Thanks Lon and GM! The guide/sawboard.. what a simple concept but so helpful! I'll be putting that to use. Now to order some Hemp Acoustics drivers. 🙂
Re: Re: 2001 monolith ratio
I got it at a big discount chain store called Menards. It's based in Wisconsin, and I think they only exist in the upper midwest. The veneers aren't good enough to finish, but the inner plys are of great quality. It was $60 a sheet. I called some lumber yards and couldn't find anybody else stocking 4x8, or I would have purchased it from a more local source.
GM: Should I deduce from this that you mount the driver off center? What do you think about making the baffle double thick? My plan is to line the inner baffle with carpet pad from just below the driver to the top of the cab, and put a layer or two in the bottom as well. Then I'd use acoustuff or polyfill in those locations to adjust as needed.
Paul
lousymusician said:
I got it at a big discount chain store called Menards. It's based in Wisconsin, and I think they only exist in the upper midwest. The veneers aren't good enough to finish, but the inner plys are of great quality. It was $60 a sheet. I called some lumber yards and couldn't find anybody else stocking 4x8, or I would have purchased it from a more local source.
GM said:
GM: Should I deduce from this that you mount the driver off center? What do you think about making the baffle double thick? My plan is to line the inner baffle with carpet pad from just below the driver to the top of the cab, and put a layer or two in the bottom as well. Then I'd use acoustuff or polyfill in those locations to adjust as needed.
Paul
Re: Re: Re: 2001 monolith ratio
Greets!
I would if the walls were parallel, but the sloped baffle wall negates any need to offset the driver.
Can't hurt, but BIBs don't generate much pressure except at the throat and mouth, so a rigid material and the geometry of the BIB takes care of the throat, leaving the mouth, which might need some vertical bracing on the long walls like any large mouth horn.
GM
Greets!
I would if the walls were parallel, but the sloped baffle wall negates any need to offset the driver.
Can't hurt, but BIBs don't generate much pressure except at the throat and mouth, so a rigid material and the geometry of the BIB takes care of the throat, leaving the mouth, which might need some vertical bracing on the long walls like any large mouth horn.
GM
GM said:
What sort of brace would you envision? I know you've mentioned 1" hard wood dowels before. I am thinking of something a bit larger, like a panel somewhere between 6" and 4' long between the long walls, equadistant between the internal baffle and the mouth at all points, and full of holes. I understand this would mass load it a bit, but would the difference really be substantial? It would sure make the walls stiffer.
Also, how about the double thick front baffle; good idea, or not worth the effort/weight?
pj
This was my next item to worry about. What kind of bracing I'd need for that monolith. I mean, when you get up to 72"x32" pieces of wood, I'd assume they'd have some flex. Not sure what kind of bracing would be needed. I am referencing GM's post as to where the pressure points are in a BiB so that extra bracing would be used there. I'm going to look through some BiB photo threads to see how others brace (if any). I've also got some old wood I'll prototype all of this with. Baltic Birch seems appealing if I can find it in a size big enough for 72" in at least one dimension.
pjanda1 said:
The Baltic Birch ply, --if-- you can get it is generally 60X60 inches only.
However, I would try to find the stuff from Quebec, which is at least of similar quality, and far less expensive, thanks to its domestic"" source, NAFTA, etc. If you are in Michigan, I would think there ~might be a better possibility of finding some.
I found marine grade plywood from Quebec, in San Diego, which represents a large demand for ply of this quality and grade, due simply to the amount of tonnage alongside, in this town. Hope this helps.
However, I would try to find the stuff from Quebec, which is at least of similar quality, and far less expensive, thanks to its domestic"" source, NAFTA, etc. If you are in Michigan, I would think there ~might be a better possibility of finding some.
I found marine grade plywood from Quebec, in San Diego, which represents a large demand for ply of this quality and grade, due simply to the amount of tonnage alongside, in this town. Hope this helps.
Greets!
For the most part I made horn cabs from 3/4" void free marine grade plywood and a few hardwood dowels cut from closet rod material. Early on though I braced them 'six ways to Sunday' as if they were mini-skyscrapers (I was an architect wannabe for awhile) until I started studying monocoque design like is used in aircraft, etc., and realized that as long as the basic cab was made from a fairly rigid material it didn't take mass quantities of bracing to make it really rigid and that it only needed to be super rigid at certain points. About the same time I learned about how much acoustic energy rolled off with increasing frequency, so I quit caring about whether it wrung like a 'ten penny nail struck with a ball-peen hammer' since the most troublesome frequencies could be attenuated enough with bracing and/or minimal insulation and concentrated on keeping the cab from 'breathing' with the 'ebb and flow' of low frequency pressure/rarefaction waves.
The BIB's angled internal baffle goes a long way towards bracing the cab and distributing resonances, so a few dowels to bisect any large surfaces should suffice if 19 mm BB ply or similarly stiff material is used since this isn't a high compression loaded horn that requires a bit more substantial mouth bracing like the flat baffles used in the LABhorn or similar.
WRT to 'skinning' the large front baffle, rigidity increases at the cube of thickness, so doubling up 19 mm BB ply or similar will seriously increase the cab's mean stiffness, but it will still need additional mouth bracing to ensure the back panel doesn't flex, though gluing some scrap plywood to the rear panel's large expanses will work too, though dowels in the mouth gives you something to support a grill or filter if desired.
Bottom line, IMO there's no such thing as too stiff/damped a horn, only a point of diminishing returns. I've told you how to get to mine, but you'll have to decide how much it takes to get to yours.
GM
For the most part I made horn cabs from 3/4" void free marine grade plywood and a few hardwood dowels cut from closet rod material. Early on though I braced them 'six ways to Sunday' as if they were mini-skyscrapers (I was an architect wannabe for awhile) until I started studying monocoque design like is used in aircraft, etc., and realized that as long as the basic cab was made from a fairly rigid material it didn't take mass quantities of bracing to make it really rigid and that it only needed to be super rigid at certain points. About the same time I learned about how much acoustic energy rolled off with increasing frequency, so I quit caring about whether it wrung like a 'ten penny nail struck with a ball-peen hammer' since the most troublesome frequencies could be attenuated enough with bracing and/or minimal insulation and concentrated on keeping the cab from 'breathing' with the 'ebb and flow' of low frequency pressure/rarefaction waves.
The BIB's angled internal baffle goes a long way towards bracing the cab and distributing resonances, so a few dowels to bisect any large surfaces should suffice if 19 mm BB ply or similarly stiff material is used since this isn't a high compression loaded horn that requires a bit more substantial mouth bracing like the flat baffles used in the LABhorn or similar.
WRT to 'skinning' the large front baffle, rigidity increases at the cube of thickness, so doubling up 19 mm BB ply or similar will seriously increase the cab's mean stiffness, but it will still need additional mouth bracing to ensure the back panel doesn't flex, though gluing some scrap plywood to the rear panel's large expanses will work too, though dowels in the mouth gives you something to support a grill or filter if desired.
Bottom line, IMO there's no such thing as too stiff/damped a horn, only a point of diminishing returns. I've told you how to get to mine, but you'll have to decide how much it takes to get to yours.
GM
mrbubbs said:
Maybe you were able to find some details on the guide
board then? Great.
I've used this technique for some time. As long as
you have the patience for repeated setups and
use a rigid guide as a straight edge you should get some
square cuts. Best to not re-measure but use the first
piece to clone the second etc. Before beginning, always
measure twice to cut once.
If I had the tools I'd use the bisquit joinery technique
but for my builds they are just sort of stuck together
hence the request for goo details on caulk materials
used.
Re: plywood,
I'm not the only one that has found 4x8 Baltic Birch in their local. Folks on another forum I used to frequent had some luck after calling around to lumber yards and cabinet shops.
Also, avoid the birch and oak veneered Home Depot ply at all costs. A few sheets look nice on the edges (many layers, few voids) but the interior is a different story. The outer veneer is nicer than the BB I got, but that doesn't count here.
pj
I'm not the only one that has found 4x8 Baltic Birch in their local. Folks on another forum I used to frequent had some luck after calling around to lumber yards and cabinet shops.
Also, avoid the birch and oak veneered Home Depot ply at all costs. A few sheets look nice on the edges (many layers, few voids) but the interior is a different story. The outer veneer is nicer than the BB I got, but that doesn't count here.
pj
I'm wondering about these cabs and their usage with a standard receiver and for home theater.
I've got an older Yamaha receiver I use now for both stereo listening and home theater. These bib's sound like a fun project but I wonder what driver would make sense since this isn't the high quality amplification most of you are used to. I figure I will build a set using some of those cheapie $11 speakers mentioned in other threads, but would like some feedback on the usage of some nicer drivers like one of the Fostex line or ???? Am I going to be wasting my money pairing a pair of Fostex drivers with my current amp? If so, what would you reccommend?
I've got an older Yamaha receiver I use now for both stereo listening and home theater. These bib's sound like a fun project but I wonder what driver would make sense since this isn't the high quality amplification most of you are used to. I figure I will build a set using some of those cheapie $11 speakers mentioned in other threads, but would like some feedback on the usage of some nicer drivers like one of the Fostex line or ???? Am I going to be wasting my money pairing a pair of Fostex drivers with my current amp? If so, what would you reccommend?
Greets!
This is a loaded Q, like asking me if you'll like the color 'green' on your walls. 😉
That said, from a technical POV it will depend somewhat on which Yamaha Receiver and how close it still matches its specs since some are pretty good.
Which $11 drivers?
Typically, speakers are the system's 'weakest link', so up to the point where its resolution is good enough to audibly highlight the rest of the system's weaknesses you go for all you can afford. That said, any competent ~fullrange driver can be improved with a low (and preferably, no) nfb amp, so if the receiver's damping factor (DF) is > ~80 (many are), I don't recommend wasting your $$ on high $efficiency drivers$.
That said, with rare exception, receivers typically don't have much clean power, so to keep distortion acceptable for music you'll need at least the 20 dB of dynamic headroom DD/DTS requires, which usually means at least a low 90s (mid) efficient system.
GM
This is a loaded Q, like asking me if you'll like the color 'green' on your walls. 😉
That said, from a technical POV it will depend somewhat on which Yamaha Receiver and how close it still matches its specs since some are pretty good.
Which $11 drivers?
Typically, speakers are the system's 'weakest link', so up to the point where its resolution is good enough to audibly highlight the rest of the system's weaknesses you go for all you can afford. That said, any competent ~fullrange driver can be improved with a low (and preferably, no) nfb amp, so if the receiver's damping factor (DF) is > ~80 (many are), I don't recommend wasting your $$ on high $efficiency drivers$.
That said, with rare exception, receivers typically don't have much clean power, so to keep distortion acceptable for music you'll need at least the 20 dB of dynamic headroom DD/DTS requires, which usually means at least a low 90s (mid) efficient system.
GM
GM said:
I may be partly responsible for BIB with $11 /each, excellent in my opinion. Take a look at the link:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=89831
gychang
I would flat out avoid Fostex wideband drivers if you are planning on sticking with the Yamaha transistor receiver. They are "meant" for Zero-NFB tube amps, and IMO are unlistenable on more conventional, read: [transistor] amps.
The Hemp FR8 sounded pretty good with sand amp, it never got out of Class A 0-nfb first 10 watts of my Hafler 9505, and fantastic with well implemented T amps but especially SET tube amps. 45 = surreal, for example.
Unless you planned an eventual upgrade of the amp, I wouldnt spend $ on wideband drivers.
The Hemp FR8 sounded pretty good with sand amp, it never got out of Class A 0-nfb first 10 watts of my Hafler 9505, and fantastic with well implemented T amps but especially SET tube amps. 45 = surreal, for example.
Unless you planned an eventual upgrade of the amp, I wouldnt spend $ on wideband drivers.
Well, that is what I thought I was going to hear, but needed to ask.
Are the receivers using digital amps any better than the normal transistor amps? Also, I see that the Pioneer Elite 82txs has a dampening factor in the 50's - though it is a standard amp. Does this figure in much or is the chasm between transistor amps and others really that large?
See, I've never heard high quality amplification so i have no idea what I'm missing. I guess that is both good and bad. A receiver would be most functional for my wife and I, but I would entertain a separate audio amp if if would truly bump everything up a level at a low, entry-level, get your first taste sort of budget.
I've got a T-amp in a box someplace. Would that be suitable for the BIB's with Fostex drivers?
Sorry for the littany of questions that are all subject to opinion. I don't have experience in this area and there are no audio shops around to go take a listen.
Are the receivers using digital amps any better than the normal transistor amps? Also, I see that the Pioneer Elite 82txs has a dampening factor in the 50's - though it is a standard amp. Does this figure in much or is the chasm between transistor amps and others really that large?
See, I've never heard high quality amplification so i have no idea what I'm missing. I guess that is both good and bad. A receiver would be most functional for my wife and I, but I would entertain a separate audio amp if if would truly bump everything up a level at a low, entry-level, get your first taste sort of budget.
I've got a T-amp in a box someplace. Would that be suitable for the BIB's with Fostex drivers?
Sorry for the littany of questions that are all subject to opinion. I don't have experience in this area and there are no audio shops around to go take a listen.
Greets!
OK, I'm familiar with this driver, or at least this Pioneer number (aka RS 970-0549) from some years ago, that I dubbed the poor man's RS 40-1197 since it traded a bit more bottom end at the expense of overall resolution. Still great bang/buck though!
Unfortunately it doesn't have enough reasonably low distortion dynamic range to work in a music/HT app unless either listened to at typical TV volume levels or it's XO'd to a mid-bass above ~500 Hz where you can somewhat overdrive it without 'letting all the smoke out'.
GM
OK, I'm familiar with this driver, or at least this Pioneer number (aka RS 970-0549) from some years ago, that I dubbed the poor man's RS 40-1197 since it traded a bit more bottom end at the expense of overall resolution. Still great bang/buck though!
Unfortunately it doesn't have enough reasonably low distortion dynamic range to work in a music/HT app unless either listened to at typical TV volume levels or it's XO'd to a mid-bass above ~500 Hz where you can somewhat overdrive it without 'letting all the smoke out'.
GM
Never apologise for asking questions; the only "stupid" question is the one unasked...
T amps sound pretty good with Fostex, and far better when dolled up with good coupling capacitors, battery power, etc, they start getting damn good. Still, the Fostex drivers behave far differently when using tubed amplifiers to the extent that they are intended for such, and have been optimized for their loads by the wizards at Fostex, all part of the Japanese paradigm of "hi fi" sound.
Again, the Hemp FR8 with the T amp would be the shortest path to success, in my opinion. In fact, a little T amp and BIG BIB with FR8 would almost guarantee a jaw dropping home audio experience. Louis' OEM hemp drivers with Vinnie's Signature 30 amp sounds sooooo good, it laughs at all that shiny shi shi so called "high end" stuff out there. Again, T amp/Hemp driver, my vote....
T amps sound pretty good with Fostex, and far better when dolled up with good coupling capacitors, battery power, etc, they start getting damn good. Still, the Fostex drivers behave far differently when using tubed amplifiers to the extent that they are intended for such, and have been optimized for their loads by the wizards at Fostex, all part of the Japanese paradigm of "hi fi" sound.
Again, the Hemp FR8 with the T amp would be the shortest path to success, in my opinion. In fact, a little T amp and BIG BIB with FR8 would almost guarantee a jaw dropping home audio experience. Louis' OEM hemp drivers with Vinnie's Signature 30 amp sounds sooooo good, it laughs at all that shiny shi shi so called "high end" stuff out there. Again, T amp/Hemp driver, my vote....
Woops, I'm actually mrpopgun. I'll have to straighten out my accounts tonight as I don't want to be using two different names and I forgot I had the popgun account registered when I setup this new one at work last week.
dmason said:
Greets!
So you're saying that either the Fostex is so high res and/or the Hemp so low res that it will mask all the SS amp's alledged shortcomings?
Regardless, we'll have to agree to disagree on all this, otherwise I'd have to declare that all FR drivers should be avoided like the plague since history tells us that for wide BW reproduction only compression loaded horns are truly 'meant' for 0-nfb SET tube amps. 😉
GM