For starters, thoughts on price performance things. I find that decent PR units can cost more than the active driver, in some cases. One that I am messing with is a $100 driver and the PRs come in at $65 each with 2x needed. Is nailing the targets justification enough to spend so much on "ports" or is that money better spent on optimising a dual active driver design? Such are today's pondering while perusing online shopping carts on what to pull the triggers on 🙂
Ya, drone cones are a rip off. Reminds me of speaker cables.
Blown woofers are a great place to start but where do you find a pair of blown 15’s for your 12” actives? Or a couple 8’s for your 6.5’s?
No need to double up the same size, just go one size up.
That’s how we did it 40 years ago.
Blown woofers are a great place to start but where do you find a pair of blown 15’s for your 12” actives? Or a couple 8’s for your 6.5’s?
No need to double up the same size, just go one size up.
That’s how we did it 40 years ago.
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Actually found myself checking out cheap drivers to use as PR. Have some $15 pair car 6.5” woofers coming in just to satisfy curiosity
Sorry for the late response, Cal. Have been trying to find the requested information for the main drivers. The last two are sourced as replacement parts and have no specs
12" 17mm 450wrms
10" 17mm 400wrms
7" unknown, around 13 to 15mm by reckoning over 150wrms
Racer, unknown, maybe more than 15mm 70wrms
12" 17mm 450wrms
10" 17mm 400wrms
7" unknown, around 13 to 15mm by reckoning over 150wrms
Racer, unknown, maybe more than 15mm 70wrms
Which driver do you want the drones for?
If it's the 12, then a single 15 will work. Just make sure the Xmax is the same or greater as you don't want to work the PR too hard. You may also need to add weight and or stiffness to the cone.
Those figures suggest that is two way Xmax.
If it's the 12, then a single 15 will work. Just make sure the Xmax is the same or greater as you don't want to work the PR too hard. You may also need to add weight and or stiffness to the cone.
Those figures suggest that is two way Xmax.
Absolutely! I remember people making their own with just a surround kit, shoe goo, some foam core, and washers. I don’t think they were any good though because they can rock in non-pistonic ways.
Surround and spider are important. Alteration of the spider can improve things if travel requires increasing.
I have played with many over the years and as always, I listen with my ears rather than analysis by machine.
Hint: Tube amps.
Same reason I am a fan of the Cornu style horn.
Everything wrong but show me a simple build that makes a little driver sound so big.
I have played with many over the years and as always, I listen with my ears rather than analysis by machine.
Hint: Tube amps.
Same reason I am a fan of the Cornu style horn.
Everything wrong but show me a simple build that makes a little driver sound so big.
I need PR units for all those drivers. At the moment, I have only shopped for the 6.5" driver. I drew up ported cabs for the other drivers but would like to step away from port issues and the volume sacrifice for all of them. Problem is affording so many PR units!
What properties would a pair of 6" PR units need t to work with a larger active driver, for example a 12" with 17mm xmax. Lets say the 12" is usually happy in a 40L ported and tuned to 40hz
You want the PR(s) have around double the displacement of your woofer (depends on tuning).
Since two 6" have roughly half the cone surface of one 12" your PRs would need 4-fold xmax of your woofer, to match the max spl of your driver.
6" PRs with 78 mm xmax will be difficult to find, I suspect.
You could either accept the reduced max spl around tuning frequency, accept some compromise and use a vent or build a sealed encloseure and equalize the low end. With 12" and 17 mm xmax you have plenty of potential output anyway!
Have a look at these photos of modifying a cheap woofer to make a low-tuned PR (scroll down):
https://www.donhighend.de/?page_id=1627
Since two 6" have roughly half the cone surface of one 12" your PRs would need 4-fold xmax of your woofer, to match the max spl of your driver.
6" PRs with 78 mm xmax will be difficult to find, I suspect.
You could either accept the reduced max spl around tuning frequency, accept some compromise and use a vent or build a sealed encloseure and equalize the low end. With 12" and 17 mm xmax you have plenty of potential output anyway!
Have a look at these photos of modifying a cheap woofer to make a low-tuned PR (scroll down):
https://www.donhighend.de/?page_id=1627
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Thanks for that, been trying to digest it. My last earthquake sub had 75mm xmax, and it was visually extravagant but had mechanical noises but.....
What do you personally think about a PR driver around 6" with about 100mm of xmax if one can be found at a really good price?
What do you personally think about a PR driver around 6" with about 100mm of xmax if one can be found at a really good price?
I strongly doubt that you can find it, mostly for a good price!
High xmax is always much more lossy, non-linear and noisy than simply using a bigger PR.
So it's usually a good idea to chose one PR bigger than the driver (e.g. 10" or 12" PR for a 8" driver). Or install two PRs of the same dimension as the driver.
You can't beat price performance of a good dimensioned and flared port, by the way!
Of course there is: (equalized) sealed enclosure!
You just need enough displacement to reach the desired spl at your desired lowest frequency.
Randy, even though this won't help with your questions, I'm sure you'd like to check out member wolf_teeth's use of small PR's such as in these threads.:
https://www.diyaudio.com/community/...mall-3-way-with-concussive-tendencies.386164/
https://www.diyaudio.com/community/...smallest-diy-3-ways-ive-built-or-seen.392609/
https://www.diyaudio.com/community/...mall-3-way-with-concussive-tendencies.386164/
https://www.diyaudio.com/community/...smallest-diy-3-ways-ive-built-or-seen.392609/
Also check out his "overdrive" PR bandpass:
https://www.diyaudio.com/community/threads/overdrive-10-a-pr-bandpass-sub.325828/
Xmax is defined as one way travel, 200mm (~8") of peak to peak travel on a 6" driver won't be found at any price.
The Earthquake SLAPS (Symmetrically Loaded Passive System) PR's are all rated incorrectly, their rated "Xmax" is peak to peak, not one way.
Still an impressive amount of excursion, but from what I've read, they require more weight to achieve desired Fb than their TS parameters or the tuning charts predict, stiffer than their rated Vas (Volume of Air Spring) would indicate.
Difficult ($$) to make Vas large (lower stiffness, loose suspension), linear at different drive levels, support the required weight and still move pistonically at high excursion.