Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?

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#2,841
>>> I would love to have seen the mirror dance, and the janitor's face when he noticed tiles.

The mirror dance I did alone. I put the mirror against the wall where I wanted the acoustic tiles to be and sat in the listening position. The reflections were not exactly where I expected but not too far off. Then I moved the mirror back towards the speakers and eventually found the first reflection. Then I moved the mirror back and found the second reflection. It was pretty easy actually.

After scoping out several office rooms I found a few with sturdy enough file cabinets to stand on to reach and take the tiles. Fortunately, I own the building. When the missing tiles are noticed, I will have them replaced.

I will also use larger 2 x 4 tiles on the rear wall and may do something similar in between the speakers. Corner bass traps are more expensive than I thought – it’s only foam! Those are intriguing too. And I think the ceiling will have to be addressed somehow.

http://www.zillaspeak.com/systems.asp

Never did a B20 BIB.

Godzilla
 
#2,842
Greets!

Hmm, what part of this did you not understand?: "Well, I recommended a HE 8" as a compromise between LF output and the 'magic' of a smaller driver's mids/HF, so for Fostex there's only the FE206E, FE206ES-R, FE208ES AFAIK.........." I mean I didn't list it because it's not an HE (high efficiency) driver. FWIW, IMO all these require a super tweeter for best performance unless everyone likely to listen to them has age/whatever impaired HF hearing, especially when loaded in a BIB or other horn design. 8" is just too big to do HF with any accuracy over a wide enough 'sweet spot'.

GM
 
#2,844
I may try padding down the tweeter with a .33uf cap rather than the .47uf that's currently on the RS supertweeter with 165k six incher. Unless the room treatments fix the slight brightness. In my office (larger room with high ceilings and thicker carpet) the rear mounted tweeter did not call attention to itself. In my small basement listening room (bare walls, concrete slab, smaller, etc...) it does. It's not terrible but it's the first time in years i've even thought about upgrading the tweeter.
 
#2,846
GM said:
Greets!

Think about the sheer size of the WLs the pipe is trying to contain and it should become transparent that they don't care which way you turn them until they are small enough to be disrupted by going around tight corners, which will be high enough in frequency that you don't want them coming out of the pipe unattenuated.
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May I throw another view on the dish ?
A
s you well say, Greg, the waves we are conducting are too big to be disturbed by the folds. But that also happens to the room too, for most of the BW of the horn at least. So IMO it would be more adequate to talk about pressure wavefronts rather than waves... and then I would tend to think that the abrupt direction changes dissipate energy, and that hurts the horn's efficiency. Again, we have to balance between what we want to accomplish and what we definitely don't want, as putting that internal reflectors or soft-bends will let more midrange to go out through the mouth, but ignoring the effect will lead to a worse transient handling capability...

Does this make sense ?

Gastón
 
#2,847
ChrisMmm said:
Bit off subject (off track?) I spent a lot of time rewinding motors for friends. Made the wind real hot (low winds, large guage wire) - think I managed to roast a few peoples hand controllers for them. Ever the tweaker!
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Greets!

Sounds familiar! I worked for awhile at Champion in the mid '60s, wearing various design, drafting, building, testing 'hats' and we made some qualifying motors for our 'hot shoes' with as little as 24 gauge. Core temps were as high as mid 500s degF after 2 min. on a track powered by a bank of truck batteries, which necessitated a crash course on powder coating epoxy systems and re-thinking motor bushing and hand controller design. Our best overall performing mills were double 25s or 26s though.

GM
 
#2,848
Godzilla said:
Lots of 8†choices for BIBs!... and 6†and 4â€â€¦ even 3†unfolded BIBs… amazingly flexible cabinet design for the DIY masses!

Last night I moved a small mirror around my new little listening room to find reflection spots. I also took/stole 6 twenty four inch square acoustic tiles from the ceilings of the building I work in. I hope no one notices.

The system sounds great without the acoustic treatment but I am curious about the improvements. The room does seem ‘live’ when I clap my hands – echo slap.
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Godzilla ... some of the charachers you are typing are non standard and don't conform to standard encoding... could you please interpret for me (and maybe in the future avoid using them)?

I've highlited the post quoted in the snapshot below so you can decipher the characters that are troublesome.

dave
 

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#2,853
Godzilla said:
Ctrl key and MS Word. I've noticed this alot. I am also using an IBM PC. I don't see this in the reply box. It's only after i've typed it.
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The control key produces a character with ASCII code >127. Since there is no official standard for these characters each platform interprets them differently... this is one of the reasons why unicode was developed -- to aid in platform independence (as well as allow for 2 byte characters to aid in computer communication using things like the Chinese & Japanese character set)

dave
 
#2,854
Pit Hinder said:

Compared to professionals wearing blinkers, we hobbyists are allowed to make use of what we have learned elsewhere. Makes us more than competitive - allows us to be researching the cutting edge by using lateral thinking.

djn, as to racing without ever having a chance...the "Green Hell", aka Nürburgring, on a clapped out 175cc DKW was the best fun I ever had with clothes on - and ask GM how to stun people by tinkering with an ex police workhorse Harley.
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Greets!

You got that right, I probably wouldn't know near as much about pipe/horn design if I hadn't been so 'driven' to create superior intake/exhaust systems to get a Penske 'Unfair Advantage'. 😉 Then there's the plethora of things I learned in a very dynamic workplace like Champion. I probably learned/exposed to more in a few years during the heyday of slot racing than the rest of my following career in a corporate engineering environment and I serious doubt I would have progressed nearly as far or as fast as I did thanks to that experience.

I'm 'green' with envy! The closest I ever came to such an experience was racing 'C' open class carts. 150+ mph with no protection of note and only ~1" off the pavement is a life altering experience. Elkhart Lake was the closest I got to the 'Ring.

LOL! What's the drag racer's mantra? For hi-perf there's no replacement for displacement and injection's nice, but I'd rather be blown!

GM
 
#2,857
djn said:

Hi GM, what HD do you have?
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Greets!

I've owned several, a '50 Panhead police edition I turned into a street race 'chopper' as originally defined (stripped to the bone), black on black in black '80 Low Rider (piece of junk, but what a 'babe magnet'), and '88 Heritage Soft Tail Classic in police white/black paint scheme (to get the desired Pavlov response 🙂).

Currently I have '73 Yamaha 650 twin chopper, '82 Honda CBX, and '87 Suzuki Cavalcade 'dresser' rotting away because I foolishly held on to them too long after the car accident in the hope I would be able to ride again before they deteriorated too much and now it would cost more than they're worth to make road worthy. 🙁

GM
 
#2,858
ghpicard said:

........the waves we are conducting are too big to be disturbed by the folds. But that also happens to the room too, for most of the BW of the horn at least. So IMO it would be more adequate to talk about pressure wavefronts rather than waves... and then I would tend to think that the abrupt direction changes dissipate energy, and that hurts the horn's efficiency.
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Greets!

Hmm, actually, a typical room loads the horn to some extent (though not over most of its BW), increasing its acoustic efficiency, ergo damping if the horn/room transition doesn't cause strong reflections back to the throat, which few popular designs I've seen properly address this issue, consequently degrading its efficiency, damping, FR.

Inside the horn though, abrupt bends don't have any measurable effect on acoustically large WLs AFAIK since as you note there's only compression, rarefaction pressure waves.

GM
 
#2,860
Hi GM, that is a drag about your bikes rotting. I know what it is like, I have a bike I built from the ground up sitting in my garage covered in dust because of an injury I sustained 20 years ago (blown knee), but just two days ago, the doc fixed it with an injection and I walk like a 20 year old again.........I can't believe how much emotional funk I'd collected over the years with that constant pain. I will find and post pics of my '59 pan chopper and '42 80" flathead. Both were great bikes. Cheers.

An externally hosted image should be here but it was not working when we last tested it.
 
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