DiyMobileAudio.com Car Stereo Forum banner

1 - 20 of 66 Posts

·
Registered
Joined
·
867 Posts
Discussion Starter #1 (Edited)
I just wanted to know who is using a horn or a tapped horn in their car. I guess I'm appealing to Patrick Bateman, who seems to be the most knowledgeable about this. Also Chad are you out there & Brian Steele?

If the mouth dimensions are smaller than they need to be to facilitate loading in its pass-band, these calculations are out there, you basically have a flared vent on a bandpass enclosure.

It can be HORN SHAPED, but this in no way means that it's going to act as a proper horn.
Welcome! Pro audio guy here too.

nope

2 reasons:

1. The mouth dimensions to facilitate loading at subwoofer frequencies are completely impractical.

2. A folded horn works (or any horn for that matter) as an acoustic lever, with a high pressure in a small area feeding a low pressure in a large area, this is what makes the horn function as it does. In a vehicle, as the cabin pressure increases the horn no longer acts as a horn.
I hope I don't miss quote anyone, I get the impression the Patrick thinks it can work, Chad says that basically it doesn't, and I just want to get a better idea about this.

Now I came across this PWK Horn design. Pete gave me some info to read about horns, but if I'm reading Patrick and Chad correctly, this isn't a horn .. or is it?

The new Digital Design SW 6.5 sub - YouTube



DD T/S specs suggests to me that the SW6.5 would be very suitable for a horn, however I do like going low, 30-32hz tune. How achievable is this given that (form what I understand)

1) with horns you nee to go big to be low
2) The SW6.5 FS is 59hz

Series SW6.5
Voice Coil Diameter 1.5"
Magnet Weight 80 oz
Power Handling RMS/Peak 250/600
Suspension Travel 30 mm
Nominal Impedance D4.0 Ohm
Model SW6.5
Rec Box (cubic ft) .4
Port Area (sq in) 7.5sq"
Port Length (inches) 17"
Cutout Diameter (inches) 5.63"
Mounting Depth (inches) 4.125"
FS 59.22Hz
Qts 1.041
Qes 1.187
Qms 8.417
Vas 1.369L
Sensitivity 75.69dB
Shipping Weight 9lbs
 

·
Registered
Joined
·
401 Posts
I ran a wicked one with 2 RF 8" DVC subwoofers. With a flea market amp I bought for $25 that was rated at 400watts peak I was hitting 135. With a true 800 wrms amp I was in the mid to low 140's. This was in the early 2000's so it was a little easier to hit those numbers.

If you want to run a horn, go for it but you will lose all your storage space.
 

·
Premium Member
Joined
·
11,394 Posts
There is not enough air inside a car to properly load a horn.

Technically a tapped horn is not a real horn...neither is the Decware thing.

And if you want a smaller horn, you need LARGE drivers. Smaller drivers/cone area makes for larger horns.
 

·
Premium Member
Joined
·
11,394 Posts
I mean that's a nice enclosure in the video, but with that amount of space a pair of 12s or 15s would fit in the same footprint...

And there isn't enough LSD on the planet to convince me that 1 6.5 in ANY enclosure would be louder, lower distortion, or have the bandwidth the pairs of larger speakers would have.
 

·
Registered
Joined
·
867 Posts
Discussion Starter #6
I mean that's a nice enclosure in the video, but with that amount of space a pair of 12s or 15s would fit in the same footprint...

And there isn't enough LSD on the planet to convince me that 1 6.5 in ANY enclosure would be louder, lower distortion, or have the bandwidth the pairs of larger speakers would have.
So ... is PWK the God of enclosure design then, or is he pulling the wool over people's eyes? If he's suggesting one thing and the 'Horn' Fraternity are all screaming "Its not a horn." "it doesn't work like that" etc, etc.

in Pete's defense - it could be the matter of Pete's customer already having the 6.5, and this designs was what Pete felt was best for the customer given said customers requirements.
 

·
Registered
Joined
·
2,749 Posts
I've briefly looked into PWKs designs, well contructed boxes-but I wouldn't describe many/any as "horns"-most seem to be a transmission line with a massive flared vent-however I'm in the process of building my 1st horn (well, still at the design stage) and have seen there is much variance in the discription of designs and will add that I am by no means an expert!

This is my 1st "design"-I literally worked out the space and then sketched it out, someone on another forum entered into hornresp for me (that programme confuddles the fook outa me) and modeled the response, came out surprisingly well considering I was just guessing. The diagram below shows the enclosure (not to scale and outer depth wrong). I was in Alpine UK's tech dept the other week and was discussing this design and various others-his opinion was that this was a flared transmission line and not a tapped horn:
 

Attachments

·
Registered
Joined
·
1,486 Posts
A couple of comments.

A tapped horn is a Tom danley thing. And appears to be a blend of tline and horn.

Cars are too small for standard horn designs and many of the benefits (namely more efficient coupling of the cone to the air) are already present due to the small air volume in our cars compared to rooms.

Additionally I can't think of single gain that horns would provide over bandpass enclosures in an automotive env.
 

·
Registered
Joined
·
10 Posts
I mean that's a nice enclosure in the video, but with that amount of space a pair of 12s or 15s would fit in the same footprint...

And there isn't enough LSD on the planet to convince me that 1 6.5 in ANY enclosure would be louder, lower distortion, or have the bandwidth the pairs of larger speakers would have.
I guess in pwk designs he is just using cabin gain+ bandwith limiting to get more response out of that small box..
 

·
Registered
Joined
·
2,749 Posts
A couple of comments.

A tapped horn is a Tom danley thing. And appears to be a blend of tline and horn.
The classifcation of these types of designs is one of the many things I'm yet to get my head round-hornresp will probably take longer though!

Cars are too small for standard horn designs and many of the benefits (namely more efficient coupling of the cone to the air) are already present due to the small air volume in our cars compared to rooms.
I'd presume you're not including "conventional horns" as those done by ID! PB has used horns in his car-if he chirps contra to that statement I'd be inclined to believe him. If a tapped horn is a cross between a T-line and a horn surely T-lines wouldn't really work in car? As far as I know a horn is just an "air" pump.

Additionally I can't think of single gain that horns would provide over bandpass enclosures in an automotive env.
IIRC reduced xmax and therefore increased power handling-to the thermal limit anyway. To that matter I have also seen horns being refered to as a bandpass design. Also look at what the SPL guys are doing-a lot of installs look like Danley's Matterhorn but scaled down to fit in a vehicle.
 

·
Premium Member
Joined
·
11,394 Posts
I would really suggest you guys get on a home forum like DIY Audio and learn more about tapped horns.

But what SSSnake said about not being enough air in the car is true for a real horn. A real horn is an impedance transformer. And there simply isn't enough air in a car to load the throat of a real horn.

But tapped horns are not real horns...do some reading and researching and you will discover why.
 

·
Registered
Joined
·
2,749 Posts
I would really suggest you guys get on a home forum like DIY Audio and learn more about tapped horns.

But what SSSnake said about not being enough air in the car is true for a real horn. A real horn is an impedance transformer. And there simply isn't enough air in a car to load the throat of a real horn.

But tapped horns are not real horns...do some reading and researching and you will discover why.
I'm on it already, reading all I can-however its very hard finding any definitive guide to what seperates one type of design from another!

Please explain how there's not enough air in a car to load the throat of a real horn-surely it's easier in car as there's no where for the air to go?
 

·
Registered
Joined
·
17,149 Posts
I would really suggest you guys get on a home forum like DIY Audio and learn more about tapped horns.

But what SSSnake said about not being enough air in the car is true for a real horn. A real horn is an impedance transformer. And there simply isn't enough air in a car to load the throat of a real horn.

But tapped horns are not real horns...do some reading and researching and you will discover why.
That pretty much sums it up.
 

·
Premium Member
Joined
·
11,394 Posts
The volume of air inside a car or a van isn't enough to load the throat of a horn.

There used to be a guy back in the day in the UK on some of the forums who went by the name Firestarter. He had a red VW van. At first he was messing around with scoop style horns for a pair of Stroker 15s. These enclosures were placed at the very back of the van to give them as much air volume as possible...still wasn't enough air volume in the car to load the throats. He went to a ported design and his scores jumped up pretty good over the on paper much more efficient horns.

Richard Clark has said the same thing about bass horns in a car on the Carsound forums back in the day too.
 

·
Registered
Joined
·
17,149 Posts
As said before, horns work by generating a high pressure in the throat and coupling it to a low pressure at the mouth, the cuttoff point on the horn is directly correlated to the mouth or the coupling of the existing mouth to a structure (like a Klipshorn.)

As the environment goes from modal to pressure the increase in environmental pressure at the mouth causes the high to low pressure ratio of the device to lower, as this ratio goes down it acts less and less like a horn, at a 1:1 ratio it's basically a woofer in a tiny-ass enclosure.

As quoted by me, and said by THG, it's an acoustic "lever" or an acoustic transformer, nothing more. Well, with the exception to be able to control directivity above the mouth cutoff, which is not happening in a car.
 

·
Registered
Joined
·
867 Posts
Discussion Starter #16 (Edited)
So is PWK and Bill Fitzmaurice telling us porkies?

This is what Pete told me. I don't want to get in trouble by cross linking to another forum, so here's a picture:blush:



Pete's design to me ... as a no knowing newbie, looks to be a tapped horn with one extra bend, to the normal horns I've seen. The enclosure itself is still big, but it must have some advantage somewhere. Or do we throw our hands in the air and scream: forget horns, or T-lines, lets just stick to sealed and ported for ever more.... maybe an occasional IB or iso now and again (sorry everyone its been a long day).

However isn't efficiency with low power an advantage of such enclosures. Isn't that what Patrick was getting at, or have i read wrong?

I'm on it already, reading all I can-however its very hard finding any definitive guide to what seperates one type of design from another!
Agreed! I saw one site when there explanation of the difference between a ported and T-line enclosure was wadding ... wadding. Not the 1/4 theory or anything but simply ... wadding! That's not what I've read!
 

·
Registered
Joined
·
17,149 Posts
So is PWK and Bill Fitzmaurice telling us porkies?
Just because you are famous on the internet does not mean that you understand how horns work.


FWIW I don't have many trophies, more in Pinewood Derby than car audio. But then again I don't make my living in Pinewood Derby, or car audio ;)
 

·
Registered
Joined
·
867 Posts
Discussion Starter #18
Just because you are famous on the internet does not mean that you understand how horns work.
In comparison to most of you guys I know very little. OK .. I built my first T-line speakers for my Technics tape deck and Yamaha amp 20 years ago.

As most of you might know I run fakeheadphones.com I got into car audio working for Dominos Pizza whilst i was at uni studying Drawing and Image making (Art). £65 Sony stereo and a pair of 10watt 4" Toyota Starlet speakers. Then got bitten by the bug.

However it seems the more I learn the more I realise I don't understand. So here goes for the next question. For a simpleton like me, please explain what you mean by 'Loading'? I'm the kind of person that asks if I don't know. I'd rather be laughed at, than live in ignorance.

When you say there's not enough air to 'load' the throat, what does that mean ... there's not enough air pressure or resistance???
 

·
Registered
Joined
·
17,149 Posts
I wish I was not in the middle of a big project that I have to concentrate on.

horns work by having a high pressure in the throat an a low pressure outside, everything takes the path of least resistance.... and this is a VERY simple explanation.


In free-space or on a big flare the atmospheric resistance is very low compared to the pressure in the throat. In a car, because it's closed, the cabin pressure increases, it's no longer modal, it's pressure related, you are simply adding pressure to the cabin below a certain frequency... This is either the most kickass thing ever or the biggest pain in the ass, depending how you look at it.

Problem with horns, and even vented enclosures at high SPL, which PWK designs around in his vented designs is that as the pressure increases, things change. That's the challenge, the FR of the venting will change, and with a horn, as the atmospheric pressure changes, the higher it goes, the less it acts as a horn because the pressure does not allow it to work as a horn anymore. the mouth pressure begins to equal the throat pressure. Not only that, the mouth dictates cutoff frequency and a horn that plays flat to even 40 cycles is HUGE, bigger than a standard vehicle can take. Even in free space.
 

·
Premium Member
Joined
·
11,394 Posts
I am going to attach some pictures of a conical front horn that I built for an old home stereo of mine.

Things to consider- a conical does not effectively load to the lower Fc of the horn. An exponential does a much better job at doing that, but is much more complex to build. Yes, I could have made a 2 or 3 step approximation to fit the exponential flare...but very little would have been gained other than making it much more complex to build.

This particular horn was a 3/16th sized horn meant for boundary reinforcement from 2 corners. This was as about as small as you would want to go with a real horn. You can do an 1/8th sized throat if you have them pushed into 2 corners like a Klipsch corner horn.

This horn was a midbass horn. It's Fc was 78-80 hertz.

It used a 15 in each horn.

Remember for a front horn, the larger the speaker the shorter the horn can become. And the closer you get to boundaries, the small you CAN make the horn, but bigger is better.
 

Attachments

1 - 20 of 66 Posts
Top