Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 42 - diyAudio
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Old 23rd April 2006, 12:08 AM   #411
RtV is offline RtV  United States
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Quote:
Originally posted by GM

Theory and reality come together with the conclusion that as long as the 'tunnel' isn't too deep and the walls flare away at a sufficient rate to keep reflections from audibly modulating the diaphragm, then it's not an issue. Typically this means a > 20 deg chamfer and < ~3.4" deep.
This is great info! Without much experience in the matter I was going ahead by adding 1" of depth and routing out a 45 deg chamfer. Now I can do it with a little more confidence. Much thanks.

Randy
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Old 23rd April 2006, 09:23 AM   #412
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Default they are done.

well, they have been assembled and playing for a week or so. the results have been very very good. astounding, in fact.

the bass is great and all, but I am hearing all kinds of weird unexpected magic in the midrange as well that I did not know this driver capable of posessing. I suspect that the voight half of this pipe really helps here. the side panels the other. the only metal in the things is the t-nuts and hex bolts. there is a tiny bit of wool felt on the front side of the magnet. no other damping material and they sound perfect, more or less.

there are really alot of factors going on here. the wood is nice. I also sealed the driver to the cabinet with a little adhesive neoprene foam strip. bass is typical of a good horn. lots of speed. lots of impact. very instrumental. they are really amazingly clean and disgustingly accurate for how undamped they are. I really really like that. horns are supposed to be horns - straight up-. no monkey business. the goal is reinforcement. not filtering. just my opinion though...

the bases are double thick ply, and pretty wide for stability. the false baffles on the sides are cool sounding. a little ugly for now, just proportionally. I am considering cutting them in half, creating a little triangular box with what is left on the cabinet, and filling it with sand. hopefully extra power of bass, and even fewer resonances, while still a little of that nice wave launch thing. however, these things sound so clean, that the resonances are quite desirable - life. the plywood used was white maple 3/4 from home depot. it cost a pretty penny, but the results are good so eh what the hey.

It came to my attention that there is better lumber cheaper in town so for my next project I will go there.

the bass is very good as I suspected. there is the recess around 100 hz maybe about 3db in room. I used the EQ in Itunes to futz around here.

my room is notoriously bad sounding. the carpet on the relatively compliant floor, acoustic tile ceiling, huge window behind the speakers, ... they still sound great. they need a slightly smaller and much stronger room and they would be flat and quicker no doubt.

they are really pretty big speakers. the drivers sit at ear level when one is sitting up straight in an office chair. a tall sound. fun and involving.

these 166 es-rs i have had for a year now. they are really really starting to spread their wings now. though originally I considered it, I would not dream of phase plugging them, duct sealing, super tweetering, etc. the thin wool felt that partially covers the front of the magnet is all I need, maybe not even that. I have really come to understand that this banana plant fibre just takes a few seasons of humidity and temparature fluxuations to break in perhaps. even and perhaps especially in the E series stuff from fostex. there are not stricktly just hours to be logged. patience pays!!!! the tone of them now is so refined and so far divorced from their initial character, as refined as they were new. they have grown out of adolescence into young adulthood perhaps. there is alot of black in the black background, unlike when they were new. they can handle extremely complex music, totally debunking that whole single driver congestion stigma. there is alot more euphony in the tone - at all frequencies. there is perhaps some natural compression going on here. that as the cone weakens with age the loud stuff is not as loud, the quiet stuff stays relatively the same? eh who knows. I think that they are very very special indeed. so balanced, so super. very high speed. ultra detailed, especially harmonically. they are simply a good balance of what is possible. I enjoy the 168 sigma alot as well. the lack of whizzer makes it very special, still maintaining a decent top end response.

where the es-r has muscle is in the region of midrange to upper midrange. it sounds very errie. very very real and expansive. it will trick the mind time and time again. however, I feel that the 166es-r is somewhat unbalanced towards this area perhaps. that there is soooo much midrange clarity that it works to the detriment of the high frequencies especially. also, no matter how much bass there is, the midrange is just so pure that it dominates.

we as a diy community should make sure to convince fostex to maintain their relatively new policy of shipping the u.s. some of their special edition stuff.

well,

I really love horns! there is just so much logic behind back horns. so much elegance and simplicity of mechanism.

Ill get pictures to y'all soon. thanks for all the help on this adventure in musical experimentation. especially to terry cain for challenging and encouraging me so much.

Clark
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Old 23rd April 2006, 05:37 PM   #413
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Does that mean you like them then?

What do you mean big? Those aren't big! Now, the FE208ESigma boxes, or the Monoliths, on the other hand...

GM's suggested cabinets will shortly be emerging on the BIB pages, along with a few Lowther ideas (once I've finished generating the FR plots).

Best
Scott
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Old 23rd April 2006, 07:51 PM   #414
dmason is offline dmason  United States
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Scott,

I think Clark is saying he likes his BIB's. Qu'elle surprise?

Jeff,

Just saw the Hemp page and wideload. Love the Monolith. The Dawn of A New Understanding. I also think the Hempcone would do justice to that monster.

Those BIG ones are calling to me. Anyone have any thoughts about using the wide side for the 6 inchers? That nice side could be put to good use for wave launch. Great work guys!!
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Old 23rd April 2006, 10:26 PM   #415
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Dan -did we forget to warn him that these things can be addictive?

Interesting idea -once I've finished the current batch, I'll look into it some more with the ~6in drivers. I like wide baffle designs -many of the benefits of dipoles, without the drawbacks. Or so it seemed with my old test mules anyway. Martin's new OB sheet is very useful in this regard.

Re the Monoliths, the only problems I can forsee is trying to fit them through the door... watching 2001 with a pair providing the audio could be an interesting experience though!

Cheers
Scott
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Old 24th April 2006, 07:27 AM   #416
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Default addictive, no doubt.

are the BIB for 208es as tall as the nessie mk3? some time I will build a nessie or two. they seem really cool. fairly simple too.

yes, I like them. very much. I have been struggling with the p-16s in these though. I cannot seem to find a placement that I am happy with. I originally mounted 7 per side, but they totally killed the bass. yanked them all out it got way better. I have been playing with 5 per side, then 2, then 1 in all sorts of locations. avoiding the number of death for good measure. I mean they DO come 5 to a package after all. anyways, they will help some frequencies and not others. usually p-16s are just what the doctor ordered for the mouth of traditional back horns. are these things just way different? any comments?

I have a small panel at the very top of the horn which is parallel to the back which is around 5 inches long. it is the same width as the internal baffle. in fact, it is the scrap peice I cut off the internal baffle to get the void in the bottom. in either case, it is sortof meant for directivity and stability of the large unsupported area at the top of the horn. I think it helps a decent amount to strengthen the cabinet. could this have something to do with the ineffectiveness of the p-16?


Clark
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Old 24th April 2006, 12:56 PM   #417
inrank is offline inrank  United Kingdom
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has anyone used a FR125s in a BIB (back loaded corner horn thing?).
what excatley is a BIB?

thanks

Fr125s Horn
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Old 24th April 2006, 01:53 PM   #418
GM is offline GM  United States
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Quote:
Originally posted by inrank
has anyone used a FR125s in a BIB (back loaded corner horn thing?).
what excatley is a BIB?
Greets!

You answered your own question.

Anyway, measured Fs for this driver is 'all over the map', so I split the difference at 56.5 Hz:

L = 120"
SO, SL = same as the original
zdriver = 23.5"

GM
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Old 24th April 2006, 06:25 PM   #419
fred76 is offline fred76  Philippines
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Hi,

Here's an elementary question if you will... If lets say 2 drivers have the same Vas but the other one has a much lower Fs (~10Hz), does that mean the lower Fs driver would have a larger Sm most of the time (if not all of the time)? Thanks.

fred
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Old 24th April 2006, 07:12 PM   #420
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Greets!

Didn't I already list which spec determines each dim?

Anyway, Fs determines the line's length. Sm combined with the pipe's net Vb sets the gain over 'x' BW, so all else being equal, the lower Fs driver will have a longer line length and its extra Vb 'fills' in the extra BW even though both have the same Sm.

GM
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