Hi,
In very early stages of considering a first 2 way stand mount (to be used with subs, crossed over approx 80hz) and I'm struggling to understand why Pro drivers are generally capable of higher output despite less max excursion (both being the same diameter)
Example drivers might be B&C 5FG44 and SB SB15NRXC30-4.
Or perhaps I am wrong and the SB actually has the greater SPL potential...
Thanks
In very early stages of considering a first 2 way stand mount (to be used with subs, crossed over approx 80hz) and I'm struggling to understand why Pro drivers are generally capable of higher output despite less max excursion (both being the same diameter)
Example drivers might be B&C 5FG44 and SB SB15NRXC30-4.
Or perhaps I am wrong and the SB actually has the greater SPL potential...
Thanks
Pro drivers tend to be more sensitive. You get more output for the same electrical input. This is not the same as more output.
In GENERAL:
Underhung vs overhung voice coils. All else equal, more coil in the gap, the more sensitive the driver. With overhung there is less coil in the gap at any particular time so lower sensitivity, but it allows for longer cone travel which usually equates to the ability to produce a lower frequency.
There’s more to it but that’s a part of it. You’ll also note the moving mass of a PA driver is often quite low in comparison with hiding drivers, increasing sensitivity. Gap width can be less in a PA driver as with less excursion, there is a more linear stroke so less room for cone ‘wobble’ needs to be accounted for.
Still more but the dinner bell just rang. Others can take it further.
Underhung vs overhung voice coils. All else equal, more coil in the gap, the more sensitive the driver. With overhung there is less coil in the gap at any particular time so lower sensitivity, but it allows for longer cone travel which usually equates to the ability to produce a lower frequency.
There’s more to it but that’s a part of it. You’ll also note the moving mass of a PA driver is often quite low in comparison with hiding drivers, increasing sensitivity. Gap width can be less in a PA driver as with less excursion, there is a more linear stroke so less room for cone ‘wobble’ needs to be accounted for.
Still more but the dinner bell just rang. Others can take it further.
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Under normal air loading conditions (4 x the area of the sound wave when doubling the distance from the cone), cone movement is divided by 4 with every doubling of frequency. So, Xmax x cone area basically sets the low frequency limit.
Pro drivers that play higher maximum sound levels than a typical hifi driver generally accomplish this by limiting the low frequency bandwidth. Low bass requires more cone travel, limit the low bass and you will have reduced cone travel for a given SPL (or more SPL for a given cone travel). Compare the resonant frequency of the previously mentioned drivers, 63 Hz vs 41 Hz.
Is it safe to say that sd • cone travel = spl is a hard physical rule? While PA drivers optimize parameters for sensitivity, bandwidth in the lower range is the tradeoff, eh.
you must move air to increase spl and as freq decreases the amount of air movement needed increases for the same spl levels. Pro drivers don’t do large x max in favor of efficiency. If you go for huge drivers 18+ inches you can move air with low cone movement.
Voice coil power handling is a factor also. If the VC cannot push the driver to it's x-max continuously, then that becomes the limiting factor. The higher efficiency helps here also. Doing more with less...
The biggest difference is how they are used, pro audio are designed to get loud so they use a lot of cone area hence a 12"+ midrange speaker but there is 1 inherent problem and thats beaming the sound becomes very directional and higher the frequency the worse it gets so they make this up by either having multiple speakers on varying axis's or by some form of acoustic Lense to try and distribute the sound evenly.
Ever walk past a busker using a small PA mono or 2 speaker (all drivers in 1 box)and notice how quickly the mid/treble drops away as you keep walking... there's a small sweet spot where it'll sound real good.
most Domestic audio speakers are designed to have a nice wide dispersion so we can get away with just 2 speakers that will give us a nice large sweet spot without having to resort to a large array of speakers... not much WAF in that Im afraid!
Of course there's lots of caveats and 50 ways to skin a rabbit to achieve the desired results
Ever walk past a busker using a small PA mono or 2 speaker (all drivers in 1 box)and notice how quickly the mid/treble drops away as you keep walking... there's a small sweet spot where it'll sound real good.
most Domestic audio speakers are designed to have a nice wide dispersion so we can get away with just 2 speakers that will give us a nice large sweet spot without having to resort to a large array of speakers... not much WAF in that Im afraid!
Of course there's lots of caveats and 50 ways to skin a rabbit to achieve the desired results
This is an important point. In the "Pro" world, a driver with an Fs of 29 Hz is often called a subwoofer, and it will usually be at least 15", but more likely 18". It will be put into a very large vented box, and it will have an F3 in the range of 30Hz to 40 Hz. Drivers which are marketed as "woofers" often have Fs in the range of 35-40 Hz.
In the "hi fi" world, a lot of 8" woofers have an Fs of 29 Hz, and in a modestly sized vented box, they will have an F3 in the range of 30 Hz to 40 Hz. This is not considered subwoofer territory.
The low frequency extension of the Pro 18" subwoofer and the hi fi 8" woofer may be similar, but the pro driver is probably 8-10 dB higher in sensitivity, and its maximum SPL is gargantuan compared to the 8" driver.
A high quality home theatre subwoofer can generate high spl, low distortion, infrasonic energy... 18 Hz to 40 Hz is the target. You will very rarely hear this kind of very low bass from PA equipment in a concert hall or auditorium. In pop and rock music, there is almost no content below 35 Hz, so why would the sound engineers go to the huge expense of trying to cover that bottom octave.
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In the original question comparing 5" drivers from B&C and SB... At low frequencies (near Fs), most drivers are SPL limited by their excursion capability. In a sealed or vented box, they will reach max excursion at a lower power (Watts) then their voice coil capability. But at higher frequencies, the voice coil power capability and sensitivity limits the output. So it depends on how B&C and SB define their maximum output spec... if it is at 500 Hz, I bet B&C wins. If it is at 50 Hz in a sealed box, I bet the SB driver wins.
Hopefully this makes sense... ?
j.
----- ----- -----
In the original question comparing 5" drivers from B&C and SB... At low frequencies (near Fs), most drivers are SPL limited by their excursion capability. In a sealed or vented box, they will reach max excursion at a lower power (Watts) then their voice coil capability. But at higher frequencies, the voice coil power capability and sensitivity limits the output. So it depends on how B&C and SB define their maximum output spec... if it is at 500 Hz, I bet B&C wins. If it is at 50 Hz in a sealed box, I bet the SB driver wins.
Hopefully this makes sense... ?
j.
Thanks all this is very helpful info - and yes that makes sense hifijim!
Basically I have a secondary system, used often for family / friends get togethers, that consists of SVS Prime Wireless and a sub. It's very wife friendly as the speakers are almost hidden being so small, but max SPL is limited.
I want to make something not much larger (possibly active, using MiniDSP plate amps) and thought the above SB 5 inch (or the B&C) and something like a Scan Speak H2606/920000 would give me better, cleaner output when we want to turn it up a bit.
Am I wasting my time? Any better options? The speakers need to remain compact, like the SVS Primes are so 5 inch mid/woofer is really my maximum... (Will still be using a subwoofer)
Basically I have a secondary system, used often for family / friends get togethers, that consists of SVS Prime Wireless and a sub. It's very wife friendly as the speakers are almost hidden being so small, but max SPL is limited.
I want to make something not much larger (possibly active, using MiniDSP plate amps) and thought the above SB 5 inch (or the B&C) and something like a Scan Speak H2606/920000 would give me better, cleaner output when we want to turn it up a bit.
Am I wasting my time? Any better options? The speakers need to remain compact, like the SVS Primes are so 5 inch mid/woofer is really my maximum... (Will still be using a subwoofer)
Size will ultimately limit whats achievable, its gonna sound small if its small and that's about it 🙂 You could increase the system size with camouflage or rethink the system as whole. Bass speakers can be possibly hidden in furniture so all you need visible is something relatively small that plays mids and treble, but it all needs to work as a system. Power in DIY is in the fact that you can tailor fit a playback system into your situation.
If you wanna be stuck with small two way full range speakers you can push SPL capability up by using top of the line drivers like Purifi. They have made small drivers that work in small boxes with huge excursion but without great non-linear distortion so ought to get louder than some other drivers before sound gets poo. It is top of the line pushing limits situation so the price you have to pay goes parabolic as usual. Most tweeters should be fine, just make high pass high enough, its the too low high pass that makes tweeter distort just like woofers distort when they are requested too loud lows, too much excursion. Its the lows, long wavelengths that need size for SPL.
5" is not much more bigger than 4.5" in the Prime Wireless.. so don't expect miracles unless you think the system as whole and forget about full range small speakers. On the other hand, if casual listening is fine and the size/looks is more important than sound quality I'd just buy/rent some party speakers and roll them in when its time to rock.
If you wanna be stuck with small two way full range speakers you can push SPL capability up by using top of the line drivers like Purifi. They have made small drivers that work in small boxes with huge excursion but without great non-linear distortion so ought to get louder than some other drivers before sound gets poo. It is top of the line pushing limits situation so the price you have to pay goes parabolic as usual. Most tweeters should be fine, just make high pass high enough, its the too low high pass that makes tweeter distort just like woofers distort when they are requested too loud lows, too much excursion. Its the lows, long wavelengths that need size for SPL.
5" is not much more bigger than 4.5" in the Prime Wireless.. so don't expect miracles unless you think the system as whole and forget about full range small speakers. On the other hand, if casual listening is fine and the size/looks is more important than sound quality I'd just buy/rent some party speakers and roll them in when its time to rock.
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Yep, pick any 2:
Small size
High SPL
Low power.
Various compromises can be found with the shape. Some people use skinny towers, deeper bookshelves -- whatever works for them for the aesthetics. I try to keep in mind that if the top has a flat surface, it may require some water-proofing for the pot plant 😆. You can squeeze out a bit more volume for a given space by using thinner side walls with harder materials and/or bracing. Glass could be an interesting one (I haven't tried it).
A lot depends on the sub -- I personally moved away from using a mono sub in favour of more traditional stereo woofers, but you could experiment to find out what works in terms of crossover points and slopes. If you can give the sub/s more work to do, the mids/highs can also go louder and cleaner. It's basically a stealth 3-way and you need to look at the system as a whole.
Small size
High SPL
Low power.
Various compromises can be found with the shape. Some people use skinny towers, deeper bookshelves -- whatever works for them for the aesthetics. I try to keep in mind that if the top has a flat surface, it may require some water-proofing for the pot plant 😆. You can squeeze out a bit more volume for a given space by using thinner side walls with harder materials and/or bracing. Glass could be an interesting one (I haven't tried it).
A lot depends on the sub -- I personally moved away from using a mono sub in favour of more traditional stereo woofers, but you could experiment to find out what works in terms of crossover points and slopes. If you can give the sub/s more work to do, the mids/highs can also go louder and cleaner. It's basically a stealth 3-way and you need to look at the system as a whole.
I’m personally beginning to move forward with a similar project. It’s roots are dipped in spousal acceptance but the tree is enjoyment of the challenge. I have a pair of bookshelves I just built, consisting of Anarchy 704’s, Tectonic BMR 2” and Dayton Reference 8” passive radiators in a premade .5cf enclosure. They play sub 30hz fairly effortlessly for the form factor imo. The BMR is a great unit for simplification but of course a 3 way is very substitutable. 14”h x 8.5”w x ~10”d.
The above project is already built and mentioned because I find it to perform well for what it is. The more compact units that have parts in route will be .23cf parts express knock downs, anarchy 554’s, peerless 1.5” fullrangers and Dayton 5/8” nd16 tweeters. The 554’s fulfill my spl needs but the Dayton Epique 5.5” would easily be substituted. In this cabinet volume it only makes sense, to me, to go sealed with the Dayton, mayyybe the little bit of additional spl from a pr is worth it with the 554. The 554’s are still in stock as I just ordered a set. I like to use a high shelf filter and get flat response as low as possible at the cost of spl but a less aggressive filtering would allow something like these to scream with sufficient power. Denovo knock down cabinets, 7.5”x11.5”x8.5”.
The above project is already built and mentioned because I find it to perform well for what it is. The more compact units that have parts in route will be .23cf parts express knock downs, anarchy 554’s, peerless 1.5” fullrangers and Dayton 5/8” nd16 tweeters. The 554’s fulfill my spl needs but the Dayton Epique 5.5” would easily be substituted. In this cabinet volume it only makes sense, to me, to go sealed with the Dayton, mayyybe the little bit of additional spl from a pr is worth it with the 554. The 554’s are still in stock as I just ordered a set. I like to use a high shelf filter and get flat response as low as possible at the cost of spl but a less aggressive filtering would allow something like these to scream with sufficient power. Denovo knock down cabinets, 7.5”x11.5”x8.5”.
Thanks all. I think it's become apparent that I'll need to go larger for a significant increase in max output, so to feed the DIY bug I've recently got I think I'll look at doing something about subs instead ... may post for some advice very soon !