A Tapped Horn Experiment

[Triticum Agricolam]

+1 to what Patrick said.

In addition to the loss of efficiency from shrinking down the horn, you couldn't actually build a functioning version of that horn at 1/3 the size anyway, and for a number of reasons. It would be too small for the sub driver to physically fit in it. The compression ratio would be way too high and would probably destroy the sub, and your air velocity inside the horn would be much too high.

This is the trick to HornResp, it very easy to model something that can't be physically built, you just need to be aware that this situation can arise.

[Mike Gann]

Heh Vas seems to determine enclosure size for all types of boxes then, and the peeky response of a stiff suspension is actually something you'll want in a burp comp setup. What is an example of a "high Vas" number for horns, or is it high compared to the motor force you mean? I have some old JL woofers laying around that I picked up for $5 each and require a large enclosure let me pull up some parameters for you. http://mediacdn.jlaudio.com/media/mfg/9013/media_document/live_1/10_12_15W0_MAN.pdf?1317790098

They don't have the BL listed anywhere, but I have the 10w0-4 and 12w0-8. I need to find a use for them, was thinking I might just get rid of them unless I can mess around with making a box. They're suppose to be in a sealed enclosure though, I've always been under the impression that ported speakers were better for horns.

Edit: I also have a Sundown Sa-8v2 if that's a better choice, I was planning to build my first bandpass with it though. The one I have designed for it in WinISD should gain 4-8db in the range over the other boxes I made for it.

Although the response curve and the excursion is identical, the Mayhem is sucking up way more power than the E10. The Mayhem dips down to 1.3 ohms; the E10 dips down to 4 ohm. So the Mayhem is getting three times as much power as the E10. There's no free lunch; you can reduce the box size by two thirds, but you'll have to ratchet up the power by three times to make up for it.

If any of this doesn't make sense, let me know.

Still learning here but wouldnt the lower ohms mean that the amp can supply more power to it? Or does it mean low excursion and more power would drive it higher?

[Jessica]

Maybe I'm looking at it wrong but when you shrink the horn doesn't the output suffer? You took the big old beefy Mayhem and the output is pretty much the same a the E10.

That's exactly right!

You can't break Hoffman's Iron Law. The Mayhem will work in a box that's one third the size of the E10, but it needs three times as much power to get to the same SPL.

That might sound like a shitty deal, until you notice that the Mayhem has more excursion. So if you can afford a really REALLY big amp, you can get louder than the E10 using a box that's much MUCH smaller.

I think that's one of the reasons these exotic enclosures are compelling if you have a lot of money to burn; you can squeeze an extra 5-10dB out of a driver IF you can afford to buy a ridiculously large amp.

Keep in mind, that last few decibels is going to cost a LOT OF MONEY. You could easily spend an extra $500-$1000 to get it. (Due to the higher cost of drivers with very very low VAS, and the higher cost of multi-kilowatt amps.)

how much power we talking? i mean the e10 is like 400 watts rms and the mayhem is 2500. soooo...

[Patrick Bateman]

Maybe I'm looking at it wrong but when you shrink the horn doesn't the output suffer? You took the big old beefy Mayhem and the output is pretty much the same a the E10.

That's exactly right!

You can't break Hoffman's Iron Law. The Mayhem will work in a box that's one third the size of the E10, but it needs three times as much power to get to the same SPL.

That might sound like a shitty deal, until you notice that the Mayhem has more excursion. So if you can afford a really REALLY big amp, you can get louder than the E10 using a box that's much MUCH smaller.

I think that's one of the reasons these exotic enclosures are compelling if you have a lot of money to burn; you can squeeze an extra 5-10dB out of a driver IF you can afford to buy a ridiculously large amp.

Keep in mind, that last few decibels is going to cost a LOT OF MONEY. You could easily spend an extra $500-$1000 to get it. (Due to the higher cost of drivers with very very low VAS, and the higher cost of multi-kilowatt amps.)

how much power we talking? i mean the e10 is like 400 watts rms and the mayhem is 2500. soooo...

TA's box for his Sundown E10 was getting a bit over 500 watts into 4ohms.

I shrunk his box down by a third, and modeled it with the AA Mayhem 10". I didn't change the pathelength or the folds or anything; all I changed was the volume, and I reduced it by 2/3rds.

In order for me to get the same SPL number, I had to triple the power. So I modeled mine with 1500 watts into 1.33 ohms. Not coincidentally, 1500 watts into 1.33 ohms is also 500 watts into 4ohms!

So you can see that the Mayhem 10" would be a good option if you had an amp that was stable into very very low loads.

Also, due to the higher power handling and excursion of the Mayhem 10", it's not "maxed out" with 1500 watts; it still has headroom, you could go all the way to 2500 watts or even beyond.

[Patrick Bateman]

Heh Vas seems to determine enclosure size for all types of boxes then, and the peeky response of a stiff suspension is actually something you'll want in a burp comp setup. What is an example of a "high Vas" number for horns, or is it high compared to the motor force you mean? I have some old JL woofers laying around that I picked up for $5 each and require a large enclosure let me pull up some parameters for you. http://mediacdn.jlaudio.com/media/mfg/9013/media_document/live_1/10_12_15W0_MAN.pdf?1317790098

They don't have the BL listed anywhere, but I have the 10w0-4 and 12w0-8. I need to find a use for them, was thinking I might just get rid of them unless I can mess around with making a box. They're suppose to be in a sealed enclosure though, I've always been under the impression that ported speakers were better for horns.

I think I have the same woofer. I bought two of them in a box from someone on Craigslist. Paid about $50. For the money they're killer.

I put mine in a bandpass. They were actually the woofer that was in my car before the horn that I wound up building instead. The main reason that I went with a horn was because the JLs will work in a tapped horn, but the F3 is too slow. This is one of the weird things about tapped horns and back loaded horns; the FS of the driver is going to have a huge influence on the F3 of the finished box. Front loaded horns and single reflex bandpass don't suffer from this problem; with a FLH or a single reflex bandpass you can nearly attain any F3 that you want; taken to an extreme you could probably push a 4" down to 20hz if you were so inclined. (The efficiency would be very low.)

TLDR: The JL would work nicely in a FLH or a single reflex bandpass. If you opt for a tapped horn or a vented box, it will work, but the F3 might be lower than you'd like. (Lowering the F3 lowers the efficiency, so a F3 that's too low will inflict an efficiency penalty.)

Edit: I also have a Sundown Sa-8v2 if that's a better choice, I was planning to build my first bandpass with it though. The one I have designed for it in WinISD should gain 4-8db in the range over the other boxes I made for it.

SA-8 would be a good candidate for a vented box, a tapped horn, a single or dual reflex bandpass, or a back loaded horn. Due to the relatively high FS, I don't think it would be a good candidate for a FLH.

Although the response curve and the excursion is identical, the Mayhem is sucking up way more power than the E10. The Mayhem dips down to 1.3 ohms; the E10 dips down to 4 ohm. So the Mayhem is getting three times as much power as the E10. There's no free lunch; you can reduce the box size by two thirds, but you'll have to ratchet up the power by three times to make up for it.

If any of this doesn't make sense, let me know.

Still learning here but wouldnt the lower ohms mean that the amp can supply more power to it? Or does it mean low excursion and more power would drive it higher?

Yes, the lower ohms will draw more power from the amp, as long as the amp can handle it.

[Mike Gann]

Yes, the lower ohms will draw more power from the amp, as long as the amp can handle it.

Oh I misunderstood what you meant then. The mayhem is getting 3 times the power anyway, I thought you meant that you'll need to increase the amp power.

[Mike Gann]

Random thought, since the upper frequencies are pretty useless in these designs could a ported horn filter them out and maybe boost some of the lower ones some? Or maybe if box size isnt a thing would tuning the ported side really low possibly tame a peeky speaker that has too much motor force? I can't easily find a frequency response graph for a ported horn. I guess this would make it a FLH though.. did we already say that the high motor force drivers are good for front loaded?

[Triticum Agricolam]

I'm not sure what you mean by "ported horn". Pretty much all subwoofer horn are a type of bandpass box. A front loaded horn is a 4th order bandpass box and a tapped horn is a 6th order.

[Mike Gann]

Like more loaded though, the horn would handle under the tuning frequency of the ported side when it's unloading is my guess.

[Broke_Audio_Addict]

That seems like a 6th order to me.