Crazy is right! Had a several lap ride at near racing speeds at Road Atlanta ages ago and up to that time the only high speed racer that TTBOMK didn't need to 'blip' the throttle coming out from under the bridge other than Jim Hall's (1970) 'sucker' Can Am racer. The 917 coupe was later somewhat converted to Alabama street legal and later replaced with a 936 turbo Spyder!
What an amazing once in a lifetime experience that must have been. 917 is stuff of epic legend. It won every race it entered I think until it was banned. The turbo boost knob could dial in 1200hp on tap. The whole space frame was welded aluminum tubing and the trick they used to detect a crack in the frame was to pressurize the tubular frame with air and monitor its pressure with a small gauge like a tire. Any hairline crack would show up as an air leak in the tube frame. Very clever.
Road Atlanta lap in 1970
Road Atlanta lap in 1970
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X, any chance this design morphs into an Emerald Physics KC4 in the future? The KCIII has been teased by Walter but it's not clear that it's actually available.
CanAm cars were insanely fast and dangerous, I have watched interviews and read articles, the 917 scared everyone, simply to fast.
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On another note:
Sadly I have decided to not build the XSD, just not going to work out so testing some speakers I already have for now and they are not bad at all but not DIY so I will build something like in a sealed or TL, ported, etc, slim towers most likely.
I will list the drivers in a moment 8" woofers instead of the 6.5, have the mids and tweeters as well.
Rick
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On another note:
Sadly I have decided to not build the XSD, just not going to work out so testing some speakers I already have for now and they are not bad at all but not DIY so I will build something like in a sealed or TL, ported, etc, slim towers most likely.
I will list the drivers in a moment 8" woofers instead of the 6.5, have the mids and tweeters as well.
Rick
Presumably this remains the case if you use the 8” woofers instead of the 6.5” ?
I understand this is correct. Xrk mentioned a key design parameter was keeping slot area/Sd in the 0.3 to 0.35 range. Cavity depth should be as small as drivers allow, to increase natural top end drop off point. Cavity height would also be determined by the driver dimensions.
Other than making sure there is enough space for the outward facing magnets in relation to the wings, is there a rule of thumb for how wide the front baffle should be?
I made it 12in wide because I didn’t want a very wide front profile speaker. As long as the magnets have enough clearance and don’t touch the wings. Wider can work and will give deeper bass but might change crossover design a bit. If you want to use the stock passive crossover, you will need to follow the recipe for the width.
Well I’m going off piste anyway and using 8” drivers. But I want to keep the baffle narrow so good to know the magnet space is the only limitation.
Bummed about the speaker build, just not enough room after adding 2" of insulation and wall panels, just not able to open the side door I installed that will be out front door when I build the porch for it. Also after a lot of research OB just does not seem would be a good solution for the space we have for speakers though it was my second choice. I have Edgarhorns I know would not work and was going to try them when I get them out of the back of a big storage space stacked 12 ft high, I have to hire help to unpack it. I love good horns and my highly modded ones are incredibly good, OB would be dang fine and might like better, I wanted to try both before I had to do something else. Now looking into TL, MLTL, or bookshelves and small subs, etc....I wanted to use my two ID15 subs in built in enclosures with choice one and two, now I am sure not able to either so looking into something else I can make work and I have to build them, can't just buy something, only bought a few speakers already made in the 60+ years into audio🙂
Rick
Rick
I’m going to shamelessly copy the bass section of the XSD but I want to use bigger diameter woofers and keep the width of the front baffle to the minimum width (as dictated by the required cavity spaces). However I have calculated that the front slot would then be less than a third of the SD and so I need to increase it. As stated I do not want to increase the width of the slot, so I’m left with increasing the height, H. I propose doing this by angling the lines coming off the circular cut out that forms the cavity, like this (seen from the side):
That’s fine but might as well make it a semicircle to straight walls. You want room for the cone and magnet to fit in the cavity. Or were you thinking magnet out on both sides?
No I want magnet in on one side as you have done. The partial circle will have the diameter of the cut out required for the woofer, so H will be greater than that diameter.
You can also increase the width of the slot - you may need that to allow for the magnet and basket to fit?
One thing you will have to increase is the depth from the back of the slot to front baffle exit plane. That will lower the crossover frequency. IIRC, 8in woofer will be crossing around 350Hz.
One thing you will have to increase is the depth from the back of the slot to front baffle exit plane. That will lower the crossover frequency. IIRC, 8in woofer will be crossing around 350Hz.
Yup I understand the cavity depth determines the cavity resonance frequency. I plan on crossing over well below that.