After 21 years--Powered Subs and Powered Bass Systems

woodsyi · « **Reply #20 on:** 10 Feb 2005, 06:17 pm »

Wayne,

Correct me if I am wrong. DSP-4 by QSC can be programed to keep stereo subs in phase (or out of phase in push-pull) with time delays while offereing multiple band EQ. I can place it after my Crown K2 which is highpassed at 50 Hz via an analog active filter. Signals lower than 50 Hz will be digitized, DSP aplied and then sent to my sub(s) with perfect phase and parametric equalization at selected frequencies of chosen band width. I get to keep analog sound where it counts and digital control where it is most needed. HMMMMMM There has to be something wrong. It can't be true. Can it?

Wayne1 · « **Reply #21 on:** 10 Feb 2005, 06:28 pm »

The DSP-4 would be placed before the K-2. It operates at line levels.

Everything else you have written is correct.

Go to the link in my previous post and you can download the operation manual and the software that controls the DSP-4. That way you can see for yourself how it works.

gongos · « **Reply #22 on:** 10 Feb 2005, 07:12 pm »

I have a question about how to bolt one of the PE plate amps to a VMPS sub. It looks like I'd have to use 12 inch bolts unless I face the controls towards the sub.

Brian Cheney · « **Reply #23 on:** 10 Feb 2005, 07:37 pm »

Amp is about 4" deep, long woodscrews will work.

gongos · « **Reply #24 on:** 10 Feb 2005, 07:45 pm »

I have the 1000w one. It's 6 inches deep maybe a little more considering the wires coming out of the back of it. With long screws and a big plate amp hanging off the back, the sub will look pretty goofy.

ohenry · « **Reply #25 on:** 10 Feb 2005, 08:25 pm »

If you want it outboard, it's pretty simple to make a case from 3/4 in. wood and drop the amp in. It only needs the four sides (no bottom) to conceal the plastic. Also, you'll need to loosen the plastic case and route the bottom-exiting output wires to binding posts that can be side mounted.

Of course, that's one more box on the floor, but mine looks okay that way.

Bingenito · « **Reply #26 on:** 11 Feb 2005, 12:53 am »

I agree I would not bolt a plate amp to a nice sub cabinet. That would kill resale and look like crap.

I built some simple cabinets for the amps out of cabinet grade pine and stained them Walnut to match my speakers. They look good. The project took about 3 hrs total.

drboyd · « **Reply #27 on:** 11 Feb 2005, 04:14 am »

For a thousand watts, the speaker connecting wires look a little skinny. Or it that just me?

Rick Craig · « **Reply #28 on:** 14 Feb 2005, 03:49 pm »

I have a few customers using this amp and they're very happy with it. One thing to keep in mind is that without test equipment it's very difficult to set up this for optimal results. Some of the VMPS subs in particular will be hard to tweak with adding equalization and adjusting the filter "Q" for passive radiator systems.

The parametric control isn't versatile enough to really be useful in taming room modes. One thing they don't tell you is that using the parametric feature can change the crossover point and -3db points. All of these settings (gain, crossover point, Q, boost) interact with each other so testing the unit with a measurement system is really important. There are several outboard units from various companies that are much more effective in dealing with room problems. It can be used to contour the response but again this is tricky, especially if your -3db points are fairly close together.

Be sure to warn your customers about equalizing their systems with ported or passive radiator enclosures. With up to 6db of boost it will be easy to overload the woofers and possibly damage them from too much excursion. It would be better to incorporate the amp into the design so that the box is tuned properly rather than adding the amp to an existing system. That way there's no guessing with adding / removing mass with the passive radiator and you can avoid response / power handling problems.

Rick

Brian Cheney · « **Reply #29 on:** 14 Feb 2005, 04:20 pm »

I doubt anyone will be using the parametric EQ to boost LF response. The idea is to tame the worst primary room mode. We do pretune the woofer to the amp to make things easier. Owners confused by the EQ feature can leave it off.

ctviggen · « **Reply #30 on:** 14 Feb 2005, 05:10 pm »

After analyzing my room using ETF, there's no way I'd use an EQ to boost a dip, as there's at least 4 major peaks that could be tamed by the EQ. I believe the peaks are caused by room modes (though the calculated frequencies of room modes don't match the actual peaks), but I've also not done any tweaking whatsoever, and I know that the Largers I have are overdamped and my NHT X2 crossover has adjustments that could be modified.

Rory B. · « **Reply #31 on:** 15 Feb 2005, 03:40 am »

I have the 500w version of this amplifier, and I use it to drive a very clean-sounding aluminum-cone bass driver from TC Sounds (Stryke AV12MKII) and I can also say that this is one majorly clean, efficient amplifier. I think it's one of the best parts that Parts Express has ever picked up.

John Casler · « **Reply #32 on:** 15 Feb 2005, 04:03 am »

Quote from: ctviggen

After analyzing my room using ETF, there's no way I'd use an EQ to boost a dip, as there's at least 4 major peaks that could be tamed by the EQ. I believe the peaks are caused by room modes (though the calculated frequencies of room modes don't match the actual peaks), but I've also not done any tweaking whatsoever, and I know that the Largers I have are overdamped and my NHT X2 crossover has adjustments that could be modified.

Bob, where are your peaks?

rosconey · « **Reply #33 on:** 16 Feb 2005, 07:56 pm »

time to update the web sight big b. atleast you found a good one.

see why we point with pride to our products. The amplifiers in virtually all "powered" woofers are dreadful Class B or (even worse) Class D designs which no self-respecting audiophile would tolerate anywhere else in his system. Indeed, the high power Class D amps in some very expensive subwoofers, which we have examined and tested at length, are the worst measuring, worst performing (unable to reproduce even a good sine wave), worst sounding amplifiers we have encountered in the past 30 years. Cheap, bad amps combined with equalization (which robs the sub of dynamic range), limiters (100dB to 104dB max SPL), and high moving mass (up to two pounds in some subs) make most modern powered subwoofers little more than a joke, suitable only for reproducing sound effects. Our advice: use your main amp, or just about any good solid state 100W or more separate amp, to hook up the VMPS New Standard or Larger Subwoofers for performance well beyond those highly advertised competitors at about half their price.

Woodsea · « **Reply #34 on:** 27 Feb 2005, 04:05 am »

Brian or John-
I have the OSW and there is no way here in Mongolia I am going to upgrade or buy a second sub in government apts. Is the 1000w overkill? Could I, should I just get the 500w amp? I am currently using a 100w Carver stereo

Thanks,
Eric

Brian Cheney · « **Reply #35 on:** 27 Feb 2005, 04:25 am »

The Class D and Class B amps I criticize on the website are as bad today as they were a few years ago. The plate amp I like is Class AB with a downconverting power supply. Sound quality is excellent.

John Casler · « **Reply #36 on:** 28 Feb 2005, 03:52 pm »

Quote from: Woodsea

Brian or John-
I have the OSW and there is no way here in Mongolia I am going to upgrade or buy a second sub in government apts. Is the 1000w overkill? Could I, should I just get the 500w amp? I am currently using a 100w Carver stereo
Thanks,
Eric

Hi Eric,

The 500w version is $100 less for 1/2 the power. Either would certainly outdo the Carver.

The 500w version (actually 540w) should power an "Original" sub quite well.

Do you really live in Mongolia?

Woodsea · « **Reply #37 on:** 1 Mar 2005, 02:37 am »

John,
Since December...We will be here for 2 years total. I then plan on moving to either central or south america for a 2-3 years.
Thanks for the answer...would you guys be able to tune it for my OSW?
Oh I know it will sound much better than the Carver. It just was free and readily available.
Thanks,
Eric

Pocketchange · « **Reply #38 on:** 1 Mar 2005, 02:55 am »

Isn't this sub amp Big B is pitching a Carver design? Or did I miss something when reading the Carver/Sunfire website? They both seem to quack like a "Bob Carver" duck... IMO.

John Casler · « **Reply #39 on:** 1 Mar 2005, 03:16 am »

Quote from: Woodsea

John,
Since December...We will be here for 2 years total. I then plan on moving to either central or south america for a 2-3 years.
Thanks for the answer...would you guys be able to tune it for my OSW?
Oh I know it will sound much better than the Carver. It just was free and readily available.
Thanks,
Eric

Eric,

Not sure there is too much tuning that can be done here on the amp side.

It has several adjustments (phase, frequency, gain, as well a a single band equalizer)

Since you will be "adding" the amp to the sub in your room, you would have to tune the putty and the equalizer, if needed.

Remember, the equalizer should not be used to "boost" dips, but instead it should be used to "tame" the biggest or worst "spike".