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Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?
Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?
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Old 6th May 2008, 11:43 AM   #4041
BenjaminWebber is offline BenjaminWebber  United States
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Location: Yakima, WA
Default 208/T90A Cap

Thanks Guys. Nice to get home from a 16hr day, and have all this info to mull over!

I wonder what 208/T90A Bibsters have settled on. I started out using .68uf, with no attenuation. For a long time I thought I had wasted my money on the attenuator. Latter I decided that I liked it A LOT better with the T90A attenuated quite a bit. Right not I have the 208 in reverse polarity with the T90A (my pre-amp is phase inverting). I used the 1.0uf for awhile, but am back to the .68 with some attenuation. I don't have a way to measure anything. Just my ears.

Also, I think I need to dampen my room in such a way that it passes the WAF. I seem to hear more resolution with some blankets, etc. hung on some of the walls.

Sincerely,

Benjamin
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Old 6th May 2008, 12:37 PM   #4042
pebbles is offline pebbles  Australia
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Default Overdue BIB report

Well I have had the FE168ESigma BIBs up and running for a couple of months now; that was the relatively easy part but describing how they sound is a lot harder so I’ve hesitated posting about them but now here goes.
They were not as easy a build as I had expected but that was more to do with my being too fastidious and a couple of wrong turns. I used the standard box dim’s for the driver on Zilla’s site. Originally they were going to be quick prototypes but when I saw the price of even quite poor quality ply I decided to make them well enough to keep them if I liked them. I’ve used very poor quality 18mm pine ply which is definitely not void free and is so rough that I glued a layer of 3mm MDF to the outside surface to give it more strength and so as I could veneer or paint them if happy with them. The internal baffle is 18mm particle board with the same 3mm MDF layer added but this time glued using a squiggle pattern of flexible silicone bead thinking that this would create a lot of irregular shaped areas that could vibrate and lose some of the midrange/high frequencies before thy exited the mouth. I can’t be sure if it has worked but there is very little if any I can hear in the way of them exiting the mouth.
I made a panel above the driver and one at the base of each speaker removable to make tuning the damping easier as I did not like the idea of trying to fish things in or out or dislocating my elbow. If I decide to finish the boxes further I will remove the screws and replace them with a dowel.
The supra baffle was made using a sheet of laminated radiata pine available at large hardwares stores here. It is very poor timber, but soft and easy to turn. Luckily I share a workshop with a skilled cabinetmaker who guided me through the turning process which I must say was very satisfying. He also recommended gluing a layer of 3mm MDF on the back to prevent tearing away of the timber at the edge where it turns under the baffle. Unfortunately shortly after I made these beautiful things they started to warp which meant spending a day cutting away the back and gluing timber to try and straighten them out, which has been reasonably successful although I put a gasket between the baffles and box just in case they weren’t perfectly flat. I put a 19mm dowel brace across the box about 150mm down from the opening.
Damping is a sort of rough removalist felt about 6mm thick and this is tacked into place on the inner baffle and one side from the pointy end to about 50mm below the driver as per instructions. For the base I bought a damping material from Jaycar (our RS ) which is a heavy 3mm vinyl (impregnated with something I think) material with a layer of foam bonded to it, about 7mm in total. I also cut a circle of this and stuck it on the back of the driver and used duct seal to smooth out the steps around the magnet.
Wiring is the plainest bell wire, single core tinned copper about 0.6mm diam. I also wire in externally a pair of cheap attenuators to play around with series resistance as I read earlier there may be some benefits when using high damping factor SS amps (not sure whether mine is) While building the boxes I had been running the drivers in at work and they probably had about 120-150 hrs at quite high volumes on them, and I was quite impressed by their dynamics and vitality when mounted in cardboard boxes........
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Old 6th May 2008, 12:39 PM   #4043
pebbles is offline pebbles  Australia
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Default Overdue BIB report

........ At home and set up against the wall, about 1.2 mtrs in from the cnrs. and firing across the room (5.5x3.5 3.5mtr) I must say initially I was disappointed. The bass seemed no lower than my standmounts and without the slam, although it didn’t swamp the room the way the standmounts could unless they were pulled out virtually into your lap. The imaging was not as specific either, and the sound stage seemed to extend back from the speakers rather than into the room. I thought this might have been due to them being pushed up against the wall so I pulled them out a bit which improved the situation without much affect on the bass. Next evening I hooked up the attenuators and tried various settings, this certainly was not a night and day difference but somewhere along the line I found the sound more to my liking . I took the damping out of the base and that made a significant difference; more bass, more tone, more kick in the kick drums, possibly just generally more dynamic. I listened to the mouth again and could hear some higher frequencies, not much but more than previously so I cut a rectangle of the felt and put that in and that seemed to take care of them.
I then sat back and listened for a while and I must say started to be quite impressed; I don’t know what changed(cant remember what I was drinking)……maybe these drivers are like the Dyns, they need a warm up period or more likely my ears needed time to adjust to this new presentation. Anyway listening to the Buena Vista Social Club and then Ruben Gonzales on piano after about half an hour I came to the conclusion that these speakers were doing something very right.
They are incredibly dynamic and play music with verve and gusto, I’ve listened to these tracks before and found parts of them interesting and others not so, this time I found all of it exciting and sensible (as in you could understand why that sound was there, in relation to the musical whole), the bass was there, low but not overwhelming, light footed and keeping the complicated rhythms alive . There was plenty of impact of the hammer on strings from vigorous playing, dramatic, fresh and musical. Everything of a piece, nothing astray that makes you wonder what instrument was that in the background or why was it there. These speakers are fun and very alive. They don’t seem to have quite the body in the sound of the Dyns, could this be the dip above 100hz?, but its early days. They also don’t project like them, which is a surprise as I thought this would be a specialty of theirs but there may be many surprises in store. They are reasonably well run in, about 150 hrs at high volume. I would like more air and the performers projected more into the room but this might improve with time. Maybe a tweeter at some stage? Also I can hear a very slight paperyness or dryness around vocals, assuming this is not the voids buzzing as it seems to be coming from the driver and not the box.. I have not been worried by or really noticed any of the reported beaming of this type of driver and only the slightest sharpness on occasions.
I ran my test disc through them; this has tone bursts from 20 hz up to 100hz in 2hz increments and then larger intervals up to 20khz plus 20 to 10khz and 20 to 20khz sweeps. Listening to the tone bursts the BIBS start clear at about 28hz and gradually and evenly rise up to 100hz with a clear increase in level in the 50hz region, my other speakers do this and even though it doesn’t seem to be a primary room mode I guess it is likely to be something to do with it(the room). The sweep is remarkably smooth considering what the sims look like, not as smooth as the Dyns. but no less smooth than other ‘accurate’ speakers I have owned. There are by the sounds of it a few peaks and dips along the way.
The above was written not long after I built them but not posted. The following is my current view of the BIBs three months later…….…the paperyness I had noticed seems to have disappeared, there is more air and space. They are a very smooth and detailed driver and only begin to sound sharp when the volume is up high. It is a very spacious sound, not bolted into place and extremely specific like my stand mounts but big and relaxed and all of a piece, very natural sounding. It is a sound that is relaxing, not in that it is warm(although its definitely not cold) but that it is coherent and consistent across the spectrum. It seems that most instruments and voices play with the same (high) quality and can be included easily in the musical structure. There are fewer little things to irritate and distract me about the sound and that lets me enjoy it more. They absolutely love atmospheric pieces, Nick Caves Red Right Hand for instance with a swirling dynamic mixture of Caves vocal over and around crashing metallic percussion, stabbing synth and eerie notes appearing to come from distant hills is hard to imagine being reproduced more evocatively. The sound stage is still more between and behind the speakers than in front so its more of a ‘you are there’ than a ‘they are here’ presentation than I get with my stand mounts. It is not a sound stage that I feel I have to be in one spot or it collapses so either the beaming is not such an issue or I need to get my hearing checked again. My hearing probably only goes to 15khz or so in my good ear and I am pretty happy with the high frequency reproduction of the 168es in comparison to the good dedicated tweeter on the Dyns, only losing the slightest detail on cymbal decay etc and lower down subjectively losing nothing to it.
They are EXTREMELY dynamic speakers and dynamically fast. The low bass is remarkable for such a small driver, and has a clean ‘transparent’ feel to it, not wooly at all…plenty of bone and no fat! Something else they excel at is strings, they sound full and sweet and grab your attention every time.
There is still a slight lack of body or weight to the sound, depending on the music . I cannot corner load them but have tried inverting them which I think added a slight amount of fullness and also brought the driver down to a height I like more as I often sit on the floor when listening to music and quite near field. However no matter what the track they still sing like a bird set free! I think they’re a great speaker and am very happy with them but even though they are a thing of beauty they are BIG, possibly too big for our lounge. My partner, Robynne, God bless her little cotton socks, didn’t tell me to turn around and take them back when they literally darkened our doorway but I can sense she thinks..no actually she tells me…they are too big to stay and I am reluctantly agreeing so I may soon be looking for a smaller design for these drivers and a home for a pair of BIB boxes. Not just yet though.
Thanks everyone for your help and input, it’s a great design and thread. Regards, Andrew
Pictures to follow (I hope)
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Old 6th May 2008, 01:26 PM   #4044
pebbles is offline pebbles  Australia
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possibly?
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Old 6th May 2008, 01:27 PM   #4045
pebbles is offline pebbles  Australia
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hooray
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Old 6th May 2008, 01:28 PM   #4046
pebbles is offline pebbles  Australia
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....
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Old 6th May 2008, 01:30 PM   #4047
pebbles is offline pebbles  Australia
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upside down ....
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Old 6th May 2008, 02:49 PM   #4048
Godzilla is offline Godzilla  United States
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>>> It is a very spacious sound, not bolted into place and extremely specific like my stand mounts but big and relaxed and all of a piece, very natural sounding. It is a sound that is relaxing, not in that it is warm(although its definitely not cold) but that it is coherent and consistent across the spectrum.

Thanks pebbles! I agree and feel most everyone who has built BIBs feels the same based on their comments. To me, the sound is relaxed because the music comes out in an effortless way. Unless the volume is turned up very loud, BIBs don't stress.


>>> They are EXTREMELY dynamic speakers and dynamically fast. The low bass is remarkable for such a small driver, and has a clean ‘transparent’ feel to it, not wooly at all…plenty of bone and no fat! Something else they excel at is strings, they sound full and sweet and grab your attention every time.
There is still a slight lack of body or weight to the sound, depending on the music . I cannot corner load them...

Again, I agree. If you can corner load them they do sound fuller. But i have begun using a subwoofer with my BIBs to get the lowest notes and realized i can also warm the sound a little. After thinking this thru, i feel, regardless of the speakers i listen to and regardless of how large or small they are, a subwoofer is the way to get the best bass.

I love seeing the Dynaudio's off to the side! Maybe move them out of the room and begin building a second system for them. I will look at your pics again but i didnt notice any tubes. Move the Dyns out, corner load the one BIB a bit better and buy a tube amp... unless i missed it in the pic. Or, just enjoy as is! I hope they do get to stay in your home.

Godzilla
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Old 6th May 2008, 04:36 PM   #4049
seventenths is offline seventenths  United States
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Default Re: 208/T90A Cap

Quote:
Originally posted by BenjaminWebber
[B]Thanks Guys. Nice to get home from a 16hr day, and have all this info to mull over!
Congrats Benjamin!
If we have another DIY get-together this summer, you could have them air-lifted in
If I ever get my wood shop cleaned out a bit, I'm on to an 8" build myself.


till then,
7/10
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Old 7th May 2008, 12:27 AM   #4050
pebbles is offline pebbles  Australia
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Thanks for the comments Zilla. You are right I dont have a tube amp but a SS that has a rather fat midrange that has been likened to a 'tube' sound (whatever that is and only having heard one in my life). However a mate has one being repaired and when it comes out of hospital it will be dragged straight over here to play through the BIBS.
Unfortunately I dont have another room available.....it will be a fight to the death so to speak. I think the Dynaudios will end up going and the BIB will transmogrify into a slightly smaller design: one of the frugal horn designs or plain Fostex recommended box perhaps. There are so many designs out there its difficult to know where to start, but it must not need corner loading. Regards, Andrew
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