Hey guys,
Anyone have any inputs on a 3-way passive crossover system for my shop speakers? I have one option to Bi-amp the subs with about 300 RMS. These are 12" MTX Road Thunder series, 4 ohms, 200 RMS each. (Don't laugh... I got them free) The sub amp has a fixed crossover at 100 Hz. Amp is a Peavey CS-800. Is a 2 channel, can deliver 400 RMS per channel @ 4 ohms, about 300/ch., @ 2 ohms.
The mids are 5.25" generic brand and they sound fair at 50-75 watts each. I figure they can cross at 100 Hz and use a band pass (notch) filter so they get 100 - 3.5Khz. (12dB/octave slope prefered).
The tweets I have now are paper cone and metal dome but very bright. A 4-6dB attenuator is probably needed on these or dump them for a better SQ tweeter.
The mids and highs will be powered by a Yamaha Pro P-2050 2 channel amp. Delivers 50 RMS @ 8 ohms/ch. About 75 watts @ 4 ohms/ch. It has a 200 Hz HPF but that seems too high a cross point. More like 100 Hz is where I think it should be.
Anyone have any ideas on what Cap & Coil values should be for the mids and highs? I think these are both 8 ohm units... but will confirm that in a future post.
Am leaning toward a 2nd order Butterworth design for these crossovers. I have a good variety of caps and coils on hand, so may not have to buy much to accomplish this.
Comments.. thoughts... ideas? I'm open to suggestions!
Swez
Replies (5)
compvr15s on 08/5/2004 03:33:07
wow swez sounds like you have a problem on your hands lol, we come here lookin for help from you, haha. i really wish i could help you, but im clueless here, looks like your typing chinesse on me lol, good luck, im sure you can get it figured out.
uochronos on 08/5/2004 05:08:56
i dont know alot about this but i have a friend that has been building his own home speakers and crossobver units since the early 70's and i well run it by him and see what valuble tid bits i can get out of him for ya swez...
i dont know much about it myself but he just recently(last summer) did a 3way system for a friend mid tweet and woofer and he did use a 2nd order butterworth design and it sounded amazing... i was pretty amazed actualy the speakers them selves where only like 200$ for all 6. but the crossover and box design really together made them sound amazing.
swez on 08/5/2004 08:22:35
More details have come to light as I have removed the speakers from their mounts and opened up the box. There was a 3-way crossover in this box already, but the component values (inductive) are unknown on the coils. The woofer part does have a dual value coil for 8 or 4 ohm woofers, but the coil values are unknown. (not marked) I think the best thing I can do here, is bi-amp. The sub amp has a fixed LPF @ 100 Hz. (18dB/octave slope) Basically a done deal here. The subs are 4 ohms each, 200 RMS and 1.25 -1.5 cf sealed is recommended by MTX engineering specs. No SS filtering needed here as this is a sealed box. Subs are not designed for porting per MTX engineers.
The midrange driver (5.25") is covered in back so it is only good for frequencies above ~500 Hz. Too high for MB/MR applications so these will be replaced along with the tweeters. Will need to insert a divider panel between woofer and mid/tweets to prevent excess bass waves from killing midbass cone control. Or, make a mini-enclosure to isolate the MB driver from sub. Obviously a bandpass crossover on the MB/MR driver is needed here. Want MB/MR to operate between 100 -2,500 Hz. (12dB/oct. slope, Butterworth filtering) (8 ohms)
The present tweeters are toys. Will be replacing these as well. Am thinking a bullit tweeter for better dispersion and power handling as well. This will be filtered at 2,500 Hz and up. Also a 12dB/oct., 2nd order Butterworth design. (8 Ohms)
Once I get new MB/MR & tweeters, will make 2-way crossovers for this set and run the subs off the Peavy amp. I may change the woofers to a pair of 10", 4+4 DVC's. Wired at 8 ohms each, I can get 4 ohms net to amp and more power to each sub. (200 watts RMS +/sub)
Time to get out the crossover cookbooks and see what coil and cap values I will need for Notch filter and HPF's.
Thanks for the replies so far... keep em coming as we can all learn something is we put our thinking caps on.
Swez
swez on 08/6/2004 20:27:08
OK, been doing some reseach and may have found the values needed for this mess...
LP for sub:
4 ohm driver
Cross at 100 Hz. via amp active LPF
Bandpass for MB/MR
8 ohm driver 100 - 2.5Khz
HPF: C1 = 100 uF; L1 = 25.46 mH
LPF: C2 = 4.0 uf; L2 = 1.02 mH
Tweeter HPF
8 ohms, 2.5Khz - 20Khz
C1 = 4.0 uF, L1 = 1.02
This is a 12dB per octave slope crossover design, following Linkwitz/Reiley slope programs. Now, all I need is a substrate to mount all components and point to point wiring each stage as noted. Getting parts and MB/Tweeters are next on the list.
Let's see how it turns out, (crossover my fingers... hehe)
Swez
swez on 08/24/2004 19:51:18
Up date: The speakers are all installed and changed to some Bahn Comps I had sitting around. So, the whole system is now a 4 ohm unit.
I have tried using the present crossovers that were in there with some modifications for 4 ohm i/o 8 ohm components. Some success after trial and error testing.
Tweeter: This tweet came with a 12dB filter and that works fine. Very bright for my tastes and very beamy. (1" eyeball & socket design) This is a metal dome tweeter and I am used to silk domes, so these are kinda harsh w/o EQ. High output from the tweet though... just a poor dispersion pattern. May have to make a few mods to get better dispersion from same. (2.5 -3.0 Khz and up is my guess on this one)
Midbass: Using a 5.25" MB driver (Bahn) and it sounds very good in MB and MR. The passive coil that came with it sucks. Will be upgrading to a decent 12 dB version that starts at 100 Hz. Tried something new in fabrication. This is an open back cone design. So, I have to shield it from the woofer bass waves. Used a Folger's plastic coffee container (6" dia., 7" height) Cut out the bottom of the container, sealed it around the MB driver and stuffed 50% poly fill in there. Then snapped on the lid. Surprise... it works beautiful! Just need a HP filter on it now as I get full range now. Very good MB, fair MR and takes only a few watts to get this one pumpin too.
Subs: The MTX 12's are not sounding so hot. Low efficiency as compared to MB/Tweet. Can fix that with EQ though. The preset coil for LP is not good either. It seems to be crossing over in the 200 Hz range at 6dB/octave. I can hear MR coming from the woofer so that coil is not enough. Will be adding a 12 dB LP filter here too. (~80-100 Hz should do it) Decent bass performance... but more EQ below 100 Hz will help it a lot. (+8 to12dB boost is needed here) Toning down the MB/Tweet by ~6dB will work as well. Have plenty of EQ to work with here. (12 bands/ch.)
In summary, have learned a lot from this project and just how important quality crossovers are to a well balance SQL system. If I can get these speakers to sound as good or better than my Polks, nothing would please me more. Pretty hard to beat the Peerless plate tweeter Polk uses. So clean and crisp, yet not harsh either. The dispersion pattern on the Polk tweet is excellent and very clean at ~50 watts too. Even after 25 years of service, I have yet to find a box I like better than these Polks. The only negative on these Polks, cannot take a lot of bass power. Have to roll them off about 100 Hz or the woofers (6.5") will bottom out at roughly 95dB. With the roll off, can get about 100 dB of clean audio from the Polks. Hoping for more SQL in the new design.
Swez
Anyone have any inputs on a 3-way passive crossover system for my shop speakers? I have one option to Bi-amp the subs with about 300 RMS. These are 12" MTX Road Thunder series, 4 ohms, 200 RMS each. (Don't laugh... I got them free) The sub amp has a fixed crossover at 100 Hz. Amp is a Peavey CS-800. Is a 2 channel, can deliver 400 RMS per channel @ 4 ohms, about 300/ch., @ 2 ohms.
The mids are 5.25" generic brand and they sound fair at 50-75 watts each. I figure they can cross at 100 Hz and use a band pass (notch) filter so they get 100 - 3.5Khz. (12dB/octave slope prefered).
The tweets I have now are paper cone and metal dome but very bright. A 4-6dB attenuator is probably needed on these or dump them for a better SQ tweeter.
The mids and highs will be powered by a Yamaha Pro P-2050 2 channel amp. Delivers 50 RMS @ 8 ohms/ch. About 75 watts @ 4 ohms/ch. It has a 200 Hz HPF but that seems too high a cross point. More like 100 Hz is where I think it should be.
Anyone have any ideas on what Cap & Coil values should be for the mids and highs? I think these are both 8 ohm units... but will confirm that in a future post.
Am leaning toward a 2nd order Butterworth design for these crossovers. I have a good variety of caps and coils on hand, so may not have to buy much to accomplish this.
Comments.. thoughts... ideas? I'm open to suggestions!
Swez
Replies (5)
compvr15s on 08/5/2004 03:33:07
wow swez sounds like you have a problem on your hands lol, we come here lookin for help from you, haha. i really wish i could help you, but im clueless here, looks like your typing chinesse on me lol, good luck, im sure you can get it figured out.
uochronos on 08/5/2004 05:08:56
i dont know alot about this but i have a friend that has been building his own home speakers and crossobver units since the early 70's and i well run it by him and see what valuble tid bits i can get out of him for ya swez...
i dont know much about it myself but he just recently(last summer) did a 3way system for a friend mid tweet and woofer and he did use a 2nd order butterworth design and it sounded amazing... i was pretty amazed actualy the speakers them selves where only like 200$ for all 6. but the crossover and box design really together made them sound amazing.
swez on 08/5/2004 08:22:35
More details have come to light as I have removed the speakers from their mounts and opened up the box. There was a 3-way crossover in this box already, but the component values (inductive) are unknown on the coils. The woofer part does have a dual value coil for 8 or 4 ohm woofers, but the coil values are unknown. (not marked) I think the best thing I can do here, is bi-amp. The sub amp has a fixed LPF @ 100 Hz. (18dB/octave slope) Basically a done deal here. The subs are 4 ohms each, 200 RMS and 1.25 -1.5 cf sealed is recommended by MTX engineering specs. No SS filtering needed here as this is a sealed box. Subs are not designed for porting per MTX engineers.
The midrange driver (5.25") is covered in back so it is only good for frequencies above ~500 Hz. Too high for MB/MR applications so these will be replaced along with the tweeters. Will need to insert a divider panel between woofer and mid/tweets to prevent excess bass waves from killing midbass cone control. Or, make a mini-enclosure to isolate the MB driver from sub. Obviously a bandpass crossover on the MB/MR driver is needed here. Want MB/MR to operate between 100 -2,500 Hz. (12dB/oct. slope, Butterworth filtering) (8 ohms)
The present tweeters are toys. Will be replacing these as well. Am thinking a bullit tweeter for better dispersion and power handling as well. This will be filtered at 2,500 Hz and up. Also a 12dB/oct., 2nd order Butterworth design. (8 Ohms)
Once I get new MB/MR & tweeters, will make 2-way crossovers for this set and run the subs off the Peavy amp. I may change the woofers to a pair of 10", 4+4 DVC's. Wired at 8 ohms each, I can get 4 ohms net to amp and more power to each sub. (200 watts RMS +/sub)
Time to get out the crossover cookbooks and see what coil and cap values I will need for Notch filter and HPF's.
Thanks for the replies so far... keep em coming as we can all learn something is we put our thinking caps on.
Swez
swez on 08/6/2004 20:27:08
OK, been doing some reseach and may have found the values needed for this mess...
LP for sub:
4 ohm driver
Cross at 100 Hz. via amp active LPF
Bandpass for MB/MR
8 ohm driver 100 - 2.5Khz
HPF: C1 = 100 uF; L1 = 25.46 mH
LPF: C2 = 4.0 uf; L2 = 1.02 mH
Tweeter HPF
8 ohms, 2.5Khz - 20Khz
C1 = 4.0 uF, L1 = 1.02
This is a 12dB per octave slope crossover design, following Linkwitz/Reiley slope programs. Now, all I need is a substrate to mount all components and point to point wiring each stage as noted. Getting parts and MB/Tweeters are next on the list.
Let's see how it turns out, (crossover my fingers... hehe)
Swez
swez on 08/24/2004 19:51:18
Up date: The speakers are all installed and changed to some Bahn Comps I had sitting around. So, the whole system is now a 4 ohm unit.
I have tried using the present crossovers that were in there with some modifications for 4 ohm i/o 8 ohm components. Some success after trial and error testing.
Tweeter: This tweet came with a 12dB filter and that works fine. Very bright for my tastes and very beamy. (1" eyeball & socket design) This is a metal dome tweeter and I am used to silk domes, so these are kinda harsh w/o EQ. High output from the tweet though... just a poor dispersion pattern. May have to make a few mods to get better dispersion from same. (2.5 -3.0 Khz and up is my guess on this one)
Midbass: Using a 5.25" MB driver (Bahn) and it sounds very good in MB and MR. The passive coil that came with it sucks. Will be upgrading to a decent 12 dB version that starts at 100 Hz. Tried something new in fabrication. This is an open back cone design. So, I have to shield it from the woofer bass waves. Used a Folger's plastic coffee container (6" dia., 7" height) Cut out the bottom of the container, sealed it around the MB driver and stuffed 50% poly fill in there. Then snapped on the lid. Surprise... it works beautiful! Just need a HP filter on it now as I get full range now. Very good MB, fair MR and takes only a few watts to get this one pumpin too.
Subs: The MTX 12's are not sounding so hot. Low efficiency as compared to MB/Tweet. Can fix that with EQ though. The preset coil for LP is not good either. It seems to be crossing over in the 200 Hz range at 6dB/octave. I can hear MR coming from the woofer so that coil is not enough. Will be adding a 12 dB LP filter here too. (~80-100 Hz should do it) Decent bass performance... but more EQ below 100 Hz will help it a lot. (+8 to12dB boost is needed here) Toning down the MB/Tweet by ~6dB will work as well. Have plenty of EQ to work with here. (12 bands/ch.)
In summary, have learned a lot from this project and just how important quality crossovers are to a well balance SQL system. If I can get these speakers to sound as good or better than my Polks, nothing would please me more. Pretty hard to beat the Peerless plate tweeter Polk uses. So clean and crisp, yet not harsh either. The dispersion pattern on the Polk tweet is excellent and very clean at ~50 watts too. Even after 25 years of service, I have yet to find a box I like better than these Polks. The only negative on these Polks, cannot take a lot of bass power. Have to roll them off about 100 Hz or the woofers (6.5") will bottom out at roughly 95dB. With the roll off, can get about 100 dB of clean audio from the Polks. Hoping for more SQL in the new design.
Swez
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