Driver search program?

Hearinspace

Member
Paid Member
2008-06-03 5:18 am
I have been looking for a driver that will cover roughly 100Hz down that will match or better a mid's 95dB sensitivity. I don't use Home Theater and listen in a fairly small space at levels you can easily talk over. To look , I got BassBox 6 Pro as they advertise a large database , which it does have, and they have a function where you can bracket Vb and F3 and search drivers that will suit. Very nice. Except that when I put in a broad range of 100 to 200 litres with F3 = 20 to 35Hz, and check for only available drivers , I get 16 hits , almost all of which the latest data for was 2001 and are no longer available.

My question is broadly, is there another program that you can do a similar thing with that has a more up to date data base? I looked at Vituix Cad and you can scroll through the drivers very nicely with instant graphic results (Very Nice!) but it adjusts the box for every driver and I don't see a way to lock it.

Alternatively , when you know what you want but not the driver to do it, what do you do to streamline your search. It seems that the vast majority of builders use an eq program to take care of any FR issues which I'm not open to doing and there are a heck of a lot of drivers out there to go through.

Thanks very much.
 
That would btw be a good thing to have, but i'm not good at programming, and certainly not databases like that. but it could be an asset for diy audio in general if someone here would make that and everybody can add specs of drivers to it( (with a contol system off course). Because the sites i mention are not complete at all, and closed systems where only the admin or a few people can add data.
 

Hearinspace

Member
Paid Member
2008-06-03 5:18 am
I understand that as a general principle but don't yet know the real world parameters / limitations. I had thought that if I restricted the more or less 2 octaves of low bass to its own driver I would be dealing with that tradeoff.

My hope is to get at least 40Hz with a touch of margin and if lucky lower than that without resorting to bigger power than my usual 10 to 20 watt tube amp builds.
 

Hearinspace

Member
Paid Member
2008-06-03 5:18 am
Mashaffer, I have been to those sites and others but the problem is my limited ability to look at the T/S's and understand what the driver will do closely enough to take seriously. I've been reading up but am still a long way off from looking at them and knowing what enclosure setup will work. My experience with everything else has always been iterative. Too long a time line and too expensive with speakers and I'm about to give the ones I have now back to their owner , so I'm interested in arriving at perfection a few minutes ago. : )

Waxx, I'd seen the first one before but in a hurry, wasn't sure how to look at the curves and know (like I said above) but this time I noticed the "Other drivers like this one" section, so if I can take just one driver that works in a sim I can enter it and find others in the same ballpark. Good.
I went to the French site but didn't find a link to a parameter search, or a way to sign in unless you're a pro customer.

Thanks
 

AllenB

Moderator
Paid Member
2008-10-18 11:31 am
I had thought that if I restricted the more or less 2 octaves of low bass to its own driver I would be dealing with that tradeoff.
Not if the method you use doesn't change the fundamental nature of the system. You don't evoke the bandwidth efficiency tradeoff by applying a low pass filter. On the other hand you can add such effects if you use a bandpass enclosure, which brings its own resonance and can be used to increase output.
 
Mashaffer, I have been to those sites and others but the problem is my limited ability to look at the T/S's and understand what the driver will do closely enough to take seriously. I've been reading up but am still a long way off from looking at them and knowing what enclosure setup will work. My experience with everything else has always been iterative. Too long a time line and too expensive with speakers and I'm about to give the ones I have now back to their owner , so I'm interested in arriving at perfection a few minutes ago. : )

Waxx, I'd seen the first one before but in a hurry, wasn't sure how to look at the curves and know (like I said above) but this time I noticed the "Other drivers like this one" section, so if I can take just one driver that works in a sim I can enter it and find others in the same ballpark. Good.
I went to the French site but didn't find a link to a parameter search, or a way to sign in unless you're a pro customer.

Thanks
Sure, we continue learning until the day they start shoveling dirt in our faces. :D I suggest downloading a simulation / design program (I use hornresp because I also like to look at transmission lines and the like) and start playing with it and you will start to see patterns. I am working on a high efficiency design for use with my SEUL KT-88 but on a budget since my financial situation is rather poor. I am looking at getting useful output down to the low C of the 16' ranks of pipes (thus the 32Hz target). The 32' pipes will have to be handled by a sub anyway since the output transformers probably don't have much squirt at 16Hz. Desired sensitivity is in the 95-100dB/W/m range. I am looking seriously at Eminence Beta 15A, Eminence Legend 1585, Goldwood 1558, and similar Eminence Delta series. They all look like they can do it in my room down to 30Hz and should respond well to a series cap if I need just a bit more.
 

Hearinspace

Member
Paid Member
2008-06-03 5:18 am
After cramming on the band-pass enclosure reading the two takeaways are that they are very hard to get right and that they are best designed together with the assumption that active eq will be used.

I then got it in my head that transmission lines might be worth trying . I watched some Horn Resp tutorials then tried my hand at a basic design and came away thinking that's not where I want to go. Or to be more precise , I'm not ready to go there.
So it's back to a reflex box.

My question returns in a different form. How do you search . Just now I went back to WAXX's recommended loudspeakerdatabase which has that cool parametric search function. After putting in frequency band , size , and Fs parameters, I found it most natural to compare drivers by where their simmed fr plot ended up at the bottom end. Most crossed 90dB at 40Hz but a few (like this Monacor) were 90dB at 30Hz. It seems a reasonable approach to me but wonder : Is it too simplistic even for a first elimination round ?
 

Hearinspace

Member
Paid Member
2008-06-03 5:18 am
I was thinking one driver - 8Ω, but am willing to look at two, though I'd guess I would go for a smaller size than 15" in that case. But my question for starters at least is, is the sensitivity at low frequency enough of an indicator to start eliminating drivers?

I ask because I know there are many other factors that have influence I just don't yet know how much each has and how their influences mix and also because in looking through the database selection there are a lot of drivers listed as "Subwoofer" that have a large hump way up in the mid band and slope down pretty dramatically toward the area where they'd actually be wanted as a subwoofer. As much as 20dB difference in some cases. I gather the idea for those drivers is that they have power handling capability and the the way to get the LF out of them is to apply a lot of eq and power.
 
It is mostly matter of displacement, see indicative charts here https://www.diyaudio.com/community/threads/volume-displacement-for-spl-chart.5668/

Roughly so, for closed box without thinking how the room makes/ruins it anyway :D
1. Figure out how much SPL you want at which frequency
2. Find driver that has x amount of excursion with your available amplifier power, so that excursion multiplied by cone area makes the volume displacement on the chart.

Eyeballing from the charts behind the link you'd need displacement of ~200cm3 for ~105dB at ~40Hz. Quadruple the displacement to get what is require for ~20Hz. This would be roughly 800cm3, so a ~15" driver with SD of 800cm2 excursing +/-0.5cm would do it? In which case a single 15" driver can do the ~105dB at ~40Hz with quarter of the excursion of that, so +/-0.125cm.

edit.
Can your 10 Watts amp do it? Perhaps, attached Faital Pro 15fh520 in ~150l enclosure and it shows cone excursion of ~1.5mm peak, ~3mm total, with 10W input power. SPL chart shows only about 93d SPL though. What gives? f3
 

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100Hz around ~95dB at 1meter with 1W can be achieved with following drivers and systems.

  • 6pcs LAB12 in ~300litres closed, F3 ~43Hz. This is 12" 'low sensitivity subwoofer'
  • 6pcs LAB12 in ~600litres reflex, F3 ~23Hz
  • 1pcs old Beyma 15k200 in ~100 litres reflex, F3 ~50Hz. This is 'high sensitivity pa woofer'
  • 1pcs Faital 15fh520 in ~150 litres reflex, F3 ~40Hz. This is 'high sensitivity pa woofer'.
F3 here is eyeballed form WinISD graphs, where SPL is roughly 92dB /1W / 1m.

The low cut off varies with the size of the system and you need big stuff to maintain the SPL for low frequencies, with one amplifier Watt. "high sensitivity woofers" can do it by singles around 100Hz but fall of quick. Use multiple/bigger drivers and boxes to maintain sensitivity lower in frequency.
 
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I guess I skipped writing a helpful sentence how to narrow down the driver selection :D The examples posted kind of show that you can reach the target sensitivity around 100Hz with the sensitivity reading of on the driver database. But, to reach low frequencies there is no other option than pour in lots of power, or quadruple the volume displacement from what you intended.

If you don't want to use EQ, don't use the high sensitivity woofers, since they have rising response and you would have to EQ. Instead, pick the "subwoofer" types which are kind of flat to low frequency, but come with very low sensitivity and you need million of them. Either way, you'll end up roughly the same cone area * excursion for same extension no matter which woofers and sizes you chose, given the available power and box alignment stays the same.

Since your power is low, there is only two options: No low extension or huge woofers and boxes. Lets see if there is some nice middle ground, lets think it through:

I would narrow down the woofer selection so their sensitivity rating (possibly combined) hang around what you want it at 100Hz. Then, pick highest Fs you think you are okay with extension wise and you'll end up with smallest system that meets up the sensitivity goal around 100Hz. If you wan't go lower the system size goes up, or the sensitivity goes down (power requirement goes up, woofers can take lots of power!). Look for single 15" driver that meets the sensitivity requirement at 100Hz and be happy what the roll of is. You can affect the rolloff some with the box alignment and with help of the room. If you can go bigger you could get more extension with bigger/ more drivers. If you want to avoid the EQ, look for drivers with lower Fs and combined sensitivity so the 100Hz sensitivity requirement stays while extension gets lower.

Just to have an alternative for the huge woofers and boxes check out multisub systems and why one would be benefitical. Also check out how much class D amps cost per Watt. Probably single 12" subwoofer with power would be enough, even single Lab12 seems to be able to do 110dB with 200W and 100litre reflex enclosure. Only way to save space and have extension is sacrifice the sensitivity. Luckily power is very cheap.

Hopefully this was more helpful. Please post what you come up with, thanks!
 
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