Gosh, we are twins separated at birth.
A good portion of the loudspeaker posts use REW. Bit of a learning curve. For any old timers (ahem, ahem) who traced dots on graph paper labouriously, you will find REW ASTONISHING. You'll love the fast-Fourier real time analysis of your recordings. THD. Etc.
For comparative testing, all you need is a piece of chalk to mark test locations and your laptop mic. But for $70, easy to find mic with downloadable calibrations, no kidding.
I use a phantom-powered unit (in preference to turn-key USB models) together with a second-hand mic mixer with phantom power (over 300,000* available cheap on Craigslist from frustrated amateur DJs). Gives me a lot of flexibility. And a boom mic stand, about $20 (or $5 on Craigslist).
B.
* estimated
Last edited:
GREAT! Thanks, good to know! Old; HAH, with a little practice; I could still design vacuum tube circuits with a slide rule! I still use no. 2 lead pencil, hand calculator and graph paper! I LIKE it that way actually! Mid 60's is a good time for brain exercises; I try to do math in my head also. Too many members of my family (parents, grandparents, aunts, uncles...BOTH sides!!!) got dementia and Alzheimers; so I want to keep my brain jogging daily...
What about the measurement stuff at Parts Express? I don't need a woofer tester; just basic equipment and software as you mention above.
Thanks again!
Cheers to the older HiFi nuts out there among you!
Hi,
You can get an external soundcard device USB connected to a pc or laptop. around 40 euros brandnew for basics or second hand like best brands like EMU (Ebay is your friend). Best is if this little box has enough power with a phantom pc option for the mic. Be carefull to the driver compatibility of the external soundcard and the OS of your computer.
You can get an external soundcard device USB connected to a pc or laptop. around 40 euros brandnew for basics or second hand like best brands like EMU (Ebay is your friend). Best is if this little box has enough power with a phantom pc option for the mic. Be carefull to the driver compatibility of the external soundcard and the OS of your computer.
Glad you asked actually. As I said earlier; I think a pair of the 6 inch CAC 8 Ohm drivers in parallel with a good mid and a good tweeter would make for a very nice slim, smaller tower. I haven't heard the smaller units yet but I have them in mind for a future project. All SB, all CAC with twin 8 inch or twin 6 inch plus 1 CAC mid and 1 CAC tweeter. Maybe the 15's would be a better match for the 8 inch and the 12's would be a better match for the 6 inch...Just an educated guess...Anyone???
PE a big favourite on this forum and their calibrated mics are widely used. But flat enough that the calibration adjustment hardly matters.
Hooray for old.
B.
I haven't heard in person the aluminum cones but my very best guess is that the Ceramic treated cones are much better behaved and have better control on the input signal. Essentially; the CAC are most likely more accurate and portray the incoming signal with less distortion because even a minimum amount of critical dampening hard cones can make a HUGE difference. Left untreated in some way, hard cones usually ALWAYS have very severe break-up modes. If these modes are well above the X/O point then it becomes a minor issue. If the break-up modes are within 2 octaves of the X/O; then there is cause for major concern. A high frequency break-up or nasty high peak of any kind can and does affect the lower frequencies in a negative manor...
The breakup on the NAC and CAC actually look roughly the same from a frequency response perspective. Just look at both their spec sheets. I've found the breakup on the SB15NAC that I used for a 2 way wasn't too bad - pretty easily handled. Not as bad as some other Al cones, probably due to the crimping on the cone surface breaking up the resonances a bit.
Good points! Yes, the curves look very similar; I was basing my comments on what others have said about the CACs. The crimping I'm sure makes a significant difference. From what I have read from many other sources; people tend to like the sound of the CACs better than the NACs. Did you do a notch with a Zobel or just maybe a steeper X/O to avoid the break-up region? I tend to prefer a shallow slope X/O without a Zobel when I can get away with it.
Thanks guys for these inputs.
If one does not want to cross higher than second order, what frequency crossover should he choose please, how much harmonics between the xo and the main break up - peak ?
Their aluminium seems good in the low dpt so, our ears are more sensible to distorsions till 100-150 hz if I understood Fletcher curve ears power response. Does ceramic distorse less than aliminium with SB Acoustic drivers ? I strongly think about HD of bass polluting the upper bass and mid dpt, basicly upon 150 hz where most human voices beginn (not barytons or tenors related whom beginn circa one octave below)
If one does not want to cross higher than second order, what frequency crossover should he choose please, how much harmonics between the xo and the main break up - peak ?
Their aluminium seems good in the low dpt so, our ears are more sensible to distorsions till 100-150 hz if I understood Fletcher curve ears power response. Does ceramic distorse less than aliminium with SB Acoustic drivers ? I strongly think about HD of bass polluting the upper bass and mid dpt, basicly upon 150 hz where most human voices beginn (not barytons or tenors related whom beginn circa one octave below)
BROMO – Sbacoustics
Read what SB themselves say here. The Ceramic is a step up in sound quality. Maybe "dampening" is not really all that is going on here!?? Let's assume it makes the cone more stiff which means less flexing thus becoming more piston like behavior. That doesn't necessarily help with break up though; just look at the nasty break up modes with the all ceramic Accutons! People mock Accuton for their cut out "ears" but I have compared the ear type (-E in the model number) to the un treated. The type with the ear are much easier to listen to and the crossover is also much less complicated. So maybe I misspoke about the ceramic coating earlier? As I said earlier, many people from other sources tend to prefer the CAC over the NAC (I have not done so myself). From what I can tell, the CAC has improved clarity vs NAC...I will now try to go back and see if I can find out where I read these different CAC descriptions from...
Read what SB themselves say here. The Ceramic is a step up in sound quality. Maybe "dampening" is not really all that is going on here!?? Let's assume it makes the cone more stiff which means less flexing thus becoming more piston like behavior. That doesn't necessarily help with break up though; just look at the nasty break up modes with the all ceramic Accutons! People mock Accuton for their cut out "ears" but I have compared the ear type (-E in the model number) to the un treated. The type with the ear are much easier to listen to and the crossover is also much less complicated. So maybe I misspoke about the ceramic coating earlier? As I said earlier, many people from other sources tend to prefer the CAC over the NAC (I have not done so myself). From what I can tell, the CAC has improved clarity vs NAC...I will now try to go back and see if I can find out where I read these different CAC descriptions from...
Looks like I put a 3rd order electrical on the SB15NAC woofer - would've been around 2kHz give or take 200 Hz if I remember correctly.
Also, aren't the CAC series basically just NAC cones coated with a thin ceramic layer? Seems like that'd make them quite a bit different from Accuton, which I understand to be pure ceramic?
As far as I know, the CAC and NAC are the same except the ceramic. There may be other differences as well. Yes, the pure ceramic Accutons are QUITE different but I was trying to make a point about stiffness relating to break up modes. I often wondered about a sandwich cone driver with a ceramic or ceramic treated metal cone with a foam middle layer and a carbon fiber composite opposite. Similar to the Morel and SB Rohacell but metal on one side; fabric on the other side. The idea would be very light, very stiff but also very well damped to minimize or eliminate ringing, break ups, etc. (i. e. pie in the sky; best of both worlds)!
You can use a second order topology circuit on the woofer, and tame that high frequency peak... if you use a small cap in parallel with the woofer inductor. I learned about this from someone on this site, but I don't remember which thread.
image 1 is the SB17CAC35-4 with no filter (just driver response). you can see the 10 dB peak between 4k and 10k.
image 2 shows a 2k crossover to an SB26CDC tweeter. You can see the woofer's response between 4k and 10k is affecting the output.
image 3 shows the same crossover, but now with a 0.33 uF cap in parallel with the inductor. you can see that it zaps the woofers high frequency peak quite well.
Xsim allows you to "tune" the value of that cap to get exactly the response you want. In this case, any value from about 0.28 uF to 0.36 uF seemed acceptable.
I wish I could remember who showed me how to use this technique, but I don't remember.
image 1 is the SB17CAC35-4 with no filter (just driver response). you can see the 10 dB peak between 4k and 10k.
image 2 shows a 2k crossover to an SB26CDC tweeter. You can see the woofer's response between 4k and 10k is affecting the output.
image 3 shows the same crossover, but now with a 0.33 uF cap in parallel with the inductor. you can see that it zaps the woofers high frequency peak quite well.
Xsim allows you to "tune" the value of that cap to get exactly the response you want. In this case, any value from about 0.28 uF to 0.36 uF seemed acceptable.
I wish I could remember who showed me how to use this technique, but I don't remember.
Attachments
I guess it wouldn't be all that hard to try... Just buy an aluminum cone driver and pull the cone out, buy some of whatever fabric or foam you want, figure out the geometry to cut the fabric/foam, and adhere it to the cone with an appropriate adhesive. Then reattach the cone to the rest of the driver.
Seems like modifying drivers tends to be where most of us in the diy community draw the line, but I have to wonder what improvements could be made on drivers without having to justify ideas to management before trying them.
Seems like modifying drivers tends to be where most of us in the diy community draw the line, but I have to wonder what improvements could be made on drivers without having to justify ideas to management before trying them.
I use the SB17CAC35 and the SB26CDC in an active system, and I am extremely pleased with the result. I use a DSP 4th order crossover at 2kHz.
The above circuit simulation was made when a friend was contemplating using the same drivers in a passive system, and I was exploring if it was feasible.
So this filter circuit is just a feasibility study, not a final crossover. I did not model the insertion loss of the inductors, or model the baffle step gain.
My experience with the CAC series drivers has been very positive. Excellent detail and clarity, they have a very "your are there" presentation.
The above circuit simulation was made when a friend was contemplating using the same drivers in a passive system, and I was exploring if it was feasible.
So this filter circuit is just a feasibility study, not a final crossover. I did not model the insertion loss of the inductors, or model the baffle step gain.
My experience with the CAC series drivers has been very positive. Excellent detail and clarity, they have a very "your are there" presentation.
Very cool Hifijim. Any idea why that cap would do that? I'd almost expect the opposite since we're basically adding a high-pass filter to the woofer, although it may be at higher frequency than the peak. At best I'd have predicted it to have no effect on the peak, and at worst I would expect it to make it worse. It's a great trick it looks like, but I'm having trouble understanding how it works 
The way the CAC series cones differ from the NAC or NBAC cones is the anodize. The CAC cones have been deeply anodized so that the anodize layer of Al2O3 is (I am guessing) about 30% of the cone thickness on both sides, leaving the inner 40% aluminum.
Al2O3 aluminum oxide has a much higher stiffness than aluminum, and SBA and other driver manufacturers claim it has higher damping, which is entirely plausible...
Nope, I have tried to puzzle that out myself. I am not a electrical engineer, so I gave up on trying to understand it... But it works...
Al2O3 aluminum oxide has a much higher stiffness than aluminum, and SBA and other driver manufacturers claim it has higher damping, which is entirely plausible...
Nope, I have tried to puzzle that out myself. I am not a electrical engineer, so I gave up on trying to understand it... But it works...
Last edited:
There are series and parallel LC and RLC circuits that can be "tank" circuits or "notch" circuits depending on how they are used. I have forgotten most of the detailed theory; guess this gives me an excuse to do reading and homework while waiting on inductor and capacitor parts deliveries expected today. My guess is the circuit has a very high "Q" that exactly cancels the un-wanted peak. In circuits, the "opposite" is a complex conjugate; that includes both magnitude and phase. To exactly cancel an un-wanted signal; both the real and imaginary parts are needed; it's not as simple as opposite polarity (-180 degrees) in a purely resistive circuit...