sibilance on RF-7 (cont'd)

[Trey Cannon]

3 meter in chamber. (note: over look everything below 200 Hz)

RF7.doc

[Trey Cannon]

3 meter in chamber. (note: over look everything below 200 Hz)

The difference in Dean and stock

Dean's mod has nothing to do with whatever it is you are hearing.

RF7 HF only.doc

[prego]

In respecting the community (I have no other motivation), I initially wanted Dean to inspect those samples. However, I haven't gotten an answer from him yet. I'll let you judge for yourself.

In the following temporary link: http://rapidshare.com/files/63448935/cross.zip , please find two WAV files which are loseless (i.e. no compression at all was applied). They're actually the same passage. They can be burnt (accuralty) using any decent audio CD burner, and then played back on your setup.

1. "LF and HF.wav" is the passage, full spectrum.

2. "Only HF.wav" is the same passage, with just freqs above 2000hz, just to let you concentrate on the HF alone. (also you can use this one when the cross is bypassed on the HF, in case you want to neutralize everything)

While auditioning, pay attention to the "S" in the 'search' word, no matter at what volume. It rings noticably more on the DeanG'd crossover. The experiment we did was to take off the paralleled resistor Dean put on the 2ohm (i.e. the mod) from only one of the speakers, leaving the other alone. And while listenning, to play with Balance L and R and compare. It's very clear. This is just one sample, please note that problem exist in many other samples that we found, actually almost all sibillance intriguing tests.

I'd prefer Dean himself (or leok) to auditon this for themselves before others, since it requires desoldering the resistor.

Once we hear (hopefully unbiased) impressions, lets go into conclusions.

This of course applies only to those who had upgraded their RF-7 through DeanG.

[leok]

I removed the shunt resistor and there is a bit more energy in the upper midrange. There is no added distortion. Sibilances are a bit stronger, but not distorted. So, at this point the only crossover change is the capacitors. Generally I like the sound. Well recorded material is quite impressive. The added energy seems to work well, as I guess it should since it is the original design.

If I can get those wav files to a disk I may be able to give them a try.

Leo

[prego]

Trey, thanks for the attached measurments info.

1. I've zoomed(500%) in into where the sibilance exaggerations are (around 8Khz +/- 3khz) and measurements show that DeanG'd are consistently slightly stronger there (approx 0.25db) than the stock.

2. To my surprise, the zoomed picture (how can I attach a pic here) reveals also a decrease in upper midrange of DeanG'd (as leok felt).

SPL vs Freq graphs were never my reference, it can be made flat on a whooping $50 chinese made driven. However, the coloration of the speaker is what interest me (I love the horn's one), and the samples (of which I gave link to above) should demonstrate that.

3. Trey, do you also have an impendance vs. freq comparison between stock & DeanG ? Maybe there it's even more clearer, since the mod is specifically to resistance in the circuit...

4. Trey, I've found a Klipsch document on the HF crossover design of revision C, see: http://forums.klipsch.com/forums/storage/6/844278/RF7.pdf , where it appears there that the resistor is of 3ohm. Is it accurate and if so, were RF-7's horn had revision as well? (that it was necessary to compensate for them on the HF board)

Thanks.

[DrWho]

1. I've zoomed(500%) in into where the sibilance are (around 8Khz) and measurements show that DeanG'd are slightly stronger there than the stock

That's at most a 0.1dB difference, which is going to be within the error rate of the measurement itself. From an honest unbiased opinion, I really think it's stretching things to claim anything like that in the measurement. In fact, I doubt any two Reference tweeters are going to be that closely aligned with their raw acoustic output []

To be honest, I'm surprised nobody has tried to implement a p-trap on the woofers to get rid of that 3kHz peak, which looks to be some kind of resonance. Was the measurement taken with the mic on-axis with the tweeter? If so, that would explain the extremely fast drop-off of the woofer section too (comb-filtering + narrowed directivity).

Thanks for posting the measurements Trey [Y] You wouldn't happen to have one of the full response of Dean's mod would you? I'm kinda curious what happens to the phase response in the crossover passband...but perhaps it's not enough of a change to make enough of a difference.

[prego]

We've been doing a lot of measurements in the lab lately and output impedance changes that result in as little a 0.25dB changes in the frequency response are actually audible. In fact, they're enough to make the difference between ear-bleeding and smooth... []

Exactly

(EDIT (post previous post): DrWho, zoom into 7.5khz in WInWord, while in Edit Mode. There you will see accurate thin lines and not bogus. Every square is approx 2db vertically, and the jump of the blue(DeangG) there has max diff of about quarter a square , i.e. 0.5db)

[DrWho]

You're comparing apples to oranges.

We were measuring the output

impedance and frequency response of an amplifier, which was showing

changes spanning well over an octave. And if you include the

whole quote you'll notice that we think it has more to do with the

damping of cone motion, which is something that won't show up in the

frequency domain. There is a lot more involved with

output impedance than the frequency response. This is not an issue in

this case, unless the amplifiers being used are of higher impedance

(which is why I asked about it in the first place).

I don't mean to get defensive, but you're totally changing my comments to mean something other than was intended.

But for what it's worth, you still haven't addressed the fact that your

two RF-7's are not matched to within 0.1dB...which would make me wonder

why you could hear a minor difference in the network when you couldn't

hear the larger difference between the speakers. Heck, you'd be lucky if they were matched to within 1dB.

It's also pointless to get in an argument over the interpretations of

measurements. You're stretching to make your initial point valid, but

totally fail to comment on the larger changes being made. If you want

to see things one way, great. But let's keep thing in perspective and

not try to push agendas. I've given Dean a lot of crap about his

networks and I must say that I'm surprised by how it measures and I can

totally see why some might prefer the mod. Trying to claim that it's

introducing new peaks and sounds awful is clearly invalid. I might also

encourage you to present a better solution than both Klipsch and Dean's

networks and then provide the measurements yourself to validate the

claims. I don't mean to come across rude, but that's just how science/engineering works.

[prego]

But for what it's worth, you still haven't addressed the fact that your two RF-7's are not matched to within 0.1dB...which would make me wonder why you could hear a minor difference in the network when you couldn't hear the larger difference between the speakers. Heck, you'd be lucky if they were matched to within 1dB...

I'm providing you with two evidences; my samples (try them to understand what I'm refering to) and Trey's measurments. If you check those graphs in detail, given 0.1db error and/or manufacturing defect - whatever, it's still not in the direction of what the upgrade had promised. The 7.5khz diff is 0.5db, and like you said (hence the quote, apples and oranges look almost the same) can make ears bleed or smooth.

Please note that, so far (since the mod was introduced at 2004), all the discussions included words, finally you're provided with measurments and samples to try yourself. What can you ask for more.

[DrWho]

Your samples don't provide any form of comparison. One is LF and HF,

and the other is HF only (why you feel the need to have a sample of

only HF baffles me in light of the many ways to deal with

sibilance...). If you wanted to show anything, you would record one

speaker and then without moving anything, record that same speaker

again with the mod.

Also, you still continue to misquote me. 0.25dB IS NOT AUDIBLE when

you're talking such a narrow frequency range. If you think you can hear

the difference in that one measurement, then you're sorely

disillusioned.

What you're hearing is an artifact of your recording. In fact, it's called too much reverb.

[prego]

Your samples don't provide any form of comparison. One is LF and HF, and the other is HF only (why you feel the need to have a sample of only HF baffles me in light of the many ways to deal with sibilance...). If you wanted to show anything, you would record one speaker and then without moving anything, record that same speaker again with the mod.

The opposite is true. But following your path, if you wish - switch the RCAs of your transport instead of changing the balance.

Second, the HF only sample can let you concentrate (without the LF bias) on the ringing of one of the channels, when listened only to this one. second it gives you the option of wiring the horn directly to the amp withuot damaging it.

I hope my experiment was clear to everyone, let me know otherwise.

Also, you still continue to misquote me. 0.25dB IS NOT AUDIBLE when you're talking such a narrow frequency range. If you think you can hear the difference in that one measurement, then you're sorely disillusioned.

What you're hearing is an artifact of your recording. In fact, it's called too much reverb.

Alright, this argument is no big deal, so are the measruments. What's important are the samples. If you still find them insufficient for your standards, then I'll provide you one channel at a time, also - you can generate yourself - it happens on all female voice.

[DrWho]

Ah, I didn't realize you had it stereo panned...I'm running my system in mono at the moment.

[Deang]

Thanks for generating those plots Trey, very much appreciated.

Prego, Many of your comments defy reason, and my personal experience, as well as that of the dozens who have experienced the difference for themselves, reveal that excessive brightness and sibilance are reduced after the modification. Now, the sibilant range is rather large, spanning from 3.5kHz to just over 7kHz, so any apparant reduction will be strongly linked to the specific vocalist and how the vocalist was recorded. I don't accept that the miniscule increase at 7.5kHZ is responsible for what you're hearing. As for the resistor in the LCR, lowering the resistance value drops output and raising it lifts output, and I certainly don't see how a small reduction in output can cause elevated output in an area that the modification doesn't impact. I have never once received a complaint similar to yours. In fact, all feedback for the last three years runs completely contrary. In short, I have no real interest in revisting an issue that I've settled in my mind many times in the past -- that the RF-7 sounds better with the modification. I suggest that since you prefer the sound with the stock value in that position, then by all means use the stock value.

[prego]

Dean, thanks a lot for you being sincere. I really think your work is of top notch. However, IMO, I think that the interpertation of the tweak was misleading, and somewhat amateur in the sense that no substantial measurment/proof was made to support such a mod that was applied to so many. My god, did you see the peak in the horn measured by Klipsch? it's a dead evidence that the RF-7 is not for 2ch listenning, I really hope the RF-83 measuers better. Again, as always in stereo - everything is subjective and constist of many parameters. If you sure you like it - then it worth it. If I get a new speaker after the RF7 which is in need of a crossover upgrade - I'd contact you again, given that you'd be objective as always ;-)

[leok]

I played the two wave files: absolutely no distortion. Very powerful "s" but totally clean.

Leo

[DrWho]

did you see the peak in the horn measured by Klipsch? it's a dead evidence that the RF-7 is not for 2ch listenning, I really hope the RF-83 measuers better.

I can think of many superior sounding speakers that have a frequency response far worse than that provided of the RF-7. In fact, PWK design philosophy puts frequency response as 4th importance. All that to say, I think you are trying to draw way way too much from the frequency response. To illustrate the point, try measuring the speakers in your room sometime. I'll bet that you'll find something like +10dB, -60dB...

[Deang]

"I think that the interpertation of the tweak was misleading, and somewhat amateur in the sense that no substantial measurement/proof was made to support such a mod that was applied to so many."

A modified network was curved by Klipsch about three years ago. Trey wanted to curve one after hearing the mod at a Klipsch forum gathering in Arkansas, where I had brought a set so those that were there could decide. I told Trey it was the better parts, Trey said it was because I jerked around with the circuit -- so he wanted to measure it. After the measurement, Trey saw the modified output and said "it ain't the parts". Looking at the same plot I said "that resistor can't account for everything we heard." With my own RF-7's, I first started with just the resistor mod (improvement), to upgrading the parts (more improvement). I've built that network just about every different way you can imagine, and have compared to stock many times. At any rate, measurements were made, but not supplied because they were the property of Klipsch. I'm surprised Trey posted the plots, I only asked to see them again via email. All I know is that it takes the resistor mod and the caps to get it done -- so that's how I build them. There's nothing misleading regarding the description of the tweak, it does exactly as advertised -- just not in Israel. I'm at a loss. Surely you must wonder why after over three years no one has raised a similar complaint.

My god, did you see the peak in the horn measured by Klipsch? it's a dead evidence that the RF-7 is not for 2ch listening...

My opinion is that a 4dB rise in response up that high is of no real concern. The hearing of most is falling off in that area, and the worst case is that it adds some shimmer and air to the presentation. That area is far beyond where sibilance occurs. I researched that issue for over an hour today, and the highest figure I found for it was 8kHz.

If I get a new speaker after the RF7 which is in need of a crossover upgrade - I'd contact you again, given that you'd be objective as always ;-)

Right, I'm always objective about my subjectivity. Of course -- if you need another set of networks emasculated I'll be happy to do them.

[prego]

All I know is that it takes the resistor mod and the caps to get it done -- so that's how I build them. There's nothing misleading regarding the description of the tweak, it does exactly as advertised -- just not in Israel. I'm at a loss.

Maybe C.T.U. tracked down the crossover back and forth, installing some microchip device in the caps, after all it's the middle east, RF-7(or any speaker) crossovers dont pass here too frequently, perhaps jacksonbart can bart with some info he has over here []

Surely you must wonder why after over three years no one has raised a similar complaint.

All I can say is "the emperor wears no clothes" ? ;-) No ..

People dont exactly remember how it was before since they get it back only after few days. All they have in their minds is all sort of HYPE they read in the forum regarding the upgrade. I believe (never checked) that parts replacement does improve the sonic. Thats why (intuitively) top notch (aka hi-fi) amplifiers use high quality parts, and IMO the crossover is no exceptional.

The interesting point here is why so many people want their crossover upgraded - If I get new speakers which I like and enjoy I wouldn't want their crossover modified. As far as I know, It's not such a common notion in the stereo world (to new speakers whatsoever).

[Deang]

"All I can say is "the emperor wears no clothes" ? ;-) No ..."

All I can say is that neither the measurements nor the listening impressions of others support your claim -- you two are completely alone on this.

"People dont exactly remember how it was before since they get it back only after few days."

Right, but they immediately know if they like it better or not. Auditory memory is also triggered as they work through their music collection and notice that certain things that grated on their nerves -- no longer do. I've also had some who only sent me one network so they could compare to stock, always sending me the second network after a couple of CD's or records.

"All they have in their minds is all sort of HYPE they read in the forum regarding the upgrade."

LOL, not on this forum! Most are extremely skeptical and only end up doing it because curiousity gets the best of them. Most hit the chair after doing the swap completely expecting their BS meters to peg.

"I believe (never checked) that parts replacement does improve the sonic. Thats why (intuitively) top notch (aka hi-fi) amplifiers use high quality parts, and IMO the crossover is no exceptional."

Well, we agree on that point.

"The interesting point here is why so many people want their crossover upgraded - If I get new speakers which I like and enjoy I wouldn't want their crossover modified. As far as I know, It's not such a common notion in the stereo world (to new speakers whatsoever)."

Sure, if you like and enjoy them the way they are you should leave them alone.

After doing the swap for a room full of people, A. Colin Flood, a reviewer for enjoythemusic.com said:

"At the ARK gathering (May 2004), DeanG first played an obnoxious Led Zeppelin recording, where Robert Plants voice drove the refined older ears from the room. It grated the ears, ringing like a large bell, and sounding like hiss. Then Dean installed his larger crossovers in Streams RF7s. This made a huge difference in the smoothness of the mid-range, but also the treble. Cymbals sounded like metal, NOT hiss. The mid-bass didnt seem larger to to me in that brief glimpse, but it did seem to extend lower a bit better. The group that left, returned; the easy consensus was that the new larger crossovers made a significant difference. NOT as startling as a different amplifier or adding a sub-woofer perhaps, but a definite refinement. If the harshness or brightness of the RF-7s are bothering you, this is certainly one solid improvement."

[prego]

POST ERASED

mndeem is correct

No need to cross the fence. as said, I think I've made my point.