As an experiment, I've installed the Hi-Vi B3N 3" full range in my old IMF Super Compact enclosures together with the Skytronic 8" kevlar woofer, no XO, both units running full range.
The B3N is in the place of the original IMF 4" mid and has its own enclosure so is isolated from the woofer.
The end result was much better than I expected! Surprisingly well balanced sound, very clear and natural speech/vocals, decent bass but extreme top end is typically B3N, slightly metallic and 'tizzy'.
I then tried a simple 1st order XO at 1.5K. No real improvement, sounded better with both units full range so removed the XO. Finally tried a 6dB notch filter centered on 8K to flatten the peak in the B3N. This has sweetened the top end to some extent but I can still tell it's a B3N. The end result is a speaker I could happily live with but power handling might be an issue.
The B3N is in the place of the original IMF 4" mid and has its own enclosure so is isolated from the woofer.
The end result was much better than I expected! Surprisingly well balanced sound, very clear and natural speech/vocals, decent bass but extreme top end is typically B3N, slightly metallic and 'tizzy'.
I then tried a simple 1st order XO at 1.5K. No real improvement, sounded better with both units full range so removed the XO. Finally tried a 6dB notch filter centered on 8K to flatten the peak in the B3N. This has sweetened the top end to some extent but I can still tell it's a B3N. The end result is a speaker I could happily live with but power handling might be an issue.
An externally hosted image should be here but it was not working when we last tested it.
Hi there. Neat looking set up you're working on.
Couple of things. Crossover-less 2 way is an oxymoron. 2 way implies a crossover so it's kind of like ordering cheesburger, no cheese.You're making a dual driver.
Second, after more fooling around you mind find that a large cap like 100-200 mfd on the Hi Vi might be what the doctor ordered. That will give you the power handling that you might run out of without it.
keeping trying, let us know.
Couple of things. Crossover-less 2 way is an oxymoron. 2 way implies a crossover so it's kind of like ordering cheesburger, no cheese.You're making a dual driver.
Second, after more fooling around you mind find that a large cap like 100-200 mfd on the Hi Vi might be what the doctor ordered. That will give you the power handling that you might run out of without it.
keeping trying, let us know.
Personally, I'd put a 1st order low pass on the woofer. If it has a frequency response designed for use as a 2-way with tweeter, is will be designed to have extended midrange capability. It won't do vocals as well as the full range unit above it.
Chris
PS - I like projects like this. Quick and simple, but good sound nevertheless.
Chris
PS - I like projects like this. Quick and simple, but good sound nevertheless.
if you don't want to use crossover, you may try to put some thick sound absorbtion material in front of woofer. it should absorb some of the 'tizzy' kevlar cone breakup.
and you can add a piece of foam in front of hi-vi driver.
and you can add a piece of foam in front of hi-vi driver.
After I posted I realised that 'crossover-less 2-way' doesn't make a lot of sense as you have rightly pointed out 😱
Thanks for the tip regarding the 100-200 uF cap. Is this in parallel with the B3N? Excuse my ignorance!
Hi MisterTwister, thanks for the suggestions although the 'tizzy' sound quality is entirely from the B3N and appears to be a characteristic of this driver. It's particularly noticeable on, say, a cymbal crash or similar. However, it's not too serious and I can live with it.
On the other hand the kevlar woofer seems fairly neutral. Mind you, I haven't driven it hard enough to cause cone breakup, yet 😉
You might try the woofer in a bandpass cabinet and the full range in a small sealed cabinet (you are doing the latter already). With a bit of luck you may get a smooth x-over from woofer to tweeter and vice versa.
I'd have thought so, in the + lead of the B3N to reduce low frequencies going to it. It is not a driver reccomended for playing low.
Interesting project, I've used the B3N and find it quite detailed and generally good if the bass is filtered out from it. I used an active notch filter for the 8k breakup, does a good job 🙂
Oops, I really have to stop and read what I am writing sometimes. Of course it goes in series. Very sorry for this activexp and thanks to Steve for the pointer. Dr EM also.
You could add a high quality, low capacity MKP cap in parallel with the large CAP to improve overall quality.
Something like the Vishay MKP1837 (a.k.a. ERO MKP1830) 0,01uF will do.
Something like the Vishay MKP1837 (a.k.a. ERO MKP1830) 0,01uF will do.
Also , a little OT , if you have a spare amp ,a simple 6 dB-oct line level XO centered at 500 Hz would do...but I guess that the Skytronic wouldn't behave very good.
The way Activexp runs these speakers together is that they cooperate and try to do ther best.
What's a Skytronic ????
The way Activexp runs these speakers together is that they cooperate and try to do ther best.
What's a Skytronic ????
No problem Cal. A 200 uF cap in series will filter out frequencies below about 100Hz from the B3N. Right?
"A range of high-powered woofers with reinforced Kevlar cones. Incorporating rubber surrounds, vented magnets and heat resistant 4 layer voice coils, these speakers can easily handle power peaks, yet produce a smooth sound that will please any Hi-Fi enthusiast."
See here:
AVSL Group : Product : 902.420UK
Basically cheap Chinese drivers but they work well enough.
Also see here:
'Ghetto' IMF Super Compact conversion (stevesstuffproject)
Here is the impedance chart for the BN3.
http://www.parts-express.com/pdf/297-428z.txt
Check it on a crossover calculator
Crossover Design Chart and Inductance vs. Frequency Calculator(Low-pass)
That will give approximate 1st order value
http://www.parts-express.com/pdf/297-428z.txt
Check it on a crossover calculator
Crossover Design Chart and Inductance vs. Frequency Calculator(Low-pass)
That will give approximate 1st order value
Thanks Cal for the links, at some point I'll give the series cap a go.
I still can't believe how good these speakers sound for something so cheap and simple. It's a real surprise. They have the thumbs up from 'she who knows best' which is praise indeed. The same can't be said for some of my other more complex and expensive efforts that have required much tweaking and fine tuning to finally receive the seal of approval.
The cutaway shows the mid enclosure, a cardboard tube, now occupied by the B3N.
I still can't believe how good these speakers sound for something so cheap and simple. It's a real surprise. They have the thumbs up from 'she who knows best' which is praise indeed. The same can't be said for some of my other more complex and expensive efforts that have required much tweaking and fine tuning to finally receive the seal of approval.
The cutaway shows the mid enclosure, a cardboard tube, now occupied by the B3N.
Good stuff
Hi Steve (I'm assuming those are your pages linked to above!)
I really like this - it would make an ideal beginners project as the drivers are cheap and there's no x-o! However, the cabinet may be having some influence - the sealed tube will be giving some acoustic loading to the B3N rolling off below a certain frequency. If the Skytronic is this well behaved it's a real find. I can't find a frequency graph for it - do you have one? As there's no baffle step compensation are you using them near walls? Is it better sounding than the 3 way version (on your web-page) with the ribbon tweeter?
Keep up the good work,
Ian
Hi Steve (I'm assuming those are your pages linked to above!)
I really like this - it would make an ideal beginners project as the drivers are cheap and there's no x-o! However, the cabinet may be having some influence - the sealed tube will be giving some acoustic loading to the B3N rolling off below a certain frequency. If the Skytronic is this well behaved it's a real find. I can't find a frequency graph for it - do you have one? As there's no baffle step compensation are you using them near walls? Is it better sounding than the 3 way version (on your web-page) with the ribbon tweeter?
Keep up the good work,
Ian
Hi Ian, yes I'm that Steve!
I've been thinking on the same lines that it would make an ideal starter project but really need to find out how much influence the combination of drivers and enclosure has on the end result.
The sealed tube is about 90mm dia x 230mm with a volume of 1.5L, probably ideal loading for the B3N. It's lightly filled with BAF wadding. The cabinets are 460H x 300W x 280D with a volume of about 22L and vented. The port is packed tight with a slab of very dense foam rubber (looks like upholstery foam).
Although T-S parameters are available for the Skytronic 8" kevlar woofer, I haven't seen any FR graphs. There is a Zobel on it, a legacy from when I used it in a 3-way. Not sure if it's necessary without an XO.
At the moment they're running without a BSC about 2ft off the floor, 1ft away from walls and 3ft away from corners.
What I'm going to do next is try the original IMF woofers (modded KEF B200) which despite their age are still in good working order. As they were designed for use in the enclosure it will be interesting to see what effect they have on the performance.
Do they sound better than the 3-way with the mid/ribbon tweeter satellites? Difficult to answer! They do sound quite different. If anything the dual-driver system scores on presence, almost 'out of the box' on speech and vocals with very little harshness.
Cheers,
Steve
I've been thinking on the same lines that it would make an ideal starter project but really need to find out how much influence the combination of drivers and enclosure has on the end result.
The sealed tube is about 90mm dia x 230mm with a volume of 1.5L, probably ideal loading for the B3N. It's lightly filled with BAF wadding. The cabinets are 460H x 300W x 280D with a volume of about 22L and vented. The port is packed tight with a slab of very dense foam rubber (looks like upholstery foam).
Although T-S parameters are available for the Skytronic 8" kevlar woofer, I haven't seen any FR graphs. There is a Zobel on it, a legacy from when I used it in a 3-way. Not sure if it's necessary without an XO.
At the moment they're running without a BSC about 2ft off the floor, 1ft away from walls and 3ft away from corners.
What I'm going to do next is try the original IMF woofers (modded KEF B200) which despite their age are still in good working order. As they were designed for use in the enclosure it will be interesting to see what effect they have on the performance.
Do they sound better than the 3-way with the mid/ribbon tweeter satellites? Difficult to answer! They do sound quite different. If anything the dual-driver system scores on presence, almost 'out of the box' on speech and vocals with very little harshness.
Cheers,
Steve
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