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RS 2.5 driver efficiencies

As I said I do not use charts or programs. I use test equipment and do the formulas the old way. Oh yes I have a program I made in Excel to speed up the calculation . There are so many factors the programs you buy don't consider. I mentioned how the audio critics made Infinity change the crossover on the RS1B. If you look at the upper crossover for the hi/freq tweeter you will see they use a 4uf (it says .4uf on the drawing but that is wrong it is 4uf)cap and a .05mh coil. If you do the math that combo creates a tuned circuit at 11259 hz. In other words the signal sees no impedance except for the resistance in the length of the coil windings.(Just like the Watkins circuit) You then add to that the tweeter in parallel and the variable resistor and it gives you an amp killing 1.8 ohms. When I ran a sweep that is exactly what I saw. I modified that part of the crossover and it made a huge difference. No more gritty hi end.
 
Okay...maybe what I should have asked is what test equipment is necessary, at the minimum to take the necessary measurements? Also, and good reading to learn what I need to know about the interaction of crossover components? Also...and this might seem like a strange question...but can you tell me the angle at which the wings of your RS2b's angle back from the flat front of the speakers? The RS2b's are the speakers that I'd REALLY love to have...I absolutely love the looks of those speakers, and I imagine that they sound amazing...but I'm not seeing any listed anywhere right now. Thanks much!
 
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See the attached picture for the angle of the wings. It starts at 13 Deg and end at 37deg on a 6.5 " curve.
 

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Thanks! And again, thanks for all your input! What is the minimum equipment I would need to take the proper speaker measurements?
 
What you need is a signal generator and an impedance meter. you can get these all in one and they are great. There is a new product out call an SMD IM-SG which is a signal generator and impedance meter all in one. I have not tried it but it would work great for crossovers and testing coil and caps as well as sweeping your speaker. I have an old Rockford Fosgate Im-1 and it works nearly the same but this new one is more advanced. I neither suggest it or recommend it as I have not tried it bit it looks great on the You tube demo.
 
Cool...and thanks for the VERY detailed drawing of the angles! Why is it that the RS 2.5's need the acoustic damping material around the EMIMs and EMITs, but the RS 2b's can get away without it? Because of the narrow face and swept wings on the 2b's? I'm considering trying to come up with something similar for the 2.5's. Designing that could be interesting.

Just looked at the SMD IM-SG, and it looks interesting. It looks like it was designed by a car audio guy, but it looks like it's for measuring single speakers outside of the enclosure. What about measurements with all drivers working together with the enclosure?

Also...I'm assuming that the EMITs and EMIM on the 2.5's are set back so far from the woofer for time-alignment purposes? How, if at all, is time alignment performed with the RS 2b's? Driver delay can't be accomplished with passive crossovers, can it? Only active, correct?
 
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The foam in reality does not do much. If it did all high end speakers would have foam on the front. The actual design of of the Emim with the way it slopes back makes it so it can be mounted in many places. When I was designing loudspeakers in the 80's the company I worked for invested $250,000 in B&K test equipment. it was interesting because we ran both a retail and wholesale operation. We carried Infinity, Bose, Kenwood ,Sansui. ADS, Advent and many other lines so i had access to test all the current designs of the day. This is when I did extensive testing of the Emim drivers. I had a set of Q2's QLS1's and then 2.5's,4.5" and so on. So I was quite familiar with them.
The best design I heard was a hybrid of the 2.5's using a 6" midbass driver with the Watkins woofer and one Emim with 3 Emits. Sounded great A better version of the Q2's
 
What about physical and/or electrical time alignment? Also, regarding the 2.5's...what about using one EMIM as a low mid-range, and the other as a high-mid-range...basically a 4-way...this is one possibility that I've envisioned. Believe it or not, I myself thought that the 2.5's with the mid-bass from the Renaissance might be nice. Speaking of which...how do the Renaissance 90's compare to the 2.5's?
 
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The 90's sound very good. They have the best version of both the Emim and Emit's. Infinity was well aware of what was missing between the Watkins woofer and the Emim's. I actually thought when I heard the 90's beside the Epsilon's that I preferred the 6" driver over the L-Emim's. I was not the only one who felt that way. That was the speaker that made me make the hybrid version of the 2.5's with the 6" Dynaudio I spoke of and only used one Emim. The 90's lacked the output I wanted and even though the bass from that 10" was great it is no match for the 12". One trick I used on the 2.5's is to roll one of the Emim's off sooner than the other. When the 2.5's were designed vinyl was in and CD's weren't around. CD has much more output in the upper midrange and tends to make the 2.5's a little harsh. So if you roll off the angled emim sooner , say around 2,oooHZ it make for a smoother sound. Also add a .5-1 ohm resistor inline with the Emits just after the cap.
You were asking about that meter. You can attach it to your speaker terminals and measure the impedance throughout the entire audio range. As you sweep up or down it will show you. Great tool once you know how to use it.
 
How did you fit that 6" Dynaudio driver? What about my thoughts of just splitting the two EMIMs into an upper and lower mid-range...about 2 octaves for each, crossed over about 1250? That thought really intrigues me. Unless you are thinking that the EMIM is better in the upper mid-range than the lower. What would you think about using the High Energy EMIM and EMIT from the Renaissance in the 2.5's, if one could get ahold of them somewhere?
 
That is great you ordered the meter. You will learn many things with it. Once you have the crossover formulas you can use then both for design and measuring caps, coils, and woofer inductance and much more.
As to the Dynaudio driver we removed the lower Emim and made a custom mold and installed it there. We then tilted the top Emim down slightly.
As to splittling the 2 emim's you don't need to. A few post back I gave suggestion on rolling one of them off sooner than the other. You can simply put a coil in line with the top emim. Try a .7 MH coil. That way you keep the power handling of 2 drivers together and you don't give up the additional air that 2 drivers can move in the mid bass. You can play with it by adding or subtracting coils until you get the sound you like . Doing this won't mess with the phasing of the drivers.
 
You actually have me intrigued with the 6" mid-bass driver between the Watkins and the EMIM...but I'd also hate to lose too much frequency range from the EMIMs. How low can the EMIMs effectively go? In your opinion, would the new black Watkins woofers fully bridge the gap to the EMIMs that you mentioned in an earlier post? I really like the looks of the 6" Morel poly-composite drivers.
 
One Emim can work happily to around 700 HZ. If you look at the 1B and 2B crossovers that is where they have the single emims working. In multiples you can work them to around 300HZ at 12 DB . In my case I have 6 working to 225HZ rolling of at 24DB and at higher volumes they are not really happy. So if you used a quality mid bass driver you could work it from about 150-700hz
 
I was actually considering around 160 to 800 or 900, so we are close there in our thinking. Any suggestions as to what would be an excellent mid-bass speaker to use? I've been looking on both the Parts Express and Madisound websites. What about a pair of 6.5" IMG woofers from a pair of Kappa 5 speakers? I want to stay with black color because I intend to get the updated Watkins woofers. Then I need to decide whether to come up with a design for the 2.5 cabinets, or design new cabinets to get the tweeters to ear level.
 
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There are lots of good drivers out there. You need to sample a few. What you want is something around 88 db that has a FS /free air resonance of half of what your planned crossover is. So if it's 160 hz then shoot for about 80hz fs. Or if 200 hz then about 100hz. Don't crossover to high up. Keep it to 700hz or below. Don't worry that much about the height of the Emit. The dispersion is quite good in the vertical plane. Sounds like you might as well build a new speaker. It would be easier to do that with all the revisions you are planning.
 
Thanks...should be fun to play around with this...will keep in touch for sure! Thanks for all the great feedback and ideas. I'd like to keep all the drivers Infinity if I can.
 
Oh...and you never gave your thoughts on time alignment...mainly physical alignment of the drivers. I know that isn't an issue if one decides to use an active crossover.

Also, could you please rate the various incarnations of the EMIT tweeters...including the ones in the 2.5's, the EMIT-R, the EMIT-K, the High Energy, etc. How do they compare to each other? Thanks again!
 
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