Hi to all full-range lovers!
I am a rookie in speaker construction, and even moreso as far as FR is concerned. My first FR project is about to begin! I got myself a pair of Fostex FE164 drivers. I specifically sought out these drivers because they have a very smooth roll-off in the bass region ( less than 10db difference between response at fs and at mid frequencies) and higher Xmax than the newer 166/167 drivers. I also "feel" that 6,5 inch FR drivers are the best compromise.
My heart is set on building a BIB, mainly becaues of the ease of constuction and the apparent great results that can be had.
The reason for this post is that I have been running things through my mind before beginning construction. Initially I had thought/hoped that I would not need to insert anything between amp and driver, but as I searched, discovered this "nasty" called baffle step and the need for a BSC and so on and so forth.
The question that I want to ask is this:
What if we make the baffle, or even better the entire enclosure very very absorptive? Would that not attenuate the mid/high frequencies in the same way an attenuation circuit would. In this way we avoid any inductors, caps and resistors in the signal path, AND, we create a better point source( the source of sound will be the driver cone, not cone+baffle).
One fleeting idea I had in accoumplishing this is by using small felt pyramids that would be glued to the baffle/enclosure covering the entire surface. There may be better materials or methods of achieving what I am proposing.
Please share yout thoughts and knowledge regarding this idea, and my proposed project in general.
Best wishes to all
Peter
I am a rookie in speaker construction, and even moreso as far as FR is concerned. My first FR project is about to begin! I got myself a pair of Fostex FE164 drivers. I specifically sought out these drivers because they have a very smooth roll-off in the bass region ( less than 10db difference between response at fs and at mid frequencies) and higher Xmax than the newer 166/167 drivers. I also "feel" that 6,5 inch FR drivers are the best compromise.
My heart is set on building a BIB, mainly becaues of the ease of constuction and the apparent great results that can be had.
The reason for this post is that I have been running things through my mind before beginning construction. Initially I had thought/hoped that I would not need to insert anything between amp and driver, but as I searched, discovered this "nasty" called baffle step and the need for a BSC and so on and so forth.
The question that I want to ask is this:
What if we make the baffle, or even better the entire enclosure very very absorptive? Would that not attenuate the mid/high frequencies in the same way an attenuation circuit would. In this way we avoid any inductors, caps and resistors in the signal path, AND, we create a better point source( the source of sound will be the driver cone, not cone+baffle).
One fleeting idea I had in accoumplishing this is by using small felt pyramids that would be glued to the baffle/enclosure covering the entire surface. There may be better materials or methods of achieving what I am proposing.
Please share yout thoughts and knowledge regarding this idea, and my proposed project in general.
Best wishes to all
Peter
Hi Peter, I also am finishing up some BiB's for FE164 and FE166ES-R's. I've never heard of anybody using BSC on a BiB, actually. Placed in corners, the issue is often an excess of bass. What a great dilemma!
Check out the simulation made by Martin King -- he modeled using the FE167E which is pretty close to the FE164, and taking the corners into account as he does, he got tremendous bass:
General Speaker Related Articles (last article in the list)
Of course this is easily cured with stuffing and/or repositioning the BiB's. Mine should be done this weekend. Let's compare notes!
Check out the simulation made by Martin King -- he modeled using the FE167E which is pretty close to the FE164, and taking the corners into account as he does, he got tremendous bass:
General Speaker Related Articles (last article in the list)
Of course this is easily cured with stuffing and/or repositioning the BiB's. Mine should be done this weekend. Let's compare notes!
Interesting idea. The wider the baffle is, the thicker (and/or more absorbent) the treatment will have to be. You'll want to keep the baffle as narrow as possible, even with just the width of the driver itself you're looking at baffle gain starting from ~250Hz. This, I would expect, will require 50mm+ of high density acoustic foam; normal felt will only do much at 10kHz+ really. It'll be hard to figure out the exact quantities required I think. The alternative is in-wall mounting, as studio monitors often employ 
Would applying something to the baffle really attenuate the directly radiated sound? I think it would merely attenuate the diffracted energy which is already much lower in amplitude. But "mechanical eq" is a great idea.
GM has said a few times something to the effect that for acoustical problems, acoustical solutions are preferable to electrical or something like that (sorry GM for the misquote).
GM has said a few times something to the effect that for acoustical problems, acoustical solutions are preferable to electrical or something like that (sorry GM for the misquote).
AFAIK, BIB's don't typically need BSC. (Acronyms galore!) They have plenty of bass gain, as you can see in the sims The also require placement against the wall, or preferably, in corners, which also reduces the need for BSC. My BIB's actually produced too much bass for my room, and I had to use a bunch of stuffing to tame the bass. So, while your idea merits some discussion, I wouldn't worry about any form of BSC with this build.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Very encouraging that we BIBers don't need no BSC! Do we need zobels and/or notch filters though?
Another thing: would an offset driver not be a good idea? Heard it helps with baffle step. Have not seen any BIBs with offset drivers.
Regarding the absorption theory, I just try and think of it as a ''stealth'' baffle or enclosure: invisible acoustically. So yes, an acoustical solution to an acoustical problem. Very well put. I believe that with the right material, you could dampen(?) the baffle and/or enclosure to such an extent, that any reflected, refacted, diffracted etc. sound is totally absorbed/eaten up/vanished etc. so as not to interfere with, or have any influence on the sound coming directly from the driver cone.(IOW an anechoic baffle/enclosure!) I am confident that the desireable 'single point source' will be enhanced, by getting rid of the ''other sources".
Another thing: would an offset driver not be a good idea? Heard it helps with baffle step. Have not seen any BIBs with offset drivers.
Regarding the absorption theory, I just try and think of it as a ''stealth'' baffle or enclosure: invisible acoustically. So yes, an acoustical solution to an acoustical problem. Very well put. I believe that with the right material, you could dampen(?) the baffle and/or enclosure to such an extent, that any reflected, refacted, diffracted etc. sound is totally absorbed/eaten up/vanished etc. so as not to interfere with, or have any influence on the sound coming directly from the driver cone.(IOW an anechoic baffle/enclosure!) I am confident that the desireable 'single point source' will be enhanced, by getting rid of the ''other sources".
RJ, my BIBs will take a while to be up and running. Haven't receive drivers yet! Thinking of making rough/temp enclosures as a start out of paricle board/mdf to play around with, and then make ones out of BB( or even Aquapanel concrete sheets! Is that a good idea?). Placement will not be in corners,but against the long wall of a room about 6,5mx4,5m. Hope I get enough bass.
Dr EM, thick acoustic foam would probably work. My initial idea was of using tall(+-40mm) felt pyramids. Not that I've seen these pyramids as been available, but just imagined it as a rough/eneven absorptive surface-''stealth''!
Paul, great to know that BIBs don't need a BSC. The idea of a "stealth" baffle/enclosure could be very beneficial in other types of builds though. I'd like to see where this idea may lead ( I am not proposing that this is a new concept, or has not been discussed/done before)
Anyone else have any thoughts as to how to make, or benefits of, a ''stealth'' baffle/encloure?
Thanks
Dr EM, thick acoustic foam would probably work. My initial idea was of using tall(+-40mm) felt pyramids. Not that I've seen these pyramids as been available, but just imagined it as a rough/eneven absorptive surface-''stealth''!
Paul, great to know that BIBs don't need a BSC. The idea of a "stealth" baffle/enclosure could be very beneficial in other types of builds though. I'd like to see where this idea may lead ( I am not proposing that this is a new concept, or has not been discussed/done before)
Anyone else have any thoughts as to how to make, or benefits of, a ''stealth'' baffle/encloure?
Thanks
Think about what you're saying.
If your driver requires a zobel to sound half decent to your ears, then it requires a zobel. Ditto for notch filters. Both are issues with the driver's innate response, whatever the box it happens to be mounted in.Hi Scottmoose!
Glad to see you taking inerest in my rookie questions!
You're right-I should have thought more about asking that. I'm a noobie and at the moment everything I'm saying/thinking is theoretical. I haven't glued two planks together yet! I'm just gathering info/knowledge in order to be able to make the best BIB I can. You have been a great influence in my decision to build BIBs in the first place!
What's your take on this ''stealth'' baffle/enclosure?
Thanks
Glad to see you taking inerest in my rookie questions!
You're right-I should have thought more about asking that. I'm a noobie and at the moment everything I'm saying/thinking is theoretical. I haven't glued two planks together yet! I'm just gathering info/knowledge in order to be able to make the best BIB I can. You have been a great influence in my decision to build BIBs in the first place!
What's your take on this ''stealth'' baffle/enclosure?
Thanks
Hi Peter, building a prototype sounds like a good idea to me. If I can afford it, I would remake them out of BB. I have no experience with concrete board.
One point to keep in mind is that wide-band / FR drivers become increasingly directional as frequency rises, so while an absorbative baffle might be of some use initially, higher up they're beaming so much there's little to defract. That's why flush mounting some (not all) wide-band units doesn't do a great deal sonically, although naturally, the aesthetics are improved.
Aside from the practicality of moving them at any time, as well as the sonic "advantage?" in this application, fabricating an enclosure solely from concrete sheets could be tricky.
The product I've use myself for bathroom projects doesn't look particularly well suited to structural fabrication without some type of rigid sub-frame. Due to the mass, I'd be inclined to think a welded steel or aluminum angle frame would be required.
Hi Peter! The BiB's were run with FE166ES-R's for two weeks, and later today, I'm putting in the FE164's. The FE166ES-R's did not produce enough bass for my tastes (not surprising, given the gigantic magnet and lower Q compared to the FE164's).
If the FE164's have thunderous bass, I will swap them for FE167E's (since the FE164's, sadly, were de-whizzered by the previous owner although I read that Terry Cain said it made no difference, oddly enough).
I used an older version of the BiB calculator, with a Z-driver of 29.5". I think they are just fine in terms of ear level. My ceilings are 8 feet which is what the BiB expects, I think.
How high are your ceilings, and what's the best Z-driver you've come up with? (I'll let you know later in the week how the FE164's sound, plus I'm doing a comparison of them vs. the mighty Austins, to be posted later).
If the FE164's have thunderous bass, I will swap them for FE167E's (since the FE164's, sadly, were de-whizzered by the previous owner although I read that Terry Cain said it made no difference, oddly enough).
I used an older version of the BiB calculator, with a Z-driver of 29.5". I think they are just fine in terms of ear level. My ceilings are 8 feet which is what the BiB expects, I think.
How high are your ceilings, and what's the best Z-driver you've come up with? (I'll let you know later in the week how the FE164's sound, plus I'm doing a comparison of them vs. the mighty Austins, to be posted later).
All the best to you RJ !
Sorry to hear you were underwhelmed with the esr's. Surprising.
Anyway, my ceiling is 9 feet high. Using measured specs of the fe164 (page 4 at http://www.quarter-wave.com/Project02/ML_TQWT.pdf) and using the latest bib calculator, I can tune the box to fs*0.707 (ie. 58Hz x 0,707=41Hz) to get the horn mouth about 20 inches from ceiling(perfect), but z-driver is too high off the ground(52 inches!). Tuning to fs (58Hz) brings the driver to ear level, but leaves 46 inches to ceiling(too far).
My bibs wont be in corners. How critical is z-driver? Should I just make the tall bib and put driver at ear-level (that puts the driver at ~0.29*L instead of 0.216*L).
Will be looking out for the BIB vs AUSTIN comparison!
Thanks for your time.Regards
Peter
Sorry to hear you were underwhelmed with the esr's. Surprising.
Anyway, my ceiling is 9 feet high. Using measured specs of the fe164 (page 4 at http://www.quarter-wave.com/Project02/ML_TQWT.pdf) and using the latest bib calculator, I can tune the box to fs*0.707 (ie. 58Hz x 0,707=41Hz) to get the horn mouth about 20 inches from ceiling(perfect), but z-driver is too high off the ground(52 inches!). Tuning to fs (58Hz) brings the driver to ear level, but leaves 46 inches to ceiling(too far).
My bibs wont be in corners. How critical is z-driver? Should I just make the tall bib and put driver at ear-level (that puts the driver at ~0.29*L instead of 0.216*L).
Will be looking out for the BIB vs AUSTIN comparison!
Thanks for your time.Regards
Peter
I once made a subwoofer box for an Infinity 12D VQ driver out of 1/2 cement board doubled-up. Using screws and glue (with many pilot holes) I attached 1/4 'hardboard' to the exterior and then formica over that. So that was a four-layer enclosure. Once I mounted the driver (only .4 cu/ft inside!), I could lift the completed sub, but just barely. That tiny box with sub was well over 45kg.
Now I have no doubts that it is a fantastic acoustic material, but with that experience in mind, you'd have to limit yourself to monitors due to the weight.
Hi Peter,
I swapped in the FE164's into the BiB's and the bass is fantastic. The drivers are not even broken in yet but they sound fat and full. With the FE166ES-R's in the BiB, the bass was a bit lacking but that problem is now fixed with the FE164's.
The BiB's sound so good now that I will eventually swap in the (apparently equivalent) FE167E's. (The FE166ES-R's will go into the mighty Austins, built by Mssr. Serenechaos.) I'm not saying, of course, that the FE164 is "better" than the FE166ES-R but rather, that it's better in the BiB (no doubt because of the FE164's higher Qts).
Old jazz recordings sound great, and we listened for hours last night. Pretty much every record sounded from good to great. The bass is fat, full and satisfying. It's a tad exaggerated perhaps, but that could be fixed by pulling them out a few inches from the corners. What a great dilemma to have -- too much bass from a 6" Fostex.
Peter, in looking at the BiB's with a 29.5" Z-driver, standing next to the Austins, the BiB's drivers are much lower than the Austins which suggests that they could be inverted. Even inverted and standing up on "legs" of some kind, the drivers would still be a bit lower than the Austins. So perhaps you could try both ways? BiB's seem to be a very forgiving design.
I swapped in the FE164's into the BiB's and the bass is fantastic. The drivers are not even broken in yet but they sound fat and full. With the FE166ES-R's in the BiB, the bass was a bit lacking but that problem is now fixed with the FE164's.
The BiB's sound so good now that I will eventually swap in the (apparently equivalent) FE167E's. (The FE166ES-R's will go into the mighty Austins, built by Mssr. Serenechaos.) I'm not saying, of course, that the FE164 is "better" than the FE166ES-R but rather, that it's better in the BiB (no doubt because of the FE164's higher Qts).
Old jazz recordings sound great, and we listened for hours last night. Pretty much every record sounded from good to great. The bass is fat, full and satisfying. It's a tad exaggerated perhaps, but that could be fixed by pulling them out a few inches from the corners. What a great dilemma to have -- too much bass from a 6" Fostex.
Peter, in looking at the BiB's with a 29.5" Z-driver, standing next to the Austins, the BiB's drivers are much lower than the Austins which suggests that they could be inverted. Even inverted and standing up on "legs" of some kind, the drivers would still be a bit lower than the Austins. So perhaps you could try both ways? BiB's seem to be a very forgiving design.
Hi Peter, speaking strictly as a newb:
Why not resize your inverted BiB to suit your driver height requirements? Shorten the line length until the Z-driver is acceptable while keeping box volume the same as what the calculator determines. Of course this reduces the tuning (bass) but it will give you flexibility.
Here's GM on the general subject of sizing: Bigger Is Better 'BIB' Cabinet Dimensions - ZillaSpeak
Here's MJK on BiB simulation: General Speaker Related Articles (last article).
There's nothing absolute about tuning an octave below Fs -- GM seems to suggest there is flexibility. Also, you could always sim in MJK to see what works (presumably you'd sim an inverted BiB by lowering the ceiling?!) Anyway, given that you're willing to do inverted, I'm sure you can make this work.
I'll invert mine later in the week!
Why not resize your inverted BiB to suit your driver height requirements? Shorten the line length until the Z-driver is acceptable while keeping box volume the same as what the calculator determines. Of course this reduces the tuning (bass) but it will give you flexibility.
Here's GM on the general subject of sizing: Bigger Is Better 'BIB' Cabinet Dimensions - ZillaSpeak
Here's MJK on BiB simulation: General Speaker Related Articles (last article).
There's nothing absolute about tuning an octave below Fs -- GM seems to suggest there is flexibility. Also, you could always sim in MJK to see what works (presumably you'd sim an inverted BiB by lowering the ceiling?!) Anyway, given that you're willing to do inverted, I'm sure you can make this work.
I'll invert mine later in the week!
Hi RJ. You're not more of a newb than me, that's for sure!
Glad you like the fe164's! Gives me something to look forward to! Don't know if the
167e's will be an improvement over the 164's. Have my doubts, but I'm no expert.
I'm just trying to "design" for maximum bass since they won't be in corners, and at the same time keep the drivers as close to ear-level as possible. I'll let you know how I get along. Thanks for all the info and for sharing your experiences and thoughts.
Let me know how the "inversion" goes! I'd like to know how it compares. I haven't come across anyone who's tried the same pair both ways. Should be interesting.
Glad you like the fe164's! Gives me something to look forward to! Don't know if the
167e's will be an improvement over the 164's. Have my doubts, but I'm no expert.
I'm just trying to "design" for maximum bass since they won't be in corners, and at the same time keep the drivers as close to ear-level as possible. I'll let you know how I get along. Thanks for all the info and for sharing your experiences and thoughts.
Let me know how the "inversion" goes! I'd like to know how it compares. I haven't come across anyone who's tried the same pair both ways. Should be interesting.
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