[VRausch]

So, I've been lurking/reading for some time on this forum. Finally got myself registered, as we're closing on a house this month with a dedicated theater room. (More on that when it actually becomes my house ).

Anywho, I picked up a few of the JBL GTO 15s with the intentions of building a few (probably 4) F-20s for the theater. No WAF issues, as she is actually more of a bad influence when it comes to this kind of thing. I've been mulling it over for a bit now and thought I'd pose the question to you folks, as you are certainly far more well versed on matters of the bass!

I'm not concerned over chasing ULF, as I'd prefer output from ~20hz up. Size is not really an issue with the way the room is laid out, FWIW. I"ll have plenty of space to build whatever I end up with, and am certainly not in a rush, either. Room is roughly 16' x 24' and height varies between ~8' to ~10' as it is tiered for two rows of seating. I'm not a master carpenter by any means, but should have enough skill to build whatever. Creating a design on the other hand, is over my head. I haven't build boxes since the late 90s, so I am confident things will turn out a bit ugly. I'm ok with that though.

With that being said: What would you do with 4 JBL 15s? And why?

Thanks ahead for any input!

 

[kiwijunglist]

If space is not an issue just do 4x 500L boxes tuned to 21hz.

 

[More is Better]

This x4:
http://www.avsforum.com/forum/155-diy-speakers-subs/1949777-clarence-s-f-20-build.html


http://www.avsforum.com/forum/155-d...hat-design-contest-anyone-3.html#post32936065 post #220 to the end.


Why, because you don't want sub 20Hz.

 

[mobeer4don]

I'd try a pair of triple chamber bandpass subs. Why? Because JBL did it and got sued by Bose for patent infringement....and no one else would have one. Nothing to do with easy or practical.

http://www.jblpro.com/pub/obsolete/4688.pdf

 

[VRausch]

This x4:
http://www.avsforum.com/forum/155-diy-speakers-subs/1949777-clarence-s-f-20-build.html


http://www.avsforum.com/forum/155-d...hat-design-contest-anyone-3.html#post32936065 post #220 to the end.


Why, because you don't want sub 20Hz.

Yes! Second link is what started the idea, and Clarence's thread more or less convinced me that was the way to go. I figured I'd ask for any alternative suggestions, as I won't be in the house for a few more weeks and have plenty more time to pin down a plan.

I *thought* about trying to sort out a dual 15" driver horn, but in the bit of time I played with Hornresp, I learned that I know very little about designing horns.

 

[More is Better]

Yes! Second link is what started the idea, and Clarence's thread more or less convinced me that was the way to go. I figured I'd ask for any alternative suggestions, as I won't be in the house for a few more weeks and have plenty more time to pin down a plan.

I *thought* about trying to sort out a dual 15" driver horn, but in the bit of time I played with Hornresp, I learned that I know very little about designing horns.

Don't try building your own horn design to start. Copy one. Most will say "don't try a horn at all for your 1st build". If you're good with a saw, know what glue and screw is, or how to creatively use clamps, and can read a dimensioned drawing... Give it a try, worst thing that can happen is you burn $50 in plywood and have an 8 hour lesson in how not to do it.

@LTD02 knows what he is talking about, I'm definitely not the horn guy, if he says it's good...build it.

 

[VRausch]

^^ Agreed. I wasn't really expecting to make much in the way of progress with Hornresp, but I wanted to see where I stood: I have a LOT of reading to do.

Building the F20s should be no issue (Way back a long time ago I did prototyping/small volume plastics fab, and I'm pretty mechanically inclined.), but designing something is going to be a long way off! I still would love to put a couple of dual 15 horns together...Eventually.

 

[More is Better]

^^ Agreed. I wasn't really expecting to make much in the way of progress with Hornresp, but I wanted to see where I stood: I have a LOT of reading to do.

Building the F20s should be no issue (Way back a long time ago I did prototyping/small volume plastics fab, and I'm pretty mechanically inclined.), but designing something is going to be a long way off! I still would love to put a couple of dual 15 horns together...Eventually.

Perfect attitude, read a bunch, copy what is already known to work to start.
I did it a bit different, I designed my mains as my first HT build and it took me 6 tries to get them good enough to use...Plenty of firewood. I think I would have been better served by building some fusion 15's. But I wouldn't have learned how to build a line array.
If you can stand failure, you will learn lots by just diving in. But, build 2 F20's first so you have something good to listen to and to compare to while you make feeble attempts to match lilmike's experience and then finally succeed in besting his horn by 5% on your 10th try.

 

[Tip24/96]

How do the GTO15's work in the F20 as opposed to the MFW15 or Dayton DVC88? They all seem to be priced similarly, so I am just curious?

How about the OP building a nice 8cu or 10cu ported enclosure for these GTO's?

 

[VRausch]

Little update: I now have a total of 8 of the JBLs, and I'm starting to think maybe a bunch of dual opposed sealed might be a good way to go. House should be closing next week, so I'll be able to get some actual placement measurements and figure out what will be best.

 

[nograveconcern]

Little update: I now have a total of 8 of the JBLs, and I'm starting to think maybe a bunch of dual opposed sealed might be a good way to go. House should be closing next week, so I'll be able to get some actual placement measurements and figure out what will be best.

If you have the space and will not be chasing single digits then go with ported...or 8 F20's would be cool too.

7cu ft per driver tuned to 17hz is what I would do, again, if I wasn't busy chasing single digits.

I assume you got the 15d's. What's your plan for power? Getting full potential out of the DVC version isn't as cost effective as the SVC.

I have the limiter set at 73V which is 700w and it seems to work out well.

Here's what my pair of sealed 1514's + pair of sealed Dayton 385-88's are doing.

I was hearing some definite driver distress at -7 so I didn't go all the way up to -5.

 

[VRausch]

^ Nice!! And Thanks for the suggestion/input!

Yes, DVC drivers.

I was planning to power them with the Nu4 6000 +minidsp if I end up going dual opposed sealed at 4 ohms/channel. Figure a 9cu net box per pair of drivers puts them in a good spot.

Don't think that would work power wise in the 8 ported or F- 20 scenario unless they were placed in pairs around the room. (And I think space becomes an issue with 8 F20s!) 4 F-20s would work with that amplifier dialed down I'd think though.

I was surprised to find the additional drivers, as my girl saw the set I had already purchased, 'thought we might need more', and ordered them up. She's a keeper.

 

[nograveconcern]

9 cu ft / pair is about right. Mine are in 4.3 each.

Not that it's wrong to do so, but why a minidsp & 4 ch nuke? I don't see much advantage over the nu6000dsp unless you want a highpass lower than 15hz or want to control multiple amps with one DSP unit.

With the nu6k you can run 4 at 900w continuous each or 8 at 275w each. So either too much or too little.

I was surprised to find the additional drivers, as my girl saw the set I had already purchased, 'thought we might need more', and ordered them up. She's a keeper.

Nice!

 

[Stereodude]

Here's what my pair of sealed 1514's + pair of sealed Dayton 385-88's are doing.
http://i151.photobucket.com/albums/...ter/compressionsweeps-ulftard_zpslnnfkrel.jpg

That graph looks highly suspect.

 

[VRausch]

My logic for the 4 channel + miniDSP was to be able to afford the most flexibility both from now and down the road. I could adjust each box individually based on its location in the room with the minisdp, rather than only being able to adjust 2 channels regardless of where the boxes are placed. It made more sense to me to do it that way, but perhaps I'm overlooking something?
Any input is always appreciated!

 

[nograveconcern]

That graph looks highly suspect.

You don't believe the numbers of the shape? That's a heavily boosted house curve BTW. I was trying to see where the drivers gave out.

My logic for the 4 channel + miniDSP was to be able to afford the most flexibility both from now and down the road. I could adjust each box individually based on its location in the room with the minisdp, rather than only being able to adjust 2 channels regardless of where the boxes are placed. It made more sense to me to do it that way, but perhaps I'm overlooking something?
Any input is always appreciated!

Flexibility down the road is a good reason.

 

[Stereodude]

You don't believe the numbers of the shape? That's a heavily boosted house curve BTW. I was trying to see where the drivers gave out.

A little bit of both. Do you have a graph without the "house curve"?

 

[nograveconcern]

A little bit of both. Do you have a graph without the "house curve"?

Second from the bottom is basically no eq.

 

[Stereodude]

Cool. I guess I'm surprised to see such a big hump in the output at 8Hz.

 

[nograveconcern]

Curious, the iNUKE NU4-6000 claims to have a limiter but I don't see any way to adjust it.

""Zero-Attack" limiters offer maximum output level with reliable overload protection"

Speaking from experience, it's also really difficult to match levels without the plugging into the amp and using the remote connect software to watch the input lights.