Just a thought... Perhaps this driver might more closely meet your needs 10NDA610
https://www.eighteensound.it/en/products/lf-driver/10-0/8/10NDA610
I'm not an expert on these kinds of midrange drivers, but I would think that this driver would more easily be used from 250 Hz to 1 khz. It is about 2 dB less efficient than the 8NM610, but seems more appropriate... ? The Fs is 89 Hz vs 250.
https://www.eighteensound.it/en/products/lf-driver/10-0/8/10NDA610
I'm not an expert on these kinds of midrange drivers, but I would think that this driver would more easily be used from 250 Hz to 1 khz. It is about 2 dB less efficient than the 8NM610, but seems more appropriate... ? The Fs is 89 Hz vs 250.
The amplifier doesn't know it just does what it's told to do.
From the perspective of this system a DSP, or analogue active crossover, provides the needed boost to increase the effective extension of the mid driver. Ergo the signal the DSP puts out for high frequencies is low and hence so is the voltage swing of the amplifier. But as frequency decreases the DSP outputs more and more signal to counteract the dropping response of the driver. This sends more signal to the amplifier end then more voltage swing to the driver.
thank you 5th element for trying to help but ...
he's trolling he knows what we mean.
don't waste your time on him.
i put him on ignore.
he's trolling he knows what we mean.
don't waste your time on him.
i put him on ignore.
I dont think anybody is trolling
Just giving you idea what your up against
Sealed back driver significantly raises impedance curve.
the driver is not intended to be crossed over so low.
impedance peak is 250 Hz min crossover is 500hz
even manufacture rates at 500hz
many would crossover higher around 600 to 800hz
like many sealed back drivers, sensitivity is higher since
enclosure is so small.
If you look at datasheet, it does not cover the bandwidth you propose.
Cone midrange can work, Its why many have proposed using conventional driver.
The 104 dB rating is based mainly on peak response.
If you made a enclosure that was too small for a conventional driver.
you would obtain same results. Raised impedance curve and peak response.
The Datasheet has been smoothed by a far amount.
problem with sealed back is very peaky response.
This is why for smooth midrange, you can use conventional driver.
enclosure can be made ideal and stuffed/lined with damping material.
sealed back driver , just plastic or metal cup
Just giving you idea what your up against
Sealed back driver significantly raises impedance curve.
the driver is not intended to be crossed over so low.
impedance peak is 250 Hz min crossover is 500hz
even manufacture rates at 500hz
many would crossover higher around 600 to 800hz
like many sealed back drivers, sensitivity is higher since
enclosure is so small.
If you look at datasheet, it does not cover the bandwidth you propose.
Cone midrange can work, Its why many have proposed using conventional driver.
The 104 dB rating is based mainly on peak response.
If you made a enclosure that was too small for a conventional driver.
you would obtain same results. Raised impedance curve and peak response.
The Datasheet has been smoothed by a far amount.
problem with sealed back is very peaky response.
This is why for smooth midrange, you can use conventional driver.
enclosure can be made ideal and stuffed/lined with damping material.
sealed back driver , just plastic or metal cup
i didn't really ask whether to use a sealed back 8" midrange or not
i asked which sealed back 8" midrange is best
this one seems superior to B&C and RCF
but maybe there are also other ones i don't know about
i asked which sealed back 8" midrange is best
this one seems superior to B&C and RCF
but maybe there are also other ones i don't know about
Any sealed back 8" will have impendence peak around 250 to 400Hz
Bandwidth is suited around 800 to 4000
8" speaker will start to beam around 1000 and beam around 2000
They answer is= None of them are best
Bandwidth is suited around 800 to 4000
8" speaker will start to beam around 1000 and beam around 2000
They answer is= None of them are best
It's actually around 17-18dB down at 250Hz, compared to the 1kHz response. Even more, if used with horn. According to the spec sheet.
The B&C 8NSM64 have a slightly lower sensitivity but "just" 8dB down at 250Hz and more than 150 Ohm at that frequency.
This driver's natural -6dB point is at 300Hz for a "crossoverless" crossing, if someone wants like that. 😎
maybe you geniuses should consider counting decibels from the bottom rather than from the top ...
you should all be on your knees kissing my feet for sharing wisdom like this with you peasants.
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Why this anger?
The sensitivity difference between 250Hz and 1kHz is the same, no matter from where you look at it. If you want to compensate that 17dB difference with negative EQ by active filtering, then you would have 17dB worse signal to noise ratio between 250Hz and 1kHz, because a DSP (or analogue active filtering) cannot attenuate the noise that is generated after him in the signal chain.
With the B&C, I only said a more usable (in my view) sealed back 8" mid if you want to cross low. Of course, if the 100dB/2.83V/1m sensitivity is enough for the application.
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well YSDR you do have a point in that a rising response will multiply amplifier distortion ...
for example if i play a 250 hz tone and amp generates also 500 hz and 1 khz harmonics they will be much louder than with a flat response driver.
i suppose i didn't mention though that there would be four of these in parallel in an array and the acoustics of driver coupling in an array would actually add 12 db at the lower end but not quite so much at the higher end, which should help somewhat ...
so yes you raise a valid concern but it wasn't what you people were whining about previously ...
when i said counting from the bottom i meant from 0 db not from 250 hz.
it is the ABSOLUTE output that matters not output at one frequency relative to another ... well, unless of course you want to get into such details as signal to noise ratio of amplifiers ...
watt for watt this driver has more output at any frequency than any other 8" midrange and it also has the highest power handling as well ... meanwhile you people complain that " oh but it has less output at 250 hz than at 1 khz " well then stop comparing the output to the 1 khz output - it is easy i promise ! you can do it !
for example if i play a 250 hz tone and amp generates also 500 hz and 1 khz harmonics they will be much louder than with a flat response driver.
i suppose i didn't mention though that there would be four of these in parallel in an array and the acoustics of driver coupling in an array would actually add 12 db at the lower end but not quite so much at the higher end, which should help somewhat ...
so yes you raise a valid concern but it wasn't what you people were whining about previously ...
when i said counting from the bottom i meant from 0 db not from 250 hz.
it is the ABSOLUTE output that matters not output at one frequency relative to another ... well, unless of course you want to get into such details as signal to noise ratio of amplifiers ...
watt for watt this driver has more output at any frequency than any other 8" midrange and it also has the highest power handling as well ... meanwhile you people complain that " oh but it has less output at 250 hz than at 1 khz " well then stop comparing the output to the 1 khz output - it is easy i promise ! you can do it !
Except in the low-end, where you want to cross (as you said).
18Sound 8NM610: 91dB at 300Hz at 40 Ohm
B&C 8NSM64: 94dB at 300Hz at 40 Ohm
This also means that the 18Sound speaker must be given twice as much power at this frequency (where usually much more musical energy occours than at 1kHz) to do the same SPL as the B&C. That’s one of the reasons I said the B&C unit is better suited for low crossing.
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At least with tweeters my understanding is that one should stay well away from fs, due to several types of distortion caused by the drivers erratic behaviour around it's resonating frequency. Won't this also apply to a closed back midrange with such a high fs? Would appreciate some more perspective on this.
Skogs, it is related to the Qtc ( "Qts in box", for closed back: Qtc=Qts) In general, Qtc = 0.7 have acceptabel distortion att Fc. Qtc = 0.5 is good to 0.5 x Fc and Qtc = 0.25 is good to 0.25 x Fc.
This is a general roule of thumb and apply to all coil-magnet systems. Tweeters too.
The relation comes from Ingvar Öhman, Swedish sound engineer. Please correct me if I don't recall correctly.
They usually have high Qts, which conforms with your comments. Tweeters also have very low x-max, which makes them suitable for a higher cross över point.
This is a general roule of thumb and apply to all coil-magnet systems. Tweeters too.
The relation comes from Ingvar Öhman, Swedish sound engineer. Please correct me if I don't recall correctly.
They usually have high Qts, which conforms with your comments. Tweeters also have very low x-max, which makes them suitable for a higher cross över point.
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cool looking driver - I'm confused by the spec sheet's terms. Does Qts really mean"Qtc" with the back chamber?
Here's a 6.5" Emiinence sealed back speaker on a short waveguide. It would have been more fair to have a flat baffle the size of the waveguide's mouth rather than bare driver.
Here's a 6.5" Emiinence sealed back speaker on a short waveguide. It would have been more fair to have a flat baffle the size of the waveguide's mouth rather than bare driver.
Attachments
While there's still activity in the thread ... is it possible to do T/S parameter based sims for such sealed back drivers? Or the values for Fs and Qts are to be understood like the final Fbox and Qbox of a sealed box? (In this case I guess one would have to trace the FR and impedance curves, assuming that's half-space, to try to predict the boost needed for the desired low-end reponse and calculate the cone excursion manually.)
It's Xmax is 3mm, so don't expect too much spl down there...
https://www.eighteensound.it/en/products/lf-driver/8-0/8/8nm610 8ohm
https://www.eighteensound.it/en/products/lf-driver/8-0/8/8nm610 8ohm