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View Full Version : adv/disadv of hornloading a standard dome tweeter



thadman
12-17-2006, 12:48 AM
I was wondering if it was practical to hornload a standard dome tweeter to work more efficiently and control directivity down to about 1khz for a super low crossover (maybe 1.2khz?) with low distortion.

What are the advantages to hornloading a standard dome tweeter (such as Peerless HDS/Seas 27TBFCG/Usher 9950-20, <$180/pair tweeters)?

Disadvantages? Effects on Sound Quality? Does it destroy the transcient properties of the tweeter (ex. stores energy)?

Is it practical?

Where would I begin to design such a horn? How large would it have to be?

azbass
12-17-2006, 12:50 AM
in short, it probably wont work like you think...

thadman
12-17-2006, 12:58 AM
lol that doesnt help me out

Im trying to learn as much as I can about horns and weigh the tradeoffs myself

azbass
12-17-2006, 01:02 AM
the horn is probably going to be large, and hard to place in teh car. it will probably mess with the dispersion pattern the tweeter has. and probably other things.

Bolognablake
12-17-2006, 01:04 AM
the horn is probably going to be large, and hard to place in teh car. it will probably mess with the dispersion pattern the tweeter has. and probably other things.

Those other things will get you every time.

azbass
12-17-2006, 01:06 AM
its late, i know

thadman
12-17-2006, 01:11 AM
Man...im really sorry I forget to mention this in every one of my threads. It is indeed late:D

I am using a Behringer DCX2496 crossover and am limited to 3-way operation from that unit. In addition to this, I am using the lowpass on the sub amplifier to cross over the subwoofer.

The horn is for a *home* setup...thats why I have it in the home audio/video section. I'd like to make the best of my situation and my budget and realize enclosure design/optimization plays a rather dramatic role compared to actual driver use.

With that being said, lets get back on topic.

azbass
12-17-2006, 01:13 AM
im in the wrong section. :fyi:

thylantyr
12-17-2006, 01:11 PM
Old school Klipsch horn loaded a simple dome tweeter. Who knows, they probably do the same thing today. But a compression driver if you take it apart, has a voice coil much like a dome tweeter so you might as well just get a compression driver
from a good vendor and buy the appropriate horn lense that suites your needs
and low frequency response. EV, JBL, Radian, TAD, etc., high end brands.

My friend's ancient Klipsch system, he blew the tweeters and I just bought some
$20 dome tweeters and mechanically attached them to the horn lense as a quick
and cheap fix, it worked fine, he was happy as a hog.

Peerless makes a dome horn tweeter. They have two version of the tweeter,
the only different is the plastic attachment, one is regular, the other is a small
horn.
http://www.speakerbits.com/net/catalogs/images/thumbnails/PD026E.gif

Compression driver
http://www.loudspeakersplus.com/images/SND44-RD.jpg

Horn anything will have it's own unique sonic personality and you have to
audition horns to see if you like the sound. There is no other way to understand
it's behavior unless you sampled them. If you were to horn load an ordinary
dome tweeter with a small lense, frequency response will be peaky at some
frequency and SPL rises, sound quality drops. If you EQ the peak, then you
lose your SPL rise and you have a tweeter that isn't doing anything productive
vs. the standard one.

If you want lower frequency response, the horn lense gets bigger as the frequency drops.

You said you didn't want a loudspeaker with high SPL, but you want it to
operate down to 1khz - 1.2khz ? Question is ... why ? Have you identified this
as a must have design goal ? If so, you are crippling your tweeter choices and
only a few are candidates.

You will also mess with dispersion as horns are more directional. I like horns,
I have some huge EV compression drivers and HP640 horns that crank SPL
with clean sound a few blocks away, but I don't want them in an ordinary home,
theater - ok ...

That's why I collect those crazy pro planars. They satisfy alot of areas.

1. They have high SPL, not quite as high as a horn but it's much higher than any dome can produce.

2. They are flat down to 1.6khz, you can take the crossover lower if you really
wanted.

3. Waveguide option to boost the midband frequencies, boost sensitivity to 107dB. This is only good in concert application, home or cinema the waveguide is
not needed.

4. Robust driver - You can easily blow a dome or pure ribbon tweeter, but the
planars take a beating. Even the cheap $25 PT2 can handle some torture.

5. Audiophile SQ. These planar will sound as good as any high end dome tweeter
but not compress and distort like a dome will at higher SPL.

I can drive this tweeter at 1.2khz easy and get quality sound, but overal it
doesn't sound good as you are asking your tweeter to do midrange duty,
let your midrange driver do the midrange frequency. Realistically, 1.7khz
with a steep slope, 4th or 8th order is the lowest you want to drive any
tweeter in a normal 2 or 3 way loudspeaker design, any lower and you will
have bad sound with raunchy midband. If you don't need high SPL, then do look
at horns.

thadman
12-17-2006, 01:19 PM
I'd optimally like a 1.4khz crossover on the tweeter and a 1.2khz crossover on the mid.

That doesnt really matter though right now, at this point im really only looking for information on horns. I'd like the benefits of using a horn...and the disadvantages of using them so I can weigh the benefits myself. Even though these are going to be open baffle speakers, the tweeter and midrange (down to 600hz) will have dispersion patterns equivalent to conventional boxed speakers, so why not use a horn? From my understanding horns control directivity (good for low crossovers to mate w/ mids), increase sensitivity, and lower distortion. I've heard they store energy, but am not quite sure why. I'd like some objective information regarding them.

I can see some benefits and disadvantages of a horn after equalizing. If you create some peaks in the response and you EQ them out, then the driver effectively works less in that passband (less excursion necessary) and voila less distortion:D Is this a double edged sword though? If a horn creates peaks in the frequency response, even if EQ'd them out could I excite them by playing a 3rd harmonic of that said frequency? For example, if the horn created a 10dB peak at 9khz would I have a 10dB 3rd harmonic peak at 3khz and a 10dB 2nd harmonic peak at 4.5khz?

thadman
12-17-2006, 01:25 PM
1.2-1.4khz crossover for a horn-loaded design doesnt sound too far-fetched to me. If it raises overall efficiency by 6dB, then the diaphragm is effectively moving the same distance at 1.2khz as it would at 2.4khz. I gained an additional octave of response, and maintained low distortion but no gain in SPL as I would have to EQ the upper frequencies down.

I dont understand why this couldnt benefit me, even if I dont extend to the lowest octave and consume the maximum SPL benefits I am still effectively operating the driver at lower distortion. This is why I would like some objective information on benefits/disadvantages of using them...so I can weigh it for myself.

thylantyr
12-17-2006, 02:15 PM
If you listened to any horn tweeter you will realize that it's unique sonic personality dominates and any technical rewards might not swamped out
by it's personality.

There are many schools of thought on how to make a loudspeaker. You need
to verify by audition on what type of sound you like and try to get there
by doing experiments, discard the audio stereotypes. When you build something
for yourself vs. mass market, the rules can be different. I would design a speaker totally different if it's for me vs. mass market. If you make this for yourself, then you do a few experiments to understand what really works for you.

You need to identify some issues.

1. What types of tweeter technology do I like? domes, planars, ribbons, horns, etc. ?

2. What crossover frequencies do each work best in that I like ?

3. Does the design need a midrange or midwoofer? Will the midrange play
up to the tweeter ?

4. Woofers? sealed box, IB, ported, etc.

5. 2 way, 3 way, horn, line source, etc.

You have to hook this up to verify, you can't look at data only. My approach is
a tweeter down methodology, the majority of people seem to take a woofer up methodology. The tweeter is going to define your SQ assuming you like music
and not just bass rattling the house. Find the tweeter that will satisfy you
then it becomes easier to find a matching midrange, then find a woofer, etc.
Some folks will look at woofers and work up, they might pick a midrange and
then find it hard to find a matching tweeter because for some reason, they
fall in love with the midrange driver even if it's a brand name crippled design, unbeknownst to them. For instance, I found my killer tweeter. The midrange
chosen were based on listening tests and synergy to my tweeter chosen. Big
names like Focal, Seas, etc., didn't pass my audition as SQ of esoteric cone materials is vastly over-rated.

The driver audition tells you the story.

Unity Horn
http://home.pacbell.net/lordpk/lambda/circle.jpg
Of all horn designs, this one is interesting. The midrange drivers are mounted
on the horn, usually four drivers. The HF driver is located at the normal position.

http://home.pacbell.net/lordpk/lambda/hornFinish.JPG

I believe this is a unity design where the horn is flanked by two 15" woofer
above and below the horn.
http://home.pacbell.net/lordpk/lambda/majestic%20ladies.JPG

Another.
http://home.pacbell.net/lordpk/lambda/pspkr.jpg
http://home.pacbell.net/lordpk/lambda/sideViewTwo.JPG

The Lambda TD series of woofer was designed to mate with the unity,
to offer higher bandwidth clean sound, a unique woofer design.

The unity is patented by Tom Danley.
http://www.danleysoundlabs.com/

That unity horn was a DIY project from Lambda acoustics before they closed shop.
The unity was licensed, later not renewed, hence unsweet for lambda.

Yorkville's licensed unity design.
http://www.yorkville.com/products.asp?type=29&cat=38

If you want an interesting horn system, then I would look into this,
but it's very hard to DIY as the design has gremlins that need a special
crossover to filter frequency anomolies. Many have tried to make their
own unity, you can google it or check DIYaudio.com

Nick's Unity horn design.
http://home.pacbell.net/lordpk/lambda/both%20cabs.JPG

Unity horn + Lambda Apollo woofer w/passive radiator.

thylantyr
12-17-2006, 06:36 PM
Post #2
cmon guys...39 views and no responses.

DIYaudio appears to be the best forum from the naked eye, but it really isn't
the best. It's just another forum that attracts a certain type of individual and
people talk about audio. The only thing good is that Nelson Pass has his own
forum section and he contributes, else you have to filter out 99% of the BS
to get 1% of the good stuff.

Look at the DCX2496 talk over there. People are doing crazy crazy crazy mods
to it... as if they can hear the mod differences... as if their perception is immune
to the laws of science... I've look at the Yahoo board also on the DCX, it's just
as mad. To sort this madness, I bought a DCX and did auditions to the stock
unit vs. other sources and found it to be neutral - without mod. I also
sabotaged the signal chain to force gremlins, yet none were audible. Point is,
there is only so much you can learn without doing your own experiments and
even those experiments you execute can make you fall prey to voodoo if you
aren't wise to it.

Diyaudio forum
AVS forum
Audio asylum

are all forums that defy the laws of science :)

thadman
12-17-2006, 08:18 PM
I understand your recommendations about what you like...

Im looking for some concrete information on HOW A HORN works and what effects it has on the actual transducer. I do not have the time to test everything out...

Do you have any concrete objective information? Im not looking for "it sounds like...", "it does this with...", etc etc. A horns sound signature can be attributed to certain things such as diffraction anomalies, distortion, transcient response, dispersion response...etc etc. What effect does the horn have on these certain qualities? This is the information im looking for...not a recommendation of whether to use them or not or which designs to use. I havent achieved the point in my research where I can determine if I should build them or not, im looking for some objective information so I can come to my own conclusions.

What effect do horns have on the transducer?

thylantyr
12-17-2006, 10:06 PM
google?

ie

http://ldsg.snippets.org/HORNS/design.html
http://melhuish.org/audio/horn.html
http://www.quarter-wave.com/Horns/Horn_Theory.html

You can read about it, but trying to figure out what it sounds like
will be harder than just listening to one.

thylantyr
12-17-2006, 10:26 PM
Check this out.

http://www.htguide.com/forum/showthread.php4?t=18242


Within the link;
http://audioheritage.org/vbulletin/showthread.php?t=12126

Cowen unity
http://diy.cowanaudio.com/unity.html

I'd rather just make a line array and destroy them all :)