Hi!
Regarding coating, IMHO it's not needed on SPH. But who am I to say, I've not tried it. Anyway they have a quite dark signature from origin and a rather flat fr curve. At least as I can hear, no measurements done.
Regarding phase plugs I fear that youre going to loose some extension upwards. I've played with a spare pair and have removed whizzer and center dome. When center dome gone, a significant loss of treble is noticed and of course without whizzer, they die around 7k.
On the other hand, they are cheap so no loss if mods fails.
Good luck!
Peter
Without stuffing, a lot of mid and hi frequencies come out of the BIB opening at the top. Stuffing up into the point, behind the driver and at the bottom reduces these frequencies enough so that only bass is being reinforced. Stuff to taste of course, some experimentation is necessary to find the best result for your room. Part of the pleasure and pain of DIY.
http://www.zillaspeak.com/bib-howtobuild.asp
Scroll down to see some stuffing options that work well.
Godzilla
http://www.zillaspeak.com/bib-howtobuild.asp
Scroll down to see some stuffing options that work well.
Godzilla
BIB stuffing
I think that the published graphs for the BIBs are simulated with none or just very light stuffing of the closed end above the driver. In my simulations heavier stuffing in this area will reduce the peaks in the response graph, but strangely the dips seem to get deeper (but very narrow, so probably not important). A little stuffing somewhere along the line does not seem to significantly affect the simulations.
A layer of foam, felt, or wool at the bottom will help reduce any mid+hf coming out of the open end. This will however already be reduced due to the bend at the bottom, and another bend through the room to reach the listener.
The attached graph is a measurement of my BIB with microphone just in front of driver, and at the open end respectively. The sound from the open end drops sharply above 600Hz. Due to the bend at the bottom it drops more than the simulation curves. This measurement is with a little damping at the bottom. The curve for the open end (blue) from 1KHz and upwards is probably mostly sound coming from the main driver which I am not able to isolate.
Apart from this, the curves seem to conform well to simulations, with some room irregularities below 200Hz.
SveinB.
I think that the published graphs for the BIBs are simulated with none or just very light stuffing of the closed end above the driver. In my simulations heavier stuffing in this area will reduce the peaks in the response graph, but strangely the dips seem to get deeper (but very narrow, so probably not important). A little stuffing somewhere along the line does not seem to significantly affect the simulations.
A layer of foam, felt, or wool at the bottom will help reduce any mid+hf coming out of the open end. This will however already be reduced due to the bend at the bottom, and another bend through the room to reach the listener.
The attached graph is a measurement of my BIB with microphone just in front of driver, and at the open end respectively. The sound from the open end drops sharply above 600Hz. Due to the bend at the bottom it drops more than the simulation curves. This measurement is with a little damping at the bottom. The curve for the open end (blue) from 1KHz and upwards is probably mostly sound coming from the main driver which I am not able to isolate.
Apart from this, the curves seem to conform well to simulations, with some room irregularities below 200Hz.
SveinB.
Attachments
Here is an in-progress shot of a BIB with a BOFU What some of us call the Pioneer B20FU 8" It will probably be another week before I have it running. Obviously we used OSB or "flake board" . It costs only $15 a sheet in 3/4" (took 3 sheets) and is kind of cool looking. We hid the pieces with printing on them on the back and the side that will be in a corner..
OSB is made of soft wood like conventional builder's plywood but has a lot more glue, so it will probably be livelier (similar to birch? - we'll see) Total cost for a pair, with drivers is $100!!!! Just what the youth of today need to get into audio! And they will be able to drive their parents out of the house!
I plan to have it to demo at The BURNING AMP show October 20 &21 in S.F.
OSB is made of soft wood like conventional builder's plywood but has a lot more glue, so it will probably be livelier (similar to birch? - we'll see) Total cost for a pair, with drivers is $100!!!! Just what the youth of today need to get into audio! And they will be able to drive their parents out of the house!
I plan to have it to demo at The BURNING AMP show October 20 &21 in S.F.
Attachments
Monacor BiB
Hi Scott, Hi everybody!
At last my first BiB is finished
At the moment I'm running the SPH60X but I'll try soon the SPH68-X/AD that should be even a better.
The overall sound is nice, maybe just the mid-highs are a bit veiled... but I still have to finished some cables that could change the result.
Here's some pics:
and details of the supra-baffles:
Maybe not perfectly finished...But I love them!!!!!
News coming soon, Is this the beginning of a "saga"?
Ciao. Fab.
Hi Scott, Hi everybody!
At last my first BiB is finished
At the moment I'm running the SPH60X but I'll try soon the SPH68-X/AD that should be even a better.
The overall sound is nice, maybe just the mid-highs are a bit veiled... but I still have to finished some cables that could change the result.
Here's some pics:
An externally hosted image should be here but it was not working when we last tested it.
and details of the supra-baffles:
An externally hosted image should be here but it was not working when we last tested it.
Maybe not perfectly finished...But I love them!!!!!
News coming soon, Is this the beginning of a "saga"?
Ciao. Fab.
peterbrorsson said:
Hi Peter, I'm happy that you like my creature...! The sphere is made by glueing three circles of 2cm plywood, routed and than finished by hand. For the sides again I've used small circular portion of ply and then shaped it by hand.
An externally hosted image should be here but it was not working when we last tested it.
It was the hardest thing to do and the longer... but I wanted a real "super baffle".... don't know if it works better than a normal regular slab.
Vix said:
Hi Vix, thanks a lot.
Those cables are a pair of old inexpensive VDH, big and stranded and, yes, not so good sounding.
I'm working on a pair of CAT5, at the moment 4 pairs for each channel.
I want to try many configuration, also with magnet wire (already used for cabling the BiBs). I have kilometres of Cat5 retrived from the garbage dump after the winter olympics.....
I'll give a try also with just a pair, as you suggested; I'm still a bit confused about cables, looking around to commercial cables or diy recipies, it seams that bigger is better.... some JPS cables are known to use a coax with a 2.5 mm diameter solid conductor!!!!
Who knows!?!?
Ciao. Fab.
I have read about unfolding a BIB for smaller drivers in previous post but do not remember the specifics of it. Do you just build them as tall as the line length and keep the "sm" the same. How do you determine driver height? I have some experimenting with chip board coming up using 3" Tang Band drivers.
germpod said:
I received all the information from Scott and built these.
An externally hosted image should be here but it was not working when we last tested it.
gychang