2.5-way crossover tapered-array technology

[moray james]

does anyone know if Klipsch ever used the 2.5 way network design on any three driver floor standing loudspeakers. They did use it in a number of centre channels most notably the RC7. I expect that the high cost of parts may be a deterrent.  Thank you for any an all input to this.

Klipsch RC-7 diagram.pdf

[fuzzydog]

I'd read somewhere that it was only needed on the center channels to mitigate the lobing effect of a MTM speaker mounted horizontally.

[willland]

does anyone know if Klipsch ever used the 2.5 way network design on any three driver floor standing loudspeakers. They did use it in a number of centre channels most notably the RC7. I expect that the high cost of parts may be a deterrent.  Thank you for any an all input to this.

 

 

They did not as far as I know.  

 

I spoke with a Klipsch engineer(I forgot who) a few years back and asked the same question.  He said there was really no need to use that technology on a floorstander, even though some mfr's do use a similar configuration.  

 

I think the subject came up when I mentioned doing something similar with a pair of RF-63s.  The bottom two woofers would have handled the bass, top woofer upper bass and low midrange, and the tweeter horn controlling the upper midrange and highs.

 

Bill

[moray james]

well it minimizes some of the detrimental interaction between the two woofers by crossing one woofer lower than the other so that one of the woofers plays a narrow range of bass while the other plays a wider range and so acts as a woofer/mid prior to transitioning to the tweeter horn. The result is smoother cleaner response especially so at crossover to the tweeter. This works equally well in both a WWT configuration and a WTW set up.

[willland]

well it minimizes some of the detrimental interaction between the two woofers by crossing one woofer lower than the other so that one of the woofers plays a narrow range of bass while the other plays a wider range and so acts as a woofer/mid prior to transitioning to the tweeter horn. The result is smoother cleaner response especially so at crossover to the tweeter. This works equally well in both a WWT configuration and a WTW set up.

 

You build the crossover for my 63's and I will do the demos.  

 

Seriously, the 63's sound so good with music I don't want to change a thing.

 

Bill

[Coytee]

I was under the impression that the Palladium's used something like that.  Mark Blanchard did a little presentation at Indy a number of years ago.  My memory is vague, but I seem to recall hearing that the two woofers were assigned different cutoff's.

 

Not sure that this is 100% correct nor if it's what you're really after.

[moray james]

Thanks Coytee that is interesting to hear. In the world of speakers where competitive pricing is a big deal a 2.5 way three driver speaker is a an expensive way to go. I can see the justification for a centre channel but for floor standing speakers you may as well go with a three way as that will cost you less to make. After market and you can afford to play a little more and spend some coin to get some added performance. In the non Paladium price range of loudspeakers the RC7 (the matching centre channel speaker for the RF7 ll) is likely the best example of this technique. 

[pzannucci]

Thanks Coytee that is interesting to hear. In the world of speakers where competitive pricing is a big deal a 2.5 way three driver speaker is a an expensive way to go. I can see the justification for a centre channel but for floor standing speakers you may as well go with a three way as that will cost you less to make. After market and you can afford to play a little more and spend some coin to get some added performance. In the non Paladium price range of loudspeakers the RC7 (the matching centre channel speaker for the RF7 ll) is likely the best example of this technique. 

Lot cheaper to do a 2.5 way though the key is the crossover points.  In this day and age of cost cutting, the extra portion of the crossover may not be near as expensive as a dedicated midrange with associated crossover parts, but it still adds cost that bean counters (and people purchasing many speakers in Klipsch's price category's) will notice.  $10 in parts, $20K in engineering time, and poof, the speaker went up $500.  Depending on your position in the vertical plane, the suck-out will be noticed closest to the crossover point in the two way.  That is why the center speakers incorporate it.  More people will complain about the notch when sitting off axis in the horizontal plane with a laid down center speaker because of the loss of intelligibility of vocals, for which the center's main reason is for.

 

The other reason for a 2.5 way or a usage like the PSB T3 staggered 5 way is to gain bass by increasing the radiating area due to the bass loss around baffle step compensation frequency.

[pzannucci]

I need to add, size and distance of the staggered drivers (from each other and the next crossed over driver) also needs to be included in the equation for the 2.5 / staggered array and above crossover design.

[wstrickland1]

slightly....ok maybe greatly OT but has anyone here ever compared a pair of RC7s and a pair of RB75s? I would be curious as to which would come out on top. I may be wrong but isn't the RC7 tweeter exactly the same as an RF7 where as the RB75 tweeter is similar. Please ignore if this is too much of a de-rail

[moray james]

 

Thanks Coytee that is interesting to hear. In the world of speakers where competitive pricing is a big deal a 2.5 way three driver speaker is a an expensive way to go. I can see the justification for a centre channel but for floor standing speakers you may as well go with a three way as that will cost you less to make. After market and you can afford to play a little more and spend some coin to get some added performance. In the non Paladium price range of loudspeakers the RC7 (the matching centre channel speaker for the RF7 ll) is likely the best example of this technique. 

Lot cheaper to do a 2.5 way though the key is the crossover points.  In this day and age of cost cutting, the extra portion of the crossover may not be near as expensive as a dedicated midrange with associated crossover parts, but it still adds cost that bean counters (and people purchasing many speakers in Klipsch's price category's) will notice.  $10 in parts, $20K in engineering time, and poof, the speaker went up $500.  Depending on your position in the vertical plane, the suck-out will be noticed closest to the crossover point in the two way.  That is why the center speakers incorporate it.  More people will complain about the notch when sitting off axis in the horizontal plane with a laid down center speaker because of the loss of intelligibility of vocals, for which the center's main reason is for.

 

The other reason for a 2.5 way or a usage like the PSB T3 staggered 5 way is to gain bass by increasing the radiating area due to the bass loss around baffle step compensation frequency.

 

Peter": it is the woofer section of a crossover where the big part costs are with large inductors and large value capacitors. As soon as you say you are going 2.5 way you are saying that you are going to build two woofer crossover sections, one for each woofer. The more woofer you stack vertically the more radiating area you have but you also start to loose floor coupling so with three vertically stacked woofers the top woofer is going to loose some coupling to the floor compared to the two lower units. I am wondering if that at that height perhaps the top woofers response is better behaved to cross to the mid/hi horn? I have to admit to being a crossover dummy. my math skills get me into the soup when trying to design such things. Grouping woofers makes for increased radiation. I have seen a good number of  loudspeakers with a couple of woofers at the bottom of a tower then a vertical gap  and a similar size unit being used as a bass/mid so the triple stack of woofers is not be so very different. I don't have much experience with electrical filters but AI have experimented a good deal with acoustical filters doing this job. While not so dramatic as when using an electrical filter the acoustic filter makes for a nice improvement in diminishing unwanted driver interactions. I use this in my H3 on the woofer and on the woofers in my KLF20. The result is improved clarity with better stage and image.

[BusaDude]

slightly....ok maybe greatly OT but has anyone here ever compared a pair of RC7s and a pair of RB75s? I would be curious as to which would come out on top. I may be wrong but isn't the RC7 tweeter exactly the same as an RF7 where as the RB75 tweeter is similar. Please ignore if this is too much of a de-rail

 

The RC7, RB75 and RF7 all share a 1.75" compression driver attached to an 8" square, 90x60 Tractrix horn... Is that driver "exactly" the same in all three speakers???  I don't know.

 

The RC7 is crossed at 1950 Hz, RB75 at 2000 Hz and RF-7 at 2200 Hz (according to Klipsch data sheets)

[pzannucci]

 

 

Thanks Coytee that is interesting to hear. In the world of speakers where competitive pricing is a big deal a 2.5 way three driver speaker is a an expensive way to go. I can see the justification for a centre channel but for floor standing speakers you may as well go with a three way as that will cost you less to make. After market and you can afford to play a little more and spend some coin to get some added performance. In the non Paladium price range of loudspeakers the RC7 (the matching centre channel speaker for the RF7 ll) is likely the best example of this technique. 

Lot cheaper to do a 2.5 way though the key is the crossover points.  In this day and age of cost cutting, the extra portion of the crossover may not be near as expensive as a dedicated midrange with associated crossover parts, but it still adds cost that bean counters (and people purchasing many speakers in Klipsch's price category's) will notice.  $10 in parts, $20K in engineering time, and poof, the speaker went up $500.  Depending on your position in the vertical plane, the suck-out will be noticed closest to the crossover point in the two way.  That is why the center speakers incorporate it.  More people will complain about the notch when sitting off axis in the horizontal plane with a laid down center speaker because of the loss of intelligibility of vocals, for which the center's main reason is for.

 

The other reason for a 2.5 way or a usage like the PSB T3 staggered 5 way is to gain bass by increasing the radiating area due to the bass loss around baffle step compensation frequency.

 

Peter": it is the woofer section of a crossover where the big part costs are with large inductors and large value capacitors. As soon as you say you are going 2.5 way you are saying that you are going to build two woofer crossover sections, one for each woofer. The more woofer you stack vertically the more radiating area you have but you also start to loose floor coupling so with three vertically stacked woofers the top woofer is going to loose some coupling to the floor compared to the two lower units. I am wondering if that at that height perhaps the top woofers response is better behaved to cross to the mid/hi horn? I have to admit to being a crossover dummy. my math skills get me into the soup when trying to design such things. Grouping woofers makes for increased radiation. I have seen a good number of  loudspeakers with a couple of woofers at the bottom of a tower then a vertical gap  and a similar size unit being used as a bass/mid so the triple stack of woofers is not be so very different. I don't have much experience with electrical filters but AI have experimented a good deal with acoustical filters doing this job. While not so dramatic as when using an electrical filter the acoustic filter makes for a nice improvement in diminishing unwanted driver interactions. I use this in my H3 on the woofer and on the woofers in my KLF20. The result is improved clarity with better stage and image.

 

On the floor coupling, the lowest woofer should be running the lowest frequency since it is farthest away from the tweeter and closest to the floor.  A simple 6db crossover loading that lower woofer should be adequate.  By the time you get closer to the crossover point to the mid/tweeter, most output should be out of the driver next to the mid/tweeter.  The driver coupling at low frequencies produce the bass reinforcement.

 

The closer or shall I say within wave coupling / phase between each driver and the next handed off to driver, will make the behavior at crossover good or bad.  Creating timing issues, notches or bumps in the crossover region.

The higher woofer (from the floor) will usually have some cancellation from the floor bounce.  Floor coupling for bass is good.  The reason for the different gaps between the woofers will either be for looks or to mitigate floor bounce and coupling between woofer issues.  The key is frequency arrival times.   

 

The key is to increase the radiating area as the frequency goes down.  This minimizes the bass loss from not having (like the old infinite baffle designs in the closet) the whole wall to radiate from.  

 

There are interactions due to having staggered woofers between the woofers themselves and the next up driver.  The time for coupling between the mid-bass and tweeter will be less between the closest woofer and farther one.  That has to play a roll also and the more off axis you are compared to the crossover point, the worse the likely notch will be.  This is why I shy away from horizontally laid out drivers, driver interaction is much higher on the the horizontal plane.  It can be used to an advantage, such as Legacy does, by focusing what you want your mid-range dispersion to be and minimize room interaction due to the cancellation of frequencies by horizontal mid-ranges.

 

These are some of the things I think about when building or buying a speaker.  I believe the time domain is why mini-monitors can disappear. Not size but lack of time domain oddities for imaging but you don't have the bass power (nor blurring) of a multi woofer system..  To get imaging right in large speakers you need matching drivers and the crossover designed to the drivers integrate in the time domain (of course based on listener positioning).

 

My thoughts anyway.

[moray james]

this Zaph article is worth the read.

 

http://zaphaudio.com/Waveguidetmm.html