Small Stryke SAE 1204 sub enclosure with PR tuned low? (1 Viewer)

[Wes Nance]

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?

 

[Jack Gilvey]

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.

Hi Wes,

That one looks pretty good, although it doesn't have a huge advantage over a sealed box of the same size. It will take a boost better, though, if you apply it right at Fb, as it won't run into the excursion probelms of the sealed. You should certainly be able to get into the low 20's with a bit of boost and room gain.

 

[Wes Nance]

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

 

[Jack Gilvey]

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?

I've only heard commercial implementations, which I long ago learned to discount. I'm finishing up a PR sub myself now, so I'll be able to better judge. I just recently started to look into PR design, so I'm learning all this as I go along myself, it's an area where you really have to search out info. for yourself, not much in books that covers modern PR's like the Adire.

As far as your design, can you go any bigger?

 

[Wes Nance]

As far as your design, can you go any bigger?

I've been trying to stay around 2ft^3, so around 54l or so, I guess. The next size up seems to be around 3ft^3, at which I'd probably use or adapt the Adire reference PR design for 85l.

I was trying to get the best performance out of the smallest box, and it seemed that the PR design was the best anwer, as there's not much room for a long enough port, even flared, in such a small box, but by really weighting down the PR to 1200g or even higher, you could actually tune the box pretty low, and then if I used like 3db of bass boost, it would be pretty flat for the size of the enclosure.

On the Stryke site, there is a project with a 12" woofer, and 2 15" PR's in a 2ft^3 box, that looked pretty good. I don't want to spend on another PR, so I was trying to do it with one.

Any other thoughts? I wonder if I should build a sealed box for my first design, just so I would have a point of reference for the future. But really, I'm hoping to build this one sub and be happy with it, so for more performance, I started thinking PR. . .

Wes

 

[jeff lam]

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.

 

[Wes Nance]

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!

Jeff,

That's good news! Did you build the crossovers yourself, or have someone make them for you. Do you have any pics of the speakers or the crossovers?

Thanks

 

[Jack Gilvey]

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

Any other thoughts? I wonder if I should build a sealed box for my first design, just so I would have a point of reference for the future. But really, I'm hoping to build this one sub and be happy with it, so for more performance, I started thinking PR.

I think a PR is feasible as a first project, mainly since changing the tuning is so easy (much easier than a port in this regard). As long as it's built well, your chance for success is very good indeed.

 

[John E Janowitz]

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]

 

[Jack Gilvey]

Wes, I'd jump at a couple of John's PR1400's and go with the 3ft^3 myself, it looks incredible. I picked up four of them myself as B-stocks from Lambda, very nice.

 

[Wes Nance]

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:
Link Removed
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!

 

[Jack Gilvey]

Excellent, Wes, that's going to be outstanding. You won't be able to touch it commercially for anywhere near the money you've got in parts. My box is very similar, about 64 liters net, but using my Dayton 12" DVC and two of the 1400g PR's.

 

[Wes Nance]

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

 

[Jack Gilvey]

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.

 

[Jack Gilvey]

and it only moves f3 up to 25 instead of 21hz, and I can always eq it.

I just wanted to add the caution that you definitely do not want to try and boost a vented or PR sub below Fb (I'm not sure if that's what you meant). Boosting right at Fb, with the infrasonic filter's rolloff beginning just below, is the best situation. Attempting to extend response by applying boost below tuning would likely send a driver to its great reward rather quickly.