Softer surrounds provide less damping of the resonance modes of the aluminum cone. The choices of the components all interact and affect other parameters. I would expect a softer more supple surround to have more breakup than a former rubber surround.
I guess I like the RS225-8 the way it is. It is a unique driver and I have not found an equivalent performing one by another manufacturer, at any price. I like it’s sound and enjoy the synergy it has with full range drivers as a mid tweeter.
If you have a suggestion for another 8in woofer with a flat response from 100Hz to 2kHz, and relatively low distortion and 7mm+ of Xmax, let me know.
I guess I like the RS225-8 the way it is. It is a unique driver and I have not found an equivalent performing one by another manufacturer, at any price. I like it’s sound and enjoy the synergy it has with full range drivers as a mid tweeter.
If you have a suggestion for another 8in woofer with a flat response from 100Hz to 2kHz, and relatively low distortion and 7mm+ of Xmax, let me know.
Me, I would love X to try the 5x8 SB15, as it lets one do a narrower baffle that may help with imaging from the 10F. Being narrower (but deeper), it could also be easier to put in a living room and accepted (WAF). The 5x8 performs very well in a MLTL.
https://sbacoustics.com/product/5x8in-sb15sfcr39-8/
https://sbacoustics.com/product/5x8in-sb15sfcr39-8/
I've just bought a pair of the SB20. I plan to drop them into my Ref Monitors just out of interest. They will go in the baffle recess which is a bonus . I simmed it in winisd and it doesn't go as low for a given volume but is 'louder'....90db efficiency. I assume it is the same beast as the 8" SB FR but minus the whizzer
That racetrack 5x8 looks nice. I wish it had a cast alloy basket vs stamped steel though. The response looks smooth enough and bandwidth appears pretty good. I’ll need to get a baffle and box made to make a new XO though. The passive radiator with 1cuft box goes to 43Hz which is pretty nice. The breakup at 4kHz will require a notch filter so that’s 3 more added components to the XO. But not might be worth it.
“Softer surrounds provide less damping of the resonance modes of the aluminum cone. I would expect a softer more supple surround to have more breakup than a former rubber surround.”
Well, not really.
Here are some quotes I just picked from the www for you:
“From a driver engineer's viewpoint, foam is almost ideal, extremely compliant with high damping... rubber - most popular being Santoprene and butyl - lacks foam's damping potential”. -(stonessoundstudio.com.au)
A rubber surround may sound "dead" in the upper mids (too much damping, which impedes the response at upper midrange frequencies.
“With an aluminum cone a foam surround showed a better damped resonance and gave a flatter response than a rubber surround did.” - Jensen driver designer
“Butyl rubber has also proved popular with dense, heavy coned pulp cone drivers. For lighter grade cones, foamed polyurethane works well”- excerpted from Colloms and Darlington explaining how the surround functions.
Though many hate to admit it, foam is the acoustically superior surround material, with some few exceptions. Luckily in recent years we have foamed rubber replacing polyurethane foam.
In the end however it's the measurements that determine if a foamed rubber surround is what you need. Some samples will tell you.
“I guess I like the RS225-8 the way it is.”
If in your opinion the RS225-8 is the perfect driver that cannot further be improved then why would you ask for a better alternative?
In my contacts with engineers from Scan-Speak, Seas, Thiel & Partner, the chief engineer from Quadral and some other firms, one thing became quite clear: aluminium formers are second best, they all said so. I mentioned the reasons in my previous email and these make sense. Aluminium is simply often used out of cost effectiveness and less risk of overheating, that's it. And again, just look at what these companies use in their more expensive drivers; that's not aluminium. Like Dipl.-Ing. Charles Altmann (ALTMANN MICRO MACHINES (haan.de)) once wrote me: “ aluminum voice-coil is the worst you can do to a speaker.”
That you like the RS225-8 is fine and I guess it's not a bad compromise indeed. But that doesn't mean it cannot be improved upon. And like I said, these modifications are fairly simple and thus wouldn't drive you into high costs.
“If you have a suggestion for another 8 inch woofer with a flat response from 100Hz to 2kHz, and relatively low distortion and 7mm+ of Xmax, let me know.”
No need to tell you, it's all about the compromise; we can't change the laws of Physics. I guess I'm willing to make somewhat different tradeoffs then you. Those 7 mm linear aren't the holy grail for me. Great dynamics and less distortion at the expense of playing less low is perfectly fine with me. I don't regard an 8” as a subwoofer anyway.
Well, not really.
Here are some quotes I just picked from the www for you:
“From a driver engineer's viewpoint, foam is almost ideal, extremely compliant with high damping... rubber - most popular being Santoprene and butyl - lacks foam's damping potential”. -(stonessoundstudio.com.au)
A rubber surround may sound "dead" in the upper mids (too much damping, which impedes the response at upper midrange frequencies.
“With an aluminum cone a foam surround showed a better damped resonance and gave a flatter response than a rubber surround did.” - Jensen driver designer
“Butyl rubber has also proved popular with dense, heavy coned pulp cone drivers. For lighter grade cones, foamed polyurethane works well”- excerpted from Colloms and Darlington explaining how the surround functions.
Though many hate to admit it, foam is the acoustically superior surround material, with some few exceptions. Luckily in recent years we have foamed rubber replacing polyurethane foam.
In the end however it's the measurements that determine if a foamed rubber surround is what you need. Some samples will tell you.
“I guess I like the RS225-8 the way it is.”
If in your opinion the RS225-8 is the perfect driver that cannot further be improved then why would you ask for a better alternative?
In my contacts with engineers from Scan-Speak, Seas, Thiel & Partner, the chief engineer from Quadral and some other firms, one thing became quite clear: aluminium formers are second best, they all said so. I mentioned the reasons in my previous email and these make sense. Aluminium is simply often used out of cost effectiveness and less risk of overheating, that's it. And again, just look at what these companies use in their more expensive drivers; that's not aluminium. Like Dipl.-Ing. Charles Altmann (ALTMANN MICRO MACHINES (haan.de)) once wrote me: “ aluminum voice-coil is the worst you can do to a speaker.”
That you like the RS225-8 is fine and I guess it's not a bad compromise indeed. But that doesn't mean it cannot be improved upon. And like I said, these modifications are fairly simple and thus wouldn't drive you into high costs.
“If you have a suggestion for another 8 inch woofer with a flat response from 100Hz to 2kHz, and relatively low distortion and 7mm+ of Xmax, let me know.”
No need to tell you, it's all about the compromise; we can't change the laws of Physics. I guess I'm willing to make somewhat different tradeoffs then you. Those 7 mm linear aren't the holy grail for me. Great dynamics and less distortion at the expense of playing less low is perfectly fine with me. I don't regard an 8” as a subwoofer anyway.
I think that people with audio as a hobby have the most compromises of all hobbies!
We have to compromise on sound, on space, on size, and for some of us, with the significant other!
So, I guess that's why we are always looking at things to get better and have a few less compromises. Hence X's comment about driver suggestion.
Same as my post about the racetrack driver. It has a peak at 4kHz, so might be harder to implement using 1st order XO. But it allows for a much narrower enclosure, which was a factor to get them accepted by my wife! And in a MLTL, they easily dig down to the mid 30Hz, which for many people, is low enough and won't need subwoofer support. Not me thought! I like subs! From deep organ notes to movies. 😀
We have to compromise on sound, on space, on size, and for some of us, with the significant other!
So, I guess that's why we are always looking at things to get better and have a few less compromises. Hence X's comment about driver suggestion.
Same as my post about the racetrack driver. It has a peak at 4kHz, so might be harder to implement using 1st order XO. But it allows for a much narrower enclosure, which was a factor to get them accepted by my wife! And in a MLTL, they easily dig down to the mid 30Hz, which for many people, is low enough and won't need subwoofer support. Not me thought! I like subs! From deep organ notes to movies. 😀
Hi Lucas,
Thanks for your suggestions and I will keep them in mind. If you have an existing commercial driver with a foamed-rubber surround you would like to suggest, I am all ears. I do have one question for you - have you ever listened to this 10F/RS225 FAST speaker with the RS225-8 woofer? Are you making suggestions that the woofer can be improved simply based on specs of the construction? The speaker is a synergistic system of cabinet, alignment, drivers and crossover. I can tell you that this speaker, using a very humble and under-spec'd aluminum former, rubber surround driver is one of the best I have heard. The ScanSpeak 10F/8424 is arguably one of the finest full range drivers/midranges and it also has a rubber surround.
I have used the Purifi 6.5in woofer before. It’s very nice and well controlled and smooth. It’s got about the same bass output as an 8in woofer since it can move so much. But at $388, I could buy 6 RS225’s for the price of one. Purifi uses a special crinkled rubber surround (NBR).
A woofer I like very much that has a linear motor and measures well is the XBL aluminum cone 6.5 designed by Dan Wiggins. I used one on the new Statement 100 speaker that I designed.
Notice the very low levels of distortion. This is only at 2.0vrms but still beats many other drivers. The peak at 2kHz is the usual bell-mode resonance distortion often seen in aluminum drivers of this size.
Sorry, it’s also got a rubber surround.
Perceval might like this, it’s got a 5x8 racetrack passive radiator on the back.
Thanks for your suggestions and I will keep them in mind. If you have an existing commercial driver with a foamed-rubber surround you would like to suggest, I am all ears. I do have one question for you - have you ever listened to this 10F/RS225 FAST speaker with the RS225-8 woofer? Are you making suggestions that the woofer can be improved simply based on specs of the construction? The speaker is a synergistic system of cabinet, alignment, drivers and crossover. I can tell you that this speaker, using a very humble and under-spec'd aluminum former, rubber surround driver is one of the best I have heard. The ScanSpeak 10F/8424 is arguably one of the finest full range drivers/midranges and it also has a rubber surround.
I have used the Purifi 6.5in woofer before. It’s very nice and well controlled and smooth. It’s got about the same bass output as an 8in woofer since it can move so much. But at $388, I could buy 6 RS225’s for the price of one. Purifi uses a special crinkled rubber surround (NBR).
A woofer I like very much that has a linear motor and measures well is the XBL aluminum cone 6.5 designed by Dan Wiggins. I used one on the new Statement 100 speaker that I designed.
Notice the very low levels of distortion. This is only at 2.0vrms but still beats many other drivers. The peak at 2kHz is the usual bell-mode resonance distortion often seen in aluminum drivers of this size.
Sorry, it’s also got a rubber surround.
Perceval might like this, it’s got a 5x8 racetrack passive radiator on the back.
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“I do have one question for you - have you ever listened to this 10F/RS225 FAST speaker with the RS225-8 woofer?”
I haven’t.
I recently bought a couple of 10F’s. I’d like to pair it with a suitable 8” or 10” midwoofer, with a 6db filter preferably. And an ambient tweeter perhaps with Lpad, or perhaps a perpendicular placed fullrange in dipole on top or behind the speaker.
“Are you making suggestions that the woofer can be improved simply based on specs of the construction?”
Based on the construction. I never denied that the Dayton RS 8” driver has a nice flat response up to 2khz. Or that the waterfall shows a fast and even decay Except a small wrinkle, the impedance plot looks good too.
Btw, do you know if and when Dayton will upgrade the basket for a modern one with ventilated spider?
“The speaker is a synergistic system of cabinet, alignment, drivers and crossover.”
Of course, no denial.
“I can tell you that this speaker, using a very humble and under-spec'd aluminum former, rubber surround driver is one of the best I have heard. The ScanSpeak 10F/8424 is arguably one of the finest full range drivers/midranges and it also has a rubber surround.”
Don’t get me wrong, your concept is certainly appealing. But did I doubt the quality of sound or did I say there’s room for improvement of the woofer?
“I have used the Purifi 6.5in woofer before. It’s very nice and well controlled and smooth. It’s got about the same bass output as an 8in woofer since it can move so much. But at $388, I could buy 6 RS225’s for the price of one. Purifi uses a special crinkled rubber surround (NBR).”
Which further supports the thesis that upgrading the existing surround may lead to a better driver.
Resonances in the surround can be a real pain, not only in the design of the crossover, but certainly also in terms of sound, as any rapid phase shift in upper-mid/lower treble is clearly audible. Not necessarily unpleasantly, but nevertheless distortion of the music we feed our drivers. And we can only know what it does once it’s gone!
Have you noticed their PTT8.0X04-NAB-02 yet?
Or the Accuton C220-6-222? Or the Duelund Coherent Audio 8” Precision Driver? All examples of good drivers for your purpose.
It’s a challenge to find a manufacturer offering such quality for a reasonable price. When I have some time I’ll have a look, but it will be hard. An option is to have such driver made to spec in China, but you’ll need some patience. But after several prototypes you will get there for sure. Tang Band has some nice 8” standard baskets for whatever speaker you want as well.
“A woofer I like very much that has a linear motor and measures well is the XBL aluminum cone 6.5 designed by Dan Wiggins. I used one on the new Statement 100 speaker that I designed.”
Unfortunately not for sale here in Europe, as far as I know.
I haven’t.
I recently bought a couple of 10F’s. I’d like to pair it with a suitable 8” or 10” midwoofer, with a 6db filter preferably. And an ambient tweeter perhaps with Lpad, or perhaps a perpendicular placed fullrange in dipole on top or behind the speaker.
“Are you making suggestions that the woofer can be improved simply based on specs of the construction?”
Based on the construction. I never denied that the Dayton RS 8” driver has a nice flat response up to 2khz. Or that the waterfall shows a fast and even decay Except a small wrinkle, the impedance plot looks good too.
Btw, do you know if and when Dayton will upgrade the basket for a modern one with ventilated spider?
“The speaker is a synergistic system of cabinet, alignment, drivers and crossover.”
Of course, no denial.
“I can tell you that this speaker, using a very humble and under-spec'd aluminum former, rubber surround driver is one of the best I have heard. The ScanSpeak 10F/8424 is arguably one of the finest full range drivers/midranges and it also has a rubber surround.”
Don’t get me wrong, your concept is certainly appealing. But did I doubt the quality of sound or did I say there’s room for improvement of the woofer?
“I have used the Purifi 6.5in woofer before. It’s very nice and well controlled and smooth. It’s got about the same bass output as an 8in woofer since it can move so much. But at $388, I could buy 6 RS225’s for the price of one. Purifi uses a special crinkled rubber surround (NBR).”
Which further supports the thesis that upgrading the existing surround may lead to a better driver.
Resonances in the surround can be a real pain, not only in the design of the crossover, but certainly also in terms of sound, as any rapid phase shift in upper-mid/lower treble is clearly audible. Not necessarily unpleasantly, but nevertheless distortion of the music we feed our drivers. And we can only know what it does once it’s gone!
Have you noticed their PTT8.0X04-NAB-02 yet?
Or the Accuton C220-6-222? Or the Duelund Coherent Audio 8” Precision Driver? All examples of good drivers for your purpose.
It’s a challenge to find a manufacturer offering such quality for a reasonable price. When I have some time I’ll have a look, but it will be hard. An option is to have such driver made to spec in China, but you’ll need some patience. But after several prototypes you will get there for sure. Tang Band has some nice 8” standard baskets for whatever speaker you want as well.
“A woofer I like very much that has a linear motor and measures well is the XBL aluminum cone 6.5 designed by Dan Wiggins. I used one on the new Statement 100 speaker that I designed.”
Unfortunately not for sale here in Europe, as far as I know.
Finally got my TLs done to the point of listening – nice 😊 Great to have something sound so good straight off the mark !
At first they sounded way too bright to me, but over a day or so my “learned hearing memory” adjusted & I realised the 3ways I did a coupled of years ago had the mid/highs rolled off way too much in comparison. Adjusted 3ways & now have a much more interesting comparison on my hands.
ATM I haven’t adjusted the TLs at all. Curiously I got Z plot lower peaks around the 21-22R region with no stuffing apart from the “ball” at the bottom of the line. I’ve started with 12g in the cones for the B80 & will experiment with more. Sorry now I didn’t break out 2 wires to shunt the series B80 atten resistor for easy adjustment. (currently 1.65R for a 0R22 XO inductor – XO board screwed into rear top side)
Thanks X for a very interesting and high quality build !
At first they sounded way too bright to me, but over a day or so my “learned hearing memory” adjusted & I realised the 3ways I did a coupled of years ago had the mid/highs rolled off way too much in comparison. Adjusted 3ways & now have a much more interesting comparison on my hands.
ATM I haven’t adjusted the TLs at all. Curiously I got Z plot lower peaks around the 21-22R region with no stuffing apart from the “ball” at the bottom of the line. I’ve started with 12g in the cones for the B80 & will experiment with more. Sorry now I didn’t break out 2 wires to shunt the series B80 atten resistor for easy adjustment. (currently 1.65R for a 0R22 XO inductor – XO board screwed into rear top side)
Thanks X for a very interesting and high quality build !
Attachments
Peerless by Tymphany TC9FD18-08 3-1/2" Full Range Paper Cone Woofer
ScanSpeak Revelator 22W/8857T-00 8" Woofer, Aluminum Cone
(2) cross-over looks better.
TC9 is down an extra 12 dB at 100-200 Hz.
22W looks better also.
FRD and ZMA files are attached to this post.
IN XSIM -- 22W "mod sensitivity" is 21.25 dB
IN XSIM -- TC9 "mod sensitivity" is 25 dB
Took me 100's of tries to create these.
Mainly the graphs Y axis scale was off when transferring from FPtrace, so I kept having to redo FPGraph tracing.
Also I had to use a lot of photoshop for the 22W graphs, so FP trace would trace the FR correctly.
FR curves look pretty spot on, impedance are close enough.
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Wow that’s a lot of work. Can you show a crossover curve with woofer, tweeter, and system on same graph?
If you build it, show us the measurements. I've been usng SS drivers for over fourty years, crossovers built from their measurements are never more
than vaguely related to the finals.
I think they measure prototypes, and publish that. Or there is some parameter that's different, and not mentioned.
than vaguely related to the finals.
I think they measure prototypes, and publish that. Or there is some parameter that's different, and not mentioned.
Please go ahead and post your complete speaker designs.
I never can design a good XO using published FRD files. The measurement needs to be made in one’s own actual baffle and own ZMA curve to be truly accurate. The FRD files give an idea of where the curve falls off etc. - the intrinsic limitations.
I was wondering how to do that after I made the post. I don't know.
I actually I don't and can't do speaker measurements anymore.
I don't think even changing the woofer matters, that much. See graphs.
You can literally drop in different woofers without changing cross-overs, nevermind measuring the woofers myself.
One of the reasons I actually made the graphs to show that putting in a different woofer (or FR graph) doesn't change the response that much.
Some "audiophiles" say that caps sound different? Do they?
One time I thought I heard the difference in different speaker cables? Did I?
I don't meet to many "audiophiles" that don't seem to be psychotic.
But most people are like that.
I have a theory that being delusional is part of the human condition, if you will, lol
In xsim you can add a curve trace, S1, S2, etc. I like to use green for tweeter and red for woofer and blue for mid and black for combined system.
Changing woofers certainly matters. They have different response smoothness, breakup frequency, distortion levels and peaks, TS parameters like Vas, Qts, Fs, Xmax, Le, Re, all affect the response. Aluminum vs paper vs fiberglass vs plastic cones all sound different. It matters a lot more than changing cap brands in a crossover.
Changing woofers certainly matters. They have different response smoothness, breakup frequency, distortion levels and peaks, TS parameters like Vas, Qts, Fs, Xmax, Le, Re, all affect the response. Aluminum vs paper vs fiberglass vs plastic cones all sound different. It matters a lot more than changing cap brands in a crossover.
I understand we're all striving for perfection in a field that doesn't really matter too much.
However I have been listening to my TV speakers for 20 minutes one time, thinking the DIY speakers I built sound really good.
So will measuring my drivers help me make a better cross-over? Maybe.
Why is it a had Bose 301's that sounded better (to me) than my Usher 9950-8948a 2-way speakers I bought from Joe D'Appolito himself?
Actually as he was nice enough to measure them for me in his house; I told him that I was not interested in that as soon as he started.
See if you do blind A-B testing and people say the Bose 301 is a better speaker than the Usher 2-way, the Bose is a more-liked (better) speaker, no matter what your graphs say, that's what science is.
Some variables are duration of the test/experiment, how much can the people move, volume, room, etc.
I'm more concerned with the type of screws I use than if my caps are 2.2 uF or 3.3 uF.
If my router hole is off by .3 mm it's a mile (km) for me.
Instead of hating Bose 100%, just hate them 80%.
Want to improve your FAST, build this:
In some seriousness, I do like the Bose swivel cube design.
However I have been listening to my TV speakers for 20 minutes one time, thinking the DIY speakers I built sound really good.
So will measuring my drivers help me make a better cross-over? Maybe.
You know what would make this speaker "better" and you would be able to hear it?
And would alter your beloved graphs (I like graphs too, spend less time looking at them, if you can) significantly, including getting rid of the (annoying?) rising top end response of your 10F and TC9 (FR better than 10F?)?
While improving the off axis frequency response, even in the bass woofer section(lower x-over possible)?
Adding a second 3 inch driver 30-60 degrees (or some other angle?) off axis to the other 3 inch driver.
You ever notice a 3 inch driver usually starts to "beam" and the SPL on axis starts to go up roughly in the same region?
What do you think you should do in that situation? Measure the FR of your bass woofer?
Guess you might have some lobing / other effects. Plus ruin the point source, whatever that means.
Now do I want to make a baffle to accommodate that? No, I don't, just like I don't want to do a lot of other things.
You can confirm online that people who have measured the ScanSpeak 22W, aluminum, paper, 8 ohm, 4 ohm, they don't get much different results than ScanSpeaks published FR, in my humble opinion (as "audiophiles" say).
Certainly won't affect your cross-over design, especially in this design.
Why is it a had Bose 301's that sounded better (to me) than my Usher 9950-8948a 2-way speakers I bought from Joe D'Appolito himself?
Actually as he was nice enough to measure them for me in his house; I told him that I was not interested in that as soon as he started.
See if you do blind A-B testing and people say the Bose 301 is a better speaker than the Usher 2-way, the Bose is a more-liked (better) speaker, no matter what your graphs say, that's what science is.
Some variables are duration of the test/experiment, how much can the people move, volume, room, etc.
I'm more concerned with the type of screws I use than if my caps are 2.2 uF or 3.3 uF.
If my router hole is off by .3 mm it's a mile (km) for me.
Instead of hating Bose 100%, just hate them 80%.
Want to improve your FAST, build this:
In some seriousness, I do like the Bose swivel cube design.
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