Hello, newb here so skip if that will annoy you.
I'm planning on using 2x Alpair 11MS in conjunction with a woofer to assist with the lows. Right now I've got some preliminary ideas, but before I go further, I wanted to ask about the crossover. The 11MS drivers will be sealed, with an F6 of 71.3hz. Am I correct in thinking that if I allow them to rolloff naturally, and build a 1st order low pass crossover at 70hz for the woofer, this will be ok? I can't tell if I should crossover lower because
Also I'm a little stuck with matching the drivers to a woofer. If I go in series with the pair of 11MS, and end up with a USPL of 88.1/2.83, against a woofer with a USPL of 87.9/2.83, that should be ok right? I read that generally you aim for 3db higher in your mid/high than the woofer, because of crossover loss, but that won't apply here, right? I understand there's more to matching than that, and I'm still trying to absorb all of it.
My next question is about that, impendence. The woofer I'm eyeing has a F3 of 49hz, F6 of 32hz, F10 of 23hz. That's about as good as I can hope for, right, without going for a separate sub? I am hoping to go with 2 floorstanders. Space isn't an issue for them, but would be for a 3rd box. For the impendence, the woofer is basically all over the place, and I need to just read more on that. Both are nominal 8ohms.
These may be totally dumb questions, but there is just a lot to absorb, and I was hoping for confirmation that either I need to do a lot more reading, or I'm on the right track. Thank you to all!
edit3: answering a lot of my own questions.
I'm planning on using 2x Alpair 11MS in conjunction with a woofer to assist with the lows. Right now I've got some preliminary ideas, but before I go further, I wanted to ask about the crossover. The 11MS drivers will be sealed, with an F6 of 71.3hz. Am I correct in thinking that if I allow them to rolloff naturally, and build a 1st order low pass crossover at 70hz for the woofer, this will be ok? I can't tell if I should crossover lower because
Also I'm a little stuck with matching the drivers to a woofer. If I go in series with the pair of 11MS, and end up with a USPL of 88.1/2.83, against a woofer with a USPL of 87.9/2.83, that should be ok right? I read that generally you aim for 3db higher in your mid/high than the woofer, because of crossover loss, but that won't apply here, right? I understand there's more to matching than that, and I'm still trying to absorb all of it.
My next question is about that, impendence. The woofer I'm eyeing has a F3 of 49hz, F6 of 32hz, F10 of 23hz. That's about as good as I can hope for, right, without going for a separate sub? I am hoping to go with 2 floorstanders. Space isn't an issue for them, but would be for a 3rd box. For the impendence, the woofer is basically all over the place, and I need to just read more on that. Both are nominal 8ohms.
These may be totally dumb questions, but there is just a lot to absorb, and I was hoping for confirmation that either I need to do a lot more reading, or I'm on the right track. Thank you to all!
edit3: answering a lot of my own questions.
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If it annoys people, you know they aren't worth wasting time with anyway. This place is supposed to be about helping each other. We don't always get everything right but most of us do our best.
There isn't a single / simple / fixed answer to whether it will 'be OK' because it depends on exactly what you're aiming to achieve, and how you're planning on achieving it. You don't give any details about your intended supporting woofer, or the 'because', so we're a little limited in terms of offering suggestions. However, the immediate reaction is that unless the woofer is in a max-flat impedance TL, you'll need to cross actively or at line level -while it's not impossible to use a speaker-level passive in other circumstances, you'll need LF impedance compensation which means very large (& expensive) components; it's not an especially realistic condition.
Aside from the fact that series wiring the 11MS will give a nominal 16ohm load (so check your amplifier is happy with that), the general ROT is to ensure your HF leg (however low down it stretches) has an SPL equal to or greater than the LF as it's much more straightforward to pad it down than a woofer; quantity of excess is relatively immaterial as far as that goes.
Not necessarily for the first -you haven't said what woofer you're looking at (not even its size) so we don't know what can be done with it within your size constraints, nor suggest any possible alternatives. For the second, it depends what you mean by 'all over the place'. If you can be more specific we might be able to make some suggestions.
As a broad observation, unless you're basically using the LF leg like subwoofers with a suitable active filter (a good adjustable plate amp would suffice), then in my view, you're crossing too low & your system design may need some rethinking; if you can give some more information on the overall goals, size, desired configuration etc. we'll have a better idea of what to suggest.
Thank you for your reply. Now that you say all that, it all makes sense. Sorry about my incomplete post, I originally had more questions, but some were answered as I kept reading and googling, so my edits left it sort of incoherent.
The size of the entire enclosure isn't a big deal, it could be 5' by 14". The intended goals are to have a great music system, but in the current house, the only place they can go is by our TV, so really they will be used for TV/home theatre 90% of the time for the next 1-3 years. I want something that will do fine with that now, and be musical afterwards, in a new house/room, so FR drivers sort of make sense.
I've read some reviews of people cautioning against driving the 11MS too hard with home theatre, so I wanted to run 2 per channel. Looking at crossovers last night, yes I realized that I'll need to put the 11MS in parallel. I would also rather assist them with a woofer (8" is what I had) in the same enclosure, than have a separate sub, especially in the current room, and sealing them v porting seems like it might help their excursion a bit.
The woofer I was looking at in particular was the Seas H1208-08, but as you say, the impendence in its intended range is ridiculous. In VituixCad I can't even see how high its spike goes towards 49hz or so.
Thank you for your response. I was wondering if there were woofers out there that did what I want, and there were! If I don't know what I'm doing. Just too good to be true. I'd go with a 12" woofer if it helped me, but I will go back to the reading on this project. I'm still having fun with it, so until it's downright depressing I'll keep going.
edit: I do want to roll off the FR drivers naturally, that seems somewhat important, otherwise why use them? So finding the woofer that can be made to work is the thing I guess.
The size of the entire enclosure isn't a big deal, it could be 5' by 14". The intended goals are to have a great music system, but in the current house, the only place they can go is by our TV, so really they will be used for TV/home theatre 90% of the time for the next 1-3 years. I want something that will do fine with that now, and be musical afterwards, in a new house/room, so FR drivers sort of make sense.
I've read some reviews of people cautioning against driving the 11MS too hard with home theatre, so I wanted to run 2 per channel. Looking at crossovers last night, yes I realized that I'll need to put the 11MS in parallel. I would also rather assist them with a woofer (8" is what I had) in the same enclosure, than have a separate sub, especially in the current room, and sealing them v porting seems like it might help their excursion a bit.
The woofer I was looking at in particular was the Seas H1208-08, but as you say, the impendence in its intended range is ridiculous. In VituixCad I can't even see how high its spike goes towards 49hz or so.
Thank you for your response. I was wondering if there were woofers out there that did what I want, and there were! If I don't know what I'm doing. Just too good to be true. I'd go with a 12" woofer if it helped me, but I will go back to the reading on this project. I'm still having fun with it, so until it's downright depressing I'll keep going.
edit: I do want to roll off the FR drivers naturally, that seems somewhat important, otherwise why use them? So finding the woofer that can be made to work is the thing I guess.
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Wel, on woofer i would ook at the SB34NRX75-6. It goes very low (even sealed) and still can go high enough for a waw config. Second option (the one i use) is the Scanspeak 26W/8534G00. I did not know about the SB34 when i bought it (years ago) but at that time it was the best that i knew that was not very expensive. The Scanspeak needs 77L sealed (F3 of 31Hz) or 150L ported (F3 of 26Hz), the SB34 about double that to go real low sealed, and more if ported (but i don't think it's needed).
And i would cross a bit higher (150-300Hz) with a active or passive low order crossover on both drivers, leaving the 11MS without filter will not work as it still will give bass and can be overloaded in the scenario you said. If you still want to do it without filter on the 11MS you will gain bass due to the subwoofer, but not safety of the 11MS on high volume. And decent subwoofer can be used then i think (including those i mention above).
And i would cross a bit higher (150-300Hz) with a active or passive low order crossover on both drivers, leaving the 11MS without filter will not work as it still will give bass and can be overloaded in the scenario you said. If you still want to do it without filter on the 11MS you will gain bass due to the subwoofer, but not safety of the 11MS on high volume. And decent subwoofer can be used then i think (including those i mention above).
Thank you for your reply.
I do want to cross over as low as possible if I'm going to filter the full rangers, and I'd prefer a passive crossover. I've got an integrated right now, and later I'll build one of the beefier Pass amps, and I'm not super interested in messing with multiple amps, though if I built 2 Pass amps I could bi-amp with the appropriate filters from the integrated.... Trying to keep it simple though.
On the topic of filtering the 11MS, it seemed to me, knowing next to nothing, that by sealing them it was greatly limiting Xmax/excursion, but you would still want to relieve them of some of their bass duty? Hard for me to know, from the specs, what would be dangerous to them.
I do like both the subs you mention. Am I wrong, or within reason, am I going to have to compensate for any woofer's impendence?
normally not, the crossover will handle that right, even when the woofer is lower impendance than the FR. It's just making sure that your amp can handle 4ohm and that your impendance in the crossover does not go lower than 3ohm so it does not break the amp.
How you going to install two 11MS in the cabinet?
If you put them both on front panel, even if they touch each other, distance between centers will be too big to act as single sound source at high frequencies. And that can give you negative effects on HF response and dispersion.
I would stick with one full range unit on front panel, and if there must be the second, then put it on the top, rear or side.
If you havent, check this thread. Different drivers in question, but it may give you some ideas.
acoustical bass roll off
If you put them both on front panel, even if they touch each other, distance between centers will be too big to act as single sound source at high frequencies. And that can give you negative effects on HF response and dispersion.
I would stick with one full range unit on front panel, and if there must be the second, then put it on the top, rear or side.
If you havent, check this thread. Different drivers in question, but it may give you some ideas.
acoustical bass roll off
If you want to use the natural roll-off of the sealed box you want to look at the F(-3) as that XO point. 5 litres per driver, 90 Hz XO.
Trying to go passive at these frequencies is VERY VERY hard, and given parts size may actually cost more than to multi amplify.
Using the sealed box roll-off as the XO suggests a plate-amp in the woofers with a complementary second order roll-off.
As to wiring the 2 A11ms, i tend towards series, this means that one driver has a big cap shunting it, the value such that the 2nd A11ms rolls in somehwere below the quarter-wave spacing f the drivers. Sensitivity remains the same thruout the range, but in the bass the drivers are working half as hard. Most amps are happier with 16Ω, the amp can loaf. Loss of 3dB of power is probably inconsequential.
If you run both drivers all the way up, you will have less HF issues the further away you are.
50ish Hz seems a high Fs for this kind of application. One might actaully get more bass out of a pair of A11ms in something like a twin FHXL. This specualtion from the results of a small WAW with FF85wk. Turns out bass was better, more extended, and the entire range was more cohesive with just the F85wk in FH-Lite.
dave
A lot more to think about, thank you guys. Yeah I guess if I use 2 FR, I should limit the highs to just 1 of them. And Davor is right, I lose the benefit of the imaging/voicing/phase if I use 2 of them. With the SB34NRX75-6 I'd get an Fs of more like 22hz, which is low enough for me. Maybe if a single 11MS just has to handle low mids through highs, it could be ok for home theatre.
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If I got the route of dual drivers, with the big shunt cap you talk about, do you still leave both drivers in the same space, or separate them? Just curious. I imagine still the same space, otherwise you might get slightly different tuning? Or will the different cone behavior necessitate different tuning?
Ok, sounds good.
From doing a lot more reading (crossover cook book) good lord is there a lot to understand, but the advantage of this particular setup is the simplicity in 2 types of drivers, right? I can use a first order high pass filter on the pair of 11MS, and if done right, combined with the natural roll-off, will be quite effective in relieving them of some of their bass duties? At least now that's what I'm thinking.
Then there need to be more components to match everything and flatten impendence, but I will have to have the speakers in the box and measure for that, right? Unfortunately I'll need to measure the pair of 11MS as a pair, with the shunt cap already in right? Which seems like it will be difficult, and I'll just get approximations, due to on/off axis response of 2 drivers I need to function as 1?
And I'm still reading about the woofer crossover. A first order low pass filter won't be nearly as effective, unless I found a woofer with a natural rolloff starting around 150hz (just targeting that for now). I'll have to figure out something more complicated.
From doing a lot more reading (crossover cook book) good lord is there a lot to understand, but the advantage of this particular setup is the simplicity in 2 types of drivers, right? I can use a first order high pass filter on the pair of 11MS, and if done right, combined with the natural roll-off, will be quite effective in relieving them of some of their bass duties? At least now that's what I'm thinking.
Then there need to be more components to match everything and flatten impendence, but I will have to have the speakers in the box and measure for that, right? Unfortunately I'll need to measure the pair of 11MS as a pair, with the shunt cap already in right? Which seems like it will be difficult, and I'll just get approximations, due to on/off axis response of 2 drivers I need to function as 1?
And I'm still reading about the woofer crossover. A first order low pass filter won't be nearly as effective, unless I found a woofer with a natural rolloff starting around 150hz (just targeting that for now). I'll have to figure out something more complicated.
Well, if it's your first time and you absolutely want passive filters, Might I suggest the XM46SB from Marchand?
https://www.marchandelec.com/xm46-pllxo.htmlIt's a line level filter, so you put that between the pre amp and the power amp for the Alpair drivers. Works well, I've used it before.
Just get a regular plate amp for the bass.
But I would perhaps consider a filter somewhere between 120-200hz instead, especially if you're going to have 1 Alpair driver per bass driver. It makes the job easier both for crossover adaption and the 11MS.
Personally I'd rather use DSP since it's more versatile and you can adapt and tweak to your hearts desire, and it might be a better way to learn more about filters and eq by actual experience.
https://www.marchandelec.com/xm46-pllxo.htmlIt's a line level filter, so you put that between the pre amp and the power amp for the Alpair drivers. Works well, I've used it before.
Just get a regular plate amp for the bass.
But I would perhaps consider a filter somewhere between 120-200hz instead, especially if you're going to have 1 Alpair driver per bass driver. It makes the job easier both for crossover adaption and the 11MS.
Personally I'd rather use DSP since it's more versatile and you can adapt and tweak to your hearts desire, and it might be a better way to learn more about filters and eq by actual experience.
Hi, thanks for your reply.
Your post sure makes a whole lot of sense, but I'm not about to buy something that's logical rational and reasonable, am I? No sir, I'm making my life as hard as it can be.
Right now I'm reading about crossovers over and over, trying to understand more each time. I think I'll end up with a parallel 2nd order, with 3 total drivers. 2x 11MS, both limited to around 135hz, and one limited to under 450hz, tentatively, but the actual crossovers points will be different. The first order crossovers sounded great until I really started thinking about the mess it would make to have the woofer reaching up into 200-400hz range, have a 11MS basically dedicated to that range, and another 11MS doing that range plus everything higher.
So per planet10's post, I've got the second 11MS crossing over below quarter wave spacing, both in series, and my only hope is that sharing the load of 135-450hz will allow the full ranged one to have a bit of an easier time. These are rated at 35w, but I bet if they have an easier time down low they could go plenty high enough for home theatre in a small to medium sized room.
I have thought about plate amps, but I'm still trying to avoid them. Might be building a second pair for my parents, and extra cables wouldn't be practical for their usage.
This is all some time away, as I'm going to be logging and building my own plywood out of mesquite, out of the family ranch in Texas. My thought is that if I build my own plywood, I can get a nice, slightly curved shape out of the sides of the box. Might not sound as good as baltic birch, but mesquite is plentiful there, and it will be sort of cool to build the boxes out of it.
edit: By the way, I'm going down a rabbit hole of capacitors. I'm thinking of picking up a bunch of .33uf ceramic capacitors for the woofer crossover components. At woofer ranges, once you combine a bunch the ESR is very low (gets crazy high beyond 5Ghz), as long as they are suitable, is there any downside in doing this? I guess lead resistance from having a bunch?
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The 'name of the game' is for the cab to have no perceivable impact on the speaker's performance, so either make it massive enough to resonate ~ an octave below or above its intended pass-band with the latter the usual easier, cheaper, lighter solution, which usually means it needs to have a system resonance (Fs) > ~ 1 kHz.
Not really, it's fairly simple. Capacitance increases when using several capacitors in parallel, there's also reduced resistance because of increased conductor thickness so you're golden.
I would still look for some motor MKP's though, me being a frugal soul.
You could still do your own passive line level crossovers if you want to DIY, it's MUCH cheaper and A LOT less wasteful than having those low frequency filters after the power amp.
If you want to be stubborn (and I do get it, being a grumpy goat myself), at least do it cheaper, with easier load for the power amplifier and in style.
Get as many of those precious low power watts from the amplifier to the driver with little to no loss in between, it helps at least my mind achieve a sliver of peace.
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I really wouldn't use ceramics for crossovers, other than perhaps an ultrasonic Zobel for speaker wire. Especially if you're paralleling 0.33uF values, you're going to need a hell of a lot for a meaningful filter frequency. If you want to save money, just use a decent bipolar electrolytic, keeping an eye on the ESR. Otherwise, MKT or MKPs are cheap enough if you don't go crazy on the brand-name components. Remember, if you're crossing, speaker level, at the sorts of frequencies in question, you will require an Fs LCR impedance Zobel for the 11MS unless it's in a max-flat impedance TL, or it will not be rolling off as designed. That's not a matter of debate, just a basic laws of physics, electrical engineering & crossover design. So prepare to need big components. And yes, that applies even if it's a series 1st order. You know that beloved belief that series 1st order crossovers are immune to driver impedance variations? They're not. Or rather, that can be misread. They aren't as vulnerable as some, but they are not immune.
See the attached. This is using the measured driver data for a commercial speaker I designed some years ago, with the filter replaced with a simple 2-element series 1st order at roughly the frequency you mention, purely for the sake of example. Values are textbook for the impedance at the notional XO frequency. I shoved it into Xsim for speed as I'm on my laptop. Not very pretty. And unless, as noted, you flatten out the impedance, any other filter will have similar issues.
See the attached. This is using the measured driver data for a commercial speaker I designed some years ago, with the filter replaced with a simple 2-element series 1st order at roughly the frequency you mention, purely for the sake of example. Values are textbook for the impedance at the notional XO frequency. I shoved it into Xsim for speed as I'm on my laptop. Not very pretty. And unless, as noted, you flatten out the impedance, any other filter will have similar issues.
Attachments
I was planning on a high filter on the 11MS that basically avoided its impendence peak towards the low end. Hopefully that alleviates that issue. That means the woofer is crossing over quite high, but it's the compromise I think I basically have to make, and lets me avoid a Zobel for the 11MS. I also think the higher I crossover the 11MS, the harder they can be driven, right?
I'll be thinking about the line level crossover. I can't do that to my parents, they will just have a single integrated, but I will probably build 2 Aleph J variants, so biamping would be great. Might be nice to see for myself the sound difference, all other things being equal.
I guess my main questions are:
Say I bought a pair of MAOP 11, and 11MS, I have the MAOP doing full range duty, and the 11MS doubling in the 150-400hz range, would that present special issues? I get that for all intents and purposes they are 2 different drivers. And given that it somewhat works, to what extent does doubling that range actually help the full range driver? Would you expect it to help the full range drive 10% more without detriment, 30%?
I've read enough now that I'm not sure this is really what I want, but I'm still up for trying it.
One last thing, the shunt for the second 11MS. What would that look like? It's hard to find information on this. Can I put the shunt after the high filter? That's what it seems most people do...
Say I bought a pair of MAOP 11, and 11MS, I have the MAOP doing full range duty, and the 11MS doubling in the 150-400hz range, would that present special issues? I get that for all intents and purposes they are 2 different drivers. And given that it somewhat works, to what extent does doubling that range actually help the full range driver? Would you expect it to help the full range drive 10% more without detriment, 30%?
I've read enough now that I'm not sure this is really what I want, but I'm still up for trying it.
One last thing, the shunt for the second 11MS. What would that look like? It's hard to find information on this. Can I put the shunt after the high filter? That's what it seems most people do...