Simmons DA200S woofer hunt

[foetus66]

I recently acquired a Simmons DA200S amplifier off Craigslist, and for those unfamiliar with it, this is a pretty cool amp.

It's got an internal 12" sub, for which the bottom of the unit is vented. On the front it has a pair of smaller drivers (5" maybe?) and a pair of tweeters. These are facing slightly apart to accurately project the stereo field -- the idea being that you can plug your stereo drum module into it and play your electronic drum kit, making for a more realistic experience.. depending on how you have your kit panned of course.

Anyway, enough about that. It's a cool amp. The one I got was sounding like shit though, so I opened it up and found someone had stolen the sub out of it and replaced it with a beat up old Kicker 12" woofer, like you would use in a car. Lame. Thanks craigslist. I got rid of that thing and am now on the hunt for a new woofer. But, since this amp is kind of unique, I'm not sure how to determine what parameters would make a driver appropriate for the application. From the user manual I know that the original sub driver was:
12"
8ohm
150w RMS

and that's all. I don't know how I can figure out what an appropriate frequency response would be or whether the relatively small cabinet would be adequate for any particular woofer. It would be great if someone has access to the specs for the original speaker, but otherwise any other guidance would be appreciated. Sorry for the long post.

[Steve Conner]

An Eminence Delta 12LF would probably do.

[foetus66]

That seems like a good versatile driver, though more power handling than I need, and a new one is a bit beyond my ideal budget. What I am hoping is to find some specs I can look out for while I shop around. I'm hoping to keep it under $60 and I check in with the local trade shops pretty frequently.. I'd like to be able to look up specs on whatever drivers might roll in to see if it will work.

Also, another development is that I've purchased another one of these amps (presumably in good shape) and should have it in a few days. Perhaps taking a look at the stock speaker will help?

[Steve Conner]

OK, well, if you're wanting to do it on the cheap, just get any 12" driver designed for bass guitar or PA use and stick it in there.

To do a proper job you need to know the Thiele-Small parameters of the woofer that was originally in there, so you can choose a similar one. If you get it badly wrong, the bass will sound weird.

I'd want to know the resonant frequency at least. Does the manual specify a frequency range that the amp is supposed to cover? The only figure I can find is 20Hz-20kHz, and that implies quite a heavy subwoofer-style driver. Maybe the Kicker car sub that was in there was actually a reasonable replacement.

[foetus66]

Right, exactly. I am just hoping to suss out enough info about it so that I don't get it "badly wrong". I can handle some deviation, I just wish I knew how to determine some base guideline for finding a suitable woofer for the cabinet beyond what little I know: 8ohm, 12", 150watt.

I should have mentioned that the Kicker was badly beaten up with holes in the cone, etc.. Whether it would otherwise have been a suitable replacement or not, I would have never opened up the amp in the first place to discover the Kicker if not for the horrible sound.

I've been in touch with Simmons support about it, but they don't seem to want to give me the specs on the speaker.. They just want me to send in the amp for service. This is obviously not covered by warranty so I really don't want to do that -- especially because shipping it both ways would cost most of the price of buying one. These things are incredibly heavy.

I will open up the other DA200S and see if I can find anything out about the speaker from it. If there are any suggestions of what to look for, either on the speaker, or in the cabinet, I'd love to hear them.

[Steve Conner]

Well, do you know how to measure the resonant frequency and/or impedance curve of a speaker? You need some electronic test equipment, but with this method you can analyze the speaker you have and check the replacement is working more or less right.

If not, you can look at the size of the magnet and the length of the port tube in the cabinet.

First, choose a replacement driver with a similar sized magnet.

Second, if the port tube is long, it means the cabinet is tuned low to make thumping sub-bass. So you have to get a subwoofer-style driver with a heavy cone and low resonant frequency to match it.

If the tube is short, it means the designer was going for loud upper bass. So in this case get a bass guitar or PA style driver, these have lighter cones and higher resonances.

But this is only a very rough method. If it were me, and I had more time than money, I'd plot out an impedance curve for the good speaker, and then use WinISD to work backwards and estimate the Thiele-Small parameters. But you don't need to know them very accurately, they vary over a wide range with manufacturing tolerances and voice coil temperature, so most speaker cabinets will work with a few different drivers.

[foetus66]

Thanks a lot for all your help, this is exactly the kind of information I'm looking for. I don't know how to do those kinds of tests, and last time I tried to work my way through WinISD I had to stop because my brain started getting itchy... but I think this is enough information to at least start looking around for a woofer.

One thing I do have going for me is that in having picked up the same model amp in good working condition, not only do I not need to be in any rush to replace the woofer, but I will also be able to make a comparison between the stock speaker and whatever I put in there. When I get it sorted out I'll post the results here.

[J M Fahey]

I'm hoping to keep it under $60

That's exactly why the kicker got there in the first place.
That said, car subwoofers are the worst speakers in the planet for any use, (even for car audio) being that they are sold on "looks" only (and ridiculous names).
Any decent cheap (think Eminence) bass speaker will work there, whether designed for bass guitar or PA woofer use.
If the impressive Delta is way off budget, a Beta will still be very good yet much more affordable.
Or you can get for almost nothing a woofer pulled from, say, a Bassic 50/BXR60 or similar.
As a side note I have built a couple contest winning car audio systems for musician friends using 1 x 300W driven EVM15L + 2x 150W driven EVM12l + 2x 60W driven Selenium bullet tweeters; all RMS watts of course, custom designed and built crossovers, compressor/limiters and power converters.
6 or more dB louder than second-place-winners 2400 to 10000 "Car Watts" from famous Car Audio trademarks.
¿Rocket Science? . No, just stage-proven old technology, like we use and repair all day long.
In a nutshell: junk that kicker, anything will be better than that.

[Steve Conner]

6 or more dB louder than second-place-winners 2400 to 10000 "Car Watts" from famous Car Audio trademarks.

I'm pleased to hear it, but can't say I'm surprised Car watts are the second biggest joke in the industry, after computer speaker watts.

I'd like to try a car audio install in a Prius. They have a 200 volt battery, and I'm sure a rack of PA amps with switchmode power supplies would run fine off that.

[J M Fahey]

with switchmode power supplies

You don't even need them, since you already have a +/-100V DC power supply to feed them.
You will get over 60V RMS of audio there, around 450/500W RMS into 8 ohms.
A battery that runs a car motor without blinking won't bulge with such a puny power load.
The secret in my installations was an extra truck-approved 180 AH battery hidden between the engine/motor trunk and the instruments panel, and mounting the power inverter there with 4" wires. Then the +/5 55V wires went all the way to the back seat's back, where the actual amp was mounted.
*All* "regular" car amp installations run a 12V line all the way front-to-back , which is ridiculous and shows absolute ignorance of basic electrical principles, let alone electronics.
Since the path is not straight, that wire ends up measuring 4 or 5 yards; talk about resistive loss !!!
Most also use the *iron* chassis as ground return.
Nobody could believe the sheer power (compared to theirs) of my amplification system, yet I felt like I was stealing candy from little kids.