Designing and folding bass horns the easy way

[diy speaker guy]

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[diy speaker guy]

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[Pete Schumacher ®]

What kind of sensitivity boost are you getting compared to a vented enclosure?

And why is the chamber behind the woofer no longer sealed, and the horn, closed, in the picture above?

[isaeagle4031]

Pete I am going to assume the that is an access panel under the woof and maybe the mouth had not been cut out yet?

DIY guy, I am very interested in this. I've designed a couple of horns, but am always looking for something to make folding the lines easier.

[diy speaker guy]

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[diy speaker guy]

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[matt996]

Very interesting, looking forward to sequal as well!

[fastbike1]

Part 1 helps a lot. The photo and diagrams make a big difference.

[dcgold2000]

Subscribed. Please continue.

[biscuitbarrell]

Really interesting stuff. The more explanation the better! Keep it coming, along with any tips for appropriate drivers for this box type, etc...

[diy speaker guy]

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[mzisserson]

Why not just seal the box, throw a couple of good 8's, or 10's in there and call it a day.

... My #1 gripe with horns, you can get 90% of the performance out of a much smaller enclosure.

Sorry to troll, They have their purpose too, but I am not understanding the application of this...

[diy speaker guy]

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[mwmkravchenko]

My #1 gripe with horns, you can get 90% of the performance out of a much smaller enclosure.

That is so far from the truth you are calling black white and white black.

A horn done properly will outperform a vented box. I did a demonstration a while back using four different box types and all the same drivers. The horns won by quite a margin. The horn loaded configuration had dynamics up the ying yang. The vented box held it's own to a degree but not even close when put up against the lower coloration and greater dynamic range of the horn loaded system.

A well designed horn has a 10 db advantage over the same driver in a vented box. That is twice as loud acoustically and 6 times as efficient electrically.

There is a definite trade off. Larger box, lower distortion in terms of tenths of percent compared to tens of a percent with the same driver in a vented enclosure. Horns sound much more life like. But they are larger. Can't win there.

Mark

[mzisserson]

You can't get anywhere near 90% of the performance out of a much smaller enclosure, at least not with the same budget (including the cost of drivers, wood and amplification). Did you see the sensitivity comparison a few posts up comparing this 96 liter horn to a 13 liter plus port volume (let's call it 20 liter) ported box? The horn's got 7 db over the ported box on the low end and it would have much more than that on the high end if I didn't choke the rising response with a contracting mouth section.

Did you see my subjective comments about this horn easily outperforming 2 of the same drivers in a dual ported box? I didn't have another ported box to compare, but I'm confident that this horn could go head to head with 3 of the same drivers in ported boxes without embarrassing itself. At 20 liters each, that's 60 liters of ported boxes.

The horn doesn't use nearly as much power (compared to 3 ported boxes) for ~ the same output. The ported boxes will suffer from much more power compression as well as port compression, which the horn is immune to due to the large mouth, so the horn has advantages you can't even see in these graphs.

You could get the same output from a larger driver in a slightly smaller box but that larger driver costs more money, the larger amp costs more money and the savings on box material and space would be minimal.

I guess if you can't see the extra sensitivity in the graphs, the much smaller power requirements, the hidden power and port compression issue and don't trust my subjective impression that this horn stomps all over 2 of the same drivers in ported boxes (and could probably run neck and neck with 3), then there's nothing I can say except find a good horn and audition it.

I'll concede to the fact that 4 of the same drivers in ported boxes (80 liters) would easily beat the horn with 16 liters to spare, but they would require at least 6x more power, and of course the added expense of 3 extra drivers. I'll also concede to the fact that there's no real need for horns at all anymore (as there was decades ago), until your power requirements get out of hand and you start tripping breakers.

But that doesn't make horns an invalid choice, e haven't even mentioned the dramatically lower distortion yet. Sealed and ported boxes don't even sound the same as horns due to gross distortion products.

Horns are a niche area, I'll give you that too. But studying horns is a great way to learn about acoustics in general, 1/4 waves and 1/4 wave design and even gives insight into how simpler boxes work.

I am still having trouble seeing it as two 10" woofers in with a sealed, or vented 96l enclosure would have the same, perhaps more output with the same, or less power requirement.

I am still trying to see the advantage to its size vs. performance. I admit, I know very little about horns, I have built a pair of BF's Tuba 24's in the past and they had great output, but looking at modern driver performance I could have used a 15 in the same "size" enclosure, with all the eq-ing and LP filtering and likely had more output. At least from what I modeled. My horn journey ended there, and I can see where they are very important when using a full-range driver, but I feel kind of dumb when so many hail their performance and I just cannot seem to wrap my head around them.

[diy speaker guy]

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[biscuitbarrell]

"Like any other enclosure, low qts and low vas drivers will generally yield smaller horns, but then again horns are incredibly flexible themselves depending on how smooth you want the response and how much acoustic gain you want to get out of it. Low q drivers generally have more gain bandwidth, but for a bass horn that's probably not too important. Usually fs an octave or so above the horn's tuning will work well but that's not a hard rule at all. Large, weak cones and high compression ratios don't mix well, it's possible to crumple and/or completely shred the cone to pieces. Other than that you have to simulate and see what you get."

Thanks for this reply. You offer alot of info in a little space; great for we that are curious and uninformed on this kind of build. Kudos!

[mdocod]

diy speaker guy,

Trust me, you'll have quite an audience interested in the methods you are sharing for box design. Keep up the edits and finish it out if you have the time/ambition. It will be a great resource for a great many people IMO.

Regarding driver selection, since the topic has been brought up, In my limited tinkerings with hornresp, it seems to me that highly damped (low Qts, like in that 0.2 ballpark) drivers, tend not to have as much opportunity for efficiency gain in horns as more relaxed but still well controlled drivers (0.35-0.5 Qts). Does this sound right in your experience or am I doing something wrong in simulation?

Regards,
Eric

[diy speaker guy]

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[mzisserson]

A couple of good 10" drivers in the same size box would easily beat this horn, but it would have to be ported, not sealed. Even a single high excursion 10 inch sub could give this horn a run but it would require more power.

BUT... I paid $25 (+shipping and taxes) for the driver and $30 for the sheet of wood. How many high excursion 10 inch drivers are out there for $25?

(You could argue that the W6-1139 costs a lot of money now, but the 8 inch MCM woofer with 8mm excursion is close to a drop in replacement - besides the obvious cone area difference - according to the published specs, and it's frequently on sale for $25.)

Bang for the buck, they are hard to beat. THAT I can clearly see. The price hikes really killed us. Certinly keep up the work, I was just trying to understand where this all sits from a praticality standpoint.

I love that 8" MCM woofer FWIW. Thanks for the info, may not be my cup of tea, but following your thread has been very informative.