First, thanks to diyaudio.com and zaphaudio.com for the resources I needed to get this project off the ground.
I've been looking for an inexpensive project to cut my teeth on, and after reading the comparison of 10 wide range drivers at Zaph Audio I decided to try a center channel using the Hi-Vi B3S. My goals are:
- Entire speaker costs no more than $50
- 8 ohm amplifier friendly
- cover 150hz - 18khz +-3db
- 85db w/ 105db peaks at listening position 8 ft. from TV
To avoid using a baffle step compensation circuit I decided to use two drivers. The BSC would have pushed efficiency far too low, and the price of an additional B3S was well within budget.
I decided to arrange them in a bipole configuration rather than both drivers facing forward for two reasons. First, since the primary purpose of a center channel is to recreate the human voice, a single speaker seems like the best solution. Second, the bipole configuration should minimize enclosure vibration.
The front driver will have a notch filter centered at 8khz to flatten a nasty peak, caused by the metal cone of the B3S ringing. The back driver will have a some kind of a low pass filter, probably a simple first order. I will use a resistor to pad down the back speaker in case there is a midbass bump.
Parts list:
2x HiVi B3S ($19.14)
1x 0.8 mH air core inductor ($2.75)
1x 0.1 mH air core inductor ($1.58)
1x 4.3 uF capacitor ($1.86)
1x 8.0 ohm 20 watt resistor ($0.69)
1x 30 ohm 10 watt resistor ($1.25) *non-inductive
1x fancy binding posts ($6.88)
I priced everything out at both partsexpress and madisound, they were very close to each other. I chose partsexpress because they could give me a shipping quote without any hassle. Total price was about $45. You can bring that down below $40 by using standard binding posts instead of fancy ones.
Now to the testing....
(note to self, add pictures)
Dan
I've been looking for an inexpensive project to cut my teeth on, and after reading the comparison of 10 wide range drivers at Zaph Audio I decided to try a center channel using the Hi-Vi B3S. My goals are:
- Entire speaker costs no more than $50
- 8 ohm amplifier friendly
- cover 150hz - 18khz +-3db
- 85db w/ 105db peaks at listening position 8 ft. from TV
To avoid using a baffle step compensation circuit I decided to use two drivers. The BSC would have pushed efficiency far too low, and the price of an additional B3S was well within budget.
I decided to arrange them in a bipole configuration rather than both drivers facing forward for two reasons. First, since the primary purpose of a center channel is to recreate the human voice, a single speaker seems like the best solution. Second, the bipole configuration should minimize enclosure vibration.
The front driver will have a notch filter centered at 8khz to flatten a nasty peak, caused by the metal cone of the B3S ringing. The back driver will have a some kind of a low pass filter, probably a simple first order. I will use a resistor to pad down the back speaker in case there is a midbass bump.
Parts list:
2x HiVi B3S ($19.14)
1x 0.8 mH air core inductor ($2.75)
1x 0.1 mH air core inductor ($1.58)
1x 4.3 uF capacitor ($1.86)
1x 8.0 ohm 20 watt resistor ($0.69)
1x 30 ohm 10 watt resistor ($1.25) *non-inductive
1x fancy binding posts ($6.88)
I priced everything out at both partsexpress and madisound, they were very close to each other. I chose partsexpress because they could give me a shipping quote without any hassle. Total price was about $45. You can bring that down below $40 by using standard binding posts instead of fancy ones.
Now to the testing....
(note to self, add pictures)
Dan
The speakers have been waiting patiently for two weeks now while I found the time to figure out how to use Speaker Workshop. My first impedence measurements don't look great, but they are good enough to see that I need to break them in before taking further measurements.
The manufacturer quoted fs is 80hz... mine are nearly half an octave above that!
I will save you the horror of my impedence jig
, I built it by hacking up an old set of headphones and $5 in ratshack parts.
I'm breaking the speakers in by repeatedly playing a 10 second 80-120hz sweep, with left and right channels out of phase. I can't hear the bass, but I can sure hear the harmonic distortion. I'll do this for about two days, after which I hope fs is below 100hz.
Dan
An externally hosted image should be here but it was not working when we last tested it.
The manufacturer quoted fs is 80hz... mine are nearly half an octave above that!
I will save you the horror of my impedence jig
, I built it by hacking up an old set of headphones and $5 in ratshack parts.I'm breaking the speakers in by repeatedly playing a 10 second 80-120hz sweep, with left and right channels out of phase. I can't hear the bass, but I can sure hear the harmonic distortion. I'll do this for about two days, after which I hope fs is below 100hz.
Dan
I built some bipole B3S's for my girlfriend. They were originally monopole, but were too ineffecient for her amp, which was actually made for 4ohm speakers. I went back added another woofer on the back, although the box may be a little small, the sound is fuller than ever and is much better.
Good Luck,
Josh
Good Luck,
Josh
edjosh23 - did you take any measurements? Did you use a filter?
After one day of break-in, the fs of both speakers dropped by 5hz. The enclosure is cut, and half glued together. I rounded the back of the speaker cutout to promote airflow, but the fit is so tight I need to cut more.
Some progress pics..
Dan
After one day of break-in, the fs of both speakers dropped by 5hz. The enclosure is cut, and half glued together. I rounded the back of the speaker cutout to promote airflow, but the fit is so tight I need to cut more.
Some progress pics..
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Dan
Hey looks like it's becoming a great looking project. I'm building Krutke's sealed speaker right now. If it goes (sounds) good then might do a center channel as well with the HiVis. Let us know how it sounds to you, room size, preferred listening volume...
Just a basic question: how are you connecting the male connects of the speaker--are you using female connects or just soldering?
Thanks for your expertise
Mark
Just a basic question: how are you connecting the male connects of the speaker--are you using female connects or just soldering?
Thanks for your expertise
Mark
pasomark said:
Running full range, near field, and open baffle, they were great with simple music. To my ears, acoustic guitar and the human voice sounded outstanding. Once the music became more complicated they started sounding muddy.
... more later.. just completed first acoustic measurements and they came out horrible... I need a better mic and sound card
Dan
After watching a few movies using this center I've decided to scratch this project. While clarity is great, this driver just doesn't have the output for HT use.
The new plan is use these drivers to build a pair of multimedia speakers for work, where high output and bass are not a priority. I've already purchased the parts for another notch filter and BSC circuit, now I just need to duplicate this enclosure find an amplifier.
Dan
The new plan is use these drivers to build a pair of multimedia speakers for work, where high output and bass are not a priority. I've already purchased the parts for another notch filter and BSC circuit, now I just need to duplicate this enclosure find an amplifier.
Dan
Owdi--do you think the HiVi have sufficient output for surround back speakers in a HT set up? Just asking b/c its been suggested 5 of these speakers would make a decent HT setup but you clearly aren't impressed with the output ...at least for the center (and then assuming the front) speaker.
Also, what size connection do you use on the speaker wire to the HiVi?
Mark
Also, what size connection do you use on the speaker wire to the HiVi?
Mark
pasomark said:
I agree that 5 of these could make a decent HT setup, so long as you're not looking for high output.
My speaker wire was thin, 5 feet of 24 awg to each speaker, and the speakers were wired in series w/ no filter. My amplifier is capable of 50wrms at 16ohms, so lack of power wasn't the problem.
I have to admit that my decision to stop this project was influenced by wanting to try these as multimedia speakers. My computer speakers here at work are junk.
Dan
Hi, I'm planning on building B3S bipole surrounds for use in my new HT setup and was just wondering if you still have the enclosure dimensions for your design handy. Working from the Zaph Audio B3S design I got the following box dimensions : 300 x 228 x 127 (D x W x H in millimeters). Size wise, those are acceptable, but if I can make them smaller without messing things up I will happily do so!
pasomark said:
Mark,
I am using 5 of them for my HT and the output is plenty for me. I am using less than full baffle step compensation because mine are very close to the wall, this does increase the maximum output. Mine are driven by a 90 w x 5 Yamaha receiver and are crossed over at 120hz, crossing even higher would probably help even more, but my sub sounds muddy if I cross it much higher. I would not cross them any lower, and I wouldn't want to drive them with much less power. I soldered the speaker leads on to my HIVi's, the terminals are quite delicate looking but it worked good for me.
Jason
owdi said:
I'm not positive, but I'm pretty sure that if you are using a notch on one of the B3S's and it is wired in series to the rear driver than the combined impedance of the two drivers is going to affect the function of the notch filter. Can somebody else confirm this? I also noticed that your parts list included the parts for the baffle step portion of the filter, I assume you were not using these parts?
Jason
owdi, did you ever make a diagram for the xo design you used? As I mentioned earlier, I'm building B3N bipoles, and while I can handle adapting the box dimensions, adapting zaph's crossover design (to remove the BSC and factor in the two drivers) goes right over my head at the moment (this is my second diy project).
BTW, Jason B, I think you will find an answer to your question in this thread: http://www.diyaudio.com/forums/showthread.php?s=&postid=1191183#post1191183
BTW, Jason B, I think you will find an answer to your question in this thread: http://www.diyaudio.com/forums/showthread.php?s=&postid=1191183#post1191183
The XO design I used is super easy to adapt from Zaph's design.
On the front speaker, use exactly the same notch filter as Zaph. Do not connect the BFC filter to the front speaker.
On the back speaker, use only the inductor from the BFC filter, and drop the resistor.
After scratching the center channel idea, I used these as multimedia speakers for a few months. I then tried a woofer+tweeter in my multimedia speakers, and went back to using the center B3S bipole. The second time around it sounded much better, probably because I set the levels correctly on my receiver. I eventually sold the drivers to another fellow diy'er, because I didn't have time to finish the center enclosure, and it was ugly. Now I'm working on a Vifa XG18 + Seas 27TBFC/G in beautiful PartsExpress premade enclosures.
Dan
On the front speaker, use exactly the same notch filter as Zaph. Do not connect the BFC filter to the front speaker.
On the back speaker, use only the inductor from the BFC filter, and drop the resistor.
After scratching the center channel idea, I used these as multimedia speakers for a few months. I then tried a woofer+tweeter in my multimedia speakers, and went back to using the center B3S bipole. The second time around it sounded much better, probably because I set the levels correctly on my receiver. I eventually sold the drivers to another fellow diy'er, because I didn't have time to finish the center enclosure, and it was ugly. Now I'm working on a Vifa XG18 + Seas 27TBFC/G in beautiful PartsExpress premade enclosures.
Dan
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