Sure, that is JBL's oen TS parameters, so should be good to use for modelling.
Nice subs, but it's known, that dome have issues out of the box.
And i don't know how well they do at 200hz +?
Look into Widget's build on lansing heritage forum, closed box sub. Along with TAD components on top.
Thr 251J, is basically a 2251J with a heavier, Aquaplased cone, and modified suspension.
You will see the similarity with the 2250 also. The original CMCD driver from JBL.
I think a xo in the 150-250 range is the ideal, depending on how low the 251 goes on your chosen baffle/box combo.
With the sub below it, the lower the better.
Nice subs, but it's known, that dome have issues out of the box.
And i don't know how well they do at 200hz +?
Look into Widget's build on lansing heritage forum, closed box sub. Along with TAD components on top.
Thr 251J, is basically a 2251J with a heavier, Aquaplased cone, and modified suspension.
You will see the similarity with the 2250 also. The original CMCD driver from JBL.
I think a xo in the 150-250 range is the ideal, depending on how low the 251 goes on your chosen baffle/box combo.
With the sub below it, the lower the better.
Thank you, I know that they will do fine up to 200 Hz, and actually, I took some advice from widget. He told me about his 4 way using it and the Tad drivers. I’m pretty sure it was determined that the woofer to be used up to 300 Hz, but he crossed it lower.
I was aware of the issues of the glue on the 15 inch woofers, I followed that saga. I currently have seven of those woofers and all of them appear to be just fine, so far. I ran them free air and a pretty high excursion for a while and didn’t see any issues, it seems most of the people that did have issues may have overdriven them. that’s why I’m trying to keep their excursion low by crossing them 40 Hz and being sealed there’s no chance of them getting a frequency above their tuning frequency. The unfortunate event did happen, though I am very confident that I would be able to break the woofer down and re-glue anything needed, hopefully the coil former would be okay.
I just finished cutting the cabinet panels for the midbass test cabinets, about 0.65 cubic feet. If I could do it over again, I probably would’ve made the panels a little larger so that I could get around one cubic foot and then take up volume with wood as needed. What if I want to cross the woofer and the midbass at say 100 hz? Will .6 cubic feet be enough to reach that low? I want to say widget crossed it to the 10 in his 4 way below 100hz. I’ve read really great things about the 251J and I think if I had it take on frequencies fr 80-100 hz and up it would do just fine. I may find that it has more visceral impact than the 15 inch woofer. Do you have any thoughts on this?
I also remember him telling me he did a two-way using the sub1500. Not sure what the crossover point would’ve been there. I could be remembering that wrong though.
A 150-250 hz crossover point is likely where I’ll land but I know that the 251j alone in a ported cabinet can reach fairly low, but it definitely doesn’t have the most excursion out there, so it can only move so much air.
Dan
The phase shift of a port above 100Hz sounds really bad, you should really avoid that.
E: I doubt they do too much excursion, you have two per side. Simulate which spl they reach at the Xmax.
Oh sorry, I was not implying that I was going to port them. I’ve heard them in a porting cabinet and I was just saying that they do have the ability to run on their own, they get pretty low. So I don’t see any issues with them playing as low at 70hz. Regardless, they will be in a sealed cabinet. I’m guessing that if I did cross them as low at 70 hz I would need a bigger test cabinet. I don’t know off the top of my head, but I’m guessing at frequencies of 150 and up that room gain starts to become not a thing.
I really need to get my computer fixed so I can model, plus I’ll need it when I take measurements. Never leave your laptop unattended around toddlers. Does anybody have any recommendations on modeling software to be used on an iPhone? Theoretically how low will the 10 be able to go in 1/2 cubic foot before the cabinet volume becomes an issue? The cabinet is actually 0.65 cubic feet, but I am accounting for driver displacement. I don’t see that spec on the parameters, is 0.15 or less seem reasonable?
Dan
I’ll post some photos as I set the speakers up for a listen. For now DSP is going to be handled by a couple MiniDSP 2x4HD. From what I understand these aren’t the last word in cleanliness, bet they’ll get me by.
I built the midbass cabinets to a volume of about 0.68 cubic feet and stuffed them moderately with cotton/denim insulation. After talking with a couple of people I’m thinking I might take the midbass down to about 100hz to meet with the 15. I will need to model it a bit later when I have some free time, but thought I’d ask, what do you all think about the 251J reaching 100 hz in the cabinet? I’m guessing after driver displacement it’s around .55? I don’t know, I can’t find a spec on the driver displacement.
Is it possible that it could be faulty flat-ish down to 100 hz? I plan on taking a first listen on Wednesday or Thursday after my wife leaves for the coast for a few days.
Thank you,
Dan
I built the midbass cabinets to a volume of about 0.68 cubic feet and stuffed them moderately with cotton/denim insulation. After talking with a couple of people I’m thinking I might take the midbass down to about 100hz to meet with the 15. I will need to model it a bit later when I have some free time, but thought I’d ask, what do you all think about the 251J reaching 100 hz in the cabinet? I’m guessing after driver displacement it’s around .55? I don’t know, I can’t find a spec on the driver displacement.
Is it possible that it could be faulty flat-ish down to 100 hz? I plan on taking a first listen on Wednesday or Thursday after my wife leaves for the coast for a few days.
Thank you,
Dan
No judgment lol, these are literally just test cabinets to see how they do. The final cabinets will have a good amount of bracing, therefore be a bit bigger and size. If you want to make any suggestions to my stack please say so.
I need to figure out how exactly I’m going to get the 045Be to sit on top of the H9800 horn.
Dan
I need to figure out how exactly I’m going to get the 045Be to sit on top of the H9800 horn.
Dan
Just place the horn tweeter on the top and let it point at the same spot the large horn aims at. You may experiment with it's polarity and position when all other problems are solved. If you want it timed correctly, get rid of the passive x-over and use the DSP. As you use a 2x4HD per side, remove all parts of the lower high pass from the passive crossover and do it in the DSP instead. That way you are not limited to the 800 Hz point. 1.200 Hz should sound better with this horn as you reduce distortion that rises the lower the horn play's. 800 Hz is something you choose if a two way has too large a woofer, like a 15". A compromise, but nothing to prefer. It is not a crossover point you choose with that horn if you don't have too. You have got a very good 10" that will reach much higher without any problem, it should do even 1.800Hz just fine. Next, there is no advantage to let the 10" run too low. It should not have to bother with frequency lower than 200 Hz to get the best performance as a low mid. Low frequency increases the cone movement, which has a negative effect on higher content, reproduced at the same time. Try to write a letter inside a car while driving off road. The result has some similarity to bass and mid frequency reproduced at the same time.
The aim is to get the sweet spot of all drivers, that is why you go 4-way. So don't use a 2-way frequency.
If you measure distortion, you will see it by your self.
If you use a passive crossover, 12 or a maximum of 18dB/oct are usualy best. With an active one, your best bet will be 24dB/oct or higher without the degradation of sound quality and dynamics the passive parts brings you. Don't listen to people bashing active crossovers and DSP's or those that try to transfer all rules of passive design to active. Use the advantages a DSP has. Again, you will see yourself when you measure.
Setting up such a system is nothing you do on a single evening. Take your time, do some brakes in listening and reset your ears between sessions if possible. Don't drink while tuning the system. Even a little alcohol changes your perception of sound to a great degree.
The aim is to get the sweet spot of all drivers, that is why you go 4-way. So don't use a 2-way frequency.
If you measure distortion, you will see it by your self.
If you use a passive crossover, 12 or a maximum of 18dB/oct are usualy best. With an active one, your best bet will be 24dB/oct or higher without the degradation of sound quality and dynamics the passive parts brings you. Don't listen to people bashing active crossovers and DSP's or those that try to transfer all rules of passive design to active. Use the advantages a DSP has. Again, you will see yourself when you measure.
Setting up such a system is nothing you do on a single evening. Take your time, do some brakes in listening and reset your ears between sessions if possible. Don't drink while tuning the system. Even a little alcohol changes your perception of sound to a great degree.
what if...
1) Just for the sake of it, I just want an old stereo with two speakers.
It follows that if I'm set with six woofers and four midrange and two CDs+horns, I want the maximum in my room, so no faults admitted. Digital is natively perfect or so they say, so why worry?
2) Reset of the ears is a fraud. If you need to reset you might think that you are overloaded, so you deliberately did something wrong. Like turning the volume up with a certain program. The processment involved in all the audio chain is the sound you ear.
And it doesn't end at the thympanum, there's the man machine, which is also told to be a fraud, full of errors, bias, memory. And that lives in the real world so it's influenced by surrounding, which might reflect to the mood.
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Some food for thought. When Greg Timbers did his personal home system he used 9800 horns and turned them on their side and placed the 045 up top. This morphed into how the Array horns were set up for production. It's an option you might want to try. I have a pair of 1400 clones with the same Be drivers and they sound very good and image much better than a traditionally oriented horn.
Rob 🙂
Rob 🙂
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No, that's wrong, at least partly. After listening for a while, fatigue sets in and you can't do anything against it except doing something else and return it to later. When and how strong you are affected differs from one person to the next but it happens to everyone.
But you should investigate on the origin of it. wouldn't you? I was replicating to Turbowatch2's assertion to abandon analog ( passive crossover it's analog)...what if it's DIGITAL the cause of the fatigue?
@pico There are fine speakers out there, with a passive crossover. Build them, buy them, love them. Perfectly OK. I still do it, too.
Here is a guy that, compared to the size of the project, has no clue what he does.
Tell me, in your opinion, what chance does he have to build a 4-way passive crossover for all these totaly randomly selected chassis with non matching spl's?
In much to small cabinets? What budget of caps, coils, resistors would you need to give him enough values to test build them?
Beside from the cost to reinforce his floor, so it can carry the weight of the crossover without collapsing?
With a measuring mike and a DSP he has at least a chance to build something you can, in the end, maybe, call a decent speaker.
I have written various posts why anyone without a few years of experience in speaker building should stick to proven kit's. Also, what he has to expect if he doesn't.
Anyway, people start such projects and some here try to help a little. Others seem to have the idea that these newbies should suffer like they did, learn crossover topologies, filter theory, understand simulation programs and waste huge amounts of money. This is a hobby and not anyone will reach heavently perfection. I try to accept that.
Here is a guy that, compared to the size of the project, has no clue what he does.
Tell me, in your opinion, what chance does he have to build a 4-way passive crossover for all these totaly randomly selected chassis with non matching spl's?
In much to small cabinets? What budget of caps, coils, resistors would you need to give him enough values to test build them?
Beside from the cost to reinforce his floor, so it can carry the weight of the crossover without collapsing?
With a measuring mike and a DSP he has at least a chance to build something you can, in the end, maybe, call a decent speaker.
I have written various posts why anyone without a few years of experience in speaker building should stick to proven kit's. Also, what he has to expect if he doesn't.
Anyway, people start such projects and some here try to help a little. Others seem to have the idea that these newbies should suffer like they did, learn crossover topologies, filter theory, understand simulation programs and waste huge amounts of money. This is a hobby and not anyone will reach heavently perfection. I try to accept that.
I don't deny some parts in the signal chain can cause fatigue, Especially increased treble, high distortion and generally too high volume. But: Everyone experiences listening fatigue, no matter if it's analog or digital. Some don't recognize it, others find it unbearable. Yes, digital components can cause that but even analogue components from A to Z can do that. You are right, you should search for overly straining components but it takes a long time to realize which one it is because you have to hear them from a relaxed state till you are fatigued. And to test the next component, you have to be completely relaxed again. Not only do the components have an influence in that, the fight with the wife, a teacher, the boss, stress, anger, the weather, your exhaustion level, air pressure, temperature, you name it, all that changes how you perceive the sound. The result of that is, even if nothing in the chain changes, you still hear differently.
There are a lot of reasons for listening fatigue. I don't claim digital is free from that but I refuse to believe "it MUST be digital!" as the only source. Get an oscilloscope and a test CD with sine wave sounds, you'll see the output is actually a perfectly shaped sine wave! No "steps" at all. I thought that myth was debunked for good 30 years ago.
That looks great and the vertical orientation fits the speaker well optically. However, it seems your supertweeter may be too high, if I compare the driver sizes (15" and 12" I guess) and the CDs, records and shelves, which results in about 1,50m height? 1,60m? The tweeter should be at ear height, so either you're short and listen standing or you are probably 3m tall and sitting brings you to that height. 😀 No, seriously, how high are your supertweeters?
Since the mid cab was only a test, I’d place the super tweeter above the 10, below the horn. This will be your main vertical listening axis so best the HF content be within that window.
Also consider an Aperiodic enclosure for the midwoofer……..or in other words a resistive leaky enclosure. You don’t need the extended bass response and the leak will tame the impedance peak of the mid making for a much more consistent load for your amplifier. Not sure if you’re using any modeling software but most worth anything can simulate the leak and show you the effect on impedance and Q.
That not my system so I can't say for sure. In my Arrays they are at 48" which is my seated ear height. I use an office chair so I can adjust my height as required. They are 30 degree vertical horns so you have some lee way depending on distance. Agree they should be at or close to ear height.
You really need to look at the system stack height or be prepared to drop the system on stands. Also gets the woofer up off the floor depending on cabinet layout. The stands come in handy as it make them easier to move around.
Rob 🙂
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I am open to running full DSP, but the reason I am running the passive crossovers is to protect these expensive horns. Heaven forbid one of my amplifiers to put out full rail voltage DC, which would be near or over 100 V depending on the amp I use, and those drivers would be gone in a flash. I am going with the 800 Hz crossover point, because that’s what JBL came up with. If you think the 251J can cleanly play higher without any break up then I’m certainly open to trying it. If I cross at 1200 Hz, it basically just becomes a large 3” tweeter. I know of some diy designs where a 1” dome is crossed near that.
If I ran the horns on DSP, how about putting a large capacitor in line to prevent any DC from reaching the drivers? Would that negatively affect the speaker?
The only reason I am thinking about going lower with the midbass is because of the experience of widget over at the Lansing Heritage forums. He did something similar to what I’m doing, but with Tad drivers, but used the same sub1500 woofers. He has the 10 inch TAD crossing to the 15 at 75hz. I’m pretty sure he said he did not try any higher than 100 Hz though. Here is his speaker
But I 100% understand the negative effects of a woofer moving a lot while at the same time producing frequencies up higher. Same reason why I’m not super fond of 5-1/4” or 6” two ways that are supposed to be capable of full range. I built these to use in my lab, and while they can produce some fantastic bass on their own it can sound a little off when that woofer is going full tilt.
So I decided to build and put 4 ten inch Peerless NE265w under the bench and high passed the speakers. Much, much better. But I figure even at 100 hz the 251Js wouldn’t be moving all that much right?
That is a fantastic idea, and I’ve actually thought about that in the past, kind of wanting to clone one of the array speakers. But with WMTMW design that will put this center to center spacing of the midbasses further apart, won’t that increase the comb filtering? I thought I would want them as close to each other as possible, is that correct? I do love the look of it oriented that way though. if you think I could get away with it in my design, I am 100% down to installing it vertically.
Nice, is that your setup? Or was?
Oh, wow, that’s a fantastic idea. I had not thought of doing aperiodic. I have never built one, only experience being with basically the Dynaco. What would you recommend? Drill like a 3 inch or a 2 inch hole in the back of the cabinet, staple in some screen material, and stuff the denim insulation up against it?
Dan
Oh yes, I wanted to mention, with the 15 on the floor, 10 on top of it, horn horizontal and the super tweeter on top the super tweeter is centered at 42” which seems about right I’d think. If I turn the horn vertically it would be at 51”. The good thing is that I can aim that small horn. And when I was speaking earlier about, not sure what to do with it, I meant specifically how to mount it on top of the other horn. I don’t know if I should use some Velcro or these testing phases. I don’t think Velcro would hold it very well though.
Dan