Stereo-Lab cf400/cf250 Tactrix or Jabo KH-55 Exponential Horn for Radian 950PB - Page 2 - diyAudio
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Multi-Way Conventional loudspeakers with crossovers

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Old 5th December 2012, 06:44 PM   #11
pos is offline pos  Europe
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Has anyone tried the square steero-lab horns?
It looks like it is shallower than the equivalent round one, so it might be less beamy...?
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Old 6th December 2012, 01:30 AM   #12
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"What does the 20ohm resistor do ?"

A compression driver (like most woofers) is a changing load (unless copper cap, shorting rings, etc). It usually increases as it goes higher. A 20 ohm in series with an 8ohm compression driver may knock 1-4khz down by 6db or more, while the driver maybe be 30ohms at 10khz, so it only knocks it down by a db or 2. Or simply, it lowers the level but boosts the highs a little.

Tractrix horns narrow their dispersion as frequency increases, they get free hf boost. They really need the decade rule for dispersion though (say 600hz-5khz), and yes, the 400hz stereo lab should be crossed at 800hz. It really would make for a great 3-way horn setup crossed at 2khz.........

I have a cd horn ((constant directivity the ev hr90) that doesn't provide any lift. I use a 16ohm compression driver with a 30ohm resistor and a 1uF in parallel with the resistor. And I have cd-eq on (I usually listen less than 90db so I like the hf boost).

But those round horns should sound great. I'd stay away from any horns with pinching (like yours), parallel wall, and ideally no corners. And the horn paths should be smooth, without angles or breaks (like mine). Each one of these adds a reflection, making it sound more live or reverby. Fun but false.

I use foam in the throat and the side edges that helps my sound.
Click the image to open in full size.


I remember a post where a guy loved his stereolab 400hz, till he stood up (no highs).

I still want some. Or some jbl 2384's.
Click the image to open in full size.

But good luck with your choice.

Norman
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Old 6th December 2012, 04:03 AM   #13
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I am very appreciative of the information and advice. As typical of this interest there are various choices with compromises in cost and performance dependent on individual preferences and means. I have looked for a while at the Autotech horns but they don't appear to be available from the USA distributor at the moment. I hope they will be soon.

There is about 18" of vertical distance between the two 15" mid-woofers in D'appolito arrangement in my speakers. The Autotech Le Cleac'h are 23.5", the Stereo Lab tactrix are 17", and Jabo KH-55 are 21". I believe all three would work and obviously the only way to really know is to listen to each one. That is not likely to happen so I will give it my best shot. I do not have any curent plans to add a higher frequency tweeter. One thing I hope to do is completely separate the compression driver and horn from the vibration of the rest of the speaker since they are now mounted in the same baffle with the mid and low woofers.

Mike
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Old 6th December 2012, 08:14 PM   #14
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i'd get the l'cleach.
just don't expect much dispersion past 5khz.

good luck!!!!!!

pics???
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Old 10th December 2012, 12:31 AM   #15
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Here are my current speakers. Not pretty but do look much better than the picture. No longer use embarrasing cheap power strip. Idea is to replace CD horn with freestanding horn/compression driver separate of baffle. Crown K-1 drives Hawthorne Audio Augies.
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Last edited by mberrync; 10th December 2012 at 12:35 AM.
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Old 10th December 2012, 12:42 AM   #16
JoshK is offline JoshK  Canada
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The Le'Cleach or the Iwata would be my vote. You can always mask the nearer woofers a bit and add some wool to the back to control from diffraction. That keeps C-t-C close enough
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Old 10th December 2012, 03:26 PM   #17
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Please see the file below with a comparison of the various horn sizes versus the current baffle arrangemant. I did not know if using a 24db slope would allow use of the JMLC Le Cleac'h 350 horn, which is said to be useable with a crossover to 520hz. I assume that would further limit the dispersion. Do the advantages of the larger horns outweigh disadvantage of overlapping the mid drivers? I also may try crossing the 950PB as low as 350 in the future.
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Old 13th December 2012, 02:23 PM   #18
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Default Specifics on serial resistors

I saw the image below from a Euro Triode Festival Horn Shootout where a series of at least 6 resistors were used on TAD 2001 drivers. Is this what is intended? Questions would be are they all 20 or 30 ohm resistors or do they all add up to 20 or 30 ohm? Is there a typical number in series or does it depend. I would think this many along with the wiring and connections involved would take away from the sound? Are the resistors placed only on the positive wire?
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Old 18th December 2012, 12:16 AM   #19
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The question of what value of resistor is to be used is going to depend on a number of factors, the most important of which is going to be the sound that you are looking for. Wild response aberrations excepted, loudspeakers are a very personal choice. In the TAD 4002- the driver I use in my own system, I used a value I remember being suggested somewhere when I was looking for another piece of information a long while back. In my case, that value turned out to be 20 Ohms. I needed a LOT of attenuation for the CD to match the transmission line bass I was using at the time, so I had a 3.9 Ohm resistor across the terminals of the TAD. I tried about 40 different brands of resistor- I have access to large numbers of them- in parallel, series, old carbon comp types, some I wound myself from various resistive alloys, metal films, power films, some exotic, some mundane… In the end, I ordered a set of 4 Duelund silver/carbon resistors- just the standard ones. They cost about $25 a piece, but they are far and away the best sounding resistor that I have heard on these horns. Highly recommended.

My guess is what you saw was a bit of a voicing experiment. Either someone wanted to quickly sample (or demonstrate) a number of different resistors for sound, or this was the end result of a number of hours tinkering with the sound by fiddling with resistors. I tend to gravitate toward the idea of finding the one part that gives me the sound I like, with the right combination of compromise, and just use that ONE part. Currently, my entire crossover consists of a single paper/foil/wax capacitor and a pair of Duelund resistors. I'm using a bandpass midbass horn, so no crossover of any kind on that, so I've 3 parts in each crossover, total. Its working quite well with a little sub- next up are the bass horns that are too big to fit in this room, so they'll have to wait.
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Old 19th December 2012, 08:17 PM   #20
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Quote:
Originally Posted by Corvus corax View Post
In the end, I ordered a set of 4 Duelund silver/carbon resistors- just the standard ones. They cost about $25 a piece, but they are far and away the best sounding resistor that I have heard on these horns. Highly recommended.
What is the reason for the sound of the Dueland resistor?
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