maybe i should consider them for lighting instead!
how important is this factor on other drivers though? because alot of the subs(direct radiating ones) i see playing at venues are definately running outside of xmax(granted alot of times the bass really suffers, but in other less extreme cases, it doesnt seem to be too bad).
also, still wondering about wether the same excursion reduction is experienced by multiple horns with couple mouths
how important is this factor on other drivers though? because alot of the subs(direct radiating ones) i see playing at venues are definately running outside of xmax(granted alot of times the bass really suffers, but in other less extreme cases, it doesnt seem to be too bad).
also, still wondering about wether the same excursion reduction is experienced by multiple horns with couple mouths
cowanaudio said:
I thought as you reactance annulled, and made the rear chamber smaller, that you made the compression ratio higher to keep a balanced load on the driver??? And that a relatively large rear chamber would use about 2:1, and a relatively small rear chamber would be 4:1. (as kind of a 'estimate' or rule of thumb to follow, while not going outside of 2:1 through 4:1)
That dayton FLH hornresp sim has about as small of a rear chamber as practical, so I went straight for 4:1.
Am I way off on my compression ratios?
jbell said:
Reactance annulling and compression ratio aren't directly linked; a driver with low Fs will need a small rear chamber, one with high Fs will need a large one, but the total stiffness is the same in both cases.
A higher CR will usually mean more air mass load on the cone which will need lower compliance to reactance annul which means a smaller chamber, but the above still applies.
It's nothing to do with a "balanced" load on the driver, both horn and rear chamber have exactly the same cone loading for both directions of cone movement -- otherwise rectification would occur and the cone would move to one end of its travel.
Ian
Thanks for that clarification on chamber vs compression ratio... Somehow I got that in my head awhile back that as you went smaller on rear chamber, that you also needed to up the compression ratio... I know in hornresp, that when you modify both that way, you keep a similar spl profile, so that probably reinforced that idea.
I still can't seem to beat a double driver 55-2421 with an inductor, in various flavors for pa sub on the cheap. I've not personally blown up a 55-2421, but I could see how it would be easy to do.
This design would get me 120db, and with a pair of $25 drivers, which leaves plenty of spare $$$ for cabinet, finish, etc.. to keep total cost under $100.
I've never been able to sim an unmodified 55-2421 in a TH, that works well for PA. Unfortunately a pair of TB 8's doesn't fit my budget.
hmm... still thinking.
I still can't seem to beat a double driver 55-2421 with an inductor, in various flavors for pa sub on the cheap. I've not personally blown up a 55-2421, but I could see how it would be easy to do.
This design would get me 120db, and with a pair of $25 drivers, which leaves plenty of spare $$$ for cabinet, finish, etc.. to keep total cost under $100.
I've never been able to sim an unmodified 55-2421 in a TH, that works well for PA. Unfortunately a pair of TB 8's doesn't fit my budget.
hmm... still thinking.
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GM:
Less than 300liters, 120db in 2pi from 40-100hz, under $100.
How unworkable is this? It eliminated the inductor, and a front chamber makes it easier on the cones, but compression ratio is an incredible 8:1
I would really like a 55-2421 TH, as it's the biggest air mover for the $$$. I know others have posted TH's for 55-2421's, but they are REALLY peaky. I need a design that's about as flat as possible, and something I can turn over to someone who doesn't know any better.... (meaning I can't guarantee a HP filter at 40hz, or how far up the volume knob is turned...)
thoughts?
Less than 300liters, 120db in 2pi from 40-100hz, under $100.
How unworkable is this? It eliminated the inductor, and a front chamber makes it easier on the cones, but compression ratio is an incredible 8:1
I would really like a 55-2421 TH, as it's the biggest air mover for the $$$. I know others have posted TH's for 55-2421's, but they are REALLY peaky. I need a design that's about as flat as possible, and something I can turn over to someone who doesn't know any better.... (meaning I can't guarantee a HP filter at 40hz, or how far up the volume knob is turned...)
thoughts?
Attachments
if you cant garuntee a HP or how far the volume knob is turned, not even a th115 is gonna last too long id tend to think...
ive been playing with some 100$ selenium 15 driver in a TH, and it seems to get flat and loud and have alot of powerhandling (250ish before excursion exceeds linear), last time i checked it hit around 125, in a 400 litre box, meaning that one of these could end up being better value than a pair of the MCM ones. they start getting more interesting as you add more as with all horns. its far from idiot proof, you need a highpass filter below 40hz, if youre not driving em too hard you coudl get away with mid 30s if you wanted a little mreo extension.
my computers on the fritz, so i need to wait till i get it running smooth again before i allow myself to play around on hornresp, but i should get some graphs and dimensions up later on today.
ive been playing with some 100$ selenium 15 driver in a TH, and it seems to get flat and loud and have alot of powerhandling (250ish before excursion exceeds linear), last time i checked it hit around 125, in a 400 litre box, meaning that one of these could end up being better value than a pair of the MCM ones. they start getting more interesting as you add more as with all horns. its far from idiot proof, you need a highpass filter below 40hz, if youre not driving em too hard you coudl get away with mid 30s if you wanted a little mreo extension.
my computers on the fritz, so i need to wait till i get it running smooth again before i allow myself to play around on hornresp, but i should get some graphs and dimensions up later on today.
xstephenax:
I know anyone can blow any driver up with about anything... yes, true.
I suppose if I'm asking for TH (or other) sub designs that fit my purpose, I should be a little clearer on the what & why.
This design is for a band/dj in a box. 2 mains, 2 small monitors and 1 or 2 small subs. Total system should be able to fit in a corolla, or other midsize car. This is a design I'd like to market to church's and/or other small PA needs folks in my area, at the lowest price point possible. I'm tired of seeing 2 plasti-boxes on sticks sounding like garbage...
The idea is that with very small 12 ohm monitors (8ohm driver, 8ohm lpad + 4ohm of resistance), a pair of 8 ohm mains, and a pair of 4-8ohm subs, that you could run the entire thing off of a single amp, and a 80hz 12db/oct crossover.
As far as making it idiot proof, most low end amps end up voltage limited, so for my example of a dual 55-2421, wiring in series keeps me safe up to the 40volt or so range, and a simple breaker should be enough to keep from blowing the drivers. My guess is that my target audience would end up with a behringer ep1500 as a 'high end' amplifier... (doesn't that put things in perspective) With the small rear chamber, at 40volts, I'm under 11mm at 20hz, and a 55-2421 is +-8mm, so I think that's a relatively safe design without a HPF, if the cones can stand the pressure. 2 subs gets me in the 127db range 2pi, at 4ohm load, and if they were to be corner loaded in a typical venue, should outrun anything I can design for tops..
The price point is what makes this design challenging. I'm targeting $100 total per sub, $50-70 per top, so $100 drivers are out of my budget.
So far the $80 dayton, and the dual $25 55-2421 are the only 2 contenders, both in FLH, and in very high compression ratio (risky to unworkable) designs. I've considered BP, BLH, and TH.. and really like TH, but so far no dice on any of them with the drivers I've sim'd.
Because my goal is low $$$, I have to assume that bass eq, HPF, deq2496, driverack, etc.. are not an option, so eq'ing a ragged response flat, or 48db/oct HPF for an inherently non-safe design is just not realistic.
that help explain my design goals?
see... it really is a challenge... It sounds easy enough on it's face, but the more brain cycles I spend on it, the more challenging it turns out to be.
I know anyone can blow any driver up with about anything... yes, true.
I suppose if I'm asking for TH (or other) sub designs that fit my purpose, I should be a little clearer on the what & why.
This design is for a band/dj in a box. 2 mains, 2 small monitors and 1 or 2 small subs. Total system should be able to fit in a corolla, or other midsize car. This is a design I'd like to market to church's and/or other small PA needs folks in my area, at the lowest price point possible. I'm tired of seeing 2 plasti-boxes on sticks sounding like garbage...
The idea is that with very small 12 ohm monitors (8ohm driver, 8ohm lpad + 4ohm of resistance), a pair of 8 ohm mains, and a pair of 4-8ohm subs, that you could run the entire thing off of a single amp, and a 80hz 12db/oct crossover.
As far as making it idiot proof, most low end amps end up voltage limited, so for my example of a dual 55-2421, wiring in series keeps me safe up to the 40volt or so range, and a simple breaker should be enough to keep from blowing the drivers. My guess is that my target audience would end up with a behringer ep1500 as a 'high end' amplifier... (doesn't that put things in perspective) With the small rear chamber, at 40volts, I'm under 11mm at 20hz, and a 55-2421 is +-8mm, so I think that's a relatively safe design without a HPF, if the cones can stand the pressure. 2 subs gets me in the 127db range 2pi, at 4ohm load, and if they were to be corner loaded in a typical venue, should outrun anything I can design for tops..
The price point is what makes this design challenging. I'm targeting $100 total per sub, $50-70 per top, so $100 drivers are out of my budget.
So far the $80 dayton, and the dual $25 55-2421 are the only 2 contenders, both in FLH, and in very high compression ratio (risky to unworkable) designs. I've considered BP, BLH, and TH.. and really like TH, but so far no dice on any of them with the drivers I've sim'd.
Because my goal is low $$$, I have to assume that bass eq, HPF, deq2496, driverack, etc.. are not an option, so eq'ing a ragged response flat, or 48db/oct HPF for an inherently non-safe design is just not realistic.
that help explain my design goals?
see... it really is a challenge... It sounds easy enough on it's face, but the more brain cycles I spend on it, the more challenging it turns out to be.
jbell said:
I know that you're hardly competing in the same market as Tom (about 10x lower price!), but if you make and sell tapped horns (as opposed to just building them for your own use) you will be infringing his patent, assuming it gets granted.
If I were you I'd ask him whether he was happy with this to avoid any possible future unpleasantness -- and if he says no, build another type of box to sell...
Ian
ive been playing around with some 4th order bandpass designs in winisd, and it seems reasonably easy to get close to your performance goal.(120db from 40-120hz in 2pi, under $100 300L) with a pair of cheap 15s.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-384
try two of those in a 4th order bandpass, sealed chanber is 170litres, vented one is 120 tuned to 70hz. i add 3b to my calculations to predict 2pi response. with 150 watts itll go a little over xmax(about 2mm over) so that might be a problem, but id tend to think it wouldnt be(2mm is pretty small, but my last xmax assumption turned out to be incorrect).
you dont see many 4th order bandpass designs in pro audio, im surprised, they dont expose your drivers to damage, get reasonably good efficiency, have good powerhandling, and make steep low pass filters less neccesary. they have higher GD than alot of boxer, but a BR tuned to 40hz doesnt look great either, so whats up, why dont i see more of them?
you could build these things 60wide, 50 tall and 100, put the wheels so that they roll when theyre up tall, and lay flat (for stacking) when you put em largest face down, ports on the opposite smallest face as the wheels. both 15s could be on a baffle inside firing up/down wired in phase( to help cancell nonlinearieties). one of the larger faces could be removable for driver access.
what do you guys think? should come in under 100if you live in the US.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-384
try two of those in a 4th order bandpass, sealed chanber is 170litres, vented one is 120 tuned to 70hz. i add 3b to my calculations to predict 2pi response. with 150 watts itll go a little over xmax(about 2mm over) so that might be a problem, but id tend to think it wouldnt be(2mm is pretty small, but my last xmax assumption turned out to be incorrect).
you dont see many 4th order bandpass designs in pro audio, im surprised, they dont expose your drivers to damage, get reasonably good efficiency, have good powerhandling, and make steep low pass filters less neccesary. they have higher GD than alot of boxer, but a BR tuned to 40hz doesnt look great either, so whats up, why dont i see more of them?
you could build these things 60wide, 50 tall and 100, put the wheels so that they roll when theyre up tall, and lay flat (for stacking) when you put em largest face down, ports on the opposite smallest face as the wheels. both 15s could be on a baffle inside firing up/down wired in phase( to help cancell nonlinearieties). one of the larger faces could be removable for driver access.
what do you guys think? should come in under 100if you live in the US.
jbell said:
If by 'peaky', you mean the pumped up horn loaded BW above ~100 Hz seen in many TH sims, then yes, being a very wide BW driver the BW you want to use them for is anything but optimum. Otherwise, two in series sims with Johnny-Pat's? measured specs to be nominally flat >125 dB from ~40-170 Hz/2pi/70 V/~214 L net without exceeding Xmax till ~28.5 Hz, but being a for profit venture using a proprietary technology I leave you with your conscience to figure out the details.........
WRT your FLH, it's so misaligned that you'll have to rely on the sim for a proof-of-concept and work from there.
WRT protection against 'headbangers', the time honored light bulb limiter is cheap/effective and can be set up to show when power limiting is becoming excessive and/or easy to replace if ignored.
GM
GM:
70V??
35V per 4 ohm 55-2421, really? Isn't that about 300watts into a 125watt driver? or are you referring to something else? (like the post about a 55-2421 TH quad) If so, a quad of 55-2421 doesn't fit in my budget of a completed cabinet for $100.
Since this is for church's... it's not exactly 'for profit' but yes, if I come up with anything that looks like it's infringing on Tom's IP, I'll ask for permission first. So far, that's not the case, and FLH looks like the ticket.
70V??
35V per 4 ohm 55-2421, really? Isn't that about 300watts into a 125watt driver? or are you referring to something else? (like the post about a 55-2421 TH quad) If so, a quad of 55-2421 doesn't fit in my budget of a completed cabinet for $100.
Since this is for church's... it's not exactly 'for profit' but yes, if I come up with anything that looks like it's infringing on Tom's IP, I'll ask for permission first. So far, that's not the case, and FLH looks like the ticket.
All I did was find predicted Xmax limits for transients without looking up rated power specs since most folks typically ignored them in prosound apps way back when I was helping them out. For continuous SPL, then double whatever the driver's long term rating into a nominal 8 ohms since there's two drivers and wired in series to get the benefit of doubling Le.
GM
GM
Hi jbell,
Here are some hornresp input screens for a very small dual MCM 55-2421 tapped horn without use of an inductor, and a 3:1 throat compression ratio (the generally agreed upon (?) maximum). The first one is a single box, and the second screen just has the cross-sections doubled and the speaker count adjusted to reflect two boxes.
This little speaker just seems to be designed for use in horns, and in pairs. Obviously, it would take a test box to see what this will really do, but 5/8" OSB is not that expensive.
As to "idiot proofing" loudspeakers: Good Luck.
Regards,
Here are some hornresp input screens for a very small dual MCM 55-2421 tapped horn without use of an inductor, and a 3:1 throat compression ratio (the generally agreed upon (?) maximum). The first one is a single box, and the second screen just has the cross-sections doubled and the speaker count adjusted to reflect two boxes.
This little speaker just seems to be designed for use in horns, and in pairs. Obviously, it would take a test box to see what this will really do, but 5/8" OSB is not that expensive
.As to "idiot proofing" loudspeakers: Good Luck.
Regards,
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I agree -- theft of IP is theft of IP. Intellectual property is valuable, and I would not sell anything I thought infringed on tom's IP without making the appropriate arrangements.
In my particular scenario, FLH looks more promising, than TH due to the drivers I have available to me in the price range I need, so there is no concern.
However this brings up an interesting point that's been debated many times before -- the slippery slope argument of what is truly a BLH, a TH, or a BP.. as they are variations of the same alignment. what 'really' infringes on tom's IP?
Is this a TH?
In my particular scenario, FLH looks more promising, than TH due to the drivers I have available to me in the price range I need, so there is no concern.
However this brings up an interesting point that's been debated many times before -- the slippery slope argument of what is truly a BLH, a TH, or a BP.. as they are variations of the same alignment. what 'really' infringes on tom's IP?
Is this a TH?
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![s18r_big[1].jpg](/community/data/attachments/120/120886-1c5cb1458243ef03f85c7a32de3bfef7.jpg)
Well.... The "horn path" isn´t long enough to raise acoustical resistance in the lower bass regions so this opening is more like a widening port at a "normal ported enclosure" in terms of "what it does". A real "horn effect" is only present in the midbass regions. Of course, transmission line effects are allways present, too... The transission between those types (TL, ported, horn) allways is floating (is this the correct english expression?)....
So I´d assume that for this enclosure the answer is easy to give... Put of course you have a good point here.. Make the port even longer and you get what people in Germany like to refer as a "hybrid" (of course, the name is not very good..), much like the MTL from EVoice... Is that a TH?
There really is no clear line to draw, I guess.... I stick with Ian, I didn´t want to go there either
So I´d assume that for this enclosure the answer is easy to give... Put of course you have a good point here.. Make the port even longer and you get what people in Germany like to refer as a "hybrid" (of course, the name is not very good..), much like the MTL from EVoice... Is that a TH?
There really is no clear line to draw, I guess.... I stick with Ian, I didn´t want to go there either
It can be moddelled as such. It can be implemented from the patent-picture as such. But designs like this were there long before the patent was granted, so I guess the answer must be "no".
Basically this kind of design is similar to a BR but a lower sensitivty in the <45 Hz region and a higher sensitivity in the 80 Hz+ region, like a BLH-BR hybride.
Regards Johan