I am about to order a pair of Satori MR13p midrange drivers, and would appreciate some advice on the 4ohm vs the 8ohm version; the latter has lower Qes, Qms, moving mass and engine strength (Bl). Will I be able to hear any difference? (Is it possible for the 4 ohm version to have lower Bl and lower Qes at the same time? And why do you think SB Acoustics has given the 4/8ohm versions different t/s-parameters?)
The context of using this unit is unknown. Try to simulate if you can and then decide. There is no mistery hiding behind TS parameters. They are useful in the sense they give us a picture how sensitive and what the response around Fs(Fb) will be like if they are to be used in that region at all. Full scaled simulation of the complete loudspeaker design will reveal differences and whether it would be better to use one over the other.
I suspect that the demands of using a common motor gap and a common short coil length in the underhung motor, plus a common 30W max power, forces the larger differences in BL and T/S parameters.
If you have a solid state amplifier which can easily drive a 4-ohm speaker load, the 4-ohm version of the underhung MR13P-4 with 91db efficiency simulates well with the SB21SDC-4 tweeter plus a parallel pair of SB23NRX45-8 woofers. This combination should provide good dynamics plus good detail.
If you plan on using a single woofer, the lower 88db efficiency of the 8-ohm MR13P-8 in a sealed volume would likely integrate easier after baffle step compensation.
If you have a solid state amplifier which can easily drive a 4-ohm speaker load, the 4-ohm version of the underhung MR13P-4 with 91db efficiency simulates well with the SB21SDC-4 tweeter plus a parallel pair of SB23NRX45-8 woofers. This combination should provide good dynamics plus good detail.
If you plan on using a single woofer, the lower 88db efficiency of the 8-ohm MR13P-8 in a sealed volume would likely integrate easier after baffle step compensation.
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The MR13P is overhung from what I can see! I wish they'd gone with underhung motors for the mid variants, but alas
The Satori MR13P-8 datasheet SPL graph shows early beaming starts around 2kHz, and I've been simulating 2.4-2.6kHz =5.5" wavelength crossovers to assure the best extended frequency on-axis polar pattern until the SB21SDC-C000-4 tweeter starts noticable beaming at ~8kHz.
Your cabinet shape, edge treatments, and driver location on the baffle affect high frequency wiggles and waggles until the main baffle width diffraction frequency. e.g. locating the tweeter 5.5"-6" below the top would showcase midrange room interactions.
Do you have a sketch of your cabinet ideas?
Your cabinet shape, edge treatments, and driver location on the baffle affect high frequency wiggles and waggles until the main baffle width diffraction frequency. e.g. locating the tweeter 5.5"-6" below the top would showcase midrange room interactions.
Do you have a sketch of your cabinet ideas?
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Thanks for your work, really appreciate it. I was thinking of a straight forward 3-way standmount ala Truels Gravesens Classic 3-ways, with 8" SS 8554 woofer, MR13 4,5" mid and OWI 3/4" tweeter, the last two vertically offset vs the 8554.
I've had good experience with crossing the old Seas MCA11FC paper mid around 3500Hz, and hope that the Satori MR13 (a little bit larger Sd) can do 3000Hz. I will cross it to the 8554 around 550Hz, and was wondering if the 4 ohm versions maybe would be a better sounding choice than the 8 ohm version.
I've had good experience with crossing the old Seas MCA11FC paper mid around 3500Hz, and hope that the Satori MR13 (a little bit larger Sd) can do 3000Hz. I will cross it to the 8554 around 550Hz, and was wondering if the 4 ohm versions maybe would be a better sounding choice than the 8 ohm version.
In Troels design the midrange is padded down with resistors.
The 4 ohm MR13 is 3 dB more sensitive than the 8 ohm version.
I guess that the difference between the two soundwise is less important than the (ugly) necessity to pad down the midrange with resistors.
My preference would be the 8 ohm version; with the crossover frequencies you have in mind you would have to pad down the midrange anyway.
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