I tried using those cones with the same SB mid, it didn't seem to make any detectible difference and it was a pain to mount to the inside of the baffle, I even used two stacked about a 1/2 inch apart and stuffed the space between them with homemade MDF (sawdust and glue). In the end I just built a rectangular mid enclosure with some MDF cut into triangles glued to the back. I crossed the SB at 450 and 4200, I went higher because the tweeter is a ribbon, but 300 and 3000 would work better. The one thing about the SB is a bump and dip between 1000 and 2000, nothing I did could flatten it, I think it is caused by the surround because it shows on the manufactures spec sheet.
Thanks for the feedback. MDF Sawdust/glue/water mix can solve a lot of problems. I used it onces to make a tweetercutout smaller. worked perfect. mixture is stronger then MDF itself. I saw the bump dip, I guess it is from the rubber surround. The foam version someone pointed me too, is flatter.
Guess It would be easier to go for golden ratio cabinet with some stuffing. aiming for 3L box.
I wouldn't be put off by bump dip, it isn't noticeable by ear and last I looked Madison is discounting them.
Speed of sound (SoS) used by Hornresp = 34400 cm/sec.. Acoustic power is exponential (1/f), so the mean is where the air mass load is evenly divided. The 'dish' isn't a factor, only its flat disc area since as I understand it the local air pressure only 'feels' the acoustic impedance mismatch of a circular pulse 'train'. Regardless, the math has long since been proven by untold thousands of measurements over the decades.
Covering 300Hz to 3K is a wide range, a driver that can do it without being very expensive is the Wavecor 120BD03.
https://hificompass.com/en/reviews/wavecor-wf120bd03-midwoofer
The SB15NBAC is another option
https://sbacoustics.com/product/5in-sb15nbac30-4/
Most of the fullrange or midrange centric hifi drivers will run out of steam quickly if used much below 700Hz.
Thanks for the suggestions. The wavecor looks promising but its price is already 100+ 😕
I like the SB15NBAC too. Trying to keep the C-C small though. You have feeling the SB12 Mid isnt up for the task? I havent seen any distortion plots of them yet
The SB12 has 2.2mm xmax like the Visaton so it will behave much the same as frequency goes down. If you cross them at 700Hz or so then thermal dissipation becomes the limiter for SPL rather than excursion.
Smaller drivers equals higher crossover points or accepting lower SPL's. Put the drivers in a box simulator and you can easily see where excursion becomes a problem for the smaller drivers.
The Wavecor is not as cheap as some but it is half the price of a Revelator. It has the Symmetric Drive motor.
The Discovery 15W drivers are another slightly cheaper option. Really good frequency response easy to work with. Less xmax than some other similar size drivers.
Smaller drivers equals higher crossover points or accepting lower SPL's. Put the drivers in a box simulator and you can easily see where excursion becomes a problem for the smaller drivers.
The Wavecor is not as cheap as some but it is half the price of a Revelator. It has the Symmetric Drive motor.
The Discovery 15W drivers are another slightly cheaper option. Really good frequency response easy to work with. Less xmax than some other similar size drivers.
Thanks for pointing out....I made some checks in WinISP
There is some difference between the SB12MNRX and the Visaton B80.
My amp is MAX 40W for 4ohm.
In a 3L box @ 40Watt the SBacoustics goes over its excursion limit @ 200Hz. The visaton @ 260Hz. So I guess scrossing @ 300-350 should be OK for both. A bit better for the SB driver.
The max power of the SBacoustics = 50W , Visaton 30W. At max power (40W) Visaton will go over its limit. Dont know when that will happen though. mostly listen at -medium and low level. But SB-driver is on the safe side.
Visaton distortion start to rise @ 500Hz.
I dont have distortion plot of the SBacoustics mid driver. So not sure if it reach 300Hz without a problem.
Does this evaluation make sense? 🤔
It makes sense and gives you some idea that the driver is capable of doing what you want without being very unhappy. With midrange drivers it is better in general if they do not have to use much excursion as there are other parameters that can change with excursion.
Here is an example of another nice small driver the 4" Discovery, nice flat frequency response, no nasty breakup, good CSD and acceptable distortion to even 100Hz at 90 to 96dB which might be as much as you could get with your amp. Have a look at the Lex graph in the voice coil review. That is showing how the inductance of the driver is modulated by excursion. If you stop the driver from moving it won't matter but if you make it move it will.
https://www.dibirama.altervista.org...k-12w-4524g00-mid-woofer-4-4-ohm-70-wmax.html
https://www.scan-speak.dk/datasheet/reviews/12W-4524G00-VoiceCoil_2011-3.pdf
Now are you beginning to understand the need for a ~5.5" driver to reach 300 Hz? 😉
Well not sure though. Haven't seen any distortion plots of the SB12MNRX. The normal version seems capable of doing 300Hz.
Also as fluid pointed the scanspeak 4.5" looks great.
Want to keep the C-C small. Visaton would have been nice as it's 104mm, same like most tweeters. But that's pure ascetics.
Thanks for thinking with me and pointing me to some good drivers.
The THD plots are quiet different between the 2 links. One show a resonance @ 800Hz while the other doesnt.
Then the waterfall shows just the opposite. the one with the resonance has smooth waterfall, the one witout resonance doesnt.
Problem of scalling?
Really would love to see some measurements on the SB12MNRX2 to see how it compares to the ScanSpeak
hello MrHifiTunes,
just in case: user MrFoLLgoTT published a distortion measurements of 4" midrange-drivers in a german forum, including SB12MNRX. it's a german document, but i suppose it should not be too difficult to understand/translate:
document with all measurements:
http://hannover-hardcore.de/infinity_classics/!!!/Zusammenfassung Messung 4 Zoller.pdf
just in case: user MrFoLLgoTT published a distortion measurements of 4" midrange-drivers in a german forum, including SB12MNRX. it's a german document, but i suppose it should not be too difficult to understand/translate:
document with all measurements:
http://hannover-hardcore.de/infinity_classics/!!!/Zusammenfassung Messung 4 Zoller.pdf
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I don't see much difference between the two, the scales are different and waterfalls are very difficult to compare without the exact same settings.
Both show a rapid drop in the first millisecond over the intended range.
Yes scalling is different. One has waterfall over only 25db range. Too small to see the resonances. But they show the resonance @ 800Hz second order which match the rise @ 1600 in the FR plot. Resonance is like 7-8% distortance. Dont see that in the italian version.
On the Italian site it looks like the FR plot is from the manufacturer. But they show some resonances on the waterfall but not on the TDH graph.
Me too. Not sure how applicable it is to modern drivers & design but always interesting to learn what's been done before.
Thanks great info. There seems 2 that do well. SB12MNRX and MONACOR SP4/60. The SB driver is a little bit better, showing some resonances at @ 1k4 2nd and 1k5 3th order. But they fade out quickly so I guess nothing to worry about. Monacor driver has a more 2nd order distortion. Both seem capable for 300-350 XO. monacor is 1/2 price of SB driver. Maybe can buy 4 and put them in an MTM config ? 🤔
Strange that Monacor claim 68cm2 while all other 4" are around the 50cm2 mark
Totally argree.
I notice that Troels also goes to 5" when lowering the Xo to 3-400Hz while in the 3WC, XO around 6-800Hz he use 4" driver
🤔