# Compression drivers



## mayhem13 (Feb 2, 2008)

What's the opinions of using high quality compression 1" drivers for HT applications. As an example coupled with 2 8" midbass drivers in an MTM alignment. Would such system benefit from a waveguide as opposed to horn loaded. Are these drivers capable of high SQ for critical music listening as well?


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## BrianAbington (Mar 19, 2008)

From my experience in car audio I know that horns are very efficient. Most car audio horns are rated at 25-50...some times maybe 80 watts. Yet they have very clean sound and can play pretty loud. 
Also many can play down to 650-500 hz. 
I've never used horns in a home application but I've never had anyting bad to say about them from my front of house experience.

I would try to find some used JBL horns cross them from 600hz and up and then use 2 10" woofers for your midbass. Now that would be sweet.


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## superchad (Mar 7, 2008)

A guy in our Audio club uses Compression drivers and horns in his DIY open Baffle speakers...he changes designs every few months the last design being a WW on bottom and MTM on top with 4 10ft horn loaded subs but they play clean and loud...not just loud I am talking 130db with Crown amps with no break up, distortion or clipping, the should work fantastic for HT, music or even your own Concert! They do have a "Pro-ish" sound that you either know exactly what I mean or I cant convey in words but still they are awfull impressive and not too much money to make, ofcourse the open baffle has ALOT to do with this, cheers


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## Synthsayer (Dec 19, 2007)

I am getting readyto put together a 3-way system using EV DH1012 Compression drivers and HR4090 Horns(40"x16") with JBL E140 short-throw bass bins and JBL2402 bullet tweeters. Will cross over at 800 and 4500Hz. Will position horns vertically or hang from ceiling. Just have to figure out best way to mount horns and bullets.
Will let you know how it works out.


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## mayhem13 (Feb 2, 2008)

Thanks DS. I've been toying with this for a while and have come up with an initial design of a WCW using two Dayton RS8 4ohm woofers with a Radian 8" coax loaded with a 1" Titanium Comp( forget the waveguide). I won't be driving these to extreme levels so i'm figuring the headroom available should make for a very clean system. Just don't know if the extra $$$ for the radian stuff is warranted verses the eminence coax with a cheaper eminence 1" comp ( crossed as low as possible of course).


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## kouack (Jan 17, 2007)

i do have a set of P audio horn for my front L and R mid-hi freq (1,2 khz to about 10 khz) they are cat as* :bigsmile: extremely efficient and clean sound love them.


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## mayhem13 (Feb 2, 2008)

There's a pair of i6's on ebay for $110 used, Is this a good deal worth trying?


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## Synthsayer (Dec 19, 2007)

kouack said:


> i do have a set of P audio horn for my front L and R mid-hi freq (1,2 khz to about 10 khz) they are cat as* :bigsmile: extremely efficient and clean sound love them.


I would recommend looking for Compression drivers that have 2" throat and low end cutoff of 500Hz. Horns that focus on the 1k-1.5k area can be very 'squawky' and grating. 2" throat horns with lower response like this are pretty$$$
Also take into consideration the crosssover area of the woofer you will use. Many 10''-12'' drivers will get realy muddy above 500Hz. Also, get woofers that are as efficient as possible to reduce the padding necessary for the mid horns. Many may disagree but look at Parts Express for the B&C or Eminence pro drivers. These will be very efficient and have surprisingly good sound. Selenium makes some very good drivers, too. Both for horns and woofers.
The previous post regarding padding of the compression driver/horn and baffle step compensation is spot-on. You can find a baffle step circuit calculator that will run in Excel for free. Without this you may have a hard time getting the sound you want.
If you go with 8" drivers or 10" drivers that have good mid response up to 2k you can cross over your mids around 1.8k at 12db per octave. Again, the B&C or Selenium units should be good for this. If you can find some JBL Pro 2400 series 'butt' horns,( I'm series that is what they used to be called) on eBay or from Pro Sound surplus companies for a good price, get them. They have a high end response up to 20k and sound great. I don't remember the exact model# You can look at JBL archives and high frequency drivers. 
If you have the amplifiers, use an electronic crossover. Again, amps and crossovers get into more moneyof course. If using and AVReceiver this is won't work unless you have pre-amp outs.
What will you be powering the speakers with?
You may want to look at some of the Klipsh designs to give you some ideas. You would be surprised how inexpesive the drivers they use are and who makes them. 
Be careful mixing 4 ohm and 8 ohm drivers. Some amps just don't like it and there is really no benefit unless run in series. Plus you will have to use larger component values for inductors and caps which will cost you more money. With two woofers in series you will obviously have an 8-ohm load.
Best of luck.


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## Synthsayer (Dec 19, 2007)

"I don't necessarily agree with either point.

Yes, I think larger horns with a lower cutoff are desirable, because they let you control directivity down to a lower frequency. But a waveguide that gives good control below 1kHz or so will be quite wide. A friend of mine who was probably one of the first in the world to use the BMS 4590 dual-concentric compression driver in a home system (late 1990s/early 2k's) gets good directivity control down to something like 700Hz. His 90x40 waveguides are something like 2' wide.

As for the "squawky" factor, that has much more to do with waveguide geometry than with the size of the compression driver. In a well-EQ'ed constant directivity horn, it's not an issue. See the GedLee Summa as a prime example."

This interesting. I will definitely take this into consideration in the future. I have a pair of EV-DH1012 with HR 9040 horns that are very large. They have a 1" throat and would probably be inline with the characterisitics that you outlined. I have had pretty good luck crossing them over at points as low as 350Hz. Like I say though, the HR 9040s are BIG. 40" x 18". With the driver they weigh around 40 lbs. I picked them up at a pro sound company for $250. :jiggy:
My problem has been the bass region. I have vintage (old) E140 15" drivers in short-throw bass bins. Crossing them over above 500hz in a small listening area is where I have had problems with muddiness in the mids. When about 20' or more away from the system crossed over at 800 and 4500Hz for JBL 2402 bullets, this is not a problem.
I am completely hooked on horn systems. I know this site is not specific to these systems, and there are sites devoted to them. But, I had to reply when the original thread brought them up. In my experience horns have a detailed and dynamic response that cannot be matched.
I have considered making some diferent cabinets to use the EV horns and bullets with and replacing the bass bins. Another problem with the bass bins is there size. 
Maybe I should consider a pair of 10" drivers that would go up to 800Hz or greater, myself.
Since I was unhappy with the sound using passive crossover points of 800Hz and 4500Hz, I could try lowering the Low-Pass cutoff and the Low-pass section of the band pass filter. But that doesn't solve the problem of size with the bass bins.
For the time being I switched back to a smaller dynamic cone 2-way system with HiVi Research 8" and Morel MD-20T dome tweeter. They sound okay, but the sound does not jump out at you like it does with the horns. Until I switched to using a cheap Harmon Kardon AVR-146 to get surround FX, I used a QSC RMX 1450 to drive the bass bins and either a Hafler DH-220, or Ramsa P1200 to drive the EV horns and a bridged BGW 250E to run my subwoofer. I used a cheap Behringer crossover that was surprisingly flexible and uses very nice op-amps and Alps pots in its design. It was a decent system for stereo reproduction. Unfortunately I did not get an AVReceiver with pre-amp outs. I was wanting to try using smaller speakers, but have not been entirely pleased.
It's an on-going project. I work with one system for a while and then try something else.
Have a nice day


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## mayhem13 (Feb 2, 2008)

DS-21 said:


> I don't necessarily agree with either point.
> 
> 
> 
> ...


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## mongo22 (Dec 2, 2007)

I just put a pair of the Hawthorne Silver Iris 15" open baffle coaxial drivers (15" mid with 1" compression driver) in my listening room and was completely blown away. I will be adding the 15" augie driver to this pair eventually to turn it into a 3-way setup for real bass but for now im totally happy. High sensitivity, large driver, open baffles are really amazing and it doesnt get much easier (or cheaper) then the Silver Iris. They are only driven with 60 watts a piece from an old Onkyo reciever too! I listened to Jimi Hendrix the other day at insane volumes and it sounded clear and detailed the whole time. By the way, I dont work for Hawthorne Audio, ive just been so impressed by them i thought you might take a look before you buy a bunch of other drivers.

Here is the site:
http://www.hawthorneaudio.com

-andy


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## Synthsayer (Dec 19, 2007)

IMO Compression drivers are the absolute best for detail and dynamics. A good reason Klipsch has been in business over 50 years. When I have the time I will be setting up my own 3-way system again. The aforementioned EV DH1012 driver with HR 9040 horns, JBL 2402 Bullets, and JBL E140 short throw basss bins. I preiously had them tri-amped with over 2000 Watts. They could cause serious hearing damage if played at extreme volume levels. Also use a 500W OAudio BASH sub driving an Infinity 12" sub with passive radiator in 80lb. cabinet. I unhooked them because I did not want to disturb my neighbors. I replaced the system with Harmon Kardon AVR 146 driving 2-way retrofitted Advent Large speakers for surrond sound benefit, but it cannot match the sound I had before.
Another thing I noticed however is that since compression drivers and horns focus the sound towards the listener so much better, it is possible to play them at lower volume levels and still get most of the detail and dynamics. 
Dynamic cone drivers and dome tweeters sound okay, don't get me wrong. I have a friend that is a producer for Warner Brothers and has done sound engineering work for films such as 'The Thin Red Line' and 'Godzilla'. He travels with active KRK 2-ways for mixing bluegrass and other genres of music and loves them. But, for big time mixing, you can look at the big time studios and mastering houses and see 12" or 15" drivers with horns that cost huge bucks. 
I have some cool pics somewhere but don't have time to find them. Will try to post them when I get more time.
Enjoy your Hawthornes. They look like they would be very nice.
Where can I find more info on open baffles. This was somthing I experimented with in the late 80's but everybody told me I was nuts. Oh well... I would like to find out morer.
Thanks


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## mayhem13 (Feb 2, 2008)

Upon further investigation, the b&c 6.5 neo woofer has an even flatter response and less peaky at 4k. A little less efficient so may match better with a Morel 1-1/8 inch MDT30 dome. I think the waveguide thing will be a trial and error since the math is waaay complicated. I could build a trial enclosure with a removable mid section and try different guide dimensions since i do have access to a lathe. Cutting these from Plastic stock should be fairly easy. How low can i cross the tweeter or better yet, using the 6.5 B&C's where should i cross? Oh by the way this will be a sealed monitor with dual dedicated ported powered subs handling the lows tuned to 26hz with the monitors crossed at 120hz.


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## Synthsayer (Dec 19, 2007)

Don't worry about the math for calculating horns. Go to www.madisound.com and check out free loudspeaker calculators. This may be enough to get you in the right ballpark. They have many useful calculator and freeware links. No, I don't work for them. But, I have bought parts from them for over 20 years. Great tech support.
Visit the Linkwitz site http://www.linkwitzlab.com/crossovers.htm and you will find enough info about crossovers to make your head spin. Take your time and you will get the general drift of what he is saying. He recommends active 24db Linkwitz-Riley filters, but also has info about passive networks.
I am using the Morel MD-20T and HiVi Research M8N in a 2-way crossed over at 1600Hz. The woofer is first-order, 6db per octave, and tweeter is second order 12db per octave. I believe a typical rule of thumb is to take resonant frequency of tweeter times 1.5 for minimum crossover point. Also, be sure to use Baffle Step Attenuation, Zobel, and L-Pad circuits. They are much, much easier to understand and build than they sound. For your crossover circuit boards I recommend using 1/8" Masonite with brass rivets for soldering point-to-point connections. To simplify connections to drivers use 5-way binding posts for inputs from terminal plate and output to drivers. Plot out the general physical layout of components before drilling holes for rivets. Allow a little extra room and you can easily experiment with various crossover points. Look at www.hawthorneaudio.com/ for pics of their crossovers and you will see what I mean. They use a thicker piece of wood but the basic concept is almost identical. Some VERY expensive loudspeaker makers use this method.
Have fun.
Peace


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## mongo22 (Dec 2, 2007)

Synthsayer said:


> Where can I find more info on open baffles. This was somthing I experimented with in the late 80's but everybody told me I was nuts. Oh well... I would like to find out morer.
> Thanks


try here, scroll down to the open baffle forum
http://www.audiocircle.com/circles/index.php?action=circles

As of now i dont think i could go back to a "box" style speaker system. The detail and impact in an open baffle is really amazing. Couple this with a very sensitive driver and you can easily best most other speakers that cost far more.

-andy


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## looneybomber (Sep 20, 2006)

Maybe I need to mess with compression drivers more, but the one's I've heard (various clubs, bands, concerts, venues, Klipsch, ect...) have not sounded that good to me. There was always something about that horn/compression driver combo that didn't sit well with my ear. I heard some JBL's that had nice woofers, but their horn top end just didn't work for me.


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## mayhem13 (Feb 2, 2008)

Yeah, me either. The 2 inch JBLs sound very nice and can cross low but way too expensive and sensitive. I'm gonna give a Dynavox 1 1/8 dome a try-sensitivity is close to the B&C and i can cross it pretty low-I'll give 1.7k a try in an 8" round waveguide. I should expect an efficiency gain of about 3-4 db with the guide. Do you have testing capabilities?


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## 1Michael (Nov 2, 2006)

I have 2 15'' Silver Iris and 2 15'' Augies for sale.


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## looneybomber (Sep 20, 2006)

mayhem13 said:


> Do you have testing capabilities?


I've got a Behringer mic (model something 8000, I forget), a DEQ to power it, and a computer  But I may need a new audio card for REW or other software.


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## mayhem13 (Feb 2, 2008)

If i might ask, when these are done, could i ship them to you for an evaluation ?


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