These type of drivers (metal or poly cone, foam or rubber surrounds) do not sound as good as a paper cone with treated cloth surround.
The above is a Misco JC4C 4" midrange. If you are not going to use a sealed back speaker, then something like this works the best.
I've been wondering about the drivers used in Logitech computer speakers. I believe that the old ones were Tang Band 3"ers. Is there a chance that Tang Band 2"ers are hidden among the current line ups?
People are always selling old computer speakers on ebay. Maybe there is a bargain to be head for Synergy mids?
People are always selling old computer speakers on ebay. Maybe there is a bargain to be head for Synergy mids?
It would have to be modeled to see if it is suitable. Still don't like the rubber surround. Single roll rubber, or single roll cloth surrounds deform under pressure and allow the cone to tilt eventually causing voice coil failure due to rubbing.
Funnily enough that`s exactly what has happened and we have a phase inversion way up higher than expected. Spent the last few days with our prototype Unity top and our subs ( SS15`s) trying to get it all to make sense! The flip was moved from 120 up to 180hz and seemed to be wider! Also getting it to cross into the subs is pretty tricky..been playing with a lot of different filter slopes to try get a nice smooth transition.
So hopefully this week we will properly fill the back of the box with closed cell foam to really reduce the volume and then see what we get!
You`re right...it`s endless fun!
.p.
Closed cell foam? You should be using cement or bricks for proper density
.The Unity top will need to be delayed by about 7 ms (rough start) and the SS15 polarity should be wired so positive voltage makes the cone move towards the throat ( + to red terminal on a "normal" speaker).
A BW24 on the TH and a LR24 on the Unity with a gap of around 10 Hz would get in the ballpark for alignment.
I'm not one hundred percent certain that's true.
The wood divider is likely just a brace, but it IS possible that Kessito is right, and that the divider is designed to increase the path length.
Lately I've been studying vented boxes a lot, inspired by the JBL paper on optimum ports. And one thing I've discovered is that you can improve the phase response of a vented box by manipulating the length and the shape of a port. (Many of you probably knew this already, but it was new to me)
Here's how this works, based on my limited understanding of phase:
When we build vented subs, we generally assume that the output at the tuning frequency is 180 degrees out of phase. But this isn't correct; there are a pile of factors that can change the phase:
1) length of the port adds a delay
2) distance from the driver to the port adds a delay (and as Kessito noted, that brace may have an acoustic function)
3) shape of the port changes the Q of the resonance, and this changes the phase
The elephant in the room is that 100hz is about twelve feet long. So you'd need a long pathway to create a measurable change in phase.
Only way to know for sure would be to measure it both ways.
Blatant self promotion:
I've listed my last two JC5RTF-Bs, along with some 3" Vifa and Peerless woofers that should work well. All the auctions are under my 'majestik6' pseuodonym.
Auction ends in a week.
Misco RDC3T-A
Before I decide to import some Misco RDC3T-A's I would like to hear if these Misco's are Synergy/Unity wonders? I know that some of you guys already have worked with them, and I would be greatful if you would share your experiences.
I'm asking because they are not available in Europe which means that I'll have to import them from the States...$$$
/Thomas
Before I decide to import some Misco RDC3T-A's I would like to hear if these Misco's are Synergy/Unity wonders? I know that some of you guys already have worked with them, and I would be greatful if you would share your experiences.
I'm asking because they are not available in Europe which means that I'll have to import them from the States...$$$
/Thomas
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Any ol' cone tweeter will do won't it?
They're so ubiquitous, I can buy them over the counter in Seattle.
If I'm not mistaken, the reason that they work great in a Unity horn is because the mms on a cone tweeter is insanely low. So when you mount them on a big horn, you can manipulate the geometry of the horn so that the peak in the frequency response of the cone tweeter disappears.
IE, the speaker in a sealed box has a big fat peak around 1500hz. But put it in a horn that's built correctly, and that peak disappears. And you end up with a ten buck driver that's basically behaving like a $500 ribbon driver.
JLH, GM and Danley have discussed this here and on audioasylum. IIRC, the hornresp docs talk about this. The term is 'reactance annuling.'
As for my own personal experience, I tried building some Unity horns with the Goldwood cone tweeters and it worked pretty darn well. Probably the main reason that I did not pursue it was that it's really hard to come up with a proper model of the driver. It's similar to modeling a compression driver, it's a bit of a crapshoot because it's not easy to separate what the driver is doing from what the enclosure is doing.
Many roads lead to Rome. There are an unlimited number of ways to build a Synergy horn. You can choose whatever dispersion angles you want, and the drivers you want to use. You can do B&C DE250 with Misco JC5RTF-B, BMS 4555 with a pair of Eminence LA6-CBMR, RCF ND350 with Misco RDC3T-A, or BMS 4550 with Celestion TF0410MR. The possibilities are endless. It all depends on what you want to do.
Thanks guys!
Well I like the Misco because of its resisitive behaviour once mounted in a horn.
I've been doing some T/S measurements on the Ciare HT-080 and the Visaton M10-8 and so far it doesn't look very promising, for the Visaton at least. With the Ciare I'm having som trouble measuring the -6dB points due to its almost resisitive impedance charateristics.
/Thomas
Well I like the Misco because of its resisitive behaviour once mounted in a horn.
I've been doing some T/S measurements on the Ciare HT-080 and the Visaton M10-8 and so far it doesn't look very promising, for the Visaton at least. With the Ciare I'm having som trouble measuring the -6dB points due to its almost resisitive impedance charateristics.
/Thomas
I'm calculating the T/S parameters from ESP:
Measuring Loudspeaker Driver Parameters
Can anyone recomend an alternative approach/method to the -6dB volltage?
/Thomas
Closed cell foam? You should be using cement or bricks for proper density
The Unity top will need to be delayed by about 7 ms (rough start) and the SS15 polarity should be wired so positive voltage makes the cone move towards the throat ( + to red terminal on a "normal" speaker).
A BW24 on the TH and a LR24 on the Unity with a gap of around 10 Hz would get in the ballpark for alignment.
Almost there..... reduced volume, tidied up slot ports, measured outside away from reflections, mic on ground plane...
This is lows + mids ( yes they don`t go so high as the prototype horn has very rough mid ports)
Just a bit more juggling with the delays and phase....
Had the whole system out and A/B comparison of the old 2 way Unities vrs the new 3 way Prototype..... much better ! You were pretty close with the xover to SS15 ..turned out at 10ms using a Butt 24 on both filters.... didn`t need the 10hz gap though?
.p.
What would be the benefit of using the Misco over the LA6? I realize that the Misco enables you to cross over higher to the tweeter. Contrarily, the LA6 allows for a lower cross over to the wooffers.
I've been trying to do some T/S measurements on the Ciare HT080, but its almost non-exixting impedance peak makes it close to impossible to get the -6bB (or even -3dB) points.
The other candidate (Visaton M10-8) is not looking too primising, sadly!
/Thomas
There are no clear advantages, only trade offs. It just depends on what you value the most.