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Old 2nd June 2008, 04:30 AM   #1
djkib is offline djkib  United States
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Default Inherited a pair of Yamaha S3115H (long?)

To all,
I am relatively new to DIY audio, but have been lurking and studying for a while now... I'm a DJ (roughly 12 years, now) and am always looking to improve my rig...

I just inherited a pair of Yamaha S3115H Pro Audio speakers. These cabinets contain JA 3803 15" woofers (white) rated at 8 ohms, 120 watts. The horns are JA 4204A, rated at 20watts, 2000Hz-20,000Hz. From what I have read and seen of other examples of these speakers, they appear to be completely stock and un-mucked with...

The cabinets are really beat up (I would never play out with these cabinets), made out of 3/4" particle board. External dimensions are 18.5"W x 14.5"D x 26"H. There are no internal baffles. The front baffle is about 1.25" inset, for an internal volume of roughly 2.83 ft3.

There are two ports in the front baffle roughly 2 5/8" in diameter, no tubes.

All the electronics are there, and to tell the truth, these speakers sound great as they are. I have a pair each of Yamaha S112V and S115V, and am using these as a comparison.

Now to my questions. First, I would like to re-use these speakers but as I mentioned above, the cabinets need a lot of work. I would really like to build new cabinets (I consider myself a decent wood worker), but am not sure if I should build to the current dimensions, or would a newer trapezoidal design work/sound better (or Bill Fitzmaurice DR design?). Can I back into the T/S parameters of the 15" drivers based on the current dimensions of the cabinet?

Second, the cones of the 15" woofers are slightly stained. Is there a method for cleaning these? If they were black, I would not worry so much, but in white, I would like them to "look" their best as well...

Third, since these are only rated at 100W continuous, is it even worth the effort? In the original cabinets, they were rated to 98dB sensitivity... and I believe it. These were LOUD and CLEAN as tested... (I am considering building a pair of gainclone amps for them if I keep these...)

Last, where can I find the T/S parameters for these drivers? there is next to nothing published about these drivers. I don't really know how to test myself...

Thanks in advance for your help,
Keith
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Old 2nd June 2008, 04:44 AM   #2
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Unless you're able to find the T/S for the drivers, build the cabs to the same internal volume, port dimensions etc. Not sure of the driver used but www.thielesmall.com may have it.

I don't know of a way to get stains out of cones, but you could either dye them black or use a grille that's optically opaque. Some mates in the US who DIY PA/MI speakers suggest 'Pet Screen' as it's cheap and tough.

I'd also suggest getting the cabs covered in truck bed liner or a specialist paint like Rockard (DIY with roller). Looks better, alsts longer and doesn't smell like rat fur and vinyl and straight paint look abused very quickly.

One other thing you get to do when you build new cabs is to adjust any handle positions (if necessary) to where they suit the balance of the cab etc. I loathe bad ergonomics, especially at load out.

The 100W rating could be correct, and would get you near 120dB, depending upon the excrsion capabilitys of the LF driver at LF. On top of a pair of subs and crossed over say 150Hz, they will be loud and clean and last a long time.
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Old 2nd June 2008, 02:18 PM   #3
sreten is offline sreten  United Kingdom
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Hi,

Listen to the speakers. If you think bass could do with being tighter
/ deeper line the ports with foam and listen again. Generally you can
make the new cabinets up to ~ 50% bigger and by keeping the same
port dimensions the tuning will automatically adjust downwards.

Depends on what you want them for. Portability wise 50% bigger
is 50% worse, the possible extra bass may not be worth the hassle.

/sreten.
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Old 3rd June 2008, 07:24 PM   #4
djkib is offline djkib  United States
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Default Thanks for the info...

Brett, sreten,

Thanks for the replies... any info is great...

What about shape of the cabinet? Do rectangular cabinet? Do trapezoidal cabinets (wider at the front baffle than at the rear baffle) affect the sound waves differently than rectangular cabinets?

Does the size/shape of the cabinet affect the power handling capability of the speaker? I know the cabinets can affect the overall SPL OUTSIDE the cabinet, can the cabinets affect the electronic response of the speaker?

Again, I am a relative noob here, so pardon what may be stupid questions...

Thanks again,
Keith
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Old 3rd June 2008, 08:30 PM   #5
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Default Re: Thanks for the info...

Quote:
Originally posted by djkib
What about shape of the cabinet? Do rectangular cabinet? Do trapezoidal cabinets (wider at the front baffle than at the rear baffle) affect the sound waves differently than rectangular cabinets?
Shape won't make any real difference in this application.

Quote:
Originally posted by djkib
Does the size/shape of the cabinet affect the power handling capability of the speaker? I know the cabinets can affect the overall SPL OUTSIDE the cabinet, can the cabinets affect the electronic response of the speaker?
Power handling will be affected at the low end, depending upon the porting, box internal volume and the T/S specs of the driver. If you build them basically the same as stock and use them with subs above (guess) 150Hz then it won't matter. Without the T/S I can't say more for the region below 150 as that is highly box and driver dependent.
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Old 5th June 2008, 01:57 PM   #6
djkib is offline djkib  United States
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Default Still no T/S info...

Thanks for the info and help...

I still have not been able to find the TS parameters for the JA 3803... must have been a proprietary design, with not much of a following...

I think i will be rebuilding the cabs as they are. I will be adjusting the depth of the cabinet to allow a double thickness of MDF for the front baffle - this way I can recess the 15" so the grill doesn't interfere as much with my ... uh ... how shall i say ... uh ... portly stature...

Again, THANKS to all for posting!

Keith
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Old 5th June 2008, 07:01 PM   #7
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Keith, if you are going to be moving these about a lot and using them for PA, I would 1: recess the entire baffle say 1cmand flat mount the 15 and 2: use a high quality play, not MDF as MDF has an aversion to liquids and impacts. No quality Pro gear is made from MDF.
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Old 6th June 2008, 05:00 PM   #8
djkib is offline djkib  United States
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Brett,

Thanks for the info... the front baffle is already recessed from the front of the cabinet about 1.25" - I plan on keeping that and making the baffle 1.5" (double thickness of 3/4" material) thick, to allow the 15" to be mounted to the "inner layer" of the front baffle.

I also plan to recess the horns, not the full 3/4", but enough to get it closer to the plane of the 15".

I have a pair of 12" speakers I made a few years ago out of MDF with great success. I painted all exposed surfaces (inside and out) first with a couple coats of flat black to "seal" the MDF. I also used cabinet carpeting, which also adds a layer of water protection. Plus, I'm cheap and I like to experiment - MDF meets the needs on both those accounts!

I rarely gig outside, and when I do, I make sure the client knows that if it rains I either pull the plug or move inside - 1000 watts of power amp and water do not mix very well...

Again, Thanks for the suggestions - I LOVE this forum!

Keith
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Old 6th June 2008, 10:50 PM   #9
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Quote:
Originally posted by djkib
[B]Brett,

Thanks for the info... the front baffle is already recessed from the front of the cabinet about 1.25" - I plan on keeping that and making the baffle 1.5" (double thickness of 3/4" material) thick, to allow the 15" to be mounted to the "inner layer" of the front baffle.
Get a couple of offcuts or but a small sheet of BB ply and use epoxied T-nuts and a single baffle to do it.

Quote:
Originally posted by djkib
I also plan to recess the horns, not the full 3/4", but enough to get it closer to the plane of the 15".
Not necessary or worth the effort. Will make no audible difference.

Quote:
Originally posted by djkib
I have a pair of 12" speakers I made a few years ago out of MDF with great success. I painted all exposed surfaces (inside and out) first with a couple coats of flat black to "seal" the MDF. I also used cabinet carpeting, which also adds a layer of water protection. Plus, I'm cheap and I like to experiment - MDF meets the needs on both those accounts!

I rarely gig outside, and when I do, I make sure the client knows that if it rains I either pull the plug or move inside - 1000 watts of power amp and water do not mix very well...

Again, Thanks for the suggestions - I LOVE this forum!

Keith
Use the truck bed liner on the outside, and epoxy the inside if uing MDF. And be gentle moving them.
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