Chorus II vs RF7

[ClaudeJ1]

Also, the passive radiator suspension isn't linear enough to keep up at the stock tune, let alone trying to push it lower in frequency by adding mass. I would sooner switch over to a different passive - I'll have to take a look too see if there's anything commercially available that can just drop in. I can even take some measurements to show proof of concept...

Like the Nike commercial said: "Just do it."

[moray james]

Quote:

What do you mean by spider talk? The K48 has the least suspension
resonances in the pass band of any driver I've measured - almost a
prefect compromise between excursion linearity and HF extension. Damping
the spider might help other lessor drivers, but the K48 don't need it.
As far as reflections - the cabinet can be tamed a bit, but don't go
overkill because it will reduce the efficiency of the passive. However,
1/8" thick felt on the suspension will have no impact on acoustic
reflections. Also, the passive radiator suspension isn't linear enough
to keep up at the stock tune, let alone trying to push it lower in
frequency by adding mass. I would sooner switch over to a different
passive - I'll have to take a look too see if there's anything
commercially available that can just drop in. I can even take some
measurements to show proof of concept...

I have not modified any K48 woofers so I can only go on my experience doing so to a good number of other drivers of assorted types from full range to mid drivers to woofers including several fifteen inch one an auto unit. Every unit I have modified has spider talk which is separate from spider resonance, even the smallest 3 inch full range Fostes units make this noise. The higher the efficiency of the driver the more likely you will hear the noise from the spider and from cone reflections. The preceived difference of this mod can be stunning.

I would think that you are right on about the passive in the Chorus ll I normally suggest folks only shoot for 3 - 4 additional hertz for this reason and while that may not seem like much it has lots of impact. What about looking at a cheap Chinese 15" woofer with the right Fs that will be a lot les expensive than buying a new passive unit?Best regards Moray James.

[Vital]

Also, the passive radiator suspension isn't linear enough to keep up at the stock tune, let alone trying to push it lower in frequency by adding mass. I would sooner switch over to a different passive - I'll have to take a look too see if there's anything commercially available that can just drop in.

Keep us informed, I would love to hear about what you find.

[moray james]

no reason that you cannot convert to reflex loading it is almost free to do. Best regards Moray James.

[DrWho]

Every unit I have modified has spider talk which is separate from spider resonance, even the smallest 3 inch full range Fostes units make this noise.

Are you talking about the spider itself making its own noise? Suspension noise can be an issue at higher excursions, but I've found that it's usually dominated by the speaker surround flapping around. The spider gets attenuated by the actual cone of the driver, usually has less total surface area, and tends to be stiffer than the surround - which all mean less propensity to generate noise. I don't think I've ever heard a spider making noise - apart from the occasional tinsel lead slapping against it.

Maybe another way to ask it would be, "How would you go about quantifying the magnitude of spider talk"? I know this isn't for everyone, but I typically like to find ways to measure artifacts so that I can know when they've been addressed completely. It also helps with making informed decisions when mods impact other aspects of performance.

[DrWho]

What about looking at a cheap Chinese 15"
woofer with the right Fs that will be a lot les expensive than buying a
new passive unit?

You get a notch at the Fs of the passive radiator....I don't know of many cheap woofers with an Fs in the <10Hz range.

Btw,
the biggest reason I haven't pursued doing my own cheap modifications
to the Chorus II is because I took my xovers apart in college when
working on a tri-amp solution and in the process I ended up with
mis-matched xovers and my compression drivers got blown up when the
amplifier connected to them blew up. It ended up being cheaper to
purchase this horn and buy brand new drivers:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=245-625

I went with the BMS 4550 for $150 (http://www.usspeaker.com/bms%204550-1.htm), but the Selenium D220Ti is supposed to be really good too at only $50:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-271

I
went with an active xover, which gave me time-alignment, a flatter
frequency response, better off-axis polars, and more control over the
voicing. $200 per speaker plus an extra amplifier ended up costing about
$800 and the result will blow the stock RF-7 and stock Chorus II outta
the water. The Crown XTi 1000 amplifiers sound decent, but I'm planning
to change to something like a Mini-DSP (or my own homebrew equivalent)
and the new nCore class D amplifiers from Hypex (or my own homebrew if I
ever finish it). Once I get there, then I'll experiment with upgrading
the passives. For now, I built a new cabinet for the K48 with two 4"
ports. One of these days I'll get around to measuring the differences in
distortion between the passives and the ports. I personally listen at
such quiet levels that the ports are nowhere near nonlinear behavior.

[moray james]

Mike it has been my experience that the higher the efficiency of the driver you ususlly have a thinner lighter cone so it becomes more transparent. I first became critically aware of this decades ago when I helped to developr a voice coil driven Mylar diaphragm loudspeaker and no matter hwo small or how we damped the spider we could still hear it and measureit. So we eliminated it and used feffo fluid as a liquid bearing for the coil. Once gone the difference was amazing. With woofers I really dont think that you would see much difference in the measured response but as I said the preceived difference is substantial. I dont think that the bass goes any lower but because things are cleaner and less smeared it sound like more ore perhapd it is just that much more well defined. I am sure that if you give this mod a try you will be pleased. It has been decades (1988) since I did the intital experiments and I can't recal the exact response range but everything sounded better without a spider once we removed them.

First off I place a layer of dynamat on the inside of the basket struts and on the ouside of them as well. Normally I also brace the magnet assembly to the top of the basket with stamped steel baskets. I use three separate layers of 1/8 inch thick F-11 acoustical felt. Don't wast time with synthetics they don't come close. I cut the three disks out as doughnut shaped rings. The lowest felt has the smallest od and id each disk has a slightly larger od and id to accomodate the increase in size of the basket and the cone. You have to place a cut from the outside edge to centre to install them around the VC and I re connect them with five small dots of white glue so the joined seam is not stiff with adhesive. Floppy motion of the disks eats up a lot of energy. I use string or fabric to make a loose fitting but secure harnes to insure the felt disks do not push on the tinsel leads but still have room to move easily

As to your last question we measured a lot of loudspeakers with and without the cone and we even added back the cone mass in a good number of cases. As far as I am concerned suspension noise id a necessary evil but you don't have to put up with as much as most manufacturers see fit to see you.Wish I could provide more but I don't have any of tthe original data available any longer. Hope this is of interest. Best regards Moray James.

[moray james]

Like Mark knofler said "that's the way you do it, get your money for nothing and your chicks for free" Sounds like a great set up and so very flexable. Did you measure the TS paramaters for the K48? What were you able to tune it down to in your new cabinets? Very nice horn and driver by the way too.

I expect that if you chose a woofer with plenty of throw and a slightly higher Fs than what you needed for the passive and then plied some mass the added weight would help a lot with the spike that you mentioned. I have not done this but if I owned a Chorus ll and the passives were toast I would simply make a pair of fifteen inch plywood blanks and vent them. Taakes not time and is dirt cheap to do. A good passive costs an arm and a leg and cardboard tubes or plumbing pipe are almost free. Best regards Moray James.

[CECAA850]

but I'm planning to change to something like a Mini-DSP (or my own homebrew equivalent) and the new nCore class D amplifiers from Hypex (or my own homebrew if I ever finish it).

Are the nCores amps available anywhere yet?

[tigerwoodKhorns]

It ended up being cheaper to purchase this horn and buy brand new drivers:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=245-625

I went with the BMS 4550 for $150 (http://www.usspeaker.com/bms%204550-1.htm), but the Selenium D220Ti is supposed to be really good too at only $50:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-271

How do these tweeters compare to the JBL 2404s?

[moray james]

Google like you.... http://www.hypex.nl/ Best regards Moray James.

[moray james]

Did Mike say he was going two way rather than three way? I must have missed this. Thanks. Best regards Moray James.

[CECAA850]

Google like you.... http://www.hypex.nl/ Best regards Moray James.

That's just the module. I was wondering about a finished amp.

[wuboy]

I agree, I have Chorus II's, Forte II's and Quartets. Sure the Chorus II's have the largest sound stage, of the three pair, I use the Quartets as center channels for both the Forte II's and the Chorus II's. Through the miracle of YPAO ( Yamaha Parametric Audio Optimizer) all sounds balanced and really good. My neighbor has RF-82's, an RC-62, subwoofer and surrounds, all Klipsch and he likes the sound state better in the Chorus II's and the Forte II's. He is newbie to Klipsch, his first pair, the RF-82's and nothing remotely resembling Heritage line to compare to.

All of the above said, I do enjoy gaming on his system, sure my speakers are richer, fuller and far better for movies, at least this is what friends say, they come to my flat for movies and music, his flat for games. We live in identically sized condo's, each 1850 sq ft, the the main entertainment room is 35' x 20'. I call them flats because they are all one floor. Our power is identical, Yamaha receivers RX-V573 models which are up to the task. The characteristic that makes my speakers is that they don't ever screech at me the way horns can, Maybe it's the 3 way system, maybe it's the passive radiators on all three models, even my center channels. The whole thing comes down to personal judgement. Personally I do prefer the sound of the Heritage line, but it's my preference. Same with the RF-7's, they are two way speakers and do suffer some of the horn characteristics that PWK would never have signed off on, although in fact I think he did later in his life, The total surround sound of my friend's system \is awesome for MOH Warfighter, COD games and that kind of thing, although dynamic range is definitely is on my side. We're both Xbox people.

The Palladium series, the Heritage series are all three way systems. Different horn lenses are for different frequency ranges, at least that is the theory. In practice it works well. My neighbor loves his R*-82 system, but he concedes both sound stage and that "fullness" of sound to my heritage 3 way systems. I'm sure that an RF-7 owner will come up with arguments based on personal taste. I have totally restored the Chorus II's and Forte II's, crossovers and titanium tweeter diaphragms. I love these speakers and will not part with either pair in the future. As center channels go the Quartets are really good, a real, full range center channel, although I roll them off at 80 Hz.

Dave Brubeck has never sounded better from the string bass to the cymbals.

[Heritage_Head]

I have owned the RF-82/RC-62 ht set up and like you said they are very nice. But they are not on the same plant as the 7s imo.

[Heritage_Head]

I have been on the hunt though for some Heritage. Im going to set up something upstairs and have been looking hard for the last 6mo for corns or some nice h3. You guys have sold me after reading on here for the last 2 years lol. I got to at least try them (can always sell).