Four 12's or just three?

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lukeman269
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Four 12's or just three?

Post by lukeman269 »

Hey guys, I am doing a new setup soon after I get my ZX500 recapped. I have four bnib boston acoustics g112-44 subs. I am pondering on running all 4 or just 3. The amp will push 3 better than all 4 but having all 4 would be kind of neat.

My plan for running just 3 of the 12's. Both boxes would be sealed with the recommended 1 cube per woofer. I might try to go 1.2 cubes per sub to get a little extra low end.

My vehicle is a Yukon XL so I have 49" wide to work with. I was going to build a box that is 49" wide by 14" tall by 13" deep and recess the front baffle in about an inch or so to accommodate a grill panel that would screw into the box. Recessing the front baffle would allow the subs to move without touching the grill. I would use a black wire mesh that is stiff enough to withstand some abuse from stuff in the cargo area. I was planning to probably cut out a 3 ring board to match where the subs are going in the box then carpet that piece and then glue or staple the wire mesh behind that so there appears to be a separate grill for each woofer and so you can see each woofer. Maybe I would do some blue lights along the recessed part of the box to have a nice glow effect coming through the grill. Then screw that whole assembly to the box.

Plan for running 4 12's

Do a flatter box that fills the whole cargo area so like 49" wide by 32"? deep and like 7 tall. Then face them all up and then do a false top on hinges so I can show them off when I lift the top, but leave enough room so they don't load the board too much. I would probably do a spring hinge so it doesn't just flop there and maybe even do a latch on the front to keep top from wanting to move from bass. I guess I could still do the black mesh thing on the false top to prevent the subs from loading onto the board. Then I can still utilize the cargo area by putting anything right on top of the box. The box overall WITH the false top would be about 10-12" tall. That still leaves room for groceries, stroller, etc. But is 4 12's too much bass? They would be at a 2 ohm load on the zx500 getting about 150rms each. Whereas if I run just the 3 I can get them the 200 rms each that they are rated for.

I guess my goal is to be satisfied with the amount of bass as well as have a sleek setup and to still be able to utilize my cargo area to an extent. I used to run two of these g1's in a pre fab sealed box when I had my blazer and I loved them on 400 watts. They seem to hit every note when given appropriate power.

Let me know what you guys think and what you would do differently. I would appreciate the feedback/constructive criticism.
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Jacampb2
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Re: Four 12's or just three?

Post by Jacampb2 »

I may have missed it, but what impedance are the subs? I think if you only have one ZX500 that you are probably pushing it with 4 subs. It will run 2 ohm mono, but it won't be happy with it.

I used to run 3 eclipse 6 ohm subs off the ZX500 side of a reactor in my Camaro and I hit ~152 dB. I later went to a MS1000TA for the 3 subs and it hit ~156ish... I never blew a ZX500, and I ran them hard, but it's probably not up to the task of 4 subs...

Good luck,
Jason

Sent from my SM-N910V using Tapatalk
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
lukeman269
Posts: 442
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Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

Subs are dual 4 ohm each. Yeah I'm leaning towards 3 just to save more space and I think it would be plenty loud. Then I can push them with rated power and not stress the amp out too much. Thanks for the feedback Jason!
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Jacampb2
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Re: Four 12's or just three?

Post by Jacampb2 »

So, are you thinking voice coils in series and 3 subs in parallel for ~2.6 ohm load? That's probably your safest bet. I'd try not to blow a ZX500 at this stage in their life. The output transistors are getting really tough to find. There are some decent substitutions, but I haven't checked on their availability in ~5 years. High power through hole BJT's for audio are going the way of the dodo unfortunately...


I love PG to death, but honestly it makes more sense these days to go class D and save the awesome AB amps for mids and up.


Good Luck,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
ttocs
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Re: Four 12's or just three?

Post by ttocs »

agreed I would do 2 or try to add a 2nd or bigger amp for more.
what else can I say I am a grumpy asshole most of the time.
lukeman269
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Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

I think I am still going to run this amp with the 3 subs at the 2.67 ohm load. I have always wanted to do a triple woofer setup. I don't plan to run full tilt all the time. I really hope the amp will run strong for me though. Already bought it haha.
ttocs
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Re: Four 12's or just three?

Post by ttocs »

Its been a decade or two so correct me if I am wrong but if I remember correctly with a series/parallel wiring the power will not be split evenly between the three woofers? I can't remember the output at 2 ohms, obviously this would have less power so one woofer will almost get the rms rated power while the other two will be half that and probably lower power then we would all want. Three woofers is neat but I think you would get better sound from two. If I had the woofers to play with I would probably try to design the sub enclosures so you can add/remove one enclosure if it isn't what you hoped. It would probably be easier to install if you made 3 separate enclosures that you can screw together as well.
what else can I say I am a grumpy asshole most of the time.
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Jacampb2
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Re: Four 12's or just three?

Post by Jacampb2 »

Voice coils in series at each individual sub and all three subs in parallel is fine. It will power them evenly. Just use a fairly large gauge wire to put the coils in series and keep each jumper the same length and it will be no issue. I think what Scott is thinking of is if you had say two subs in series and in parallel with the third. That would definitely deliver power unevenly...

IIRC the amp is technically only rated for 2 ohm stereo or 4 ohm mono, but as long as you run adequate power and ground (I'd go at least 4 gauge copper if it is only the one amp) the amp will most likely be perfectly fine at 2.67 ohms.

Good Luck,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
lukeman269
Posts: 442
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Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

The boston subs have the easy impedance system right on the terminals so wiring is a snap. And yes keeping the wiring all the same length to each woofer is a must. I have seen daisy chained woofers and the first woofer in the chain gets more power as I saw black coil on the first woofer and copper colored coil on the second in the chain. So I plan to run each speaker wire into their corresponding + or - bolt for even power distribution.

I thought in the manual the zx500 gives ratings for 1 ohm stereo and 2 ohm mono. It just says "current limited" for the 2 ohm mono.

I do currently have good 4 gauge ofc ran right now with one of those little kintetik hc600 batteries to help stabilize voltage. I don't have any voltage drop now with my Rockford Fosgate t500-1bdcp running at 2 ohms now. I would assume the zx500 should draw about the same amount of current.
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ttocs
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Re: Four 12's or just three?

Post by ttocs »

I didn't know they were DVC
what else can I say I am a grumpy asshole most of the time.
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Jacampb2
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Re: Four 12's or just three?

Post by Jacampb2 »

Yes, you are right, 2 ohm mono. I've got this old sapphire amp on my mind. You are going to be just fine with the three subs.

Later,
Jason

Sent from my SM-N910V using Tapatalk
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
lukeman269
Posts: 442
Joined: Sat Sep 11, 2010 5:18 am
Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

Yep they are DVC. Sorry, I should have specified what impedance they were.

Do you guys know where I can get thick grill mesh material?
ttocs
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Re: Four 12's or just three?

Post by ttocs »

I just got a large piece off of ebay for my diffuser. Its not the best if you are going to press it into a funky shape but there are others on there that will work. How big of a piece do you need as I have some extra.
http://www.ebay.com/itm/CCG-UNIVERSAL-1 ... Kk&vxp=mtr
what else can I say I am a grumpy asshole most of the time.
lukeman269
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Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

That stuff would be perfect. I was going to do a big integrated grill cover for all 3 subs. I would need a whole sheet pretty much or 3 pieces of 13" by 13".
lukeman269
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Re: Four 12's or just three?

Post by lukeman269 »

Hey guys, another question. So I sketched up something in paint to show the idea of the box. So I want to recess the front baffle which will hold the woofers about 1 inch into the box to accomodate the grill panel I wanted to use. My question is, will this front grill panel act as a port or cause any loading onto the woofers. I plan to cut 12" holes for the grill panel and place it onto the box so it will line up with the subs. I have these grills I plan to use that will go over each hole on the grill panel.

I just don't want to go with this idea if it will make the subs sound weird or cause unnecessary loading. I feel that 3 12" holes on the panel will allow any air the subs will move to come out with little resistance. This box will be sealed so maybe that won't matter?

My picture sucks but think of it as looking into the enclosure and the baffle is recessed into it. It appears to be coming outward if I look at it different but I can't make it look any better lol. And there will be steel grills that will cover the gaps on the grill panel.
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Jacampb2
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Re: Four 12's or just three?

Post by Jacampb2 »

An inch won't matter. But might i suggest just 3/4"? Simply because it's dirt simple, you would just have to double the front baffle.

Later,
Jason
M: M100, M44 for a custom amp project
Zx: Zx500, Zx450, Black Zx350
ZxTi: 4 Zx600Ti's, 1 Zx400Ti
Ti: 5 800.1's & 900.7 for a custom amp project. 1 1200.1, 1 1000.2
Tantrum: 2 1200.1's, 1 600.4, 1 500.2
XS: XS6600
lukeman269
Posts: 442
Joined: Sat Sep 11, 2010 5:18 am
Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

Here's some progress on the build. Got the box built, now I just need to put some carpet on it and run some LED's along the inside edge.
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lukeman269
Posts: 442
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Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

What do you guys think I should use to attach the front grill panel? I would like to avoid using screws to keep it a clean look. I was considering strips of velcro, but I saw these grill guides on parts express. I could glue in the guides, but I don't know if they would be strong enough to hold the 3/4 mdf panel. It's not exactly light.

http://www.parts-express.com/parts-expr ... r--260-367
ttocs
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Re: Four 12's or just three?

Post by ttocs »

I can't say I like the actual grills much as they remind me of a fan guard or something I might cook on. I like the idea of a grill and to hold the front cover on just use dowels. Clamp the top cover where you want it and drill a hole through that is tight on the dowel. Use a slightly larger bit in the box to make it easier to go in/out and round the top of the dowel and then glue it in flush with the top and your done.
what else can I say I am a grumpy asshole most of the time.
lukeman269
Posts: 442
Joined: Sat Sep 11, 2010 5:18 am
Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

Oohh I like the dowel idea. Very cheap option that I can get to pressure fit. Yeah they remind me of the zx fan guards. Was going to try and do an amp rack of the zx amps on top of the box and paint the grills white to match but I don't really want to mount the amps on a vibrating surface.
ttocs
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Re: Four 12's or just three?

Post by ttocs »

Dowels have been used for this job as well as for heavier duty jobs for centuries, I have been using it myself since I can remember as my dad liked to make furniture and its common there as well as boat making long ago. They do the same job as those connectors you show and the more you add/longer they are the better it will stay up. Don't go directly through the corners as it can cause problems but if you get 2 on each side you will probably be surprised how well it holds up. Now if your going to carpet the box its easy to enough to hide some screws if the carpet it thick enough.

Another fun though is if you throw an led strip along the inside edge of that cubby created for the front of the woofers it makes a pretty darn cool effect. You can get the multi-colored strips that flash to music or sweep through colors for cheap now for bonus points.
what else can I say I am a grumpy asshole most of the time.
lukeman269
Posts: 442
Joined: Sat Sep 11, 2010 5:18 am
Location: Minnesota

Re: Four 12's or just three?

Post by lukeman269 »

Yeah the LEDs will definitely look cool. Thanks for the idea in the dowels! I will work on that this weekend.
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knightrider358
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Re: Four 12's or just three?

Post by knightrider358 »

hey some neo magnets for attaching the grill. they are strong as fuck and allows u to remove the front for service if need be and u wont see them nor holes

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zeropoint0.5
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Re: Four 12's or just three?

Post by zeropoint0.5 »

a zx500 can handle 2ohm mono all day, so at 2.6 ohm no problem....

don't forget to put a 50A fuse just before the amp...that is the most important factor

to keep the amp from frying.....

unless the amp is in a bad condition and the bias is way to high setted, like the most i get

in my hands last years (same story with all zpa amps), it will not shut down thermally.....


i played then years with mine, two boston pro 12.4lfs at 2ohm mono, with a bass cube before the amp,

never could shut it down thermally....only problem i had was then in the crossover board, the green quad

pot that started to fail... after that replaced it was fine......


but yes, there are maybe better options as sub amp.....

you wanna go loud, go class d...you wanna beautiful sound, stay with the oldskool PG.........
zeropoint0.5
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Re: Four 12's or just three?

Post by zeropoint0.5 »

a factor you have to think of, the more coils connected, the more induction you create.....

when it is too much, the amp can fail, that is correct.....

maybe using 2 subs both in a vented enclosure was a better option.....

try out and you'll see.... don't forget the 50a fuse.....unless you love the smell of

fried powersupply fet's in the morning :doh: :doh: :doh: :doh: :doh:
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