Small Stryke SAE 1204 sub enclosure with PR tuned low?

Discussion in 'Archived Threads 2001-2004' started by Wes Nance, Jan 21, 2002.

  1. Wes Nance

    Wes Nance Stunt Coordinator

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    Hi,

    Still planning my sub enclosure, and am thinking about going with a Stryke SAE 1204 driver, which seems like a really nice piece for the price. I was originally looking at the Shiva, which is also obviously a fine driver.

    I have a 14x25 room with an 8' ceiling, so not super big, and I need a small box to have the WAF rating high. I was originally thinking about going with a 54L sealed box, like the Adire reference design, and using the 250W PE amp, with the boost at 20hz or so by 4-6db to help with the rolloff on the bottom. I will be using this sub for music and home theater, and I listen to a lot of classical/orchestral, plus some pop and jazz. I play in an orchestra for a living, so my ears are a bit sensitive there. . .

    After messing around in unibox for the first time, now I'm thinking about using a 50l box with a 15" passive radiator, possibly the Adire PR15, weighing in around 1400g, for an fb around 18.5 hz, and an f3 of 33.5hz. Using some bass boost from the amp again, I think I can move the f3 down into the 20's or so.

    Does this add up? Is there some downside of using a PR tuned this low? Adire lists the limit at 1500g, so I'm well under it. This sub will be blending in with bookshelf speakers, right now Paradigm Atoms, but I am building a pair and center of MB1's this summer (Dennis Murphy design), which should work a bit better. . .

    Any comments or instruction? I'm a total novice, but learning more all the time. I want to do the project in 2 weeks, so I need to order parts.

    Thanks for the help!

    Wes Nance

    Rochester, NY

    ps Anyone live in Rochester and have a Shiva sub or something else I could hear?
     
  2. Jack Gilvey

    Jack Gilvey Producer

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  3. Wes Nance

    Wes Nance Stunt Coordinator

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    Jack,

    Thanks for the reply! It's a bit tough to get a response on basic design as I feel a bit late to the party. I'm sure as soon as I start actually building the sub there will be plenty of interest. . .

    I'm trying to find someone who has used the Stryke SAE 1204 or at least has an informed opinion. It's a bit cheaper than Shiva, and seems in some ways to be engineered a bit stronger. I might buy one just to be off the beaten path a bit, you know? Have you had any interaction with Stryke audio?

    I'll look at unibox again- obviously a sealed box would be cheaper and simpler to build- do you have an opinion of the sound of a sealed box vs a PR sub?

    Thanks again for the input-

    Wes
     
  4. Jack Gilvey

    Jack Gilvey Producer

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  5. Wes Nance

    Wes Nance Stunt Coordinator

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  6. jeff lam

    jeff lam Screenwriter

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    Wes,

    You look like you are getting set up for an excellent sounding system. I just wanted to say that the MB1's are simply outstanding! I received my enclosures last week from a guy that built them for me. I had already ordered the drivers from GR-Research and I just soldered them on and mounted them in. They are excellent speakers.
     
  7. Wes Nance

    Wes Nance Stunt Coordinator

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    Wes
     
  8. Jack Gilvey

    Jack Gilvey Producer

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    Wes,
    You may have seen this, but this is a good FAQ on PR's:
    http://www.lambdacoustics.com/librar...pers/prfaq.htm
     
  9. John E Janowitz

    John E Janowitz Second Unit

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    Hi Wes,
    I actually have 2 designs worked up using the SAE1204 woofer. The first will be sold as our MiniThunder subwoofer for around $600-$800 completed, but you can also build it yourself. This enclosure for the SAE1204 is a 15" cube with 1" thick walls made from 2 layers of 1/2" MDF laminated together. It gives a little over 1 cubic foot of air space. It uses a pair of 12" 1000 gram PR's for a tuning of about 23Hz. The F3 of this system without EQ is around 34Hz. However, this subwoofer is also built around the AMP350 with the bass boost modified to 25Hz. This gives the system an overall F3 point of 25Hz with very good power handling. IMO, not bad at all for a small 15" cube enclosure.
    The other system that works well for the SAE1204 is the Thunder 12.3 cabinet. This is the 3 cubic foot cabinet with dual 15" 1400gram PR's. This gives an F3 point of 20.5Hz with no bass boost required from the amplifier. The cabinet is 2 layers of 3/4" thick MDF laminated together. The cabinet is 23.5" tall, 17" wide, and 21" deep with a single vertical brace in the center of the cabinet. I have plans available for this cabinet if anyone is interested.
    The woofer can work well in other cabinets too, but these are the two that will become finished subwoofer systems sold by Stryke Audio shortly. I do suggest the dual PR setup though with one PR on each side of the cabinet. Opposing PR's cancel the forces created on the cabinet by the PR's motion. With only one PR on one side, the enclosure may rock quite a bit.
    Also, if you want to play around with PR's without spending a lot of money, I have a few Bstock ones left yet that I can let go very cheap. Email me if you're interested. [email protected]
     
  10. Wes Nance

    Wes Nance Stunt Coordinator

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    I talked with John today, and bought a SAE 1204 driver, and 2 b-stock 1400g 15" PR's ($25 a piece!!) and am going to build the Thunder 12.3, but the 2ft^3 version as it's a bit smaller, and it only moves f3 up to 25 instead of 21hz, and I can always eq it.
    It would be modeled after this one:
    http://basszone.stryke.com
    go to projects and thunder 12.
    I'll be powering it with the PE 250w sub amp, with bass boost defeated to start, and then see from there.
    Thanks to all who gave me input, and I'll post when the project starts!
     
  11. Wes Nance

    Wes Nance Stunt Coordinator

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    Jack,

    Did you use a double box design like the 12.3? That thing's going to be unbelievably heavy, but with so much mass, I can probably actually use it as an end table! I thought about only going with the single box to make it smaller, but if I'm going to the trouble, I might as well do it right.

    Wes
     
  12. Jack Gilvey

    Jack Gilvey Producer

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    Actually, I went a different route as far as enclosure construction. I used just a single layer of 3/4" void-free marine ply with a single 2x2 cross-brace from top to bottom mounted slightly off-center, keeping any unbraced span to less than 12" (per Greg Monfort). Three sides are already taken up almost completely by driver and PR's, so I only have the back unbraced, and it'll remain that way until I decide if I want to mount an amp there (just binding posts at the moment). This ply is quite a bit stiffer than an equivalent thickness of MDF, and its resonance is much higher to begin with, so it doesn't take much in the way of bracing to push any resonances well above the sub's bandwidth. Even though it literally rings like a bell when struck, there won't ever be frequencies present in its operation which would excite these resonances, so it's functionally "dead". It's much lighter than 1.5" of MDF would be, and I don't need a heavy enclosure since the movements of the PR's will basically cancel each other out as far as net force on the cabinet is concerned.

    MDf requires a more "brute-force" technique of using enough mass to quell any resonance in the passband,so a double layer would be the way to go.

    One interesting thing I had an idea about is making a plywood circle that can be installed in place of one of the passives, giving me the choice of two tuning frequencies. The Fb with dual PR's will be about 23Hz and have quite high output capabilities, a real home-theater monster. With just one PR, though, Fb moves down below 17Hz and I gain about 5-6db at that frequency, although at the considerable expense of output above (one PR1400 appears to be just enough with about 150 watts input). The very shallow rolloff down to Fb may well be flattened by room gain, making for response down to below audibility from a 17.5" cube, although not near reference levels. This may be the "music" mode. You can model this very easily, of course, in your own box.
     
  13. Jack Gilvey

    Jack Gilvey Producer

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