Parts Express Subwoofer Plate Amps on Sale Now

RGordonpf · « **on:** 19 Feb 2007, 02:48 am »

The PE subwoofer plate amps that have been discussed here of late are on sale right now:

1024 watts @ 4 ohms (part #300-808), normally $399 is on sale for $330

540 watts @ 4 ohms (part # 300-806), normally $299 is on sale for $240

I am buying two of the smaller amps for my stereo Larger.

MikeyMouse · « **Reply #1 on:** 19 Feb 2007, 10:12 pm »

Are these the same PE plate amps used in the new VSS subwoofers?

-Mike

Jon L · « **Reply #2 on:** 19 Feb 2007, 10:28 pm »

Too bad these don't have speaker-level inputs

RGordonpf · « **Reply #3 on:** 19 Feb 2007, 10:50 pm »

Quote from: MikeyMouse on 19 Feb 2007, 10:12 pm

Are these the same PE plate amps used in the new VSS subwoofers?

-Mike

The 1024 watt plate amp is the one used for the VMPS subwoofers. It is also the plate amp used to drive the bass on the floorstanding speakers, except that Brian has to modify them to match the crossover in the speakers.

Yar762 · « **Reply #4 on:** 20 Feb 2007, 03:59 am »

I saw that deal and ordered the 1000W version yesterday. I have had a Legacy Pacemaker with a blown amp sitting around for a long time. Figured I'd give the new amp a real torture test - driving two 4-Ohm 15" drivers. The finish on the sub is rosewood, so it will match the new RM40s I have coming. Any advice on how to wire the drivers? Parrallel will maintain the 4-ohm load right (series halves it to 2 ohms?)? Or am I backwards on this?

Bingenito · « **Reply #5 on:** 20 Feb 2007, 04:08 am »

Quote

Parrallel will maintain the 4-ohm load right (series halves it to 2 ohms?)? Or am I backwards on this?

Series would yield an 8ohm load. Parallel with 2-4ohm drivers would be 2ohm nominal and a blown amp

Yar762 · « **Reply #6 on:** 20 Feb 2007, 04:21 am »

Thanks Bingenito...

Us MEs never paid attention in the EE circuit classes.

James Romeyn · « **Reply #7 on:** 20 Feb 2007, 04:32 am »

Quote from: Jon L on 19 Feb 2007, 10:28 pm

Too bad these don't have speaker-level inputs

Jon
They do! Well, almost: Put a 9k resistor in series from the source, then a 1k resistor to ground on the load, 1/8th watt is fine. It's a speaker to line attenuator.

I've done it several times. As recommended by Jack Elliano of Electra Print Transformers, called a "bridging circuit". (He actualy recommended using a 10k pot. Use the pot, figure out your ideal values, then replace the pot w/ fixed Vishay, Dale or Caddock resistors)

Try it out yourself right now. You might need 1/4W resistors if the speaker source is very high power, unsure about that. I'm doing it now w/ an 85W integrated. The input is the speaker outputs from my Pathos, then the output of the pots goes to the input of my ATI bass amp. Wahlah! Done!

Yar762 · « **Reply #8 on:** 23 Feb 2007, 03:38 am »

Wow - installed the 1000W plate amp in my Legacy Pacemaker sub w/dual 15s - that amp will slam those cones right out of their baskets if I'm not careful. Sounds great - still have to dial it in. A great buy at $330.

RGordonpf · « **Reply #9 on:** 24 Feb 2007, 06:05 pm »

My two 540 watt PE plate amps arrived yesterday. Wired them into my Larger sub (each driver has its own binding posts). After listening, adjusting, listening, adjusting, listening, adjusting for several hours I think I have them dialed in. My RM30Ms go down to 37Hz. I have the plate amps crossed over over at 52 Hz. I am going to borrow a friend's PAA2 hand held frequency analyzer so that I can flatten the room hump using the parametric equalizer.

So far I am very impressed with the plate amps. They do have more punch than my Eagle 400 monoblock amps. I can see why Big B uses them in his speakers. Highly recommended, and at $240, each, a steal.

Yar762 · « **Reply #10 on:** 24 Feb 2007, 07:09 pm »

I am very pleased with the amp also. I agree - lots of punch. Unfortunately I'll probably have to invest in some better drivers. The limited excursion, 10+ year old technology 15" drivers in my Legacy Pacemaker, which I believe are Daytons, are bottoming out too easily.

Brian Cheney · « **Reply #11 on:** 24 Feb 2007, 08:54 pm »

Roger:

The floor-to-ceiling room mode is the one best addressed with the parametric EQ since it does not yield to speaker placement or listening position changes.

Measure ceiling height with a tape measure and divide the result into 565 to get the mode frequency. Dial this into the EQ and set the bandwidth to start at .25. Changing the bandwidth, frequency and level settings will allow you to notch out this mode without destroying the lowbass. You can do it by ear.

RGordonpf · « **Reply #12 on:** 24 Feb 2007, 09:48 pm »

Thanks for the info Brian. However, my ceiling is peaked, 10' high down the center and 8' at the sides. Plus, I have all of those panels hanging from the ceiling which may or may not break-up bass frequencies. In addition, the room is sealed at the back for high frequencies, but not for bass. The bass escapes into the rest of the house and up the stairs. Some gets reflected back, but I have not been able to measure how much.

Nobody said being an audiophile was easy, so I could try all fifteen frequencies between 57Hz to 71 Hz. However, I think it will save time to analyze the response curve of the room so that I know what the center frequency of the hump is and how wide it is.

I do appreciate your advice, Brian. Thank you.

ctviggen · « **Reply #13 on:** 24 Feb 2007, 10:25 pm »

With a room like that, you might want to look at the frequency curves for each speaker individually. You might have different modes for different speakers. You may want to add some bass trapping in the corners. Also, you could lift the sub using, eg, ASC subtraps (or just a small table) to minimize the floor-to-ceiling mode:

http://www.asc-studio-acoustics.com/sub-trap.htm

This way, you could affect another mode using the EQ. Are you using the bass amp on the subs or on the RM30s (or both)? I think using these to drive the bass of the RM30s/RM40s is a great idea.

RGordonpf · « **Reply #14 on:** 24 Feb 2007, 10:57 pm »

The plate amps are driving the separate drivers of the Larger. The RM30Ms are being driven full range by the SET amps. I am thinking about putting caps at the input of each SET amp and rolling off at 70Hz. That will require retuning the sub, of course.

The room and its acoustic treatments were designed by Rives Audio. The frequency response curve is fairly flat except for a broad 4dB hump in the bass which makes things a bit warmer than they should be.

Question - is it really possible to get floor/ceiling modes when the ceiling is sloped for its entire width.

Brian Cheney · « **Reply #15 on:** 25 Feb 2007, 12:10 am »

My soundroom ceiling slopes from 7ft 10" to 8ft 10". I ended up with a pole frequency of 70Hz, .25 bandwidth and 5dB of cut.

Feel free to experiment, you'll get the hang of the EQ controls quickly. Small changes make a big difference.

refmedia · « **Reply #16 on:** 25 Feb 2007, 04:09 pm »

Quote from: Brian Cheney on 25 Feb 2007, 12:10 am

My soundroom ceiling slopes from 7ft 10" to 8ft 10". I ended up with a pole frequency of 70Hz, .25 bandwidth and 5dB of cut.

Feel free to experiment, you'll get the hang of the EQ controls quickly. Small changes make a big difference.

True enough works for me too

. My ceiling is 7' 10" with no slope and I am using a DEQ at 72 Hz 1/5 oct at -4 db and my side walls are 14' 10" with a 38 Hz at 1/6 oct at -3db. and a little bump at 144 just 1/5 oct -2 db.
Matt

John Casler · « **Reply #17 on:** 27 Feb 2007, 02:47 am »

Quote from: RGordonpf on 24 Feb 2007, 09:48 pm

Thanks for the info Brian. However, my ceiling is peaked, 10' high down the center and 8' at the sides. Plus, I have all of those panels hanging from the ceiling which may or may not break-up bass frequencies. In addition, the room is sealed at the back for high frequencies, but not for bass. The bass escapes into the rest of the house and up the stairs. Some gets reflected back, but I have not been able to measure how much.

Nobody said being an audiophile was easy, so I could try all fifteen frequencies between 57Hz to 71 Hz. However, I think it will save time to analyze the response curve of the room so that I know what the center frequency of the hump is and how wide it is.

I do appreciate your advice, Brian. Thank you.

You know I haven't thought this out fully, but it did cross my mind that since you are running two of the amps to the same SUB, you actually have 2 equalization bands (one in each amp)

I am just wondering if that might in some way allow you to set 2 different bands???? Obviously it would "sum" since it waould be coming from the same sub, but it might have either "interesting" control ability, or maybe it will add nothing.

Try to wrap your head around what advantages it might have, or drawbacks you might encounter.

RGordonpf · « **Reply #18 on:** 27 Feb 2007, 04:41 am »

Hi John,

Your comments have gotten me to think. Unfortunately, I suspect that I will have to try all permutations before I find the correct settings. For example, each Larger driver can have a different crossover point. I suspect that I should have the 12" at a higher crossover point than the 15". You are correct that I could have the two parametric equalizers set for different center frequencies and different Qs. There are many permutations and it will take a long time to try all of them. Since I will be working seven days a week thru April 17, I suspect that I won't be able to test very many permutations until late April.

I hope with a PAA2 spectrum analyzer that I can get close to the optimal point and then fine tune by ear. Any thoughts on what procedures I can use to eliminate many of the permutations quickly?

tbrooke · « **Reply #19 on:** 27 Feb 2007, 02:17 pm »

All this has gotten me thinking that since I have 2 twelve inch drivers that I took out of my original subs when I put in megawoofers; I bet I could pickup an amp and with my drivers I'd have 2/3 of a nice sub. Anybody got any ideas?

Tom Brooke