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View Full Version : Quarter Wave Rear Loading a Horn, Who's Tried It?



sexiewasd
06-02-2012, 09:03 PM
Well, I have so I know what it sounds like in my application, but I want to know if anyone else has tried it. I did some research before giving up and just going ahead with it anyways for the heck of it. It would be awesome if I could find out more about it. Due to the space I had available it turned into a pure SPL setup, but I still think it could work well in a SQ project as well (in a larger vehicle).

Here's what I mean by Quarter Wave into a horn, just so we are on the same page.

http://i297.photobucket.com/albums/mm229/sexiewasd/sub.png

Moble Enclosurs
06-02-2012, 11:58 PM
You can utilize quarter wave resonance in any design technically. If you think about it, everything has a quarter wave resonance anyhow...just at their own frequencies. The whole purpose of quarter wave is to be utilized with the idea of corner space loading rather than just inner design work. The application of quarter wave in the actual design work is based from the environmental resonances than a tuning factor, just for thought. SO, if you have a small room and still want to get some great low/very low extension, then quarter wave can be used to do that as harmonics of a wave still resonate to a point above and below the actual full wave resonance in any room or space, so in the sub frequency range of audibility, we can hit one of those resonances from even a note that is 4x the spacing in the frequency response passband.
So, technically, you use quarterwave in all designs, just with/without the knowledge of it making the difference of knowing/not knowing the control you have over the rooms natural response curve. Since we are in a vehicle platform, we ALWAYS have a quarter wave design in use at all times of some full wave frequency that is too large to fit the volume of the vehicle with full efficiency.
Hope that makes sense.

Exist_ential
06-03-2012, 01:53 AM
^^^not even a little HAHA

sexiewasd
06-03-2012, 06:29 AM
No that does make sense to me, I've been trying to understand the topic. It's very interesting and I've got some really really good results paying attention to quarter wave design. In my application the horn mouth is placed behind the drivers seat five feet from the windshield and the box creates a near wall. I'm running a SAZ1500D to two tens at 2ohms on the stock electrical in a 96 Camry wagon. I don't know yet how much power it's actually seeing, but it's not much as my lights don't dim at all, as opposed to when I was running one ten in a sealed box at 1ohm they dimmed far too much (sorry my multimeter is broken), but this is easily the loudest setup I've run. It actually hurts you. I'm really hoping that I can find someone in my area with a Termlab so I can get a response chart. There is an absolutely massive and steep peak at 58hz.

phemps
06-03-2012, 07:21 AM
You can utilize quarter wave resonance in any design technically. If you think about it, everything has a quarter wave resonance anyhow...just at their own frequencies. The whole purpose of quarter wave is to be utilized with the idea of corner space loading rather than just inner design work. The application of quarter wave in the actual design work is based from the environmental resonances than a tuning factor, just for thought. SO, if you have a small room and still want to get some great low/very low extension, then quarter wave can be used to do that as harmonics of a wave still resonate to a point above and below the actual full wave resonance in any room or space, so in the sub frequency range of audibility, we can hit one of those resonances from even a note that is 4x the spacing in the frequency response passband.
So, technically, you use quarterwave in all designs, just with/without the knowledge of it making the difference of knowing/not knowing the control you have over the rooms natural response curve. Since we are in a vehicle platform, we ALWAYS have a quarter wave design in use at all times of some full wave frequency that is too large to fit the volume of the vehicle with full efficiency.
Hope that makes sense.

I wish i could sit down and just be taught everything this guys knows, i would come in handy with enclosure design

hispls
06-03-2012, 08:30 AM
No that does make sense to me, I've been trying to understand the topic. It's very interesting and I've got some really really good results paying attention to quarter wave design. In my application the horn mouth is placed behind the drivers seat five feet from the windshield and the box creates a near wall. I'm running a SAZ1500D to two tens at 2ohms on the stock electrical in a 96 Camry wagon. I don't know yet how much power it's actually seeing, but it's not much as my lights don't dim at all, as opposed to when I was running one ten in a sealed box at 1ohm they dimmed far too much (sorry my multimeter is broken), but this is easily the loudest setup I've run. It actually hurts you. I'm really hoping that I can find someone in my area with a Termlab so I can get a response chart. There is an absolutely massive and steep peak at 58hz.

What part of Maine are you in? Can you make the Sanford show next weekend? Any pics of this box?

Looks like a true horn at least....most ppl here think a large flared port = horn.

From what I've gathered 1/4 wave (t-line) serves a whole different purpose than horn loading. What is your purpose of trying to do both at once? I've been very interested to try to pull off a true horn, but never got motivated enough to invest the wood, space, and time.

Moble Enclosurs
06-03-2012, 09:07 AM
No that does make sense to me, I've been trying to understand the topic. It's very interesting and I've got some really really good results paying attention to quarter wave design. In my application the horn mouth is placed behind the drivers seat five feet from the windshield and the box creates a near wall. I'm running a SAZ1500D to two tens at 2ohms on the stock electrical in a 96 Camry wagon. I don't know yet how much power it's actually seeing, but it's not much as my lights don't dim at all, as opposed to when I was running one ten in a sealed box at 1ohm they dimmed far too much (sorry my multimeter is broken), but this is easily the loudest setup I've run. It actually hurts you. I'm really hoping that I can find someone in my area with a Termlab so I can get a response chart. There is an absolutely massive and steep peak at 58hz.


Yea, the good news about quarter wave is it allows you to "load" the output more efficiently so you get less amplifier resistance in the end at certain passbands. Great concept for anyone to look into. Thats kewl that you like it as much as you do with the output and all :D Very editing to hear you got good results! The peak you mentioned may not have much to do with the box if it is coupled to the vehicle as part of the line length. IDK without looking into it, but it does seem very resonant like by what you are saying. What it the design tuned to and what are your vehicle dims, if you don't mind me asking?

Moble Enclosurs
06-03-2012, 09:16 AM
What part of Maine are you in? Can you make the Sanford show next weekend? Any pics of this box?

Looks like a true horn at least....most ppl here think a large flared port = horn.

From what I've gathered 1/4 wave (t-line) serves a whole different purpose than horn loading. What is your purpose of trying to do both at once? I've been very interested to try to pull off a true horn, but never got motivated enough to invest the wood, space, and time.

HAHA very true my friend! Even a 6th can utilize a flare, but it doesn't make it a bandpass "horn" lol. A true BPH is more so a TH if anything. Those are the only real horns in car audio in my eyes due to the need for surface area cutoff in all other designs being too large to fit.

I can do true horns all day long, but in vehicle loading, they do have higher efficiency than standard flares and BRs, BUT the output capability is limited almost ALWAYS. The main gained part of using horn effects in the vehicle is for a breeder range of high output capabilities, rather than one note wonders or less than 90dB 1w/1m output designs.

And yes, quarter wave is MUCH different than horn design. The two almost have nothing in common at all. BUT they do work well together if you DO in fact calculate the environment with the entire design. Without the room as a factor, neither are very effective in getting the most out of it.

Many people get lucky in this respect and get a few extra Hz spacing in their response, and feel they are performing better than a standard BR, but in fact it only does wonders mainly to the electrical at that point. To keep design simple for ANYONE, and I have actually seen a few designers in the past get away with this (kinda sad in respect to professionalism), is you can take a quarter wave@33Hz and get ANY design to perform very well in a vehicle of any size..........not optimal always, but good enough for most to notice a difference from a prefab. I am writing a blog about that also and why that is the case, not for quarter wave, but the 30-35Hz tuning effect. Gonna be very interesting if I can finish the slot vs aero blog first lol.

In order to get a true horn effect form any design, you have to account for LF cutoff at the lines surface area of the mouth. That is the key to getting the best coupling possible, and by doing that, you smooth output. Even a DD sub can get a flat response in a horn if it is done right lol.

sexiewasd
06-03-2012, 04:07 PM
What part of Maine are you in? Can you make the Sanford show next weekend? Any pics of this box?

Looks like a true horn at least....most ppl here think a large flared port = horn.

From what I've gathered 1/4 wave (t-line) serves a whole different purpose than horn loading. What is your purpose of trying to do both at once? I've been very interested to try to pull off a true horn, but never got motivated enough to invest the wood, space, and time.

When is the show? I didn't know there was one this weekend. I only know for sure that I've probably got Saturday off from work, but I've got a friend who help me with the box who would defiantly be up to making the trip. I'm up in Bangor, so it's a bit of a drive.

The purpose was really just to give me something to do for fun. I really didn't put a whole lot of effort into the design, I didn't even model it in hornresp. I just went by some "Rules of Thumb" that I came a crossed. I predicted that it would work as a pretty decent QW line and the "horn" would just work as a loading wall like a hatch would, but when i tested it I was really surprised at the 58hz peak which was actually where I had the horn tuned, and the amount of air it moves at the mouth. I really didn't expect it to work as a horn at all, but that was kind of the point in trying it, just to find out what would happen. I already had the subs and amp, and the car is a beater that I don't plan on keeping long.

I'll get a few pics up, but I've only got my iPod, and it's rainy out today.

hispls
06-03-2012, 04:24 PM
it's rainy out today.

Thats an understatement!

Show is next weekend, check newenglandspl.com Sanford is practically neighbors to you in Maine, under 100 miles. You won't see anything closer than the Sanford shows AFAIK.

Anyway, I'll be there and can lend a meter if you want to do more than just 30 seconds on one. Sort of interested to see how that does.

sexiewasd
06-03-2012, 04:55 PM
http://i297.photobucket.com/albums/mm229/sexiewasd/2b645a2b.jpg

http://i297.photobucket.com/albums/mm229/sexiewasd/02ea2074.jpg

http://i297.photobucket.com/albums/mm229/sexiewasd/4c3ae39f.jpg

http://i297.photobucket.com/albums/mm229/sexiewasd/10ff8663.jpg

http://i297.photobucket.com/albums/mm229/sexiewasd/fca6351e.jpg

http://i297.photobucket.com/albums/mm229/sexiewasd/bbffeeab.jpg

http://i297.photobucket.com/albums/mm229/sexiewasd/1f83ccfc.jpg

sexiewasd
06-03-2012, 04:59 PM
Sweet, the shows the 9th, Saturday, time to make some plans.

hispls
06-03-2012, 05:17 PM
LMFAO. That is why people don't use true horns in a car!!! Freaking huge for a pair of 10's. I have high expectations though.

sexiewasd
06-03-2012, 05:47 PM
For it's size, maybe you won't be impressed, but for a pair of SQ 10's on less than 800watts, it's pretty impressive.

wenn_du_weinst
06-03-2012, 06:01 PM
I'm all for trying stuff out but I wouldn't be running that in my car lol.

hispls
06-03-2012, 06:03 PM
Have you tried firing it to the rear?

Kangaroux
06-03-2012, 06:10 PM
Well, I have so I know what it sounds like in my application, but I want to know if anyone else has tried it. I did some research before giving up and just going ahead with it anyways for the heck of it. It would be awesome if I could find out more about it. Due to the space I had available it turned into a pure SPL setup, but I still think it could work well in a SQ project as well (in a larger vehicle).

Here's what I mean by Quarter Wave into a horn, just so we are on the same page.

http://i297.photobucket.com/albums/mm229/sexiewasd/sub.png

+10 for using the hammer editor to make boxes lol

sexiewasd
06-03-2012, 06:28 PM
lmao, I tried to cut most of hammer out of the pic so nobody would notice. It's the strong grid system that makes it easy, I just build everything in hammer where 4 units = 1 inch so I've got 1/4" 1/2" and 3/4" measurements.

I've not tried firing it backwards, I would really like to but it weighs over 400lb.

It's not staying in there long, it's way too hard backing up with the tiny side mirrors.

sexiewasd
06-07-2012, 10:21 AM
Alright so I've had it in for a few days and I think that now I've got a pretty good understanding of how it's working as a design.

The transmission line gives it some pretty good low end extension, down to 20hz, although it starts it's rolloff at 32hz it's a really gradual slope. At around 50hz it starts loading the horn and peaks at 58hz, and doesn't really go back down at all from there on up. I think that a with a tapped horn you would get a much smoother response curve, and at 14' long it would only be a little bit larger, with more low end output.

One of the drivers was new and had never seen power, it's broken in fairly well now. It's lost some of it's output higher up, but sounds much smoother and would make a good daily setup if it were not so huge. It's also much louder with the windows down. I don't think that there is enough airspace in the car to load the horn properly with the windows up. I think that with the space available for SPL it's a better approach to fit as much cone and power as you can into a ported wall rather than to use a horn, except maybe for drive-by's windows down. For a daily setup I think that the t-line is an excellent choice if you've got the space. It could easily be designed to fit in only the third row seat area. I'm pretty much sold on the t-line, it's doesn't have near the output of the horn, but is about the same as a similarly tuned ported box, except it has some really tight punch to it like a sealed box does.

It's still impressive how much output you can get from only two tens on low power if you have the space.

quackhead
06-07-2012, 03:51 PM
lol...im glad to see this done...I've been wanting to TH load one of those freaky little saz 8's for awhile...it just doesn't want to model out for me too well. I bet your set up would sound pretty good as a living room table...but 400 lbs of unbound hell in a car wreck.