Need help selecting drivers for DIY 3 way or 4 way music/home theater speakers

Hello all! First post here. So I’m strongly considering selling off my pair of L300s to fund a project I’ve been wanting to tackle for some time. These will be used for music a lot of the time, but also home theater so there will be 3 in total built (left-center-right). I have a number of drivers on hand which I was thinking I’d like to use to keep costs down, but if it seems like a bad idea and the Summits won’t cover the cost then I may consider selling my only other two pair of JBLs which are XPL200As and L7s. Hopefully I won’t need to though.

Anyways for top end, I was thinking of using the large Heil AMT. I have a pair of ESS AMT-1Ds which I’ll pull them from. So I’d have to source one additional one, hopefully with the original diaphragm. If this is a poor choice please do let me know. I see there is another member using the Heil in an 18” 3 way.

For the mid, I have a few option. I’m thinking I’d like to go with a 10” driver. I happen to have exactly 3 McCauley 6222. From what I’ve read this is supposed to be an excellent driver with good midbass. It’s the only 10” with a standard roll type rubber surround.

Attachment 90157Attachment 90158

Another option for a 10 is the JBL 251J. These were pulled from a set of SK2-3300s. I have 6 in total, I thought maybe an MTM with the Heil would be cool, if not maybe just align them side by side as they did in the S2K-3300. If I should only use one per speaker let me know on that as well.

Attachment 90159Attachment 90160

the other 10” option would be the JBL 2251J. Again with these I have enough to do 2 per speaker if that’s optimal. From what I understand these are the same as the 251J except that the 251J has aquaplas and is considered a bit better???

Onto the bottom end. This one is tricky for me. For home theater there will be a pair of 18” Dayton Ultimax woofers in large ported cabinets. So the mains won’t have to go super low, maybe cross at 50hz for home theater and full range for music.

I happen to have 3 JBL sub1500s (or W1500H?). My brother suggested I use them on the bottom end. I’m guessing something with a high efficiency would be better. I was considering doing something like the 2235 or similar 15 and then the sub1500 under it essentially making it a 4 way. The other option is to go with a trio of 18s, like the 2241h, or similar. If I go with an 18 I’d still like to use the trio of sub1500s, but more like true subwoofers for music duty. I posted some pics, in hopes to give folks an idea of what I have on hand. I want to make these the best they can be, so please let the suggestions roll.

Attachment 90161

Oh, for crossover, I’d likely go active to start off with and then if I can design a passive that does the speaker justice then I’d use it.


Thank you,
Dan

Welcome to the forum!

I'm a little surprised that no one has popped in with suggestions and comments. I have been meaning to, but am too busy to give your post the time it deserves.

I'll return to this in a bit. In the meantime, hopefully others will chime in.


Widget

Quote:

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Originally Posted by Mr. Widget

Welcome to the forum!

I'm a little surprised that no one has popped in with suggestions and comments. I have been meaning to, but am too busy to give your post the time it deserves.

I'll return to this in a bit. In the meantime, hopefully others will chime in.


Widget

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Thank you! Appreciate the welcome. I’d love to hear your suggestions when you have a moment to do so. Hopefully others will give their input too!

Dan

Opinions and bench racing is easy from this end... sounds like a fun project.

My initial thought would be to go MTM with the 2251Js and Heil, if you have the space and won't be too close (listening position).
Keep the mid cones light and efficient to blend with the Heil unit better. That could all be crap if the 251J units suit you better.
I know Todd is enamored of his "Merman" system which transitions from a 10" to an 18" driver, but if you're expecting to add subs
(perhaps small distributed subs using the heavy JBL 15" units... sealed, with -significant- amps and EQ/limiting?) and other 18" driver systems,
you could likely use something smaller under the mid/hi units. A mid-bass unit can add a surprising amount of info to music ... e.g. compare
the JBL 240Ti vs L250Ti; both sound nice, but the 4-way makes a difference. Also, you wouldn't have to drive the 10" units as hard/low.
The Gauss units might work, if they spec out for such duty...might have to drive them separately.

I have a hard time imagining the work required to iteratively build, assemble, and test all of this with passive crossovers without a lot of experience
(which you may have), and some difficulty matching driver levels. A successful, complex, multi-way system from scratch is quite a challenge.
Will be interesting to see how this comes along!! :)

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but am too busy to give your post the time it deserves.

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+1

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A successful, complex, multi-way system from scratch is quite a challenge.

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+ 1

I usually try to help newcomers to this site, while some others may have less interest in that.

However last night i did look carefully at the post and came to the conclusion there's simply too much work involved here, LOT of time that i don't have unfortunately.

The poster has a bunch of drivers, each driver's specs need to be analysed for proper fit in his project, then explain to him the why of choices made. Its practically designing a system for him which is time consuming.

Moreover the OP will likely have a legitimate 2nd and 3rd round of questions to be answered. This can easily become quite a long ride... Sorry, for now.

Richard

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Originally Posted by RMC

+1



+ 1

I usually try to help newcomers to this site, while some others may have less interest in that.

However last night i did look carefully at the post and came to the conclusion there's simply too much work involved here, LOT of time that i don't have unfortunately.

The poster has a bunch of drivers, each driver's specs need to be analysed for proper fit in his project, then explain to him the why of choices made. Its practically designing a system for him which is time consuming.

Moreover the OP will likely have a legitimate 2nd and 3rd round of questions to be answered. This can easily become quite a long ride... Sorry, for now.

Richard

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Well not really. I’m not asking for you all to design a crossover or design the speaker or anything like that. What I’m asking for is the knowledge of those who are fans of these drivers and who know these drivers. If someone thinks the 251J is clearly a better midbass than the 2251J that’s what I want to know. If someone thinks a JBL 18 handling the bottom end and would cross to the 10 better than the sub1500, that’s what I want to know. Can’t really think of any 2nd or 3rd round of questions I’d have unless someone’s answer provokes a question.

I’m not asking for a system design from the ground up, as my title states I’m just hoping to get suggestions as to which are the better drivers, which would you select for use. Once I have the drivers selected I’ll run them active, measure the drivers and mic them and slowly work on designing a passive crossover. I have a bit of experience designing crossovers and have access to some folks with more knowledge than I in that department. Though they don’t have knowledge of these drivers.

I see several threads in this area of people asking for recommendations on which drivers they should use in their build, this is the same.

Thank you,
Dan

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Originally Posted by grumpy

Opinions and bench racing is easy from this end... sounds like a fun project.

My initial thought would be to go MTM with the 2251Js and Heil, if you have the space and won't be too close (listening position).
Keep the mid cones light and efficient to blend with the Heil unit better. That could all be crap if the 251J units suit you better.
I know Todd is enamored of his "Merman" system which transitions from a 10" to an 18" driver, but if you're expecting to add subs
(perhaps small distributed subs using the heavy JBL 15" units... sealed, with -significant- amps and EQ/limiting?) and other 18" driver systems,
you could likely use something smaller under the mid/hi units. A mid-bass unit can add a surprising amount of info to music ... e.g. compare
the JBL 240Ti vs L250Ti; both sound nice, but the 4-way makes a difference. Also, you wouldn't have to drive the 10" units as hard/low.
The Gauss units might work, if they spec out for such duty...might have to drive them separately.

I have a hard time imagining the work required to iteratively build, assemble, and test all of this with passive crossovers without a lot of experience
(which you may have), and some difficulty matching driver levels. A successful, complex, multi-way system from scratch is quite a challenge.
Will be interesting to see how this comes along!! :)

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Thank you for your thoughts. I’m assuming the 251J would have more moving mass, I don’t know of any T/S parameters for them, but in the SK2-3300 the 251J did play lower than any 2251J that I know of. (Which isn’t much as I’m not super familiar with this side of JBL, I’ve only had the L65, L300, L220, L7, XPL200A, and a couple other consumer products)

I was just wondering if since they put the 251J in such an expensive speaker if it might be a “super” 2251J lol.

The MTM is somewhat of a new though, I’m trying to play with the idea of what this speaker will look like and trying to keep the Heil at ear level. I considered using a waveguide or horn for the Heil, but not sure it would need it. It crosses low enough and is fairly efficient. If an MTM wouldn’t work I think the side by side layout like the SK2-3300 would look nice as well unless others tell me one would be better.

As far as adding the subs, I probably didn’t make it clear, but I’d like to limit the sub use for movies only, unless the sub1500 is used for sub duty, I’ve read it’s pretty clean and accurate. If I ran the sub1500 up to meet with the 10” midbasses then I guess they’d be used as woofers, I’m sure they’d offer plenty of low end, my only concern with them is efficiency and that thump you in the chest impact.

Of course if I can get away with a 3 way speaker where each driver is comfortably playing their frequencies and sounds as good as a 4 way that would be ideal. I’ve designed both 3 way and 4 way passives and 3 ways are definitely less complicated and easier to design. I figure the Heil could cross at 1000hz as it currently does in the AMT. I could play with 1200 or maybe even a little higher depending on the roll off (if I’m going active at first I’ll try 18-24 db per octave). I’d have to play with that once I have the cabinets built, I wouldn’t want to the 10s to get to “beamy” by playing them too high. I’ll have to do some research once the midbass is picked out and once the woofer is picked out to figure on the band pass of the midbass. No need to take this into account for an answer to my question, I’m just laying my though process out once drivers are selected.

You mention the “Gauss units might work” pardon my ignorance, what are you speaking of?

Thank you,
Dan

Sounds like a fun project :)

You may find researching the 251J/2251J a little frustrating, as there were several variants with really similar model numbers (I think they maybe did some -1 and -2 variants?) - it’s been so long I don’t remember them. I do remember that JBL modified the drivers for the SK2’s during assembly, using a heavier, aquaplassed cone, and a mass ring. I think that added 20g or so of moving mass total to the driver, to get the frequency response low enough to use in a THX home theater with a 80hz high pass crossover (I think the SK2’s fall apart somewhere around 65hz. I think the SK2’s drivers are the ones I would start with, as you know they’ve been used successfully in the same range before.

I’ll wait for Widget to chime in with more detail, as he as built some really nice music speakers with the SUB1500’s, but I don’t remember where he cuts them out. I’ve played with them, and would keep them low - low pass them at 100hz or 125hz. Also, as you may know, they had a problem with these drivers coming unglued, especially if you use them in a small, sealed enclosure with EQ. If you’re trying to do a 3way, using a 2216 woofer may be a better idea, though prototype with what you have first :)

Post pics as you go - I’d love to swing by when you have something to listen to - I’m just around the corner :)

I think you are asking the wrong question unless you can clearly advise a set of performance criteria?

Have you determined how loud you want this loudspeaker to go for a given amount of amplifier power?

What low frequency range are you aiming for and what box size can you tolerate?

Depending on what you want to your design to do some drivers might suit and some might not.

If you look at how JBL used these driver you have it will give you some glues on how best to use each driver. Jbl drivers are not general purpose. They are mostly designed for specific applications and are sometimes derived from other driver designs. So you are going to have to do a lot of research yourself.

From that step you might measure these drivers in a test box with REW and look at the real frequency response, the efficiency and the distortion level.

Then put these test boxes in a stack and start working on a practical design. You will find some drivers are chalk and cheese while others might be similar in some way. Only you can work this out.

I would think about the total box size first and keep it as simple as possible. Only use an additional drive if you absolutely have to. Tools like REW are your friend and will keep you thinking objectively while your ears tell you what you like more or less of.

As l recall all the ESS systems were two way designs or used passive radiators.

If box size is a criterion then the sub 1500 drivers can use used in compact enclosure but they are a sub woofer. The question then will be which of your other drivers will fit your design spec the best ?
Will a particular driver function properly down to a crossover point to meet the sub 1500 drivers?

You can simulate drivers with software and determine the limitations of a driver. Is a vented or sealed driver best or should you use one driver as a helper woofer (as JBL did in some of its Synthesis centre channel designs)?

I would steer clear of a D’appllito design until you have done some matter of fact tests with single drivers.

If you can obtain something like a JBL drive rack that will do your active crossover work.

Good luck with your project.

Quote:

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Originally Posted by HCSGuy

Sounds like a fun project :)

You may find researching the 251J/2251J a little frustrating, as there were several variants with really similar model numbers (I think they maybe did some -1 and -2 variants?) - it’s been so long I don’t remember them. I do remember that JBL modified the drivers for the SK2’s during assembly, using a heavier, aquaplassed cone, and a mass ring. I think that added 20g or so of moving mass total to the driver, to get the frequency response low enough to use in a THX home theater with a 80hz high pass crossover (I think the SK2’s fall apart somewhere around 65hz. I think the SK2’s drivers are the ones I would start with, as you know they’ve been used successfully in the same range before.

I’ll wait for Widget to chime in with more detail, as he as built some really nice music speakers with the SUB1500’s, but I don’t remember where he cuts them out. I’ve played with them, and would keep them low - low pass them at 100hz or 125hz. Also, as you may know, they had a problem with these drivers coming unglued, especially if you use them in a small, sealed enclosure with EQ. If you’re trying to do a 3way, using a 2216 woofer may be a better idea, though prototype with what you have first :)

Post pics as you go - I’d love to swing by when you have something to listen to - I’m just around the corner :)

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I did see that there were several different versions of the 2251J lol, too many. I did forget to mention that the 251J had the mass ring added, I do remember reading that. Unfortunately it seems I can’t find too much info out there on the 251J. Obviously these changes allowed it to reach low enough as you mentioned, but I’m curious if the Aquaplas and mass ring have any negative effect on midrange quality compared to the other 2251Js out there. I would hope not since they were used in such an expensive speaker. Hopefully someone who has had the chance to listen to both can chime in.

Awesome info, thank you!!! I’ll look out for Widget’s thread on the speakers her made if there is one. That was really my thought as well, keep the sub1500s low, basically sub duty. Though also though maybe someone used them higher with great success and would say so. Luckily the 251J would cross low enough to meet up with the sub 1500 regardless. I did read that there was an issue with the glue, but that was awhile ago. I can do some searching later, but if you know, do you remember where the glue failed and is it preventable? Meaning can glue be applied to prevent the failure? I repair drivers (but mostly amplifiers and electronics) for a living so could handle some work on it, I just wouldn’t want to remove the dust cap to shim the coil. So hopefully it doesn’t need taken that far.

As for the cabinet for the sub1500, I don’t know if there is a difference in the woofers, but I see Revel used them in a sealed cabinet with eq I’m sure. JBL used the woofer in ported cabinet in the 1500 array. Is there a recommended alignment? I was figuring on going sealed as for music I just prefer a sealed cabinet, and will have huge ported 18s for the HT.

I think you’ve convinced me to eliminate the sub1500 from the running in the bottom end. I’ll still run them as subs, but I’ll go with a proper 15 or 18 inch woofer, I think my brother has some 2241hs.

I will absolutely post pics once I get started and you’re more than welcome to come check it out once done, maybe grill something up. I have a few friends in Bend, nice area for sure!


Dan

Quote:

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Originally Posted by Ian Mackenzie

I think you are asking the wrong question unless you can clearly advise a set of performance criteria?

Have you determined how loud you want this loudspeaker to go for a given amount of amplifier power?

What low frequency range are you aiming for and what box size can you tolerate?

Depending on what you want to your design to do some drivers might suit and some might not.

If you look at how JBL used these driver you have it will give you some glues on how best to use each driver. Jbl drivers are not general purpose. They are mostly designed for specific applications and are sometimes derived from other driver designs. So you are going to have to do a lot of research yourself.

From that step you might measure these drivers in a test box with REW and look at the real frequency response, the efficiency and the distortion level.

Then put these test boxes in a stack and start working on a practical design. You will find some drivers are chalk and cheese while others might be similar in some way. Only you can work this out.

I would think about the total box size first and keep it as simple as possible. Only use an additional drive if you absolutely have to. Tools like REW are your friend and will keep you thinking objectively while your ears tell you what you like more or less of.

As l recall all the ESS systems were two way designs or used passive radiators.

If box size is a criterion then the sub 1500 drivers can use used in compact enclosure but they are a sub woofer. The question then will be which of your other drivers will fit your design spec the best ?
Will a particular driver function properly down to a crossover point to meet the sub 1500 drivers?

You can simulate drivers with software and determine the limitations of a driver. Is a vented or sealed driver best or should you use one driver as a helper woofer (as JBL did in some of its Synthesis centre channel designs)?

I would steer clear of a D’appllito design until you have done some matter of fact tests with single drivers.

If you can obtain something like a JBL drive rack that will do your active crossover work.

Good luck with your project.

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Efficiency isn’t necessarily all that crucial. I’m sure anything that is built will be plenty efficient. The room is about 16’ wide and 23’ long. There is plenty of amplifier power, while running active each driver will have 300-400 watts each depending of the amplifier dedicated to that driver. If I get the passive crossovers setup I’ll then switch over to some Yamaha amplifiers I have rated at 925w at 8 ohms and 1400 at 4 ohms, so plenty of power.

Fir frequency response I’d like them to be a true full range speaker, for music my thoughts are running the speakers only so hopefully they’ll make it to 30hz (-3db) or so give or take a few hz. If I’m really in the mood for bass I can kick in the sub1500s as I’m sure they can do music justice. For HT the plan is to kick in the 18s and cross them to the mains at somewhere between 50-70hz. So these main speakers will start rolling off at that crossover point. Cabinet size would be whatever is optimal for the drivers picked. They’ll likely be behind an acoustically transparent screen/wall. The 18” sub cabinets will be 14 cubic feet afrer subtracting port and driver volume, so pretty large.


“Depending on what you want to your design to do some drivers might suit and some might not.”

Basically I’m after the 10” mid driver that will give me the cleanest most coherent midrange, where vocals will be as clean as possible. If at the same time they can give some good impact in the midbass region that would be a plus, but I’m sure the woofer they cross to can handle most of that if needed. Same goes for the woofer, I would hope for tactical clean bass with very little decay. I don’t want boomy, but I know that has a lot to do with the cabinet. On the tweeter, nobody has said not to use the Heil, so I may just go with that. I really like it, it’s fairly efficient and sounds good while being able to being able to cross low. I’ll have to double check, but I may have the mid and tweeter from the SK2-3300 as well, maybe those would be a better option than the Heil?

Indeed you are correct, building test boxes and taking measurements with REW would get me the answers I need. With twins that are a couple months old at the moment my time is externally limited, so if there was someone that had some time with these drivers I figured they might be able to save me time. Like I know there is a member here with a 3 way using the Heil with a 2251J and an 18 (not sure which 18). He could share his thoughts, cabinet volume, crossover frequency and slope, etc. Someone recently asked on another forum if there was anyone that preferred the midrange of the Scan Speak Revelator 12M4631 or the Seas W14CY001. I told him that sound is obviously subjective, but I much preferred the sound of the paper cone Scan. I shared my crossover info with him along with the other drivers used. Hopefully I was able to save him a bit of time. If I have some info he is looking for, why not share it?

Od course if in the end I can’t get definitive answers then I will indeed build test cabinets and measure, but it would greatly delay my progress. Do you happen to know if two screaming babies would mess up my measurements of the frequency response lol?

Yes, this Heil was used in a 2 way matching up to a 12” woofer and a passive. Most of the designs were 2 ways using a passive, but they did have the Rock Monitors like the Rock Monitor 3 which was a 3 way using a 6” mid.

Do you have any thoughts as to my question on my last response for the sub1500? As far as saving it from glue failure and truly the best cabinet alignment? I have DATS and a WT3, but again, if it can save me a little time…

Yeah, the MTM idea was just a passing though. Im not sure how the Heil would behave with a cabinet for the mids both on tap and below it, as it’s also rear radiating. Plus the center to center spacing on the 10s may not be ideal with the Heil between them. The more I think about it, the side by side may look better. Maybe make the front baffle as it was in the 2SK-3300, mounting the drivers on a slight slant away from each other. Did they do that to eliminate combing and improve horizontal dispersion? My last home speaker design was in a D’appolito configuration using a pair of 5-1/4” midwoofers and a 1” dome tweeter. So I was just curious if would work here.

I will keep my eyes open for a JBL drive rack, thank you!


Appreciate it!
Dan

Never heard of a 251J and don't see specs on it anywhere though the cooling fins look to be substantially longer than the 2251J.

The 2251J is a nice match for the Heil and while an MTM would be cool, it is really not necessary. Run at its own impediance level (~3.3-3.7 ohms), the Heil will be a bit loud for one 2251J if it is not padded down a bit. It may be be just about perfect for an MTM arrangement without padding. BTW, the Heils really like/need a high current solid state amp.

Crossing the Heil over at 1kHz is a mistake. It's just too low and my Heil would "complain" where it interfaces with the 2251 at less than ~1,500 Hz. I bring it in at 2,150 hz and it really likes that. Keep it over 2kHz unless you use a steep slope on the crossover.

The 2251J has a natural rolloff below 300 Hz. Just forget about it going down to meet a subwoofer. Ain't gonna happen. Maybe this is where the 251J accels.

But, will the 251J run up high enough to meet the Heil at >2khz? The 2251J goes well over 4kHz and actually gets louder in this range so the 2,150 Hz crossover is no problem, and this is actually where the volume would normally be increasing. Still, there are those that would say that this is too high a frequency for a ~10" speaker based on the wavelength.

I subscribe to the theory that I always sit in the sweet spot and that crossing over @>2kHz keeps all of the fundementals in the 2251J adding a sense of coherency, soundstage, and imaging.

I like the 2241H for the bass because the accordion edge and relatively light cone give the woofer "speed" thereby letting the texture of bass instruments come through. The 2241H is actually rated from 30 Hz - 3kHz and I cross it over at 300 Hz. I run these as 2.5 ways and let the 2251 naturally roll off on the low end. I don't put the 2251 through a cap.

If you want to do this passively, this schematic will get you there. BTW, I typically run the L-pads at their max settings for the flattest response unless the music has lots of HF noise in which case I may turn down the Heil a bit.

https://cimg3.ibsrv.net/gimg/www.cor...8625237deb.jpg




https://youtu.be/W66SQS1wDUA

This shows the nearfield spectrum for the 2251J. The dip at ~800 Hz is from a cabinet resonance/reflection, and I think a bit more insulation will take it out. It was much worse, with a subsequent peak, before I insulated the interior back of the cabinet, and I will try to do the sides in the near future to remove the remainder.

Typical 30 dB span:
https://cimg7.ibsrv.net/gimg/www.cor...9271d5e404.jpg

Quote:

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Originally Posted by saabracer23

I did see that there were several different versions of the 2251J lol, too many. I did forget to mention that the 251J had the mass ring added, I do remember reading that. Unfortunately it seems I can’t find too much info out there on the 251J. Obviously these changes allowed it to reach low enough as you mentioned, but I’m curious if the Aquaplas and mass ring have any negative effect on midrange quality compared to the other 2251Js out there. I would hope not since they were used in such an expensive speaker. Hopefully someone who has had the chance to listen to both can chime in.

Awesome info, thank you!!! I’ll look out for Widget’s thread on the speakers her made if there is one. That was really my thought as well, keep the sub1500s low, basically sub duty. Though also though maybe someone used them higher with great success and would say so. Luckily the 251J would cross low enough to meet up with the sub 1500 regardless. I did read that there was an issue with the glue, but that was awhile ago. I can do some searching later, but if you know, do you remember where the glue failed and is it preventable? Meaning can glue be applied to prevent the failure? I repair drivers (but mostly amplifiers and electronics) for a living so could handle some work on it, I just wouldn’t want to remove the dust cap to shim the coil. So hopefully it doesn’t need taken that far.

As for the cabinet for the sub1500, I don’t know if there is a difference in the woofers, but I see Revel used them in a sealed cabinet with eq I’m sure. JBL used the woofer in ported cabinet in the 1500 array. Is there a recommended alignment? I was figuring on going sealed as for music I just prefer a sealed cabinet, and will have huge ported 18s for the HT.

I think you’ve convinced me to eliminate the sub1500 from the running in the bottom end. I’ll still run them as subs, but I’ll go with a proper 15 or 18 inch woofer, I think my brother has some 2241hs.

I will absolutely post pics once I get started and you’re more than welcome to come check it out once done, maybe grill something up. I have a few friends in Bend, nice area for sure!


Dan

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Here’s a link to Widget’s latest (?) build:
http://www.audioheritage.org/vbullet...Project-Widget

Is your woofer a SUB1500 or a W1500H? The SUB1500 wasn’t used in much; one sub for the Japanese market (HB1500), and one for the European market TiK series. I don’t remember if Revel used that driver in any of their products, and I don’t know if Harman knew they had a problem before they sold their stock of raw drivers to Parts Express, which is where all of us got them. However, they knew there were problems, as they redesigned the driver to the W1500H, which is what is in the Array1500 sub, Japanese HB5000 sub, and probably some Revel stuff that hit the market, unlike the prototype Revel sub in my avatar, which used the W1500H, but never made it to market. I think the spider was coming unglued where it connected with the VC former on the SUB1500, but I don’t really remember. Either way, if you’re going to use it in a large ported box, you should be OK, small sealed box with lots of EQ, like a factory would do, is probably where you could have issues if you’re pushing volume. If you’re going to use a small sealed box for music because of sound quality, fine, I think I’d either use multiples (I use 4), or keep the volume and excursion low.

SUB1500 -> Ultima Sub-15 (iirc)

I ran them in ported cabs under a pair of L96 for awhile, to very nice effect.
SUB1500 is really intended for subwoofer duty only.

MTM notion wasn't magic, just a thought to get the driver level matching up.
Not a big fan of side-by-side mids, but center-channel systems do it all the time...
ESS has one they're pushing on sale currently. Might get by with one mid/tweet per channel... simpler.

Gauss? was thinking of that as the mid-bass element... I have no idea how/if it would match up with the Heil driver on it's own.

Really kind of a dog's-breakfast driver combination. Could work... just mostly unknown territory. You're in for some fun/sweat/frustration/fun.

Interesting project.

I have no opinion or knowledge regarding either mid bass driver. The ESS unit is interesting and is readily available from the current incarnation of ESS. I bought a pair and used them with 10" woofers while waiting to get my Project Widgets on line. If you are interested, mine are available. I found them to be very enjoyable, but I do prefer a 4" beryllium driver on an appropriate horn.

Regarding the Sub1500. They were originally built for Revel as the SUB-15 and used with a Madrigal/Levinson custom amp the LE-1 in a very compact sealed box with a boost/cut EQ curve. JBL did offer a slightly larger ported version for the Asian and possibly European markets. There is info on the SUB-15 here: https://www.stereophile.com/standlou.../89/index.html

The W1500H is a slightly "improved" version of the Sub1500 driver. At one time I knew the differences, but I don't remember the changes other than the basket change.

I have used the Sub1500 in a previous home theater to great effect. The room was pretty large. 25' by ~30' by 10'. A pair of Sub1500s in 5 cu ft ported enclosures tuned to 20Hz and powered with 600 watts per woofer were able to seriously pressurize the room with "full" bass. The sound of the Sub1500 in sealed ~2 cu ft enclosures is more taught, and more appropriate in my 2 channel system, but the extra group delay from the larger ported enclosure gave a very pleasing and subjectively more massive bottom end in a HT environment.

In small sealed boxes you need to boost the bottom end to flatten and extend the low end. In the larger ported enclosures as I used the Sub1500s, no EQ is required. In both applications I crossed over the Sub1500 at 80Hz or lower. I would not recommend using them above that.

One word of caution. Movie soundtracks can have very deep bass. A high powered signal below the tuning frequency of 20Hz will cause the woofer cone to violently slam the VC former into the back of the magnet structure. (A deeper gap is likely one of the differences between the Sub1500 and W1500H) To avoid loud bangs from the former slamming into the backplate and possibly damaging the voicecoil, you must filter subsonic signals or closely monitor high level playback.

Good Luck with your project!


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