lousymusician said:
Cool. Thanks Bill - I heard good things about them. Was thinking of a metronome myself, but have been doing open baffle stuff at home.
I never did mange to get a good sounding shelf and/or zobel on mine. The EnABL seemed cure a lot of what was bothering me, anyway, so it's less urgent now. But might have to try the shelf + zobel again. Or a better sub.
pjanda1 said:
So Dave confirmed. Thanks for pointing it out.
Yes it do. This is true for high output impedance amps where the interaction between it and the driver creates a low/high 'smiley face' EQ, but typical SS amps have only a tiny fraction of an ohm, so you don't get it with these.
I'm trying to finish a composite spreadsheet, and there's something I can't remember seeing here (or anywhere, FWIW)...
GM has helped us with the minimum distance from the terminus to the ceiling (floor for inverted BIBs).
Now... what would be the maximum ? This is, the point where it makes less sense to go ceiling-loading and than floor loading instead ?
Once in the past, ron told me that the maximum distance for the A166 to the corner where it theoretically loaded should be no more than 90 cm (3 ft.), but I don't know if we are looking at the same operating principle.
Gastón
GM has helped us with the minimum distance from the terminus to the ceiling (floor for inverted BIBs).
Now... what would be the maximum ? This is, the point where it makes less sense to go ceiling-loading and than floor loading instead ?
Once in the past, ron told me that the maximum distance for the A166 to the corner where it theoretically loaded should be no more than 90 cm (3 ft.), but I don't know if we are looking at the same operating principle.
Gastón
Greets!
It's dependent on the room and the amount of gain BW required to make it ~flat in-room, so all of this would ideally need to be calc'd on an individual basis using pressure wave math. As a general rule though, the pioneers of audio considered mouth sizes in the 110 - 120 Hz range sufficient for corner loading, so Ron's ~36" would be my point of flopping it over for floor loading if corner loaded and the longer of ~18" or the (3*mouth radius) for mid wall mounting.
GM
It's dependent on the room and the amount of gain BW required to make it ~flat in-room, so all of this would ideally need to be calc'd on an individual basis using pressure wave math. As a general rule though, the pioneers of audio considered mouth sizes in the 110 - 120 Hz range sufficient for corner loading, so Ron's ~36" would be my point of flopping it over for floor loading if corner loaded and the longer of ~18" or the (3*mouth radius) for mid wall mounting.
GM
Thanks, GM, the grey beards way will do, for BIBs, IMO !
I'm trying (not very hard, I have to admit it) to add Dave diagram and the wood calculator into the integrated calculator, but keeping loninappleton drawing inside the page and making all fit single sheet is complicated.
I think I will start to split the calculator in multiple sheets in the same file, but I don't know how will affect usability for non-excel users (OpenOffice, Mac'sters, etc.)
Thanks again
Gastón
I'm trying (not very hard, I have to admit it) to add Dave diagram and the wood calculator into the integrated calculator, but keeping loninappleton drawing inside the page and making all fit single sheet is complicated.
I think I will start to split the calculator in multiple sheets in the same file, but I don't know how will affect usability for non-excel users (OpenOffice, Mac'sters, etc.)
Thanks again
Gastón
Use this info. It sounds VERY good :
http://www.diyaudio.com/forums/showthread.php?postid=1334151#post1334151
The BOFU BIBs got VERY positive response at Burning Amp!
Nelson Pass gave away 24 Pioneer BOFU drivers there also so I expect to see a lot more being made!!
fe108es
still tweaking my bibs and looking for some advice. i've tried various amounts of stuffing, hanging a pennant shaped cloth, and covering the mouth with thin cloth (which is my current fav) and still haven't gotten rid of the lean sound. the bass extends pretty low and there's lots of it when you turn it up, it's just that there's much more midrange. but if i overstuff it kills everything not just the mids.
so would adding series resistance help things out? if so, what values to start with? will i need to use bypass caps as well? i'm running a charlize tripath amp and single strands of cat5 wire to the speakers. kookaburra pre with ipod as source.
thanks!
still tweaking my bibs and looking for some advice. i've tried various amounts of stuffing, hanging a pennant shaped cloth, and covering the mouth with thin cloth (which is my current fav) and still haven't gotten rid of the lean sound. the bass extends pretty low and there's lots of it when you turn it up, it's just that there's much more midrange. but if i overstuff it kills everything not just the mids.
so would adding series resistance help things out? if so, what values to start with? will i need to use bypass caps as well? i'm running a charlize tripath amp and single strands of cat5 wire to the speakers. kookaburra pre with ipod as source.
thanks!
You beat me to it Jeff. 
Sounds like they are upward-firing cabinets to me, and with drivers as small as the 108, the upward-firing type is not going to couple especially well to the room. I usually recommend the inverted type for a driver with an Fs of more than ~60Hz. You'll need to get them rammed hard into corners to complete the horn flare & get as much gain as possible from the room with a little unit like that, especially if venting upward.
I doubt adding series resistance will help much. Charlize has a fairly low DF, and the Sig. has a pretty moderate Q as-is.
Sounds like they are upward-firing cabinets to me, and with drivers as small as the 108, the upward-firing type is not going to couple especially well to the room. I usually recommend the inverted type for a driver with an Fs of more than ~60Hz. You'll need to get them rammed hard into corners to complete the horn flare & get as much gain as possible from the room with a little unit like that, especially if venting upward.
I doubt adding series resistance will help much. Charlize has a fairly low DF, and the Sig. has a pretty moderate Q as-is.
I started a thread just on the BOFU BIB here.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=110703
It's an amazing speaker..
http://www.diyaudio.com/forums/showthread.php?s=&threadid=110703
It's an amazing speaker..
i have them up against the walls but only one is in a corner. they are in a weird part of the room where the ceiling is only 76 inches high. the room is quite large though -- 70 sq meters or about 750 sq feet.Godzilla said:
Scottmoose said:You beat me to it Jeff.
Sounds like they are upward-firing cabinets to me, and with drivers as small as the 108, the upward-firing type is not going to couple especially well to the room. I usually recommend the inverted type for a driver with an Fs of more than ~60Hz. You'll need to get them rammed hard into corners to complete the horn flare & get as much gain as possible from the room with a little unit like that, especially if venting upward.
I doubt adding series resistance will help much. Charlize has a fairly low DF, and the Sig. has a pretty moderate Q as-is.
yeah, these are upfiring as they were built with the original dimensions you gave me way back in the thread. i have a pair of double folded downward firing cabs awaiting suprabaffles but i would like to optimize the original pair as they are made of nice baltic birch that cost me more than the drivers.
the only thing i can think of is to flip them over and mount them to the wall (they are quite heavy) or make some legs to get them off the ground and get the driver up into listening position. gm posted a way to calculate how far they should be from the floor but it went over my head.
Once in the past, ron told me that the maximum distance for the A166 to the corner where it theoretically loaded should be no more than 90 cm (3 ft.), but I don't know if we are looking at the same operating principle.
That was based on the rear deflector being used and measured from the front of the cab to the intersection of the walls.
At low frequencies the gain is established from the edge of the deflector to the walls and the support of the conical expansion of the rear exiting wave front. If you study the final expansion of the A166 its not exactly conical, but a slight bit less so the corner forms the final expansion in a controlled wave front. This is also a calculated loading. The room is also part of the loading which is a variable.
ron
That was based on the rear deflector being used and measured from the front of the cab to the intersection of the walls.
At low frequencies the gain is established from the edge of the deflector to the walls and the support of the conical expansion of the rear exiting wave front. If you study the final expansion of the A166 its not exactly conical, but a slight bit less so the corner forms the final expansion in a controlled wave front. This is also a calculated loading. The room is also part of the loading which is a variable.
ron
168es's down under
Hello, my 168 sigmas have arrived from Madisound within a few days of ordering....amazing what a few electrons in one direction and a lot of avgas in the other can do. Never having had high efficiency full range drivers before I am surprised at their size and weight; they are one seriosly chunky driver, incredible looking suspension and spider not to mention magnet, frame and egg carton cone. They make the Dynaudio 6.5" in my existing speaks which is no slouch in the power handling stakes look quite puny. Funny but for some reason I was expecting the central part of the cone to be a phase plug, dont know why other than it appears to be a good modification on the other Fostex drivers and thought these would be an evolution of those.
I have been running them in free air at my workshop to get hours on them , I might make some sort of OB so I can listen to them here until I get time to build the BIBs. They sound very lively.
Thanks for advice so far and probably well into the future, Andrew
Hello, my 168 sigmas have arrived from Madisound within a few days of ordering....amazing what a few electrons in one direction and a lot of avgas in the other can do. Never having had high efficiency full range drivers before I am surprised at their size and weight; they are one seriosly chunky driver, incredible looking suspension and spider not to mention magnet, frame and egg carton cone. They make the Dynaudio 6.5" in my existing speaks which is no slouch in the power handling stakes look quite puny. Funny but for some reason I was expecting the central part of the cone to be a phase plug, dont know why other than it appears to be a good modification on the other Fostex drivers and thought these would be an evolution of those.
I have been running them in free air at my workshop to get hours on them , I might make some sort of OB so I can listen to them here until I get time to build the BIBs. They sound very lively.
Thanks for advice so far and probably well into the future, Andrew
IMHO i consider the 168 sigma to be the best design out of Fostex.
However they can sound shrill on axis and require a great deal of break in.
Funny but for some reason I was expecting the central part of the cone to be a phase plug, dont know why other than it appears to be a good modification on the other Fostex drivers and thought these would be an evolution of those.
I do not know if they have developed their physics far enough to include phase plugs. Its also an additional Mfg. cost. I have spent some time in the study of nearfield wave form and sometimes its difficult to achieve the trade off of efficency vrs dispersition.
ron
ron
However they can sound shrill on axis and require a great deal of break in.
Funny but for some reason I was expecting the central part of the cone to be a phase plug, dont know why other than it appears to be a good modification on the other Fostex drivers and thought these would be an evolution of those.
I do not know if they have developed their physics far enough to include phase plugs. Its also an additional Mfg. cost. I have spent some time in the study of nearfield wave form and sometimes its difficult to achieve the trade off of efficency vrs dispersition.
ron
ron
Personally I couldn't care tuppence about any of the primadonnas lurking in the background. I've had no involvement & no dealings with any of them; and that's not going to change as I have little interest in either of their products
Very true Scott. i have to operate on logic and physics. Its necessary in my line of work. I am not a primadonna, just a guy who crunches numbers and comes up with answeres. (At least that is what THEY think LOL!!!). The question is all i have ever done is depend on the work of early physics development, i truly havent come up with anything new, just used/refined/combined their work.
ron
Very true Scott. i have to operate on logic and physics. Its necessary in my line of work. I am not a primadonna, just a guy who crunches numbers and comes up with answeres. (At least that is what THEY think LOL!!!). The question is all i have ever done is depend on the work of early physics development, i truly havent come up with anything new, just used/refined/combined their work.
ron