Ah, the port. Well, it's neither actually. In fact, I suppose you could say that there isn't a port per se at all. The BIB is a bit of an oddball cabinet really you see. All vented cabinets are variations on the horn theme (heavily over-simplified, but you get the picture), and this one strays a lot closer than most in my opinion. The top of the cabinet is left completely open, and that forms the vent / horn mouth.
Tweeter mounting could be interesting. Front, below the driver would be fine. Alternatively, you could mount it on the rear baffle. Although these cabinets must be shoved right backa against a wall to work, or better, stuffed into corners (Martin says that this effectively doubles the apparant mouth area, amonsgst other things as I understand it), there'll always be some room for diffusion. Front would probably be the safer bet though. One thing I can suggest -if the test boxes sound choked or closed in, then you'll know the drivers need more room to breath -the large version I mentioned before, or something larger still. I think I've cracked it now, and basically, optimum for these pipes appears to be a mouth area of approximately 4.25 times the driver surface area. Wince. Well, I did they wouldn't be small!
Tweeter mounting could be interesting. Front, below the driver would be fine. Alternatively, you could mount it on the rear baffle. Although these cabinets must be shoved right backa against a wall to work, or better, stuffed into corners (Martin says that this effectively doubles the apparant mouth area, amonsgst other things as I understand it), there'll always be some room for diffusion. Front would probably be the safer bet though. One thing I can suggest -if the test boxes sound choked or closed in, then you'll know the drivers need more room to breath -the large version I mentioned before, or something larger still. I think I've cracked it now, and basically, optimum for these pipes appears to be a mouth area of approximately 4.25 times the driver surface area. Wince. Well, I did they wouldn't be small!
Here is a bit of 'food for thought' regarding the xmax of a driver. Found it while doing a search for something completely different!
http://www.diyaudio.com/forums/showthread.php?s=&threadid=36935
-Hans
http://www.diyaudio.com/forums/showthread.php?s=&threadid=36935
-Hans
Sorry for reactivating this thread, which has been dormant for a while. But since the FF225K has come up again elsewhere, I thought I'd refresh it slightly. And while I think I'd tend to agree with Nelson's remark that the fact that it looks like a certain defunct JBL (do I need to specify which? Didn't think so!), I've always liked the look of this driver. Now I've heard it, and actually built a BIB enclosure for a pair, I like it all the more. Like cream in the midrange, but plenty of detail too, and it can go loud. Like any driver, it depends on how you load them. This appears to be one of the better ways. And decent bass too -30Hz, no problem.
Have some better domestic dimensions for the FF225K BIB:
10" wide, 18" deep. Use the original 70" height with driver 39" from the base or it'll be too high to be at all sensible. Baffle terminates in the internal middle of the cabinet 7 12/16" from the floor and the inner rear and front baffle walls. I completed a pair like this a few days ago for a friend -just the thing for orchestras. I didn't add a tweeter -he's mounting one of those Fostex T90s I think (the ones in the neat pod) on a little extension on the side, firing forward. 24AWG wire at least, preferably 30AWG to get the response down into line. Hyper-neutral? Nope. Did it make my hair stand on end in the recent Naxos recording of The Planets? Oh yes. K.T. Tunstall wasn't bad either (control yourselves, I know what your minds are thinking... ;-)
Scott
Have some better domestic dimensions for the FF225K BIB:
10" wide, 18" deep. Use the original 70" height with driver 39" from the base or it'll be too high to be at all sensible. Baffle terminates in the internal middle of the cabinet 7 12/16" from the floor and the inner rear and front baffle walls. I completed a pair like this a few days ago for a friend -just the thing for orchestras. I didn't add a tweeter -he's mounting one of those Fostex T90s I think (the ones in the neat pod) on a little extension on the side, firing forward. 24AWG wire at least, preferably 30AWG to get the response down into line. Hyper-neutral? Nope. Did it make my hair stand on end in the recent Naxos recording of The Planets? Oh yes. K.T. Tunstall wasn't bad either (control yourselves, I know what your minds are thinking... ;-)
Scott
And this is the in-room response, with a BSC circuit in place. The anechoic response is deliberately sloping downward to account for room-gain, with a slight peak to add a touch of warmth or weight to the sound. It assumes a carpeted floor, with you sitting in the nearfield, on-axis with the drivers, the front baffle of the speaker cabinet (and therefore the speaker) 32" from the rear wall. As you can see -I'm still playing with Martin's new sheet... ;-)
The dip at circa 230Hz I assume (unless someone tells me otherwise) is floor-reflection, and should decrease in severity the further away you sit from the speaker, and also increase in frequency.
The BSC values for the cabinet as-is, calculated by MathCad, are pretty fierce: 2.5mH inductor, 10ohm resistor -I don't believe it needs that as most of use do not sit in the nearfield, on axis with the drivers. I would suggest a 2.5mH inductor, with perhaps a 4 to 6 ohm resistor as a good starting point as going through every combination would be a bit of a lengthy and pointless exercise. Also, note that you'd probably need smaller values if the speaker was closer to a rear wall.
Best
Scott
The dip at circa 230Hz I assume (unless someone tells me otherwise) is floor-reflection, and should decrease in severity the further away you sit from the speaker, and also increase in frequency.
The BSC values for the cabinet as-is, calculated by MathCad, are pretty fierce: 2.5mH inductor, 10ohm resistor -I don't believe it needs that as most of use do not sit in the nearfield, on axis with the drivers. I would suggest a 2.5mH inductor, with perhaps a 4 to 6 ohm resistor as a good starting point as going through every combination would be a bit of a lengthy and pointless exercise. Also, note that you'd probably need smaller values if the speaker was closer to a rear wall.
Best
Scott
Scottmoose said:
We want a photo. We want a photo. We want a photo. We want a photo. We want a photo. We want a photo. We want a photo. We want a photo. We want a photo. We want a photo.
And some more scotch. And some more scotch. And some more scotch. And some more scotch. And some more scotch. And some more scotch. And some more scotch. And some more scotch. And some more scotch. And some more scotch.
Kofi! Kofi! Kofi! Kofi! Kofi! Kofi! Kofi! Kofi!
Kofi Annan said:
Too much Scotch? What kind? (given my tolerance levels, only very good gets past my lips)
dave
You know, I finished a bottle of Macallan 12 and decided to move on to Glenmorangie 10. I'd had some Glenmorangie 10 at a bar, of all places, and loved it, but I thought that maybe I was too loaded and I was relying too much on beer-muscle memory.
I bought some on a whim and I think that its got a very smoooooth quality-- buttery beginning and a slightly salty finish. Being that its made near the sea, the salt would seem to make sense.
Its got less going on than the Macallan, but its easier to handle. Like a caramel apple with a little spice.
'Course, now the booze is talkin', so take this with a grain of Scottish salt. Bought it on Monday and it will be gone by the weekend. Maybe earlier.
Had the week off.
Kofi
I bought some on a whim and I think that its got a very smoooooth quality-- buttery beginning and a slightly salty finish. Being that its made near the sea, the salt would seem to make sense.
Its got less going on than the Macallan, but its easier to handle. Like a caramel apple with a little spice.
'Course, now the booze is talkin', so take this with a grain of Scottish salt. Bought it on Monday and it will be gone by the weekend. Maybe earlier.
Had the week off.
Kofi
Kofi Annan said:
Both excellent...
dave
planet10/for whom a glass of Scotch means as little as you can get in a shot glass and still cover the bottom
planet10 said:
Would that make a 10 year old scotch into a 20 year scotch by the time you finish a bottle?
Max
maxro said:
Probably... someone got me one of those airplane bottles of Glen Livett (35 ml?) and it lasted 6 months.
dave
I think the state of the world is weighing Kofi down a bit- but he'll cheer up.
Hey Kofi, have you considered a Scotch tasting as an ice breaker for all the reps? You could probably get Scotland to donate it... A more relaxed attitude could only help-unless some of them are belligerant drunks 🙄
Hey Kofi, have you considered a Scotch tasting as an ice breaker for all the reps? You could probably get Scotland to donate it... A more relaxed attitude could only help-unless some of them are belligerant drunks 🙄
Hmm... I like Islay single-malt myself. You can taste the peat, so strong, and smooth and warming on a cold evening in front of the burning log-fire in the hearth... oh, just pass the bottle will you. No ice for Scott though. That would be sacrilege.
I'll try to post a picture of the 225K BIB boxes soon. Two problems with that at the moment: 1) Scott doesn't even own a box-brownie, let a lone a digital camera (photography is not my forte I fear), and 2) they are now 60 miles away in Sheffield with the bloke I built them for. However, so you know, Simon is painting them white. They're at the sides of a wide bay window, in the corners, so they look like pillars. His wife's idea. Sounds mad, but she could have a point, and who am I to dispute interior decor with a young female? ;-)
Cheers
Scott
I'll try to post a picture of the 225K BIB boxes soon. Two problems with that at the moment: 1) Scott doesn't even own a box-brownie, let a lone a digital camera (photography is not my forte I fear), and 2) they are now 60 miles away in Sheffield with the bloke I built them for. However, so you know, Simon is painting them white. They're at the sides of a wide bay window, in the corners, so they look like pillars. His wife's idea. Sounds mad, but she could have a point, and who am I to dispute interior decor with a young female? ;-)
Cheers
Scott
--OFFICIAL THREAD REVIVAL IN PROGRESS--
Two and a half years later, Kofi found himself interested again in the Fostex 225K with the 17H tweeter. This, of course, after feeling the weakness of the US Dollar in his quest for the Supravox Signature Bicone here.
So, I'm thinking about picking this one up again with the idea that I'd go with Scottmoose's BIB recomendation:
The amp will be Thorsten's version of the 300b DRD in monoblock form. Given that I have a sizable living area, I need the bass, so I'm hoping the BIB will provide it, although the xmax of the 225K may be a limitation. The DRD will supply about 8 clean watts in theory, but in practice when sourced with a low output MC cartridge and a phono pre with gain on the lowish end, maybe a bit less.
Given the time that has elapsed, I'm guessing it's possible that a new, even more fantastic enclosure has been theorized for the 225K / 17H combo as we a now living in the future...
I'm liking the BIB proposed above, but I'll hear other arguments, should you decide to present them.
Kofi
Two and a half years later, Kofi found himself interested again in the Fostex 225K with the 17H tweeter. This, of course, after feeling the weakness of the US Dollar in his quest for the Supravox Signature Bicone here.
So, I'm thinking about picking this one up again with the idea that I'd go with Scottmoose's BIB recomendation:
The amp will be Thorsten's version of the 300b DRD in monoblock form. Given that I have a sizable living area, I need the bass, so I'm hoping the BIB will provide it, although the xmax of the 225K may be a limitation. The DRD will supply about 8 clean watts in theory, but in practice when sourced with a low output MC cartridge and a phono pre with gain on the lowish end, maybe a bit less.
Given the time that has elapsed, I'm guessing it's possible that a new, even more fantastic enclosure has been theorized for the 225K / 17H combo as we a now living in the future...
I'm liking the BIB proposed above, but I'll hear other arguments, should you decide to present them.
Kofi
There's been quite a few new box designs since naught-5.
How would this work in something similar to the 0.5Chang?
How would this work in something similar to the 0.5Chang?
>>> Fostex 225K with the 17H tweeter...
Can't believe i missed this thread until now. I think it's a great combo of drivers and well worth building. BIB or other back horn is a must but i would imagine based on my experience with the 165k that the 225k would be amazing!
I want to sell my 165k BIB so i can build the 225k BIB. Someone make me an offer. Pick up only, i live on long island in NY.
http://www.zillaspeak.com/bib-godzillabib.asp
http://www.zillaspeak.com/systems.asp
BTW, i would mount the tweeter on the front right above the driver or on the back. Mounting on the back requires you to leave about 3 or 4 inches of space from the back wall and to play a bit more with the capacitors to get the right amount of splash in the treble.
Godzilla
Can't believe i missed this thread until now. I think it's a great combo of drivers and well worth building. BIB or other back horn is a must but i would imagine based on my experience with the 165k that the 225k would be amazing!
I want to sell my 165k BIB so i can build the 225k BIB. Someone make me an offer. Pick up only, i live on long island in NY.
http://www.zillaspeak.com/bib-godzillabib.asp
http://www.zillaspeak.com/systems.asp
BTW, i would mount the tweeter on the front right above the driver or on the back. Mounting on the back requires you to leave about 3 or 4 inches of space from the back wall and to play a bit more with the capacitors to get the right amount of splash in the treble.
Godzilla
OK-- so I know this means I need slab 'o' wood inside the BIB, but could someone dumb this down for the K-dog? Does the inner slab run the length of the pipe starting at the middle floor and ending at the mouth (top of cabinet) at the back?
Kofi
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