Scan- Speak 18W8531G

A Stone · « **on:** 26 Jul 2007, 10:33 am »

This question has probably been asked previously but I couldn't find it. However, I would like to know if you ever tried the Scan-Speak 18W8531G as a woofer in the "1801"? At least on paper it appears to be ideal. The unit has good low end extension, excellent distortion specs, and extended frequency response with minimal breakup. (This of course is theory, I have never heard it)

WEEZ · « **Reply #1 on:** 27 Jul 2007, 11:20 pm »

Dave,

I'd be interested to know your 'take' on this also....

WEEZ

JoshK · « **Reply #2 on:** 27 Jul 2007, 11:50 pm »

I know some "purists" say that the 800hz impedance glitch means that the cone has some break-up at this point which means it isn't pistonic up to the point of xo, which is why some don't like it or choose others. It may just be a reflection from the surround from what I gather, but the criticism does merit a response/further looking. Its a nice driver none-the-less but this breakup, if it is that, might be why it isn't as "resolving" as the excels, as some say.

DSK · « **Reply #3 on:** 28 Jul 2007, 02:42 am »

I think it comes down to the implementation and skills of the speaker/xo designer. Unfortunately, many people see "ScanSpeak" or "paper" and automatically respond with "warm" and "unresolving" with no real personal experience of the particular driver model in question ... they are just repeating what they have heard from others who often have no real personal experience either (Chinese whispers anyone?). I can't say I've heard many different ScanSpeak driver models, but I have heard the Excels and I have been listening to Selah's SSR's for the last 10 months. Based on all the ScanSpeak hearsay, I actually expected the SSR's to sound a little warm and smooth and not be the last word in detail. However, they have proved to be true chamelions and their sound readily changes character with gear changes. Actually, sometimes I think a little more warmth would be nice. These speakers actually highlighted a couple of small weaknesses elsewhere in my system that I was able to resolve for even better sound. My previous speakers were ribbons that are known to be very detailed but they masked these issues and were clearly not as resolving (or dynamic) as the SSR's which also sound more natural to me than the Excels.

I'm not saying that the SS 8531G is a better or worse driver than the Excel, I am just saying that it all comes down to the particular implementation and personal taste. However, before ignoring the 8531G because you have read somewhere that it is "warm" or "unresolving" (because it is a ScanSpeak), try to hear it somewhere for yourself (and in as many different speakers as possible). You might just prefer them.

BTW ... Here is the impedance plot of the 8531G in the SSR http://www.selahaudio.com/id127.html. The miniscule blip at 800 ohms doesn't appear too troublesome. (Note that I have no speaker/xo design experience though). I am using the sealed version of the SSR (with a sealed sub at ~65Hz) running full range and although I have some HPF's in a drawer somewhere, I have not felt the itch to use them on the SSR's as they remain so clean and detailed without congestion even when cranked pretty loud in a large-ish room.

PS. None of these comments are directed at anyone in particular, like Josh for example. For all I know he may have a wealth of personal experience with these drivers and have different personal tastes and points of reference etc etc and drawn different conclusions. If so, that is fine and differences of opinion are useful to the reader.

Vapor Audio · « **Reply #4 on:** 28 Jul 2007, 04:55 am »

Anybody who's biased against a Scan 8531 because of an impedance curve obviously spends their time pontificating instead of working to gain any relevant experience. From what I gather, you're not one of those misguided "purists" JoshK. Fact is, one has no idea if that 800hz blip is a cone resonance unless you have a 30000 frame per second hi-res cameras recording cone movements, like Harman references many times in the white papers about development of their CMMD cones.

Pistonic is just another one of those internet buzz-words tossed around by forum pundits. Sure in theory it could be beneficial to have a speaker system remain pistonic throughout it's entire range, but since there probably isn't a speaker system in existance that does, it's obviously not that bit a deal

MikeyMouse · « **Reply #5 on:** 30 Jul 2007, 08:09 am »

Let me provide 3 more data points for this discussion:

1. I like the SS 18W-8531 paper cone speaker, in fact I am using 16 of them in my new Selah Audio line arrays. These mid-woofers used in this configuration have excellent bass performance and smooth and detailed midrange. They reproduce the sound of musical instruments accurately; in particular the sound of cello, trumpet and violin.

2. John "Zaph" Krutke did some tests on a group of 6.5 to 7" drivers, the SS 18W-8531 is among the best in this group. See:

http://zaphaudio.com/6.5test/

3. This may not be directly relevant as the design could be different. Even, Sonus Farber used a 6" SS paper cone midrange in their latest Elipsa speakers.

-Mikey

Kris · « **Reply #6 on:** 30 Jul 2007, 07:22 pm »

I own the SSR and the SEAS W15CY001+OW1. Both excellent monitors, the SS8531 is a little warmer, but also more enjoyable and engaging and the spatial image is larger, i guess due to 7" driver.
The 5.5" seas is neutral, accurate, with sharp pinpoint imaging and excellent resolution. As a whole, the smaller seas is darker, seemingly more balanced , easier for long listening sessions. The ssr is brighter, with more palpable and organic-liquid sound.
I'm happy i don't have to make a choice, as i enjoy both of them every day. It goes to show that in hi-end audio, you reach a point where (no) easy choice can be made, and personal preference is more important than specs or measurements.

PaulHilgeman · « **Reply #7 on:** 30 Jul 2007, 08:57 pm »

The 8531 is an awesome driver, but if it were used in the 1801, it wouldn't be an 1801 anymore!!! I think Dave would agree with both of those points.

-Paul

WEEZ · « **Reply #8 on:** 30 Jul 2007, 10:31 pm »

...8531-01?

BrianM · « **Reply #9 on:** 30 Jul 2007, 10:53 pm »

Quote from: PaulHilgeman on 30 Jul 2007, 08:57 pm

The 8531 is an awesome driver, but if it were used in the 1801, it wouldn't be an 1801 anymore!!! I think Dave would agree with both of those points.

-Paul

Considering he's abandoning the W18, I'd say this bird has flown. I think it's time for a name-that-speaker contest.

WEEZ · « **Reply #10 on:** 30 Jul 2007, 11:14 pm »

Who's abandoning the W18?

WEEZ

opnly bafld · « **Reply #11 on:** 30 Jul 2007, 11:34 pm »

Quote from: WEEZ on 30 Jul 2007, 11:14 pm

Who's abandoning the W18?

WEEZ

http://www.audiocircle.com/index.php?topic=40349.0

Start of 2nd paragraph.

Lin

WEEZ · « **Reply #12 on:** 30 Jul 2007, 11:43 pm »

Lin...yeah, I had read that. But I thought I read somewhere else that the 1801c would be offered in addition to the 1801b...can't find where..

WEEZ

opnly bafld · « **Reply #13 on:** 30 Jul 2007, 11:50 pm »

Quote from: WEEZ on 30 Jul 2007, 11:43 pm

Lin...yeah, I had read that. But I thought I read somewhere else that the 1801c would be offered in addition to the 1801b...can't find where..

WEEZ

You are right.
http://www.audiocircle.com/index.php?topic=42586.0

See Dave's comments- 2nd paragraph.

Lin

WEEZ · « **Reply #14 on:** 31 Jul 2007, 12:45 am »

Whew...for a second I thought my old age had got the better of me...

Thanks, Lin. Yup, that's where I read it

WEEZ

I'd still be interested to know if Dave thinks the 8531 would be a match with the OW1......Dave?

BrianM · « **Reply #15 on:** 31 Jul 2007, 12:07 pm »

Ok, technically not "abandoning" it entirely, but he did say the C would replace the B in his own living room.

David Ellis · « **Reply #16 on:** 1 Aug 2007, 03:32 am »

I'm sorry about being slow in addressing this. However, the previous remarks have been very valid and accurate. I don't really see anything that I disagree with. There are certainly several areas of these topics that could be addressed, but I will address what appear to be the most prevalent queries regarding MY opinion and direction.

First, I fully agree with this comment regarding the SS8531:

Quote

These mid-woofers used in this configuration have excellent bass performance and smooth and detailed midrange.

This is very true, and has always been true regarding the Scanspeak 7" midwoofers. They are THE benchmark for bass performance among 7" drivers. In my few commercial auditions with the newer Scanspeak midwoofers, this continued to be true, but the midrange was slightly too mushy for me. It was very smooth, but lacked the detail and transparencey I seek. Nonetheless, the Scanspeaker midwoofers are very pleasing and the ACI Jaguar was a sublime implementation with the SS8545

. My very first DIY speaker was a Dennis Murphy crossover installed in one of Rick Craig's (Selah Audio) kits using the SS8545 and SEAS T25 tweeter. This speaker was called the STS. Here is a photo of this speaker from about 6 years ago:

Yes, it was very good. I built several pair of these speakers for local friends and lived with the STS for about 2 years. But the Scanspeak transparency remains lacking when compared to the SEAS W18. IMO, the only way to get the the SS midwoofer bass quality and the SEAS W18 midrange quality is via the Accuton C95. I now understand why folks pay a profound quantity of money for a 2-way Kharma speaker using the Accuton 95.

My only caveat that I should probably offer is that I haven't heard the SS8531 in a good 2-way DIY application. I have only auditioned this driver in a 2 commercial speakers. One was an MTM and the other was a 2-way. IMO, a good DIY implementation will most often sound superior to a good commercial implementation. I believe many average price commercial crossover designs are quite hasty in an effort to reduce R&D cost. Please for a moment imagine the cost of paying Dennis Murphy for 5,10, 50, or 100 hours of his time. Dennis has a PH.D. (very smart) and 30+ years of experience. I believe his "real" fees should be on par with Joe D'Appolito. I also believe part of this problem is quality control. Measuring a completed speaker is very important. My guess it that I make some sort of mistake in about 5-10% of speakers. A more significant factor are driver changes across production runs and rubbing voice coils (especially in tweeters). Most DIY folks spent significant time with their speakers in the design process and can isolate/eliminate the quality control problems.

Anyhoo, I am rambling. At the root of my response to the initial query regarding my desire for the the SS8531 is the sentiment... it's not going to happen. While it's a very good driver, I prefer more midrange clarity. And, candidly, following my few commercial auditions with the SS8531, I like the sound of the older SS8545 better.

Quote

Lin...yeah, I had read that. But I thought I read somewhere else that the 1801c would be offered in addition to the 1801b...can't find where..

Yes, I will continue to offer the 1801b with the SEAS W18 driver.

My initial adventure with the 1801 was rooted in my personal desire to have a speaker with better midrange and clarity than the STS. I built this speaker for ME. I will also build the 1801C for ME. In both cases, if other folks want to purchase the parts or a completed speaker I will be glad to share the experience.

Quote

I like the SS 18W-8531 paper cone speaker, in fact I am using 16 of them in my new Selah Audio line arrays

Wow, that's a wallop of a speaker and must be quite expensive! It should also be reasonably sensitive. Have you tried a low power SET?

Quote

Anybody who's biased against a Scan 8531 because of an impedance curve obviously spends their time pontificating instead of working to gain any relevant experience.

Yep, I generally agree.

Quote

I know some "purists" say that the 800hz impedance glitch means that the cone has some break-up at this point which means it isn't pistonic up to the point of xo, which is why some don't like it or choose others.

This is on the fringe of my knowledge, but I will offer another possibility. This is really only a guess with some foundation. At about 1000 hz there will be ripple when using a soft cone IF the surround is too forgiving/squishy. The hardness of rubber is often conveyed with a durometer measurement. Race car drivers will often use a durometer to test the hardness of their tires. It measures how soft/hard the rubber really is. Anyhoo, a soft cone on a loudspeaker must have a surround that sufficiently damps the edge cone resonance. If this doesn't happen, the edge of cone will eventually get "whiplash". The edge of the cone will move in the opposite direction of the center of the cone. The result is a pinch-point that significantly restricts cone movement. I have seen this in a few lesser drivers over the years. However, a very good implementation with a surround will nicely accommodate the cone edge resonance, but MAY (I really don't know) create a small impedance ripple because that cone edge control provides feedback to the motor when resisting the cone edge whiplash. Perhaps those little slits in the cone aren't really a "free-lunch", and necessitate further accommodation in the form of a stiffer surround. So, my guess is that this impedance peak is NOT due to a cone resonance, and MIGHT be due to an engineered necessity in the surround. In any event, this small impedance ripple isn't a valid reason to avoid the 8531. Regardles of the reason, the 8531 is a very good driver.

There appears to be a very small blip in these graphs too:

http://www.seas.no/Prestige%20Basser%20PDF/CA18RLY-H1217-08.pdf

http://www.seas.no/Prestige%20Basser%20PDF/CD22RN4X-H1192-08.pdf

http://www.seas.no/Prestige%20Basser%20PDF/CA26RE4X-H1316-08.pdf

http://www.tymphany.com/datasheet/printview.php?id=126

The plot for the SS8531 doesn't really look like anything to be worried about.

http://www.tymphany.com/datasheet/printview.php?id=85

I will state for the record that stiff cones WILL have a cone resonance. All other cones flex. This is simply because the resonating energy inside the cone will either bounce ( stiff cone ) or be absorbed ( flexible cone ). This resonating energy will generally pile-up inside the cone when the 1/4 wavelength is short enough. A quick glance at the SEAS W18 and Accuton C95 graphs will convey this similarity.

W18 Waterfall via LspLab:

C95 from www.soniccraft.com:

The older SS8545 did have a minor cone resonance at 2600hz and some other artifacts at higher hz according to Dennis Murphy.

And, for what it's worth, I prefer a the sound of a very well implemented paper cone driver over all the other flexible materials that appear more High-Tech. Paper cones can be very good and have very good resolution. It is completely unfair and unreasonable to group ALL paper cones into a "muddy sound" category" - especially when compared to their other flexible cone peers. I have been a long-time fan of the older Vifa M18 driver. This was a darn good paper cone driver IMO. Many folks called this driver the poor-man's SS8545 and I agree with this sentiment.

Whew, that became somewhat long. It's time for me to get some sleep.

I am going on vacation. My attendance to this topic will likely be very sparse until @ 15 August.

Dave

David Ellis · « **Reply #17 on:** 3 Aug 2007, 04:17 pm »

I don't recall having read anything definitive on this subject, but was thinking about my post above further and realized there is significant room for misunderstanding. This is because the term "cone resonance" is perhaps overused.

My assertion herein is that there is or should be a definitive difference between cone resonance and air resonance inside the cone. Unfortunately there really isn't a clear black & white dividing line separating them. Hmmm, I should probably toss this idea to the masses on the current active speaker discussion board. But, since the issue was initially posted here, I will respond here.

First, all quarter wave instruments will create an air resonance depended up on the length of the pipe. This is true regardless of the pipe materials. The pipe WILL create an air resonance. Certainly the pipe construction will color the resonance, but even very inert materials will create a resonance. These very inert materials are not often found in instruments. They are found in loudspeaker Transmission Lines.

Inert materials are also ideal for loudspeaker cones, but even the most inert & stiff materials will eventually generate an air resonance inside cone. Even though the cone is not moving/vibrating due the air pressure, the air inside the cone IS resonating. // I fully realize that an extreme level of testing would be required to fully support my assertion. I don't have the equipment necessary to fully accomplish this test. I can only offer what has already been conveyed above via the waterfall plots.

Alternately, most cones will flex to some degree. When this happens, the dampening of the cone must be very good to accommodate this "cone resonance". The cone must have internal shock absorbers to address this movement, or some really ugly stuff will happen. I believe this is where paper cones really perform well. Paper is very well damped internally and has very good shock absorbers.

However, the hook in my clearly defined division between air resonance and cone resonance is that the AIR effects movement in the CONE. Hence, if the cone flexes should it be called an Air Resonance or a Cone Resonance ??? I am really not in a position to make an authoritative definition of the matter. However, it really appears that if the cone moves, the artifact should be called a cone resonance, and if the cone doesn't move, it should be called an air resonance. I wish to offer this food for thought on the matter because those really nice smooth sounding paper cones actually experience a cone resonance in the audible pass band. And, those frighteningly stiff Accuton cones don't.

Folks seem to make much adieu about cone resonance, but it seems the dialogue is aimed in the incorrect direction.

Dave

Vapor Audio · « **Reply #18 on:** 3 Aug 2007, 04:35 pm »

Cone resonances are almost ALWAYS called such incorrectly, that's because unless you have (like I mentioned earlier) one of those uber-expensive, super slow-mo, mega high-res cameras to watch cone movements you're speculating as to the cause of any irregularities.

As far as what you're trying to convey about air resonances, I don't get it. Are you talking about the air inside the pole? That's all I can think of ... unless you're meaning some sort of cavitation effect off the front and back of the cone face as it travels through the air.

jgb0194 · « **Reply #19 on:** 4 Aug 2007, 05:30 pm »

Hi Dave,

I greatly respect your knowledge and experience. Do you find that perceived midrange dynamics, detail and clarity are also, in part, determined by crossover point/slope (turning more upper midrange over to an appropriately-selected "tweeter"), as well as # of drivers used (single/mtm/array - does a more limited cone excursion "demand" matter?) indepedent of the intrinsic qualities of any given midbass driver?

Your comments and those of others on this forum are, as always, much appreciated.

John