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**Chris Roemer** · 04-03-2013, 01:49 PM

Re: My take on the Bose L1/vertical array with sub

You'd be wise to learn some stuff 1st. Reading "SpeakerBuilding 201" would be a good idea.

"Splaying" drivers (the way you described it) is generally not a good idea.
Your 16 driver "wire-up" WILL produce a nominal 8 ohm load, but the sensitivity will end up around 96dB.
That crossover is rated at 200w. The sub is rated at 100w, whereas the 3"ers could take 240w.
That GW "sub" only has a 3.5mm Xmax., that means it can only handle about 15w down at 60Hz, no matter what type of box it's in, and a passive radiator works the same as a vented box, but you've got the cost of the PR as well as the possibility of it getting damaged to consider.
Also, personally, that woofer has too high of a Qts value for ME to consider using it in a vented or PR box.

And this is probably only just the beginning.

**samato** · 04-03-2013, 02:44 PM

Re: My take on the Bose L1/vertical array with sub

Thanks for the reply. I have several questions & comments about it that I'll post a little later.

**samato** · 04-03-2013, 05:16 PM

Re: My take on the Bose L1/vertical array with sub

Originally posted by Chris Roemer View Post

You'd be wise to learn some stuff 1st. Reading "SpeakerBuilding 201" would be a good idea.

Yes, I probably should learn some stuff first and I am in the process of doing that but most likely I will be learning the most by doing it. That's how I normally do things. You know, learn the hard way. I also don't like to get too deep into theory, it's just not in my nature. Sometimes when I just do it without regard to the "rules" I end up pleasantly surprised, even if it costs a little more time and money in the long run. I don't think I can fight the laws of physics, I just know I will never dedicate myself to being as knowledgeable on these subjects as you and others here but I don't let that stop me from trying things.

Is "SpeakerBuilding 201" an actual document I should look for or were you just making a point?

Originally posted by Chris Roemer View Post

"Splaying" drivers (the way you described it) is generally not a good idea.

Maybe not but wouldn't it depend on the purpose and what is trying to be accomplished? I'm not going for hifi or any kind of a proper "audiophile" rig; not even a particularly robust live sound system. In fact my needs are very basic. The instruments and instrument amps will do all the heavy lifting. This system just needs to fill in what's missing in the mix. What I like about the Bose L1 Compact I used is:
1) it's ability to be behind all the mics, serving as monitor and mains, without feedback at reasonable levels
2) the horizontal coverage onstage and throughout the room; you can be almost behind the thing before you hear the high-mids/highs drop off significantly
3) it's ability to "project" or carry sound through the room better than other speakers I've used (like a couple boxes with a 15" & horn, for example)

I don't think these things would be accomplished without the splaying of the speakers.

Originally posted by Chris Roemer View Post

Your 16 driver "wire-up" WILL produce a nominal 8 ohm load, but the sensitivity will end up around 96dB.

Are you saying I should look at other drivers or that I should consider other wiring schemes? I thinking about both. I just came up with that wiring because it was the first and easiest way I thought of to do it. I don't know how to calculate sensitivity of multiple drivers with different wiring schemes. I didn't even know the one I did was around 96dB. These are things I need to learn but I don't do well with math, otherwise I would have learned and remembered all these things years ago when I studied them. What level of sensitivity do you think I should be shooting for? Maybe I can post some other wiring schemes and you can tell me what they add up to?

Originally posted by Chris Roemer View Post

That crossover is rated at 200w. The sub is rated at 100w, whereas the 3"ers could take 240w.

Not sure if this is a problem. The way I'm planning it, only the sub would be affected by the crossover. The 3" drivers would not be connected to it; instead I would use a HPF on a graphic EQ unit before the amplifier.

Maybe I should explain the overall signal flow I have in mind:

Input sources
|
Mixer
|
Mixer main out-------------Mixer aux out
|---------------------------------|
Graphic EQ (HPF)--------------|
|---------------------------------|
Amplifier Channel 1-------Amplifier Channel 2
|---------------------------------|
3" driver array --------------Subwoofer

The dashes (-----) don't indicate any connection, that's just the only way I could figure out to show 2 paths side by side. Not everything will go to the sub, probably just a little kick drum if needed and whatever else sounds thin.

Originally posted by Chris Roemer View Post

That GW "sub" only has a 3.5mm Xmax., that means it can only handle about 15w down at 60Hz, no matter what type of box it's in, and a passive radiator works the same as a vented box, but you've got the cost of the PR as well as the possibility of it getting damaged to consider.

I didn't know anything about that so that was educational. I'm not sure if it's a problem though. I really don't need much from the sub but if it means I'm likely to damage the sub then it would be a problem. I've always been able to gauge what a speaker can handle by just listening for the early signs of distortion and staying below that level. That has allowed me to use amps rated for more power than a speaker can handle by just being careful. I might also consider a 2 channel limiter for this project. Anyway, if I need to look at a different subwoofer that's fine too. My reason for choosing a passive radiator design is it seems like the design and construction of the box is less of an issue this way. I really don't want to get into calculating critically specific box dimensions, porting designs, etc.

Originally posted by Chris Roemer View Post

Also, personally, that woofer has too high of a Qts value for ME to consider using it in a vented or PR box.

I don't know what this means so I don't know if it's a problem for me. I'll have to look it up.

Originally posted by Chris Roemer View Post

And this is probably only just the beginning.

Yes but correct me if I'm wrong - you probably believe the Bose L1 is a piece of junk and is of poor design? I know I can't assume to know what you think but I've read a lot from guys who seem to know their stuff saying it's garbage, yet I like it. I think it all depends on your expectations and what you need. I think the L1 Compact I'm using as a reference (that's what I have experience with) only puts out around 130watts total for the sub and the tower so I'm hoping this design will get at least as loud as that and hopefully sound as good or better.

**samato** · 04-03-2013, 05:37 PM

Re: My take on the Bose L1/vertical array with sub

Now, if you thought I was dumb before wait until you read about my idea for mounting the 3" speakers...

No enclosure!

I'm thinking about mounting them on PVC pipe or metal electrical conduit pipe, using conduit hanger brackets to mount them. I know that will work as far as keeping them in place but I have no idea what to expect in terms of the performance and sound of the speakers. I think this could be considered an open baffle design which I only just learned about a few days ago. Apparently it has it's advantages but I know nothing about the right kind of speakers to use for open baffle. I'm guessing there is a chance comb filtering, which is already an issue with an array like this, could be worse. Not sure if I'm worried about that though. What I am concerned with is how it would affect the overall volume of the system.

Do you think I would be losing volume by having the speakers out in the open like that?

**Chris Roemer** · 04-03-2013, 06:44 PM

Re: My take on the Bose L1/vertical array with sub

"SB 201" is a book (available at PE) by Ray Alden. It's a tad over 10 yrs old now, but I know of nothing more current. You don't have to memorize everything in there to build speakers, but you'd familiarize yourself with the terms so you could talk intelligently about questions that you'd have. I don't hardly have the time (or the knowledge) to type out the 150 pages of fairly basic speaker design info that's contained in that book.

I just looked at that Bose system (online). What's its purpose? It's like a monitor (for vocals, for the band), AND vocal amplification for the audience? If it's primarily for vocals, why would you want/need the "B1" bass thingy (I guess I see that the cheapest system skips the B1?)?

How can't it give you feedback if it's situated behind you? Even if a mic is highly directional, with these "monitors" behind you, won't the mics pick them up, or isn't there enough gain (so you've got your mouths right on top of the mics then?)?

That "articulation" looks like a major side-effect would be to double the C-C spacing between drivers, creating a lobing nightmare. To possibly suppress that problem, I'd be more inclined to run 2 stacks of 8, side by side, but I'd then be worried about lobing in the horizontal plane.

For 16 drivers, you've got them wired properly. Compared to a (single) 8 ohm driver, a bunch of them wired to maintain 8 ohms (which would be series/parallel groups of 4, 9, 16, 25, etc.) will have the following sensitivity increase, a +3dB gain for every doubling of drivers. So, 2 is +3dB over 1, 4 is +6dB, 8 is +9dB, and 16 is +12dB. 16 is a good number because you can keep 8 ohms that way.

I couldn't open the B1 info.pdf once I downloaded it (it bombed my Reader), so I don't really know what's in there. I've seen the Bose mini HT subs in stores, and they ARE pretty pathetic, compared to what you can DIY. Tons of people (who don't really know any better) think they're pretty cool though.

Xmax refers to how far a driver's cone can move each side (forward/backward) from its resting point before something goes wrong (could be sorta minor - like just garbled distortion, or could be major - like the voice coil banging against the magnet assembly's back plate, which can almost sound like a machine gun, which isn't nice).

The ARE 8" "subs" that have more like 10mm of Xmax. That's what I'd shoot for. Nothing wrong with bigger drivers either. "There's no replacement for displacement." A passive radiator box is NOT like a closed box, but it IS a tuned system, just like a vented box, and can be slightly easier (or harder) to get right than a vented box. If you're afraid of box design (which isn't THAT hard, not compared to crossover design), you could go sealed, using an amp for the sub with "boost" on the bottom end. For either a vented or PR design, I personally like a Qts somewhere between 0.30-0.50, but certainly below 0.60. Higher "Q" drivers like that GW (and MOST Goldwoods - if you look) usually work better in closed boxes. A good starting point for the sub would be to determine just how low it would need to go. Very little (non-electronic) music gets down to 40Hz. Maybe an F3 (bottom end) of 60 would be OK, or maybe even just 80? I don't know. How low does that B1 go?

I think that most people would agree that BOSE stuff is WAY overpriced. It's engineered quite well to make (some) people THINK they're getting something good, and I'm sure it's engineered well enough to keep BOSE at the top of the consumer marketplace by making BOSE plenty of cash. I can't say it's engineered poorly, but I can say it's engineered poorly to create good sound.

Welcome to TechTalk.

**samato** · 04-03-2013, 11:12 PM

Re: My take on the Bose L1/vertical array with sub

Originally posted by Chris Roemer View Post

"SB 201" is a book (available at PE) by Ray Alden. It's a tad over 10 yrs old now, but I know of nothing more current. You don't have to memorize everything in there to build speakers, but you'd familiarize yourself with the terms so you could talk intelligently about questions that you'd have. I don't hardly have the time (or the knowledge) to type out the 150 pages of fairly basic speaker design info that's contained in that book.

Cool, I will check it out.

Originally posted by Chris Roemer View Post

I just looked at that Bose system (online). What's its purpose? It's like a monitor (for vocals, for the band), AND vocal amplification for the audience? If it's primarily for vocals, why would you want/need the "B1" bass thingy (I guess I see that the cheapest system skips the B1?)?

It's not only for vocals, that's just how we tended to use it at that particular club and likely how I would use this system if/when I build it. Bose suggests it be used as a monitor and main FOH system, so the musicians and audience hear basically the same thing. The cheapest version (L1 Compact) does have a sub. The L1 Compact is designed mainly for solo performers and small ensembles in small spaces. They recommend several of their more powerful units (L1 model II) for full bands, ideally 1 per musician with possibly more than 1 bass unit where needed.

Originally posted by Chris Roemer View Post

How can't it give you feedback if it's situated behind you? Even if a mic is highly directional, with these "monitors" behind you, won't the mics pick them up, or isn't there enough gain (so you've got your mouths right on top of the mics then?)?

Well, this is indeed the "magic" part. We were using standard mics - SM58 and SM57's. We used them as you normally would, no special placement or technique. Not really magic though, just physics. My theory is that because it's an array of multiple speakers firing at different angles and on different planes, no 1 speaker is pushing enough volume into the mic to cause feedback; or something like that. It will feedback though if you push it enough, it's just that by the time you start getting feedback you should already have enough volume to get the job done, unlike with a standard speaker cab positioned behind you.

Originally posted by Chris Roemer View Post

That "articulation" looks like a major side-effect would be to double the C-C spacing between drivers, creating a lobing nightmare. To possibly suppress that problem, I'd be more inclined to run 2 stacks of 8, side by side, but I'd then be worried about lobing in the horizontal plane.

Not sure I understand this but I believe that lobing (if I understand the term) is necessary to the design. That's how everybody across the stage and in the audience is able to hear the sound evenly and how it achieves it's projection ability.

Originally posted by Chris Roemer View Post

I couldn't open the B1 info.pdf once I downloaded it (it bombed my Reader), so I don't really know what's in there.

I'm not sure if these are the same files you were trying to look at but here's a link to the L1 Compact specs:

http://www.fullcompass.com/common/files/13903-td_l1_compact.pdf

And here's the L1 Model 2:

403 Forbidden

http://pro.bose.com/pdf/pro/tech_data/L1/td_l1_m2.pdf

Originally posted by Chris Roemer View Post

Xmax refers to how far a driver's cone can move each side (forward/backward) from its resting point before something goes wrong (could be sorta minor - like just garbled distortion, or could be major - like the voice coil banging against the magnet assembly's back plate, which can almost sound like a machine gun, which isn't nice).

The ARE 8" "subs" that have more like 10mm of Xmax. That's what I'd shoot for. Nothing wrong with bigger drivers either. "There's no replacement for displacement." A passive radiator box is NOT like a closed box, but it IS a tuned system, just like a vented box, and can be slightly easier (or harder) to get right than a vented box. If you're afraid of box design (which isn't THAT hard, not compared to crossover design), you could go sealed, using an amp for the sub with "boost" on the bottom end. For either a vented or PR design, I personally like a Qts somewhere between 0.30-0.50, but certainly below 0.60. Higher "Q" drivers like that GW (and MOST Goldwoods - if you look) usually work better in closed boxes. A good starting point for the sub would be to determine just how low it would need to go. Very little (non-electronic) music gets down to 40Hz. Maybe an F3 (bottom end) of 60 would be OK, or maybe even just 80? I don't know. How low does that B1 go?

Overall, I'm trying to keep everything as small and as inexpensive as possible but I don't mind using a larger woofer if necessary. It's kind of hard for me to determine how low the Bose goes based on the specs they provide. I know when I mix music I sometimes like to boost the kick drum a little around 60Hz. For the most part with this system though, I just want it to go "boom" when I turn up the sub.

The sub is mainly there just so those little speakers don't have to deal with stuff below 200Hz or so. Rather than go crazy with the design of this subwoofer I'd rather just build a more serious sub to add to the system later, if I find I'm not getting enough power down there.

Originally posted by Chris Roemer View Post

I think that most people would agree that BOSE stuff is WAY overpriced. It's engineered quite well to make (some) people THINK they're getting something good, and I'm sure it's engineered well enough to keep BOSE at the top of the consumer marketplace by making BOSE plenty of cash. I can't say it's engineered poorly, but I can say it's engineered poorly to create good sound.

I would also agree that it's overpriced, that's why I'm trying to copy the design and make one myself. Not too crazy though considering how they've managed to design and produce something unlike anything else on the market in terms of portability, style, performance, etc. Their cheapest system costs $1,000. Honestly, I don't think I can build it for less than $500 in materials, and if I count planning and labor...

Originally posted by Chris Roemer View Post

Welcome to TechTalk.

Thanks!

**samato** · 04-03-2013, 11:43 PM

Re: My take on the Bose L1/vertical array with sub

Any thoughts on post #5 of this thread? This is my main concern at the moment.

**Chris Roemer** · 04-04-2013, 02:21 AM

Re: My take on the Bose L1/vertical array with sub

Well, the SOS (speed of sound) is about 1120 fps. So a 200Hz tone has a wavelength of about 5-1/2'. That means that an open back driver (meaning that the back wave off the cone is not contained or delayed by an enclosure) would have cancellation near 200Hz (and below) if drivers were mounted on a panel that was about 5.5' wide (I think). Taking that one step farther, a 3" driver (or a string of them) hanging in "free air" would have cancellation around 4kHz and below.

I modeled this in a free software called "Edge", using a string of 3" drivers on a 3" wide open baffle, and starting at a reference point of, let's say 0dB at 3kHz, the drop-off plots like this: -3dB @ 1000Hz, -6 @ 600, -9 @ 300, -12 @ 200, -15 @ 130Hz, and downward. You can't really plan to EQ that back up because those little drivers don't typically have the Xmax to handle the power required to boost them back up, say, +6 to +12dB down in the 200-600 range.

A driver you might want to look at though, is the $12 AURA NS3 over at madisound .com

**billfitzmaurice** · 04-04-2013, 08:26 AM

Re: My take on the Bose L1/vertical array with sub

FWIW, the L1 works OK for singles or duos in small lounge/coffee shop settings. In larger rooms and with more players you need at least two of them, and at that point from both the standpoint of price and setup complexity it no longer offers any advantage over a traditional PA.
The proof of the value of the L1 concept lies in the most sincere form of flattery: Imitation. Just like the 801, which a generation ago Bose also promised would revolutionize PA, no one else has copied the L1. Not that anyone else doesn't do line array, because they do. But not in the Bose fashion, because the Bose way is the wrong way.

**samato** · 04-04-2013, 12:11 PM

Re: My take on the Bose L1/vertical array with sub

Originally posted by Chris Roemer View Post

Well, the SOS (speed of sound) is about 1120 fps. So a 200Hz tone has a wavelength of about 5-1/2'. That means that an open back driver (meaning that the back wave off the cone is not contained or delayed by an enclosure) would have cancellation near 200Hz (and below) if drivers were mounted on a panel that was about 5.5' wide (I think). Taking that one step farther, a 3" driver (or a string of them) hanging in "free air" would have cancellation around 4kHz and below.

I modeled this in a free software called "Edge", using a string of 3" drivers on a 3" wide open baffle, and starting at a reference point of, let's say 0dB at 3kHz, the drop-off plots like this: -3dB @ 1000Hz, -6 @ 600, -9 @ 300, -12 @ 200, -15 @ 130Hz, and downward. You can't really plan to EQ that back up because those little drivers don't typically have the Xmax to handle the power required to boost them back up, say, +6 to +12dB down in the 200-600 range.

A driver you might want to look at though, is the $12 AURA NS3 over at madisound .com

Okay, I think I get it. One of the things an enclosure does is reduce or eliminate phase cancellation at certain frequencies. By having little or no baffle with a 3" driver I would have cancellation at the amounts and frequencies you mentioned. With the right driver I could make up for this by boosting the affected frequencies with an EQ.

I think I'd be better off avoiding the problem by putting the speakers in an enclosure. In my experience it's better to deal with these issues physically than electronically. Same basic concept when you are recording in the studio. Why fix something with EQ when I could just get it right in the first place by making sure the instrument sounds right, choosing the right mic and mic placement, etc.

I've found that the lower end graphic EQ's I've used (and would probably use for this project) tend to add noise to the system, especially when boosting. That's a problem I like to avoid if possible. Plus, I'll save a little money by being able to use a cheaper driver.

So much for my open baffle plans!

I'm still thinking of using PVC pipe though only now I'll be mounting the speakers in the PVC, not just using it as a stand.

**samato** · 04-04-2013, 12:24 PM

Re: My take on the Bose L1/vertical array with sub

Originally posted by billfitzmaurice View Post

FWIW, the L1 works OK for singles or duos in small lounge/coffee shop settings. In larger rooms and with more players you need at least two of them, and at that point from both the standpoint of price and setup complexity it no longer offers any advantage over a traditional PA.
The proof of the value of the L1 concept lies in the most sincere form of flattery: Imitation. Just like the 801, which a generation ago Bose also promised would revolutionize PA, no one else has copied the L1. Not that anyone else doesn't do line array, because they do. But not in the Bose fashion, because the Bose way is the wrong way.

I disagree with the L1 only being suitable for solo/duo acts in very small places but your opinion is shared by many on the internet. The video I linked to in my first post shows the lowest model L1 was able to keep up with a 5 piece band, granted in a small place but not coffee shop small. This is why theory only interests me to a certain extent. I trust my ears and experience more. We're not loud compared to a Heavy Metal band I guess but not exactly soft acoustic music either. I'll admit there were times when, if the band got too loud (especially the drummer), the L1 got overpowered. In my opinion that just means the musicians need to do a better job mixing themselves for the the room and the system. That is the right approach to playing live music with other people in my book but it gets lost in the modern approach to live sound. I like that the Bose system promotes this method.

I also disagree that when you add another unit the setup complexity increases to the point where there is no advantage over a traditional P.A. I think if I could have added another L1 Compact to the one being used in the video I posted it would have given us more than enough, regardless of how loud the drummer got, and it would have been very easy to setup - basically one more audio cable run and one power connection. A system with 2 of those units would be capable of handling us in a room at least twice the size of that one, I would say.

I have some ideas about why the L1 is not being copied by other manufacturers but it's purely speculation so I'll leave that alone for now.

**billfitzmaurice** · 04-04-2013, 12:33 PM

Re: My take on the Bose L1/vertical array with sub

Originally posted by samato View Post

I disagree with the L1 only being suitable for solo/duo acts in very small places but your opinion is shared by many on the internet.

You can think what you wish, but I have been at this for a while. A friend of mine who is a single playing keyboard has an L1 Series II with two bass modules; he sounds OK through it. When he sits in with my 3 piece R&B band he runs through my PA, a pair of my Jack 10 Lites, with W6 floor monitors. He does so because by comparison his Bose is a joke.

**samato** · 04-04-2013, 01:25 PM

Re: My take on the Bose L1/vertical array with sub

Originally posted by billfitzmaurice View Post

You can think what you wish, but I have been at this for a while. A friend of mine who is a single playing keyboard has an L1 Series II with two bass modules; he sounds OK through it. When he sits in with my 3 piece R&B band he runs through my PA, a pair of my Jack 10 Lites, with W6 floor monitors. He does so because by comparison his Bose is a joke.

Ha! Well, I too have been at this for a while so I say YOU can think what YOU wish!

There, now we both have permission to think freely - even if our minds are closed.

Seriously, there are so many variables, different applications, etc. I know that what works for me may not work for others. I'm not here to debate the worthiness of the product. That has already been established for ME. I'm here to figure out how to make something similar to it.

**samato** · 04-04-2013, 01:37 PM

Re: My take on the Bose L1/vertical array with sub

Oh, the keyboard player in my band didn't care too much for the sound he got going straight into the L1 Compact either. That's fine though because I'm not trying to replace his keyboard amp with this system anyway.

More than one way to skin a cat.

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My take on the Bose L1/vertical array with sub

My take on the Bose L1/vertical array with sub

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