How fortuitous. I was just thinking of authoring a post begging Scott to propose BIB dimensions for the hemp. I know this thread is about an MLTL solution, which I am interested in too. Perhaps a broader topic is: enclosure ideas for the Hemp Acoustics drivers.
Has anybody calc'd an MLTL? I need to get a PC so I can run MathCad too.
Will the worksheets give an accurate idea of driver excursion in the BIB's? If so, what does it look like?
I recall some folks writing that it isn't ideal to load a driver below it's Fs. It seems to me that it keeps the driver from unloading and prevents over excursion in any circumstance. Thoughts?
I remember from a previous thread that you mentioned (Scott) that the BIB is the only enclosure you still calc from rules of thumb rather than worksheets. I saw where you mentioned how to spec a BIB based on Sd and Fs. Do any other specs figure in (compliance?) or will this get you most of the way there? I'd hate for you to have to chime in everytime someone needs BIB ideas.
Finally, is the standard BIB about the best we can do for the hemp? (Realizing that there really is no best, just matters of preference.) Are there any alterations that would help it? (A bigger mouth, reflectors in the bottom, or perhaps blocking the path just upstream of the driver) What about building a real Tractrix? Or, eliminating parallel side walls and creating something like an upside down Carfrae Big Horn with all straight panels?
I know, many questions. Let me know if this is off topic and I should start a Hemp BIB thread.
Paul
Has anybody calc'd an MLTL? I need to get a PC so I can run MathCad too.
Will the worksheets give an accurate idea of driver excursion in the BIB's? If so, what does it look like?
I recall some folks writing that it isn't ideal to load a driver below it's Fs. It seems to me that it keeps the driver from unloading and prevents over excursion in any circumstance. Thoughts?
I remember from a previous thread that you mentioned (Scott) that the BIB is the only enclosure you still calc from rules of thumb rather than worksheets. I saw where you mentioned how to spec a BIB based on Sd and Fs. Do any other specs figure in (compliance?) or will this get you most of the way there? I'd hate for you to have to chime in everytime someone needs BIB ideas.
Finally, is the standard BIB about the best we can do for the hemp? (Realizing that there really is no best, just matters of preference.) Are there any alterations that would help it? (A bigger mouth, reflectors in the bottom, or perhaps blocking the path just upstream of the driver) What about building a real Tractrix? Or, eliminating parallel side walls and creating something like an upside down Carfrae Big Horn with all straight panels?
I know, many questions. Let me know if this is off topic and I should start a Hemp BIB thread.
Paul
Paul
Based on the process of elimination, -- for a "box" type speaker, --one with a cabinet, the BIB is the best IMHO for ANY driver, that Q-qualifies. Sonically, effeciency, ease of build, effortlessness of sound, you name it, it is the only "box" type speaker I care to listen to, longer term. By cutting the panels to have a sloped back mouth, (vertical,) you effectively increase the mouth size, in answer to your question.
To really confuse matter, you should hear your Hemps on an open baffle. I have the Omega OEM units which are abit different, though not all that much, (Q, SPL, magnet, whizz) and with DSP applied to compensate for baffle roll off, with lower placement, ~14" they are just about fine, as is. No compression artifacts, just that fine, warm, organic hempness, now in dipolar presentation.
The Hemp midrange is as good as I have ever heard it from a wide range driver, and I have been through most of them in the past three years.
Based on the process of elimination, -- for a "box" type speaker, --one with a cabinet, the BIB is the best IMHO for ANY driver, that Q-qualifies. Sonically, effeciency, ease of build, effortlessness of sound, you name it, it is the only "box" type speaker I care to listen to, longer term. By cutting the panels to have a sloped back mouth, (vertical,) you effectively increase the mouth size, in answer to your question.
To really confuse matter, you should hear your Hemps on an open baffle. I have the Omega OEM units which are abit different, though not all that much, (Q, SPL, magnet, whizz) and with DSP applied to compensate for baffle roll off, with lower placement, ~14" they are just about fine, as is. No compression artifacts, just that fine, warm, organic hempness, now in dipolar presentation.
The Hemp midrange is as good as I have ever heard it from a wide range driver, and I have been through most of them in the past three years.
There's a fair bit more involved than just the Sd and Fs I'm afraid, and that's where background knowledge comes in. Q of the driver, what amp you're running and what wires you're thinking about all play a part. I'm no believer in voodoo cables, but their electrical properties are significant. Then there's the Vas and BL factors that you need to juggle with a bit. Hence the reason why I sometimes suggest different dimensions for nominally the same driver sizes. Then you have Xmax to take into consideration. The worksheets do give a pretty accurate guestimate of driver excursion loaded in this way, though it's sometimes necessary to do a check with both TL Offset driver and BLH sheets. I'm fooling with the idea of creating an Excel sheet for BIB sizing until Martin has time to add a vertical mouth section / addition to his sheets. It won't cover all bases, but it should give a good start.
Reflectors in the base don't make any difference in my experiece -Dan, you tried them? I prefer a 1/2" layer of wadding across the bottom myself. Chopping the rear down at an angle to increase the mouth area is also a good tweak from Terry and Dan. I tried that with my last pair, and it made a small, but noticable difference.
Reflectors in the base don't make any difference in my experiece -Dan, you tried them? I prefer a 1/2" layer of wadding across the bottom myself. Chopping the rear down at an angle to increase the mouth area is also a good tweak from Terry and Dan. I tried that with my last pair, and it made a small, but noticable difference.
I don't think the reflectors much matter. They are best for backwave dispersal in BR.
What I did was line one wall, and the bottom. No honkiness, no weirdness, just nice dry horn dynamics, very crisp, just a great horn load. The Best. The Fostex FE168Sigma is amazing in a BIB. The only persons who would believe the range of this thing are the only other people, to my knowledge, whom have built them, OneSpeed, and Terry Cain. There is a picture of one on the web somewhere, if you google, TQWT, and Cain, I suppose. These have been playing in my living room with a Korneff 45SE, for months now.
What I did was line one wall, and the bottom. No honkiness, no weirdness, just nice dry horn dynamics, very crisp, just a great horn load. The Best. The Fostex FE168Sigma is amazing in a BIB. The only persons who would believe the range of this thing are the only other people, to my knowledge, whom have built them, OneSpeed, and Terry Cain. There is a picture of one on the web somewhere, if you google, TQWT, and Cain, I suppose. These have been playing in my living room with a Korneff 45SE, for months now.
dmason said:
Does it still win when you remove "ease of build" from the qualifiers? I'm not opposed to a 6 month long project. Are you just using flat open baffles, or the elusive Dark Star? What DSP are you using?
Scottmoose said:
I figured it wasn't simple, I am just curious how close one can get with a guestimate. The design purported to be pretty flexible. My meager understanding would lead me to believe smoothing out the curve would help get higher frequencies through the path. That might not be ideal in this case. I thought I'd ask. What angle do you chop the back at? I suppose that decision isn't simple either.
dmason said:
After some searching it appears the TC was going to sell these at one point. This is shown elsewhere as well: http://www.audioexcellenceaz.com/cain.htm It also appears he displayed them at a VSAC conference, which would mean a few more folks have heard them. Curious.
I'm also trying to determine if there is a concrete reason the BIB's would the hemps in sealed boxes surported by a horn sub. In a sealed box the hemps have plenty of SPL for me, and you eliminate many possible resonance and phase issues. Fitzmaurices Table Tuba doesn't seem far removed from a folded up BIB, but the driver has 16mm of Xmax.
I am hoping to build the BIB's. It would be best to find out for myself. I'm lobbying the "powers that be" hard. I may have to make a trade off precluding the building of more speakers for awhile. That would make the BIB vs. sealed and TT comparision impossible. There are limits to the number of 6 cu ft plus speakers I can have in the house.
Paul
The BIB is deceptively simple. A big plus in my mind was the fact that the internal baffle doubled as VERY effective bracing. What a champ! If you were to build the BIB's for the Hempster, I can guarantee it will negate the need for any Auto Tuba Tables or any Fitzmaurice projects. This is a FULL range design. I am getting very strong 35Hz type bass even from Louis' 2.5ft^3 SuperHemp BR, so clearly BIB bass will be full. The driver's abilities and sound are only enhanced by losing cabinet induced compression, etc., no backwave getting through the cone, and on and on and on. Sonically, I would imagine it a NO CONTEST. A sealed box to me makes the hemps sound too forward, having tried that route, for what you gain by losing port induced colorations.
The BIB sound, as Scott will attest to, and others, is soooo effortless, as to be addictive. A speaker driver is VERY happy in this type of load. Add the warmth, resolution, and that curious organic vibe of the Hemp to the mix, and I believe we have the Master BIB. Truly. For more dynamics, HP @ 70Hz, and add a sub. This would eat the sealed box + Tuba approach.
This evening myself and two golden eared friends listened to the Telarc recording of Prokofiev's "Romeo and Juliet," and we were all completely amazed by the speaker's ability to convey the magic of that work.
The DSP I use is pro audio, Rane RPM. What a great machine. Computer linked drag and drop everything under the sun.
The BIB is deceptively simple. A big plus in my mind was the fact that the internal baffle doubled as VERY effective bracing. What a champ! If you were to build the BIB's for the Hempster, I can guarantee it will negate the need for any Auto Tuba Tables or any Fitzmaurice projects. This is a FULL range design. I am getting very strong 35Hz type bass even from Louis' 2.5ft^3 SuperHemp BR, so clearly BIB bass will be full. The driver's abilities and sound are only enhanced by losing cabinet induced compression, etc., no backwave getting through the cone, and on and on and on. Sonically, I would imagine it a NO CONTEST. A sealed box to me makes the hemps sound too forward, having tried that route, for what you gain by losing port induced colorations.
The BIB sound, as Scott will attest to, and others, is soooo effortless, as to be addictive. A speaker driver is VERY happy in this type of load. Add the warmth, resolution, and that curious organic vibe of the Hemp to the mix, and I believe we have the Master BIB. Truly. For more dynamics, HP @ 70Hz, and add a sub. This would eat the sealed box + Tuba approach.
This evening myself and two golden eared friends listened to the Telarc recording of Prokofiev's "Romeo and Juliet," and we were all completely amazed by the speaker's ability to convey the magic of that work.
The DSP I use is pro audio, Rane RPM. What a great machine. Computer linked drag and drop everything under the sun.
Is there an advantage to building the BIB taller, sonically, or does it just make it taller? I assume the answer is in the name, but just checking.
Also, is I wanted to build them to 84", where would the internal baffle terminate?
I have a pair of Hemps that I am going to use in this application. I am a new builder and this seems like the easiest of my planned projects, so a good starts.
Thanks for the help,
Matt
Also, is I wanted to build them to 84", where would the internal baffle terminate?
I have a pair of Hemps that I am going to use in this application. I am a new builder and this seems like the easiest of my planned projects, so a good starts.
Thanks for the help,
Matt
Hope he's OK, Dave?
Building the BIB taller? No reason why not, if you have a driver with a lower Fs. However, I don't go over 70" tall now for one very good reason: it puts the driver above your head, unless you listen on a bar-stool!
They really are very special: when I first tried mine with FF165Ks, I said to Dan it sounded like dipolar woofers. Amazing. Smoothing the pathllenght for the HF -well, assuming there was a difference, which is very unlikely, you need to ask yourself if you actually want HF coming from the horn...
You can indeed get pretty close with a guesstimate. Here's the absolute simplest rule of thumb possible for them: set line length to 1/2 the wavelength of Fs if your driver is of 50Hz or higher, if lower, just use a 140" total line-length. Set Sm=4.25Sd. Driver needs to be mounted at the point in the line where it equals the surface area of the driver. Normally I despise So=0, but in this case the problems are negated by the mouth position and the corner-loading. Put a light layer of wadding on the base, and either line the front of the internal baffle, or lightly stuff the point above the driver. That internal baffle terminates in the centre of the cabinet, the same distance from the base as from the internal front and rear walls.
There's more to it than that of course; you need to modify the mouth size and line cross-section etc to optimise for different drivers, but they are pretty forgiving, and this should give decent results for much of the time. Remember although Terry's originals were for the 5 1/4" RS1354, they still do well with the much larger FE166/7/8ESgima and FF165K, though enlarging reaps dividends, as Dan and I can testify.
Building the BIB taller? No reason why not, if you have a driver with a lower Fs. However, I don't go over 70" tall now for one very good reason: it puts the driver above your head, unless you listen on a bar-stool!
They really are very special: when I first tried mine with FF165Ks, I said to Dan it sounded like dipolar woofers. Amazing. Smoothing the pathllenght for the HF -well, assuming there was a difference, which is very unlikely, you need to ask yourself if you actually want HF coming from the horn...
You can indeed get pretty close with a guesstimate. Here's the absolute simplest rule of thumb possible for them: set line length to 1/2 the wavelength of Fs if your driver is of 50Hz or higher, if lower, just use a 140" total line-length. Set Sm=4.25Sd. Driver needs to be mounted at the point in the line where it equals the surface area of the driver. Normally I despise So=0, but in this case the problems are negated by the mouth position and the corner-loading. Put a light layer of wadding on the base, and either line the front of the internal baffle, or lightly stuff the point above the driver. That internal baffle terminates in the centre of the cabinet, the same distance from the base as from the internal front and rear walls.
There's more to it than that of course; you need to modify the mouth size and line cross-section etc to optimise for different drivers, but they are pretty forgiving, and this should give decent results for much of the time. Remember although Terry's originals were for the 5 1/4" RS1354, they still do well with the much larger FE166/7/8ESgima and FF165K, though enlarging reaps dividends, as Dan and I can testify.
FR8 Availability
I received an email from Perry Pecker at Hemp Acoustics this morning. A new batch of FR8's will be shipped to E-Speaker.com the week of March 17th. Andre from E-Speaker.com also emailed me and said that his web site will be updated as soon as the new shipment arrives. Thanks to both Perry and Andre. James
I received an email from Perry Pecker at Hemp Acoustics this morning. A new batch of FR8's will be shipped to E-Speaker.com the week of March 17th. Andre from E-Speaker.com also emailed me and said that his web site will be updated as soon as the new shipment arrives. Thanks to both Perry and Andre. James
Another thread rises from the dead!
The original question posed in this thread has been on my mind, since a pair of FR8's are due to hit my doorstep tomorrow! The thread kind of devolved into a discussion of BIB's rather than Hemptones.
So, has anyone actually built or heard the Hemp's in a proper MLTL?
jimmyd53 said:
The original question posed in this thread has been on my mind, since a pair of FR8's are due to hit my doorstep tomorrow! The thread kind of devolved into a discussion of BIB's rather than Hemptones.
So, has anyone actually built or heard the Hemp's in a proper MLTL?
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