Who knows if there are advantages or disadvantages by using two 5.25'' drivers instead of one 6'', 6.5'' or 7'' in a 3-way ?
The size (6'' 6.5'' 7'') depends of brand and type to choose.
Think about x-over points of 200Hz and 2000Hz. (sub)woofer to be used is 8'' or 10'' (possible double). MTMW or MTMWW configuration.
When i look for instance at Vaporsound, Wilson Audio, Avalon, Tidal or Marten; There is no one who uses two smaller units but one 6'', 6.5'' or 7''.
I think also it's not the same explanation of using two 10'' instead of one 12'' (example) or am i wrong ?
CDT Andréas
The size (6'' 6.5'' 7'') depends of brand and type to choose.
Think about x-over points of 200Hz and 2000Hz. (sub)woofer to be used is 8'' or 10'' (possible double). MTMW or MTMWW configuration.
When i look for instance at Vaporsound, Wilson Audio, Avalon, Tidal or Marten; There is no one who uses two smaller units but one 6'', 6.5'' or 7''.
I think also it's not the same explanation of using two 10'' instead of one 12'' (example) or am i wrong ?
CDT Andréas
one bigger unit is usually cheaper than two smaller, & has approx the same cone area as two of the next size down (& usually slightly higher sensitivity)
If wired in parallel, 2 drivers will be between 3-6dB louder. A single larger driver will typically result in lower frequency, driver depndent. In other words, two 6 inch woofers won't give you "as much" bass as a single 8" or 10" woofer, again driver dependent.
Mike
Mike
Advantage: Better horizontal dispersion using dual smaller driver. Cone breakup at higher mid range frequency may mean simpler crossover design. MTM or TMM options.
Neutral: 2x 5.25" = single 7" in total piston area. Lower sensitivity made up by the dual 5.25".
Disadvantage: 5.25" has smaller Xmax indicating less dynamic range or higher distortion when driven hard. 2x 5.25" costs more than single 7" in similar brand and quality, can be much more.
It may ultimately depend on the tweeter choice. Not very many tweeter can go down to 2000 Hz and sound dynamic (not just loud) that low. With an excellent tweeter at the 2000 Hz crossover frequency, I would prefer a single larger mid-woofer for the higher dynamic range.
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Another advantage of using two rather than one: you can implement baffle step correction by using two bass drivers, with one fed by a first-order high-pass filter at 200-300 Hz. Otherwise you have to use an extra inductor in the crossover, with the implications of series resistance and reduced sensitivity.
Alex
Alex
You can't implement BSC in either a 2way or 2.5way without adding extra inductance so you'll run into the problem of DCR in both cases.
The only advantage of a 2.5way from an electrical standpoint is that you aren't burning up half of the power through the midrange in the BSC shunt resistor as is required for 2way.
The main design decision between an BSC'd 2way and a 2.5way is the difference in vertical dispersion through the midrange, not efficiency.
You state a 200-2000Hz range, so basically a midrange in a 3 way speaker.
A single 6.5" has slightly less area than 2x 5.25", and has also less output, in the range of 4 dB (only if the smaller drivers are wired in parallel). Also distortion could be a little higher for a single 6.5" driver at a constant SPL (in the range you stated, for 40-50Hz it will be different). The volume needed should be similar.
At 2KHz there shouldn't be problems in crossing to a tweeter for both options for directivity reasons, and also for crossover design as the breakup should not be near, but in any case the 2x5.25" option is at a slight advantage.
It seems that the 2x5.25" drivers option wins, however you halve the impedance and some amp aren't happy with that and moreover as the price for a 6.5" driver is only marginally higher than a single 5.25", 2x5.25" will cost significantly more.
The discussion about BSC and 2.5 way is pointless here as the drivers are needed for midrange duty alone and not mid-bass, so I don't see the point in dealing with a 2.5 way design. 200 Hz is a bit low in frequency for BSC for a typical baffle for a 5.25" or 6.5" driver, so it should be handled by the bass driver. As the best way to deal with a baffle step is to position it at the crossover point between bass and mid, there are only two possibilities: a higher crossover point or a larger baffle.
One last point: for twin midrange drivers your only option is a MTM.
Ralf
A single 6.5" has slightly less area than 2x 5.25", and has also less output, in the range of 4 dB (only if the smaller drivers are wired in parallel). Also distortion could be a little higher for a single 6.5" driver at a constant SPL (in the range you stated, for 40-50Hz it will be different). The volume needed should be similar.
At 2KHz there shouldn't be problems in crossing to a tweeter for both options for directivity reasons, and also for crossover design as the breakup should not be near, but in any case the 2x5.25" option is at a slight advantage.
It seems that the 2x5.25" drivers option wins, however you halve the impedance and some amp aren't happy with that and moreover as the price for a 6.5" driver is only marginally higher than a single 5.25", 2x5.25" will cost significantly more.
The discussion about BSC and 2.5 way is pointless here as the drivers are needed for midrange duty alone and not mid-bass, so I don't see the point in dealing with a 2.5 way design. 200 Hz is a bit low in frequency for BSC for a typical baffle for a 5.25" or 6.5" driver, so it should be handled by the bass driver. As the best way to deal with a baffle step is to position it at the crossover point between bass and mid, there are only two possibilities: a higher crossover point or a larger baffle.
One last point: for twin midrange drivers your only option is a MTM.
Ralf
If you were to raise the XO points there would be the option of using two 100mm midrange drives and a smaller Neo tweeter, getting the C2C distance as small as practicable
If a narrow baffle is desired then you also have the option of 3.5-Way
BTW I don't consider a crossover at 200/300Hz to be subwoofer territory
If a narrow baffle is desired then you also have the option of 3.5-Way
BTW I don't consider a crossover at 200/300Hz to be subwoofer territory
Thanks you for your comments.
@ Moondog55
i understood that a x-over of 200Hz is better for the voices from males and femals coming from one driver as a midrange and not two, like midrange and woofer. That`s why a double 4'' isn`t in the picture. Than i`ve to cross over more higher.
@giralfino
MTM is my option for double drivers, but why not TMM ?
@keilau
''Disadvantage: 5.25" has smaller Xmax indicating less dynamic range or higher distortion when driven hard. 2x 5.25" costs more than single 7" in similar brand and quality, can be much more.''
I`ve read that for a midrange (x-over of 200Hz) a x-max of 3mm is more than enough. Most midwoofers of 5.25'' have ay least 4mm, only real 5.25'' midranges have less. But a good 5.25'' midrange that goes down to 200Hz isn't simply to find.
And you are saying that two 5.25'' have more distortion when driven had than one 7'' ? Because piston area is the same or ever more, the same for the sensitivity.
Last, dispersion is a good argument bij using two 5.25''.
CDT Andréas
@ Moondog55
i understood that a x-over of 200Hz is better for the voices from males and femals coming from one driver as a midrange and not two, like midrange and woofer. That`s why a double 4'' isn`t in the picture. Than i`ve to cross over more higher.
@giralfino
MTM is my option for double drivers, but why not TMM ?
@keilau
''Disadvantage: 5.25" has smaller Xmax indicating less dynamic range or higher distortion when driven hard. 2x 5.25" costs more than single 7" in similar brand and quality, can be much more.''
I`ve read that for a midrange (x-over of 200Hz) a x-max of 3mm is more than enough. Most midwoofers of 5.25'' have ay least 4mm, only real 5.25'' midranges have less. But a good 5.25'' midrange that goes down to 200Hz isn't simply to find.
And you are saying that two 5.25'' have more distortion when driven had than one 7'' ? Because piston area is the same or ever more, the same for the sensitivity.
Last, dispersion is a good argument bij using two 5.25''.
CDT Andréas
A good integration between drivers tend to make that a non issue - don't forget that a human voice has many harmonics over 2KHz, so the voice is not really covered by a single driver. I still prefer that the crossover point between bass and mid is at the baffle step frequency as this will ease the crossover, but 200Hz means a large baffle.
You need a real wooferBecause for a 2KHz crossover point the lower mid is too far away from the tweeter, and this will create nulls and peaks in the vertical plane.
Not true because the single 6.5" is driven harder than the 2x5.25" for the same SPL - remember you gain up to 6dB connecting 2 drivers in parallel.
Ralf
Andreas there are a few 4inch that will cross at 200-Hz [ very easy if using a Bi-Amp situation BTW] but 5 inch is a reasonable compromise; good dispersion would argue in favour of twin 4 inch drivers.
I'm actually planning such a speaker using Vifa P11s and the older Neo tweeter as I have those drivers on the shelf
With an Fs of ~50hz I'm happy crossing the little drivers over at 200/300
I'm actually planning such a speaker using Vifa P11s and the older Neo tweeter as I have those drivers on the shelf
With an Fs of ~50hz I'm happy crossing the little drivers over at 200/300
2x 6.5" will gain up to 6dB in SPL when compared to a single 6.5" feeding the same power to EACH driver. The math does not add up if you are talking about 2x 5.25" vs. single 6.5" (estimate effective piston area to be 170 vs. 145 cm2), but the later will have 40% longer linear excursion length.
Are you thinking that the impedance is only half when 2 drivers are connected in parallel? What is the 6dB gain you are referring to? The audio power amplifier is a voltage source. A 4 ohms load will draw twice the power of an 8 ohms load when driven by the same 2.83 volts reference signal (for speaker sensitivity measurement). Anyway, careful about the reference signal when comparing SPL.
The BSC inductor will be a bit larger (=higher DCR) for a 2.5way because it's driving a higher impedance but then because it's driving a higher impedance the DCR isn't as critical.
The DCR only affects the amount of baffle step in either case which isn't always a 'more is better' case anyway. A bit of DCR in the BSC inductor can help tame the response ripple caused by the resonant impedance peak of the woofer too. Midrange is almost completely unaffected by DCR.
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OK, then let's use a real world example. Two drivers from the same manufacturer with similar cone properties, the Seas ER15RLY and ER18RNX. Cone area 80 vs 136 cm2, SPL 87.5 vs 88.5 dB, Re 5.6 vs 5.9 Ohm, xmax 5 vs 6 mm.
If you connect 2 drivers in parallel, you gain 3dB for doubling the area, and up to 3 more dB for halving the impedance. In an ideal world you gain 6dB, without changing voltage from the amp. If the combined drivers give for example 90dB with 2.83V, then you need 5.65V with the single driver to have the same 90dB, and the excursion doubles. So to summarize, 2 driver give 6dB more with the same voltage or half the excursion for the same SPL at half the voltage.
If we now compare 1x6.5" to the 2x5.25", the real numbers are not what I said above because the base SPL is different (87.5 vs 88.5 dB), but is close enough to show that for a constant SPL, the single driver is driven harder and thus could have more distortion.
So all seems in favor of the 2x5.25" vs a single 6.5". The real disadvantage is the price: the above (single) drivers cost 67.5 vs 75 Euro, but the comparison is 2x67.5=135 Euro for the 2x5.25" vs 75 Euro for the single 6.5".
Ralf
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