Would someone be kind enough to run a sim on the "hemptone" FR8 mounted in a MLTL? The specs are below. I realize the cabinets will be large but I'm hoping not too large.
Specifications and Small Signal Parameters
Voice Coil Impedance: 8 ohm
Resonant Frequency: 40 Hz
Frequency Response: fo - 20k Hz
Sensitivity: 93 dB SPL (Average 500 - 2.5 kHz, 1w, 1 meter)
Rated Power: 45 watts
Program Power: 90 watts
Magnet Weight: 566 gr (20 oz)
Net Weight: 1.5 kg (3.3 lb)
Fo: 40 Hz
Re: 6.2 ohm
Qts: 0.45
Qms: 3.5
Qes: 0.53
Vas: 88 Liter
Mms: 12 Gram
Xmax: 1.9 mm
No: 1.10%
Specifications and Small Signal Parameters
Voice Coil Impedance: 8 ohm
Resonant Frequency: 40 Hz
Frequency Response: fo - 20k Hz
Sensitivity: 93 dB SPL (Average 500 - 2.5 kHz, 1w, 1 meter)
Rated Power: 45 watts
Program Power: 90 watts
Magnet Weight: 566 gr (20 oz)
Net Weight: 1.5 kg (3.3 lb)
Fo: 40 Hz
Re: 6.2 ohm
Qts: 0.45
Qms: 3.5
Qes: 0.53
Vas: 88 Liter
Mms: 12 Gram
Xmax: 1.9 mm
No: 1.10%
Hi Gavin,
The T/S parameters you have are from the manufacturer. Here is what I've measured on the drivers I have - see attached picture. The pair measured pretty close to each other.
I've tried to model MLTL for them, but did not like it. I don't remember all the details at this point. The model is on my home PC - will look it up when I get home. I think the main problem was - it required a heavy BSC attenuation, which kills the efficiency. I end up with the horn, that doesn't need the BSC at all and is about 95dB efficient. The box ended up smaller than MLTL. You can read about the design here:
http://www.e-speakers.com/pdf/vadim-infopack.pdf
The T/S parameters you have are from the manufacturer. Here is what I've measured on the drivers I have - see attached picture. The pair measured pretty close to each other.
I've tried to model MLTL for them, but did not like it. I don't remember all the details at this point. The model is on my home PC - will look it up when I get home. I think the main problem was - it required a heavy BSC attenuation, which kills the efficiency. I end up with the horn, that doesn't need the BSC at all and is about 95dB efficient. The box ended up smaller than MLTL. You can read about the design here:
http://www.e-speakers.com/pdf/vadim-infopack.pdf
Attachments
I knew someone was going to ask this... 
One quasi MLTL. 14.5in wide, 8in deep, 48in tall (internal dimensions). Zdriver 10.25in. Port 2in up from the base on the front panel, 3in diameter, 3in long. Stuff 0.2lbs ft^3 from the top 24in down. Increase the port length to 4in to roll things off a little more. As we've gone wide-baffle with this, it's unlikely to need much in the way of baffle-step compensation, if any at all. Step-point occurs at 285Hz (assuming 3/4in material is used for a 16in wide baffle, external), which should be rapidly countered by room-gain, particularly if positioned near a rear wall. If they're pulled out a ways into a big room, and it bothers you (unlikely I suspect, then parallel a 2.6ohm resistor with a 1.4mH inductor in the hot lead, which shouldn't cripple efficiency too badly. BTW -give the edges a decent round-over -at least 1in.
Using the manufacturers claimed T/S parameters gives the following FR.
Scott
One quasi MLTL. 14.5in wide, 8in deep, 48in tall (internal dimensions). Zdriver 10.25in. Port 2in up from the base on the front panel, 3in diameter, 3in long. Stuff 0.2lbs ft^3 from the top 24in down. Increase the port length to 4in to roll things off a little more. As we've gone wide-baffle with this, it's unlikely to need much in the way of baffle-step compensation, if any at all. Step-point occurs at 285Hz (assuming 3/4in material is used for a 16in wide baffle, external), which should be rapidly countered by room-gain, particularly if positioned near a rear wall. If they're pulled out a ways into a big room, and it bothers you (unlikely I suspect, then parallel a 2.6ohm resistor with a 1.4mH inductor in the hot lead, which shouldn't cripple efficiency too badly. BTW -give the edges a decent round-over -at least 1in.
Using the manufacturers claimed T/S parameters gives the following FR.
Scott
Attachments
And using the above measurements supplied by Vladim (thanks for that) the same cabinet gives the attached. Both are rolled off to compensate for room-gain BTW, as I always do. I can't see much that's bad about either to be honest. Port velocity stays well below the mach, so no noise, the FR is smooth, impedence isn't too bad, plenty of sensitivity.
Of course, the slight downside is that they're not exactly small boxes, but as they're wide baffles, which are best near rear walls & corners anyway, they shouldn't be too obtrusive either with a little creativity.
Of course, the slight downside is that they're not exactly small boxes, but as they're wide baffles, which are best near rear walls & corners anyway, they shouldn't be too obtrusive either with a little creativity.
Attachments
Scott,
Using a wide baffle for this driver seems like a very good idea. AFAIR, I've modeled 12" baffle for MLTL and it looked worst. Also, I probably used the term BSC a little wrong. On top of usual baffle step, this driver has a rize in response from about 800 Hz to about 3kHz - all of it's own. I've used BSC term, because you can fight both of those in the same way.
The far-field FR of the driver mounted in my horn is attached. Please, disregard anything below 500-600 Hz.
By adjusting the size of the CC and horn damping, it was possible to mate a response of the horn mouth to the direct radiation from the driver, to end-up with some resemblance of a flat overall FR.
Another problem I remember with MLTL for this driver, was excursion, limiting the input power to a few watts anywhere below 100-80 Hz. Did you check your sim for that?
Vadim B.
Using a wide baffle for this driver seems like a very good idea. AFAIR, I've modeled 12" baffle for MLTL and it looked worst. Also, I probably used the term BSC a little wrong. On top of usual baffle step, this driver has a rize in response from about 800 Hz to about 3kHz - all of it's own. I've used BSC term, because you can fight both of those in the same way.
The far-field FR of the driver mounted in my horn is attached. Please, disregard anything below 500-600 Hz.
By adjusting the size of the CC and horn damping, it was possible to mate a response of the horn mouth to the direct radiation from the driver, to end-up with some resemblance of a flat overall FR.
Another problem I remember with MLTL for this driver, was excursion, limiting the input power to a few watts anywhere below 100-80 Hz. Did you check your sim for that?
Vadim B.
Attachments
Greets!
I see Scott's been busy, but I started this in the wee hours waiting on the 'Sandman', so might as well post it:
First things first, Qts = 0.461 and Sd is unrealistically large to reach a 12 g Mms, so like the previous version, this one likely has a considerably higher Fs than listed. Fortunately that's not normally a big deal with a TL or MLTL......
Max flat MLTL:
L = 57.5"
CSA = 144"^2 (recommend 15.25" W x 9.43" D)
zdriver = 21.48"
vent = 5" dia. x 2.5" near/at the bottom
Sim is with minimal damping around driver and if 'boomy' in-room, either more damping and/or a longer vent can be used to roll it off. At 8", it sims identical to this one: http://www.diyaudio.com/forums/attachment.php?s=&postid=1171886&stamp=1175270122
GM
I see Scott's been busy, but I started this in the wee hours waiting on the 'Sandman', so might as well post it:
First things first, Qts = 0.461 and Sd is unrealistically large to reach a 12 g Mms, so like the previous version, this one likely has a considerably higher Fs than listed. Fortunately that's not normally a big deal with a TL or MLTL......
Max flat MLTL:
L = 57.5"
CSA = 144"^2 (recommend 15.25" W x 9.43" D)
zdriver = 21.48"
vent = 5" dia. x 2.5" near/at the bottom
Sim is with minimal damping around driver and if 'boomy' in-room, either more damping and/or a longer vent can be used to roll it off. At 8", it sims identical to this one: http://www.diyaudio.com/forums/attachment.php?s=&postid=1171886&stamp=1175270122
GM
Attachments
Nice... wish I could get 'em as good as that without damping. I try nbot to go above 0.25lbs ft^3 now. Kills dynamics.
Excursion on mine was within Xmax to ~41Hz. Below that it rises a little, but nothing to get too worried about given our acuity drop-off. As sensitivity is fairly decent, it shouldn't be too much of an issue. I prefer horns myself, but not everyone likes / wants them, (as evidenced by the request) so I reckon the MLTL is the next best option.
Excursion on mine was within Xmax to ~41Hz. Below that it rises a little, but nothing to get too worried about given our acuity drop-off. As sensitivity is fairly decent, it shouldn't be too much of an issue. I prefer horns myself, but not everyone likes / wants them, (as evidenced by the request) so I reckon the MLTL is the next best option.
Greets!
Yeah, for sims I try to limit it 0.2 lbs/ft^3 to just below the driver, though for high Q drivers have to use a bit more and for drivers that require really large vents, then a more labor intensive ML-horn is preferred since its vent harmonics decay faster. Still, none of these will handle much power, so for the 'headbangers' who don't mind the limited LF of a live rock, etc., concert, a boosted mid-bass is the 'Hot Ticket':
GM
Yeah, for sims I try to limit it 0.2 lbs/ft^3 to just below the driver, though for high Q drivers have to use a bit more and for drivers that require really large vents, then a more labor intensive ML-horn is preferred since its vent harmonics decay faster. Still, none of these will handle much power, so for the 'headbangers' who don't mind the limited LF of a live rock, etc., concert, a boosted mid-bass is the 'Hot Ticket':
GM
Attachments
Has it's uses... That'd be me then... but only on occasion.
Yup, 1w. Boosting to 10w won't help matters much, but as GM points out, these aren't intended for full-on rock & I wouldn't care to feed them that much anyway. Maybe more like 5. It's sensitive enough to give decent SPLs at most listening positions without distortion being a particular concern. If more's needed for headbanging, then either Greg's modified version above, or a horn is what is required. (Or if big SPLs and minimal distortion, period are the goal, then a 2-3 way Altec VOTT. No FR unit is going to do the loudness / dynamics & low distortion thing than a multiway). Excursion in MLTLs is primarily an issue an octave above Fc, making them with FR units a middling choice for this sort of music.
That'd be me then... but only on occasion. Yup, 1w. Boosting to 10w won't help matters much, but as GM points out, these aren't intended for full-on rock & I wouldn't care to feed them that much anyway. Maybe more like 5. It's sensitive enough to give decent SPLs at most listening positions without distortion being a particular concern. If more's needed for headbanging, then either Greg's modified version above, or a horn is what is required. (Or if big SPLs and minimal distortion, period are the goal, then a 2-3 way Altec VOTT. No FR unit is going to do the loudness / dynamics & low distortion thing than a multiway). Excursion in MLTLs is primarily an issue an octave above Fc, making them with FR units a middling choice for this sort of music.
Scottmoose said:Has it's uses...
Yup, 1w. Boosting to 10w won't help matters much, but as GM points out, these aren't intended for full-on rock & I wouldn't care to feed them that much anyway. Maybe more like 5. It's sensitive enough to give decent SPLs at most listening positions without distortion being a particular concern. If more's needed for headbanging, then either Greg's modified version above, or a horn is what is required. (Or if big SPLs and minimal distortion, period are the goal, then a 2-3 way Altec VOTT. No FR unit is going to do the loudness / dynamics & low distortion thing than a multiway). Excursion in MLTLs is primarily an issue an octave above Fc, making them with FR units a middling choice for this sort of music.
As long as they will handle a little Frampton or Zeppelin they will work just fine. Thanks guys.
Greets!
Assuming you mean a full width shelf vent = 15.25" to get ~the simmed FR, the theoretical end correction will actually require less vent area (~0.875" height) to get the vent long enough for a 0.75" baffle thickness. Since this pushes it well beyond the ~9:1 aspect ratio that defines a resistive slot vent it may 'flop' it over to a larger area, so unless you're prepared to tediously experiment with different size/length vents, best to stick with a round, square, or modestly rectangular vent centered 3.5" from the bottom as used in the sim.
GM
Assuming you mean a full width shelf vent = 15.25" to get ~the simmed FR, the theoretical end correction will actually require less vent area (~0.875" height) to get the vent long enough for a 0.75" baffle thickness. Since this pushes it well beyond the ~9:1 aspect ratio that defines a resistive slot vent it may 'flop' it over to a larger area, so unless you're prepared to tediously experiment with different size/length vents, best to stick with a round, square, or modestly rectangular vent centered 3.5" from the bottom as used in the sim.
GM
to resident:
Try the DIY Audio member Validator in Germany.
http://www.diyaudio.com/forums/member.php?s=&action=getinfo&userid=19400
I think he use to offer Hemp Acoustics products.
It may be worth sending and email to him and asking.
NW
Try the DIY Audio member Validator in Germany.
http://www.diyaudio.com/forums/member.php?s=&action=getinfo&userid=19400
I think he use to offer Hemp Acoustics products.
It may be worth sending and email to him and asking.
NW
VadimB,
I've built a horn and a number of bass reflex and MLTL enclosures for Fostex and Lowther units. I have not been totally happy with the results from either design. I have gotten closer to the presentation I like with the Visation in open baffle, but it is not quite there yet. The open baffle does not fit my listening area due to the space requirements. The midrange does not have much flesh and blood and it does not balance with the low end, although I like it better than the Fostex or Lowther designs.
I have heard a lot of great reports about the Hemp driver and was going to build a bass reflex enclosure when I found your Hemp Horn Project information package. What I have read is that the Hemp driver is more balanced and not as 'hot' in the midrange as say the Fostex or Lowthers. Could you assess the differences of the Hemp driver in the Horn Project compared to a Lowther in a Medallion horn enclosure?
Also, I would like to ask any other DIY Forum member that has built the Hemp Horn Project for their impressions. I would likely be using either a 30W p/p Cayin integrated or a Trends amp. I would primarily listen to classical and jazz.
John
I've built a horn and a number of bass reflex and MLTL enclosures for Fostex and Lowther units. I have not been totally happy with the results from either design. I have gotten closer to the presentation I like with the Visation in open baffle, but it is not quite there yet. The open baffle does not fit my listening area due to the space requirements. The midrange does not have much flesh and blood and it does not balance with the low end, although I like it better than the Fostex or Lowther designs.
I have heard a lot of great reports about the Hemp driver and was going to build a bass reflex enclosure when I found your Hemp Horn Project information package. What I have read is that the Hemp driver is more balanced and not as 'hot' in the midrange as say the Fostex or Lowthers. Could you assess the differences of the Hemp driver in the Horn Project compared to a Lowther in a Medallion horn enclosure?
Also, I would like to ask any other DIY Forum member that has built the Hemp Horn Project for their impressions. I would likely be using either a 30W p/p Cayin integrated or a Trends amp. I would primarily listen to classical and jazz.
John
John -have you tried running the B200 with cardioid bass help? The baffle doesn't have to be overly large then.
This is very rough, but you could give something like this a shot. Baffle about 16in wide x 42in tall, with two triangular side pieces about 14in deep at the base tapering to nothing at the top. Get the Viaston about 12in down from the top, and mount a 15in woofer near the base (give it about 3in of breathing room). Wire and XO in series at around 150Hz or so, using the natural roll-off of the drivers to help. There've been a few designs of this nature, particularly in the UK recently, and I can vouch for how effective they can be. One, with the FE167E and Eminence Beta15 provided amonst the finest sound I've ever heard, period. Not bad for a couple of relatively inexpensive units. The B200s would also benefit from a set of Dave's phase plugs -see www.planet10-hifi.com which will massively improve their midband and treble (no voodoo either -it's measureable).
This is very rough, but you could give something like this a shot. Baffle about 16in wide x 42in tall, with two triangular side pieces about 14in deep at the base tapering to nothing at the top. Get the Viaston about 12in down from the top, and mount a 15in woofer near the base (give it about 3in of breathing room). Wire and XO in series at around 150Hz or so, using the natural roll-off of the drivers to help. There've been a few designs of this nature, particularly in the UK recently, and I can vouch for how effective they can be. One, with the FE167E and Eminence Beta15 provided amonst the finest sound I've ever heard, period. Not bad for a couple of relatively inexpensive units. The B200s would also benefit from a set of Dave's phase plugs -see www.planet10-hifi.com which will massively improve their midband and treble (no voodoo either -it's measureable).
ooooh come on guys. There are a lot of interesting designs on these forums.........
Scottmoose,
any pic of sth like what are you suggested? Just to see how it looks like. Seems very good.
I'm confused now. I almost have decided to build the wide baffle MLTL but this OB looks a good idea, too.
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