I have a doubt .
if you look down the measures, one is for the other medium in the midbass
SB Acoustics :: 4" SB12MNRX25-4
SB Acoustics :: 4" SB12NRXF25-8
how is it possible that midbass has greater linearity in the midrange than the pure midrange driver ?
if you look down the measures, one is for the other medium in the midbass
SB Acoustics :: 4" SB12MNRX25-4
SB Acoustics :: 4" SB12NRXF25-8
how is it possible that midbass has greater linearity in the midrange than the pure midrange driver ?
I think you will find that the midrange has been optimized for efficiency whereas the midbass has been optimized for bass.
Yes the midbass has a flatter Flatter FR curve in the midrange but it is also 3.5db less efficient. I wonder whether the foam surround is what is making the difference with the midbass you linked.
I've got a couple of the SB12MNRX25-4's and I think that they sound very natural in the midrange.
Tony.
Yes the midbass has a flatter Flatter FR curve in the midrange but it is also 3.5db less efficient. I wonder whether the foam surround is what is making the difference with the midbass you linked.
I've got a couple of the SB12MNRX25-4's and I think that they sound very natural in the midrange.
Tony.
well tony!
finally someone who has tested the sb12mnrx25-4
i have some questions about it.
i have them too, but don't compared with other midrange.
i like them very much, really and i think they are one of the best cost/performance around.
so, do you compared them with other mids ?
could you describe better their sound ?
in which system do you mounted them ?
finally someone who has tested the sb12mnrx25-4
i have some questions about it.
i have them too, but don't compared with other midrange.
i like them very much, really and i think they are one of the best cost/performance around.
so, do you compared them with other mids ?
could you describe better their sound ?
in which system do you mounted them ?
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Hmmm ok first of all I took a bit of an alternative approach, and have deliberately misused them... The idea was to build a pair of computer speakers for my daughter (that we both had some fun doing). The ulterior motive was that I got a set of mids to evaluate for a potential three way 😉
I'm actually running them full range. The project is here --> http://www.diyaudio.com/forums/full...ics-sb12mnrx25-4-full-range-build-thread.html
I wanted to "push the envelope" to see just what I could get out of them 😉 Considering the very different application to what they are meant for they are surprisingly good!
What I have compared them to is not a great comparison, as my main reference is my 2 Way MTM's which use morel 5" MW144 drivers.
My old three ways had Phillips AD02160/SQ8 dome mids. I tried many other cheap mids over the years in those speakers but always came back to the domes.
I find that vocals on the SB12's are very clear and natural sounding. In my (mis)application they are a bit harsh in the higher frequencies, but that is to be expected and won't be an issue when they are used as a pure mid.
I would like to design a three way at some point and these will definitely be on the shortlist for mids 🙂
Tony.
I'm actually running them full range. The project is here --> http://www.diyaudio.com/forums/full...ics-sb12mnrx25-4-full-range-build-thread.html
I wanted to "push the envelope" to see just what I could get out of them 😉 Considering the very different application to what they are meant for they are surprisingly good!
What I have compared them to is not a great comparison, as my main reference is my 2 Way MTM's which use morel 5" MW144 drivers.
My old three ways had Phillips AD02160/SQ8 dome mids. I tried many other cheap mids over the years in those speakers but always came back to the domes.
I find that vocals on the SB12's are very clear and natural sounding. In my (mis)application they are a bit harsh in the higher frequencies, but that is to be expected and won't be an issue when they are used as a pure mid.
I would like to design a three way at some point and these will definitely be on the shortlist for mids 🙂
Tony.
In terms of output per 1 watt there is only 0.5dB difference since both have been measured at 2.83V but one is 4Ohm and the other 8.
Strangely the mid has a slightly lower Fs than the mid-woofer. It also has less than half the Xmax.
Going just by the published data I'm not sure why one would pick the 'official' mid out of the two for a 3way. Especially since I prefer butyl surrounds to foam ones.
all mid have xmax less then mid woofer because they not need of that excursion
this because the mids have shorter voice coil lenght : in this case 9.5mm for mid aginst 15mm of midwoofer
real fs measuremets give almost the same value...sometimes the specs are crazy....
probably, not sure, the light foam suspention of midwoofer give the little bit difference between both : 58 vs 63
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Thank you for stating the obvious.
Doesn't really explain why one would choose the mid which seems to feature less of everything including frequency response linearity where it matters most.
Doesn't really explain why one would choose the mid which seems to feature less of everything including frequency response linearity where it matters most.
Yes but isn't the 2.83V measurement the one that matters when measuring drivers for crossover design?
I assumed the benifit of that mid driver was the higher sensitivity.
If you were using a nominally 8 ohm woofer and a nominally 8 ohm tweeter, then would it not buy you an extra 3.5db using the mid as opposed to the midbass? The 4 ohms is what buys you that extra sensitivity! Note also that SB have a 4 ohm version of the midbass and it is actually 1.5db less efficient than the mid....
The reason for the 2.8V measure being adopted is because it allows an even playing field for comparing drivers. The 1W measure is problematic when drivers of different impedance are used within the same system.
If you prefer butyl surounds, then that IS a reason to choose the mid over the midbass. It is the midbass that has the foam surround! I was speculating whether it is the foam surround that is giving the midbass the smoother response in the 1-3Hkz region, with the dip on the mid likely being due to the surround.
Now as for the smaller xmax, obviously a midrange driver does not need as big an xmax as a bass driver. I don't know enough about driver design to make any authoritative comments on what the advantages of a shorter voice coil would be with respect to a pure midrange, but at a guess I would say that speed would probably be one of them.
Tony.
Didn't know they had versions of equal impedance, just pointed out that there isn't much in it efficiency-wise once one adds the theoretical 3dB if you look at it from a wattage point of view. From a voltage POV nothing changes of course.
Surprised that the mid has the butyl surround. Probably because I was recently looking at Audax drivers and their hi eff mids have foam surrounds while the midwoofs have rubber.
I have to be more thorough next time and stop jumping to conclusions!
The SB mid though has about 1g less moving mass than the midwoof.
Not sure if and under which circumstances that makes an audible difference.
Personally I like to cross fairly lowish to my mids and would appreciate the extra headroom the midwoof provides with regards to linear excursion as well as its more linear FR.
I'm a bit of a headroom fetishist if I may say so myself. ;-)
Surprised that the mid has the butyl surround. Probably because I was recently looking at Audax drivers and their hi eff mids have foam surrounds while the midwoofs have rubber.
I have to be more thorough next time and stop jumping to conclusions!
The SB mid though has about 1g less moving mass than the midwoof.
Not sure if and under which circumstances that makes an audible difference.
Personally I like to cross fairly lowish to my mids and would appreciate the extra headroom the midwoof provides with regards to linear excursion as well as its more linear FR.
I'm a bit of a headroom fetishist if I may say so myself. ;-)
They actually have four versions of the midbass. When I purchased these the supplier only had two types. From memory the mid and the 4 ohm foam one. I chose the mid because of the butyl surround.
It is interesting to see the different FR curves of all 5 variants, as far as I know apart from motor differences and the surounds they are the same drivers.
So we have the mid
then we have the 4 ohm butyl surround midbass (which is the closest to the mid)
and the 8 ohm butyl surround midbass
Then we have the 4 ohm foam surround midbass
and finally the 8 ohm foam surround midbass
The 8" faom surround is arguably the smoothest in the range 200Hz to 3Khz
What I find interesting is that the four ohm versions seem to be a little more ragged than their 8 ohm equivalents.
SO. The question remains what is it that differentiates all of these options!! from a purly FR plot pov the 8 ohm foam looks the best but I guess this is where the tradeoffs come into play. longevity of foam is not so good. You may need the extra db that a four ohm version gives you.
If you do need the extra sensitivity of the four ohm and want butyl surround, then the MID to my eyes is actually the best choice 😉
edit: actually one other thing is that these measurements were done on an IEC baffle and that DOES introduce some irregularities into the response compared to an infinite baffle. I think I have the corrected plot for the MID somewhere I'll see if I can find it and post it.
edit2: actually the difference was a lot less than I remembered. comparison below.
Tony.
It is interesting to see the different FR curves of all 5 variants, as far as I know apart from motor differences and the surounds they are the same drivers.
So we have the mid
then we have the 4 ohm butyl surround midbass (which is the closest to the mid)
and the 8 ohm butyl surround midbass
Then we have the 4 ohm foam surround midbass
and finally the 8 ohm foam surround midbass
The 8" faom surround is arguably the smoothest in the range 200Hz to 3Khz
What I find interesting is that the four ohm versions seem to be a little more ragged than their 8 ohm equivalents.
SO. The question remains what is it that differentiates all of these options!! from a purly FR plot pov the 8 ohm foam looks the best but I guess this is where the tradeoffs come into play. longevity of foam is not so good. You may need the extra db that a four ohm version gives you.
If you do need the extra sensitivity of the four ohm and want butyl surround, then the MID to my eyes is actually the best choice 😉
edit: actually one other thing is that these measurements were done on an IEC baffle and that DOES introduce some irregularities into the response compared to an infinite baffle. I think I have the corrected plot for the MID somewhere I'll see if I can find it and post it.
edit2: actually the difference was a lot less than I remembered. comparison below.
Tony.
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Over the years I've seen it a few times that the higher impedance version of a driver appears a bit smoother than the lower impedance option.
I have no explanation for it yet without bringing the amps damping factor into it and that appears to be somewhat controversial.
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