Subwoofer Plate amp

**hifibuyguy** · **11-26-07, 07:01 PM**

Hello all, I have a question for the Forum Gods..

I have a Polk PSW1000 sub without a amp...I need to know if anyone has direct experience with either the O audio 500 W bash or the Parts Express HPSA 5oo. They are both about the same $$ and wattage. I'm limited to size a bit as the opening for the Polk is 10.5 x 10.5 and don't want to do too much cutting.
http://www.oaudio.com/500W_SUBAMP.html
http://www.partsexpress.com/pe/showd...number=300-806
http://cgi.ebay.com/ws/eBayISAPI.dll...TODAY.m238.lVI

Or anything else?

Thanks

**nova** · **11-27-07, 04:23 PM**

I'd like to say I know something about either of those,... but I don't. And based on that knowledge,..I'd say the 0Audio BASH amp looks like the better amp. The only things I base that on is the heatsink, the variable phase adjustment (rather than just a 180 switch) and the crossover by-pass switch. Looks like its better designed and more flexible.

On the other hand, I've never heard anything bad about any of the Dayton stuff from Parts Express, so,....

I'm sure someone, who knows better than I, will be along shortly to give you some good/better advice

**brent_s** · **11-27-07, 05:14 PM**

I know it's more money, but as I suggested to another poster who bought the same Polk deal on eBay, your best solution will be the Polk OEM amp. With two 10" drivers in that small of a cabinet, Polk undoubtebly included some custom frequency shaping EQ in addition to a rumble filter to protect the driver below what is probably a mid-30s tuning point.

If you want to experiment, PE has a fairly liberal return policy, so you could probably try their amp and only be out return shipping due to the current free shipping promotion. The default rumble filter is 18hz, but the PEQ could be use to create an earlier rolloff.

Feature wise, the two amps are identical, except for the OAudio's selectable rumble filter. The PE amp has a sealed back which will prevent air leaks throught the control/input panel. I can't tell about the OAudio. Otherwise, both are highly regarded in the DIY world.

-Brent

**brent_s** · **11-28-07, 09:06 PM**

Mike, one more thought, if you're still reading.

If you have access to an unused receiver or stereo amp, you can find out how your PSW1000 will sound with a generic plate amp before spending any more money. Just get a piece of wood/MDF of appropriate size to cover the PSW's amp opening...screws and weather stripping would be best for attaching, but for this experiment, duct tape would probably work. Connect your main receiver's sub out to an input on the test receiver/amp...the 5.1 inputs would be best, if available. Run speaker wires to the PSW1000, driver's in parallel and try it out.

-Brent

**hifibuyguy** · **11-29-07, 07:02 AM**

Thanks for the Info...I may wait and pony up the extra money for the polk..The other two are just a better buy..but if they wouldn't work as well then it's not money well spent.

Thanks

**hifibuyguy** · **12-04-07, 06:52 PM**

Time for an update...
I received my Sub off Ebay a couple days ago...with only one sub driver, I emailed the guy and I have another sub on it's way not just the drive..but the box and all. He also told me to keep the 1st sub....I have a PE 1000 watt plate amp on it's way. So now what to do with the 1st sub with only one 10" driver? Find another 10'' and amp for it? Does anyone want to trade something for it..I would assume it would be a good project for someone. Let me know.

**brent_s** · **12-04-07, 07:25 PM**

Measure the internal dimensions of the cabinet and share them with us. Same with the width, depth, height of the slot port. I'm sure more than one of us will try to come up with a driver/amp solution that could be used in what looks like a solid cabinet overall.

Include some detailed photos of the interior and port if you can, so we can better visualize what you're working with. I can tell from the eBay ad that Polk didn't use any bracing, but it's a small cabinet with claimed 2" think driver baffles. I'm most curious about how that slot port is implemented...can't tell much from the seller's or Polk's site.

-Brent

**hifibuyguy** · **12-04-07, 08:29 PM**

Awesome guys...I will get on it tomorrow...My "new' sub will be here Friday but I'll take some shots and measurements with the driver out..
The amp won't be here until next week.

**hifibuyguy** · **12-05-07, 03:46 PM**

I had some time today to take some pictures and measure the polk sub box.
http://s169.photobucket.com/albums/u229/Deviate2112/
I put them up here to look at.

The Inside box dimensions are;
13 3/4'' from woofer side to side
12 1/4'' form inside bottom to top
15 1/2'' from the inside edge of the port to the back amp plate opening
17'' from the far wall to back of the amp plate opening.
Hope this helps some
Any Ideas?

Thanks

Mike

The port is 11 1/2" x 1 3/4'' it runs underneath the entire sub box..see pictures.

**Mike P.** · **12-05-07, 04:08 PM**

Just to make sure I understand you correctly, the internal measurments are 13 3/4'' wide, 12 1/4'' tall and 17'' deep. The port is 11 1/2" x 1 3/4'' and 15 1/2'' long, right?

**hifibuyguy** · **12-05-07, 04:21 PM**

That is correct

**Mike P.** · **12-05-07, 04:38 PM**

Internal volume minus a driver would be around 1.5 cubic feet. Tuning is high at 43hz. I'm not sure what to recommend for this setup. As Brent mentioned ealier, a custom amp was used for this system.

**hifibuyguy** · **12-05-07, 05:20 PM**

I guess what I'll do when the "good" sub arrives and the amp...I'll just give it a shot..if It sounds like dog crap I'll dump it and go a different direction..I'll have a nice PE Plate amp...

**hifibuyguy** · **12-05-07, 08:45 PM**

I guess another thought is that I'll have 3 nice looking 10'' drivers, I don't have the parameters for the subs but I would assume a pair of Parts Express 1c'' boxes might be ok...I'm not real concerned with extreme low end.. or I wonder what 2 of the 10'' subs in 3c'' would sound like?

Thoughts?

**brent_s** · **12-05-07, 09:30 PM**

How's this for off the wall. It will require some woodworking, though.

The Dayton RS315-HO and a DVC12 based passiver radiator with 500g added. Box tuning in 1.5 ft^3 is 20.46 hz. F3 is 35hz...20hz is only -7db, meaning it should work nicely with a little room gain. 1m groundplane with 500 watts...104db@20hz, 108db@30hz, 109@40hz, 111db@100hz.

You'll need to enlarge the current driver holes to accept the 12" driver and PR. You'll also need to seal off the existing port.

You could also seal one driver opening and the port, widen the other driver cutout and drop in a Torrent Audio Mistral SVC, which is just a TC Sounds db12-500. Add a little stuffing and you're right at a Q of .7. With 1000 watts you'll get 103dB@20hz, 109dB@30hz, 112@40, 115@100. With a BFD or even the HPSA1000's PEQ, you could probably make the curve a little flatter.

That native 43hz tune makes the slot port a pain to use. When I have more time, I'll see what else I can come up with.

-Brent

**hifibuyguy** · **12-05-07, 09:50 PM**

English...Do you Speak it!! LOL
what about my Ideas above regarding either 2 PE 1cu' boxes or 1 3cu' PE box with two drivers in it? I like EASY...

**brent_s** · **12-05-07, 10:24 PM**

Quote:

hifibuyguy wrote:

English...Do you Speak it!! LOL
what about my Ideas above regarding either 2 PE 1cu' boxes or 1 3cu' PE box with two drivers in it? I like EASY...

I don't see the point in trying the Polk drivers in another box. If anything, a sealed alignment for a given driver should be smaller than the ported box, not larger as you're experiment would be. As Mike and I keep repeating, there's "magic" in the Polk OEM amp, especially if the f3=30hz spec is legitimate with a 43ish hz tuning point.

At the risk of being repetitive, the best use of this cabinets and drivers is with the OEM amp. You've opted to go with a generic amp, which may prove acceptable, if not ideal. If you don't like the results with the HPSA1000, you're next best option is to try to find suitable drivers for the existing cabinet since the amp and cabinet are the known quantities. All, IMO, of course. I was actually pretty amazed at what those two suggestions would do in that small of a box.

You have to think of the subwoofer as a system. All of the major parts (drivers, amp, cabinet) are designed to work together to achieve a specific goal. You can substitute generic parts and the subwoofer will still make sound, but how acceptable will the overall performance be. A quick analogy would be trying to drop the Prius' engine into my 4Runner. That tiny motor will still have enough power to move the truck down the road, but I wouldn't expect it to get me very far on beach sand or a trail ride.

-Brent

**hifibuyguy** · **12-06-07, 06:52 AM**

Thanks for all the info, I'm just trying to make up for the fact that I got Taken on Ebay is all. I spoke to the polk Customer service and was told my sub is not a PSW1000 but a LSI something, and that they were not going to help stand by that product and that it's only use was to make it a coffee table.

Forgetting the Polk "boat anchors" for a moment, and keeping in mind that I live in a rented house with no garage to build anything and that I'll be using a PE 2cu'' box, can you give me some recommendations for a Music/Movie driver that will work in the that box? Can be ported but I prefer sealed, not that concerned with tons of db's my room is pretty small.

I really appreciate all the help here.

Thanks

**brent_s** · **12-06-07, 09:43 AM**

Sounds like Polk CS was simply informing you the PSW1000 is considered to be part of their LSi series as opposed to RTi, Monitor, etc. Understandably, there is no warranty since you don't even have a complete subwoofer. However, they should still be willing to sell you replacement parts if you ask nicely since you have the majority of two subwoofers.

I don't mind helping you and I'll run more driver options as I have time. However, the tuning frequency is rather high and the cabinet volume is rather small for a pair of the commonly used 10" drivers. Hence the "magic" in the Polk amp. It's possible to use the PEQ on the HPSA1000 to recreate some of the "magic". How much work can you put into modifying the cabinets? Are we limited to drop in replacement drivers or could you get access to a router or jigsaw to enlarge the driver openings a bit? I assume you have access to some cutting tools since you'll need to modify the amp cutout at a minimum. Can you make a cover plate to seal up one driver cutout if the best option is a single driver?

Let's start with you trying the HPSA on the two driver cabinet when it arrives. If you don't mount the amp to the cabinet, you'll need to seal that cutout air tight for experimentation. BTW, there were some labels on the driver in you photos, but I couldn't quite make them out. It would be beneficial to know the impedance of the drivers to determine parallel or series wiring and that info may be on the driver itself. Customer service may be willing to tell you as well. The HPSA won't like nominal loads below 4 ohms...hopefully Polk used 8 ohm drivers in parallel, but it's possible they used 4 ohm drivers or even 2 ohm wired in series.

Speaking of tuning, could you double check those port measurements. Ed reviewed the PSW505, the step down model from the 1000 and concluded the port was 1.25" high with a tuning of 35hz. The 505 and 1000 use very similar sized cabinets/ports and if I change your port height to 1.25 instead of 1.75, keeping other dimensions the same, I get a slighly more reasonable 37hz tuning for the 1000. Also, what's the thickness of that bottom wall of the driver compartment. Since the port opens into the driver compartment through that wall, its thickness is part of the port length...every little bit helps make the tuning frequency lower. Same thing with the amp wall...it doesn't sound like you included it's thickness in the port measurments. The port length should be measured from the exterior face of the cabinet to the internal wall + the thickness of the bottom wall of the driver compartment...think of it as an "L" with a really short vertical leg.

I'll do my best to help you make the best of the situation.

-Brent

**hifibuyguy** · **12-06-07, 10:55 AM**

Thanks Brent
As far as woodworking tools, I have a jigsaw and a Reciprocating Saw. The biggest problem right now is the 5'' of snow and 28 degrees outside gotta love Michigan.
As soon as my amp gets here next week I will give it a shot and give some feedback, who knows it may work out just fine.
I'll double check and give a more accurate measurement as soon as I can.

Thanks

Mike

**brent_s** · **12-11-07, 09:58 AM**

Ok, I found a couple of options that should work in the PSW1000 cabinets.

#1 - Elemental Designs 11Kv.2. Get the dual 4 ohm coil version, wire each driver's coils in series and then parallel the drivers in the cabinet for a 4 ohm load to the amp. $90/driver. I used a tuning frequency of 37hz as a guestimate between your first set of port measurments and Ed's measurement of the PSW505...probably achievable with a little stuffing added, even if the native tune is 40ish.

#2 - The NHT driver surplus sale. Specifically, the NPT-11-075-1/2 for $20 each. Recommend sealed for these. To seal the port, I'd simply stuff the slot with fiberglass insulation front to back. Line all of the walls with insulation as well, and maybe even a curtain between the drivers. 1.5 ft^3 is showing a Q on the high side of ideal at .9, so every bit of stuffing helps us give the drivers a "larger" box for a lower Q. Again, wire the drivers in parallel; looks like they're good for about 250 watts per driver before hitting Xmax. Disclaimer: I have no personal experience with this surplus sale, but there are no negative comments in the thread at DIYAudio that started back in June to announce the sale. I have used the NHT1259, which is a 12" driver that supposedly has the same motor on a 12" cone...with room gain, I measured pretty much flat to 20hz. Wish I had an even mediocre reason to snatch up a bunch of the 10s at this price...can you say steal?

Here are the graphs. Both models are dual drivers in 1.5 ft^3 with 500 watts. The eD (Green) is tuned to 37 hz. The NHT is in Yellow. Both response curves will flatten out if the tuning frequency is lower or the box is "bigger". Both will have solid output down to 30hz in room, maybe lower depending on room gain. Running both of your cabinets identically with either option could add as much as +6dB to the SPL graph.

SPL & Response curves:

**hifibuyguy** · **12-11-07, 03:00 PM**

Very nice, I will receive my PE amp Thursday and plan on trying the Polk stock setup first. I'll give some feedback then.

Thanks for your time.

mike

**hifibuyguy** · **12-13-07, 04:24 PM**

Just finished my little Mod job on the Polk cabinet and I've got every thing hooked up. The subs were 4ohm SVC so I hooked them up series, I'm glad I have the big PE amp now. So far everything sounds good. I haven't tried movies yet I have guests in this weekend so maybe next week I can tweak more..

Thanks for all the comments

mike

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