need 2 of them per channel. This will give you more efficiency, less cone movement, but I don;t think you will need it, and you will be sacrificing the imaging of a singla speaker. And you will have a 4 ohm load, which has it's own drawbacks.
jsn
I'd tend to agree in many ways. I like the FF225K too; lovely driver. However, I didn't recommend it, because our friend wants to go for what appears to be replay levels set somewhere between thunder-clap and nuclear detonation in a large room, and the FF225K is extremely limited in excursion -.03mm Xmax. Hense my advocating the F200a. Whilst I now take Xmax with a pinch of salt, and you're not going to damage this driver at least by going beyond it, as the suspension limits excursion before the voice-coil is damaged, distortion will be pretty high. And in a sealed or aperiodic enclosure it'll be even worse as the efficiency is lower than other types. Going for 2 might help a bit there, though you're 100% right about the imaging suffering. Bipolar to my mind is the only solution -a little more diffuse than a single front-firing driver perhaps, but a whole lot better than 2 on the front baffle!
How do you load yours by the way?
Best
Scott
How do you load yours by the way?
Best
Scott
I apologise that I did not notice the requirement for nearfield jet engine playback levels.
For that, multiple drivers can sound very good. I recently rewired a pair of 8-driver line arrays similar to the Bottlehead Straight 8s for a 4 ohm load to be used with a 250W amp as party speakers. They are very loud and very clean. Lots of cones doing a little bit is better than one cone doing a lot, in the same way that a little power into a high efficiency speaker is better than a lot of power into something inefficient.
But anyway, yeah - go for a dipole.
Here are my ff225k speakers:
http://boozhoundlabs.com/ff225k/
They are in Martin King ported transmission line type boxes. I really like them, but cone excursion is a problem for playing loud or music with lots of very low bass below the tuning of the cabinet.
Remember that cone excustion in a fullrange driver also introduces doppler distortion, which I believe is one of the things keeping fullrangers from reaching thier full potential.
As another way to address the cone excursion problem, I am working on a 2 way using a large but relatively fullrange woofer (Eminence Alpha 10) beneath a small open baffle fullrange driver (Fostex FX120). My hope is that the woofer will move the air needed for low bass and negate the need for baffle step correction, leaving the fullrange driver to deliver the coherence and midrange we love so much. They are only barely mocked up so far, but are already sounding really good:
http://boozhoundlabs.com/fx120-alpha10/
jsn
For that, multiple drivers can sound very good. I recently rewired a pair of 8-driver line arrays similar to the Bottlehead Straight 8s for a 4 ohm load to be used with a 250W amp as party speakers. They are very loud and very clean. Lots of cones doing a little bit is better than one cone doing a lot, in the same way that a little power into a high efficiency speaker is better than a lot of power into something inefficient.
But anyway, yeah - go for a dipole.
Here are my ff225k speakers:
http://boozhoundlabs.com/ff225k/
They are in Martin King ported transmission line type boxes. I really like them, but cone excursion is a problem for playing loud or music with lots of very low bass below the tuning of the cabinet.
Remember that cone excustion in a fullrange driver also introduces doppler distortion, which I believe is one of the things keeping fullrangers from reaching thier full potential.
As another way to address the cone excursion problem, I am working on a 2 way using a large but relatively fullrange woofer (Eminence Alpha 10) beneath a small open baffle fullrange driver (Fostex FX120). My hope is that the woofer will move the air needed for low bass and negate the need for baffle step correction, leaving the fullrange driver to deliver the coherence and midrange we love so much. They are only barely mocked up so far, but are already sounding really good:
http://boozhoundlabs.com/fx120-alpha10/
jsn
One idea I'm kicking around is loading a pair of these in an enlarged version of Terry Cain's Bigger Is Better TQWT. Terrible modelled response, but they sound much better than that thanks to the way they interact with the room, which the model can't predict / account for (yet! Watch this space though... interesting things afoot. ;-). In fact, it's completely unique in my experience in this respect. The only speaker cabinet I know that I cannot model in some way or another in Martin's seminal MathCad worksheets.
Dan reckons they're closer to a tractrix horn. Me? I've no idea, no being up on my horn theory; I just know they work. I've just had a pair of FE166ES-Rs in mine with staggering results. Not the flattest cabinet on earth (or even close, though they aren't bad either) but a heck of a lot of fun, and hugely efficient too, which is exactly what these FF drivers need. I'm curently thinking of external dimensions along these lines: 70" tall, with the driver at 39" from the base, like the originals. 10" wide x 18" deep (external). Not small then, but I've seen larger cabinets too! Could be interesting...
Cheers
Scott
Dan reckons they're closer to a tractrix horn. Me? I've no idea, no being up on my horn theory; I just know they work. I've just had a pair of FE166ES-Rs in mine with staggering results. Not the flattest cabinet on earth (or even close, though they aren't bad either) but a heck of a lot of fun, and hugely efficient too, which is exactly what these FF drivers need. I'm curently thinking of external dimensions along these lines: 70" tall, with the driver at 39" from the base, like the originals. 10" wide x 18" deep (external). Not small then, but I've seen larger cabinets too! Could be interesting...
Cheers
Scott
thank you for discuss, gentlemen!
I'm not aspire to jet engine playback levels
and 2 pcs together not for clean loud only.
they have to compensate individual distortion first.
that's why I CAN use driver with small excursion. it's ok for me.
moreover, I'll connect these pair via serial capacitor 100 mcf, couse I have active sub for low waves.
this way will make working conditions easy for Fostex.
and I 'll be able to make small box as well.
isn't it?
I'm not aspire to jet engine playback levels
and 2 pcs together not for clean loud only.
they have to compensate individual distortion first.
that's why I CAN use driver with small excursion. it's ok for me.
moreover, I'll connect these pair via serial capacitor 100 mcf, couse I have active sub for low waves.
this way will make working conditions easy for Fostex.
and I 'll be able to make small box as well.
isn't it?
Yes and no. If you'll forgive the expression. I assume that your 120db was a typing error, because that is loud. Very loud. As in damage your hearing loud. Anything over 85db in the long term will damage your hearing. Jsn is quite correct 120db is louder than a power-saw, and about equivalent to standing 10 feet from a 1945 Rolls Royce Derwent IV Centrifugal-flow turbojet at about 80% thrust, without the benefit of ear defenders.
Within reason you're correct. However, you have to take other factors into consideration. The FF225K, lovely though it is, is very low excusion indeed. 0.3mm. And plonking them into a very small sealed or aperiodic box, even capped off below 80Hz and letting subs handle the bass will probably breach those limits, despite you're wanting to use two of them, and result in distortion. Hense my advising the F200a, which has the greater excusion without distorting.
The original BIB box terry made is here: http://melhuish.org/audio/DIYTQ8.html
That was for the RS1354. However, extrapolating a bit from the dimensions this used, and the dimensions Terry seemed to use for a different version with the FE168ESigma (the design information is apparantly in those Fostex Craft Handbooks pictured in the linked article of Terry's, which are next to impossible to get hold of, though I'm going to try again soon), I noticed that several proportions were all but identical -particularly the area of Sm, which seems to be 4.25Sd or thereabouts. Line length is usually set to 1/2 the wavelength of Fs (at least for drivers with an Fs around 50Hz. Below that, I'd abandon that part, and stick to a 70" tall cabinet or things will get very big, very quickly, and put the driver well above the listening height) As I say, a lot of fun. Not particularly overly flat or neutral, but great fun, with fearsome dynamics, and, so long as they are pushed against a rear wall or into corners, bass is amazing. Best with some series resistance however -30AWG magnet wire as Terry used is ideal for Fostex drivers. More art than science? Perhaps. Like many horns, they have very different priorities to most other speaker designs. But I still like them.
Best
Scott
Within reason you're correct. However, you have to take other factors into consideration. The FF225K, lovely though it is, is very low excusion indeed. 0.3mm. And plonking them into a very small sealed or aperiodic box, even capped off below 80Hz and letting subs handle the bass will probably breach those limits, despite you're wanting to use two of them, and result in distortion. Hense my advising the F200a, which has the greater excusion without distorting.
The original BIB box terry made is here: http://melhuish.org/audio/DIYTQ8.html
That was for the RS1354. However, extrapolating a bit from the dimensions this used, and the dimensions Terry seemed to use for a different version with the FE168ESigma (the design information is apparantly in those Fostex Craft Handbooks pictured in the linked article of Terry's, which are next to impossible to get hold of, though I'm going to try again soon), I noticed that several proportions were all but identical -particularly the area of Sm, which seems to be 4.25Sd or thereabouts. Line length is usually set to 1/2 the wavelength of Fs (at least for drivers with an Fs around 50Hz. Below that, I'd abandon that part, and stick to a 70" tall cabinet or things will get very big, very quickly, and put the driver well above the listening height) As I say, a lot of fun. Not particularly overly flat or neutral, but great fun, with fearsome dynamics, and, so long as they are pushed against a rear wall or into corners, bass is amazing. Best with some series resistance however -30AWG magnet wire as Terry used is ideal for Fostex drivers. More art than science? Perhaps. Like many horns, they have very different priorities to most other speaker designs. But I still like them.
Best
Scott
I couldn't agree this time.
why you say 120Db?! it's so loud of course. but it's not catastrophe , not enough for damage our hearing.
it's just like simple rock concert hall , or classic orchestra.
but unfortunately I'll not be able to make system for this pressure.
my bass - sub don't satisfire it. let's hope to get 100 db for 30 Hz.
I'll be happy.
about excusion you're listed. do you sure about 0.3mm? 0.3 cm maybe?!
I don't like BIB box you're showed there. it's not optimal. IMHO.
but anyway hand working system it's perfect. respect!
why you say 120Db?! it's so loud of course. but it's not catastrophe , not enough for damage our hearing.
it's just like simple rock concert hall , or classic orchestra.
but unfortunately I'll not be able to make system for this pressure.
my bass - sub don't satisfire it. let's hope to get 100 db for 30 Hz.
I'll be happy.
about excusion you're listed. do you sure about 0.3mm? 0.3 cm maybe?!
I don't like BIB box you're showed there. it's not optimal. IMHO.
but anyway hand working system it's perfect. respect!
Hi Yuri
Anything over 85 to 90db for extended periods will damage your hearing in the long-term. Medical fact. And when I say extended periods, I don't just mean sitting down listening to something at those pressure-levels non stop for 100 hours or so. It also means a couple of hours of listening at those levels per night over a period of months and years. Look it up if you don't believe me. I confess, I too have been known to go for the odd 110db peak when listening to some heavy-rock (Kiss, Iron Maiden etc) but I don't make a habit of it for that very reason. The ability to hear high frequencies will be the first to go. I've seen some children who've been exposed to lots of very loud pop music (not that it matters what the noise is of course) who are deaf above 12KHz for this very reason. And I wasn't joking by the way. 120db is exactly the same as a Derwent V jet engine at 80% thrust.
Yep, the Xmax of the FF225K is indeed a spectacularly low 0.3mm. That's 1/3 of the Xmax of a Lowther, which gives you some idea of how tiny it is. I currently own their smaller cousins, the FF165K, which also has an Xmax of 0.3mm. The ultimate cone excursion is much greater of course, limited by the suspension before the voice coil is damaged, but beyond Xmax you get distortion of rapidly increasing severity. I like the MLTL's for them linked above though. As noted, they aren't going to go loud, but I bet the mid-range is superb!
Terry's BIB box is very unusual I grant you. Whether it's sub-optimal or not however depends on what you want from a speaker system. They have different priorities to most other speakers, but people who like horns tend to love them. They image like crazy, go amazingly low (I've had 25Hz out of a 6 1/2" driver would you believe?) and hurl up a huge sound-stage. They're also much, much flatter than a simulation suggests, because they deliberately use the room to smooth their response, which is the opposite of what happens to most other speakers. Not to everyone's taste of course, and you need an amplifier with a very low damping factor, and high resistance wire like 30AWG magnet wire (or a big resistor in series with the driver is you have a solid-state amp) but I keep several pairs about the house. Terry knows what he's doing, believe me. He's one of the top single-driver speaker designers in the world. This is the one exception I make to Scott's First Rule of Speaker Design (all transducers should be initially designed with Martin King's MathCad worksheets.)
Enjoy the music
Scott
Anything over 85 to 90db for extended periods will damage your hearing in the long-term. Medical fact. And when I say extended periods, I don't just mean sitting down listening to something at those pressure-levels non stop for 100 hours or so. It also means a couple of hours of listening at those levels per night over a period of months and years. Look it up if you don't believe me. I confess, I too have been known to go for the odd 110db peak when listening to some heavy-rock (Kiss, Iron Maiden etc) but I don't make a habit of it for that very reason. The ability to hear high frequencies will be the first to go. I've seen some children who've been exposed to lots of very loud pop music (not that it matters what the noise is of course) who are deaf above 12KHz for this very reason. And I wasn't joking by the way. 120db is exactly the same as a Derwent V jet engine at 80% thrust.
Yep, the Xmax of the FF225K is indeed a spectacularly low 0.3mm. That's 1/3 of the Xmax of a Lowther, which gives you some idea of how tiny it is. I currently own their smaller cousins, the FF165K, which also has an Xmax of 0.3mm. The ultimate cone excursion is much greater of course, limited by the suspension before the voice coil is damaged, but beyond Xmax you get distortion of rapidly increasing severity. I like the MLTL's for them linked above though. As noted, they aren't going to go loud, but I bet the mid-range is superb!
Terry's BIB box is very unusual I grant you. Whether it's sub-optimal or not however depends on what you want from a speaker system. They have different priorities to most other speakers, but people who like horns tend to love them. They image like crazy, go amazingly low (I've had 25Hz out of a 6 1/2" driver would you believe?) and hurl up a huge sound-stage. They're also much, much flatter than a simulation suggests, because they deliberately use the room to smooth their response, which is the opposite of what happens to most other speakers. Not to everyone's taste of course, and you need an amplifier with a very low damping factor, and high resistance wire like 30AWG magnet wire (or a big resistor in series with the driver is you have a solid-state amp) but I keep several pairs about the house. Terry knows what he's doing, believe me. He's one of the top single-driver speaker designers in the world. This is the one exception I make to Scott's First Rule of Speaker Design (all transducers should be initially designed with Martin King's MathCad worksheets.)
Enjoy the music
Scott
Scottmoose said:
not sure. even home silens is about 30Db.
all of us testing equipment by 1W and get 85-95 Db.
what's will be for 100W - it's not a lot.
I like Led Zeppelin. ok. I'm 47. and I'm realy hear nothing over 10K. it's thue.
I can't believe. incredble.
you're right.....
you know - it's something not natural, artificial concept. IMO
I call it secondary sourse of sound (SSS)
the main sourse of sound is drivers only. not port, not horn not PR, even not box capacity. it's secondary. it's virtual, although it's very significant part of loudspeaker, spectrum of these units are not the same as by driver. not the same solidity, sounds like .... imitation, depends of a lot of factors.
I can characterize it unstable, non-persistent parametres.
one way for minimizing it - makes lot of band, multibanded system
is it actual for you and other forum members?
Yuri, you make some good points there toward the end. I cannot disagree with you, even if I wanted to, because we all have different priorities, want different things, and hear in different ways.
As you go for a driver-alone approach I'm actually a little surprised you don't seem to want to go dipolar, or for line-array. Dipolar systems remove a lot of the room's influence as only, if memory serves, 30% of the energy goes toward engergising the room, unlike monopoles, where it's more like about 50-60%. Some people suggest that they sound 'un-natural' Actually, they're probably more accurate in the strict sense of the word. Contrary to popular believe, they don't actually need a huge amount of space behind them either, though they do need a bit. Going in the opposite direction, toward, say, a sealed box line-array, a properly designed domestic array places the listener completely in the nearfield, so basically removes the room's influence from what you are listening to. I imagine you'd probably like what both could do for your music. In both cases, you'd be primarily listening to drivers and nothing else, which is what you seem to want. Perhaps something to consider for future reference. Have a look at Jim Griffin's Line Array White Paper and Siegfried Linkwiz site if you haven't already -both are well worth a read even if you don't adopt either system, and most interesting.
Can't say I hear the same problems you seem to, but don't read anything into that -as I say, we all hear in different ways, and what you like, I might not, while what I like, you might not. Besides, life would be very boring if we were all the same or wanted identical things wouldn't it?
Hearing damage? Well, here's one link. There's hundreds like it, and they all say the same thing. http://familydoctor.org/226.xml
As for the FF225K -I know it sounds unbelievable, but it's true enough. I wouldn't say it if it wasn't. Welcome to the crazy world of full-range drivers. It's not that unique either -take a look at the data sheet for the Fostex FE108ESigma: Xmax... (wait for it!) 0.28mm! Have a look at the parameters on the Fostex website (www.fostex.com). They have much greater physical excursion of course, as I say, and can do so safely enough, as the suspension usually limits them before the voice-coil gets damaged, but once driven past Xmax, distortion rockets.
Regards
Scott
As you go for a driver-alone approach I'm actually a little surprised you don't seem to want to go dipolar, or for line-array. Dipolar systems remove a lot of the room's influence as only, if memory serves, 30% of the energy goes toward engergising the room, unlike monopoles, where it's more like about 50-60%. Some people suggest that they sound 'un-natural' Actually, they're probably more accurate in the strict sense of the word. Contrary to popular believe, they don't actually need a huge amount of space behind them either, though they do need a bit. Going in the opposite direction, toward, say, a sealed box line-array, a properly designed domestic array places the listener completely in the nearfield, so basically removes the room's influence from what you are listening to. I imagine you'd probably like what both could do for your music. In both cases, you'd be primarily listening to drivers and nothing else, which is what you seem to want. Perhaps something to consider for future reference. Have a look at Jim Griffin's Line Array White Paper and Siegfried Linkwiz site if you haven't already -both are well worth a read even if you don't adopt either system, and most interesting.
Can't say I hear the same problems you seem to, but don't read anything into that -as I say, we all hear in different ways, and what you like, I might not, while what I like, you might not. Besides, life would be very boring if we were all the same or wanted identical things wouldn't it?
Hearing damage? Well, here's one link. There's hundreds like it, and they all say the same thing. http://familydoctor.org/226.xml
As for the FF225K -I know it sounds unbelievable, but it's true enough. I wouldn't say it if it wasn't. Welcome to the crazy world of full-range drivers. It's not that unique either -take a look at the data sheet for the Fostex FE108ESigma: Xmax... (wait for it!) 0.28mm! Have a look at the parameters on the Fostex website (www.fostex.com). They have much greater physical excursion of course, as I say, and can do so safely enough, as the suspension usually limits them before the voice-coil gets damaged, but once driven past Xmax, distortion rockets.
Regards
Scott
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