Greg's should be the better of the cabinets -the two I did pre-date the T/S alignment based calculation for Vb that GM came up with. So that's the one I'd go for. I'll look forward to hearing your impressions.
OK...I know I asked a couple of weeks before and maybe somebody asked...bat this Thread is soooo big....
So I try again:
What would happen, if I change the length of Zdriver
Fostex FE207E
L = (Line length) 174"
Zdriver = Driver 35" down from sealed end of cabinet
I would like to build it with a Zdriver between 45" and 50"
thanx
Martin
So I try again:
What would happen, if I change the length of Zdriver
Fostex FE207E
L = (Line length) 174"
Zdriver = Driver 35" down from sealed end of cabinet
I would like to build it with a Zdriver between 45" and 50"
thanx
Martin
What will happen is you'll get a giganic hole in the midbass and various other unpleasent problems in the response. A better bet would be to reduce the line length to 138in, for a 70in tall cabinet, Zdriver of 30in (which will put it ~39in from the floor). Cabinet volume should still come from the formula Vb=20*Vas*Qt^1.25 but the CSA of Sl will be somewhat different from the longer pipe. You'll cut off a few Hz higher, but this will be about the best compromise for your desired driver position which should be 0.217 line length
New pair of BiBs
After a long pregnancy period, my 206ESRs are finally playing in a pair of BiBs.
The basic dimensions are based on the plan @ Godzilla’s site.
I mad the cabinet shorter than recommended so it can pass while vertical in a door…
I have only ~6h of listening so I cannot say a lot. But, I would like to thank all the contributors.
Thank you, Scottmoose, GM and Godzilla
After a long pregnancy period, my 206ESRs are finally playing in a pair of BiBs.
The basic dimensions are based on the plan @ Godzilla’s site.
I mad the cabinet shorter than recommended so it can pass while vertical in a door…
I have only ~6h of listening so I cannot say a lot. But, I would like to thank all the contributors.
Thank you, Scottmoose, GM and Godzilla
Enjoy ConExp!
This thread is interesting:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=106083
BIG BIB!
This thread is interesting:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=106083
BIG BIB!
FE208EZSig/T90A question
Quick question re attenuating the T90A to match the FE208. Sensitivity of the 90A is 106db and the 208 97db, difference of 9db. However should I take the pipe gain for the 208 into account when designing the LPAD - I am using a resistor LPAD rather than a pot. If so how much should I allow for? I realise there will be a bit of adjustment later so just after a good atarting point.
Panels cut and preparing for build.
Cheers
Quick question re attenuating the T90A to match the FE208. Sensitivity of the 90A is 106db and the 208 97db, difference of 9db. However should I take the pipe gain for the 208 into account when designing the LPAD - I am using a resistor LPAD rather than a pot. If so how much should I allow for? I realise there will be a bit of adjustment later so just after a good atarting point.
Panels cut and preparing for build.
Cheers
For the T90 most just use the really small cap approach. If you XO about 1.5 octaves higher than you would with equal level, things work out pretty well.
dave
dave
Thanks Dave but a little confused.
Are you saying only use a small cap and no LPAD? Fostex suggest 1-1.5uf which is a fairly high frequency (in the order of 15khz I think). Are you suggesting smaller/higher again?
Cheers
Are you saying only use a small cap and no LPAD? Fostex suggest 1-1.5uf which is a fairly high frequency (in the order of 15khz I think). Are you suggesting smaller/higher again?
Cheers
Scottmoose said:
Thank you Scottmoose!!!
There is one last problem I have.
I always read, that especially in the mids, reflections flom the back of the enclosure are a big problem.
When I build a BIB, right behind the Speaker is that...you know what I mean "piece of wood".
No reflections????
1. I opened an account on photobucket.com
2. from there you take the image address and implant it in the form (here)
3. good luck
2. from there you take the image address and implant it in the form (here)
3. good luck
picture, I hope....
An externally hosted image should be here but it was not working when we last tested it.
You can also use SnagIt or similar to convert your pics to a low res gif jpg png txt zip jpeg pdf and upload it from your computer.
Interesting observation. Yes, the inside baffle is very close to the back of the driver in a BIB.
The BIBs inner baffle is nearly right up against the back of the driver. But the inner baffle is slanted which redirects reflections. Also adding stuffing right behind the driver helps reduce the negative effects of reflections.
The BIB also differs from a more typical ported box because the opening is so much larger. If you make a shallow box with a small vent, the air inside the box bounces around looking for the vent opening. The turbulence inside the box will upset the driver. With the BIB, the opening is very large and the reflections, while still present, are directed thru the pathway created by the inner baffle into a large opening. The large opening provides an easier path for the air to flow thru leaving the driver disturbed less from reflections.
Godzilla
The BIBs inner baffle is nearly right up against the back of the driver. But the inner baffle is slanted which redirects reflections. Also adding stuffing right behind the driver helps reduce the negative effects of reflections.
The BIB also differs from a more typical ported box because the opening is so much larger. If you make a shallow box with a small vent, the air inside the box bounces around looking for the vent opening. The turbulence inside the box will upset the driver. With the BIB, the opening is very large and the reflections, while still present, are directed thru the pathway created by the inner baffle into a large opening. The large opening provides an easier path for the air to flow thru leaving the driver disturbed less from reflections.
Godzilla
