What Amp?

**moneybags** · **10-30-07, 01:17 AM**

What amp should I look into getting to push a RL-P 18D2? I was looking at the PE Plate amp,The Berhinger,QSC or Crown. The sub will be in a sonotube that is 550 liters and tuned to 14.5 hertz? Help me pic.

**Otto** · **10-30-07, 04:19 AM**

Hi James,

I have a Behringer EP2500 that would run a system like that just fine. Any of those pro amps would be just fine, IMO, and have been used for applications just like yours.

Good luck!

**Geoff St. Germain** · **10-30-07, 07:47 AM**

I'd personally stay away from plate amps for this application, largely because it will be difficult to integrate it into the sonotube. You can also get more bang for your buck (power-wise) from pro amps. I've had good luck with Crown and QSC as a gigging musician and use a Crown XTI2000 for HT sub duty, but it's hard to beat the price/power ratio of the Behringer EP series amps for home use.

**Darren** · **10-30-07, 10:35 AM**

Another vote for Behringer EP 2500. I have one driving 4 RL-P 15's and it does quite well.

**thxgoon** · **10-30-07, 02:17 PM**

Another vote for the 2500... but only if you post a build thread!

**moneybags** · **10-30-07, 11:20 PM**

So you dont think the 2500 will be to much power for 1 rlp?

**Otto** · **10-31-07, 06:50 AM**

Hi James,

I don't think it'll be "too much." You can never really have too much. I think you could get by just fine with an EP1500, but the EP2500 will give you more power, more headroom, etc.

**John N** · **10-31-07, 09:20 AM**

I vote QSC PLX (more money but many used ones around)

**warnerwh** · **10-31-07, 06:44 PM**

I'm still waiting for my 2500 to get here to replace my PE 1000 so I can't give an opinion on anything but prices.

I paid 250 shipped for my amp used but like new. The plate amp is on sale for 330 sometimes, plus shipping.

The Behringer is more than likely not only the much better amp but has more power too. Keeping the amp separate from these bad *** subs is probably a good idea too. The vibration all the time could conceivably take out your amp.

Btw the 250 costs littlel more than the 1500 and wattage is good to have.

**Blaser** · **11-02-07, 04:35 AM**

Quote:

moneybags wrote:

So you dont think the 2500 will be to much power for 1 rlp?

Never! with this sub size and tune, you will never have to worry on program material. Indeed, If you can afford a stronger power for each, I would encourage...

**Bradley** · **11-06-07, 08:01 PM**

Quote:

John N wrote:

I vote QSC PLX (more money but many used ones around)

Why the PLX over the more affordable RMX? I know the PLX series weigh a lot less, but for the HT, you obviously aren't going to be hauling it around from gig to gig (as it was designed for).

After watching War of the Worlds the other night with my newly built RL-P18 sub, I am very hesitant to run my amp (QSC RMX 2450, similar specs to the EP2500) bridged and feed it over 2000 watts. At 750 watts, it was scary enough. Plus, isn't the driver rated 1000 watts RMS?

All that said... the QSC PLX 1804 looks very attractive to me right now for the purpose of driving my two subs. You can't bridge that particular model, but it will deliver 900 watts into 4 ohms in stereo mode which isn't too shabby. Plus I believe it has a solid state power supply (no transformer) and weighs a mere 13 pounds.

Somebody please tell me what good and/or compelling reasons there are to push this thing with more than 1000 watts and convince me no harm -- either short term or long term -- will result from doing so.

Bradley

**WillyD** · **11-06-07, 09:18 PM**

Quote:

All that said... the QSC PLX 1804 looks very attractive to me right now for the purpose of driving my two subs. You can't bridge that particular model, but it will deliver 900 watts into 4 ohms in stereo mode which isn't too shabby. Plus I believe it has a solid state power supply (no transformer) and weighs a mere 13 pounds.

I'd recommend a Crown XS1200 for $500: http://www.musiciansfriend.com/produ...r-?sku=481011V

You can get a new one for $70 more. Also has SMPS instead of transformer and is rated for 1100W per channel @ 4ohms. I'll be getting one soon. I hope to send it to Chuck for testing.

Quote:

Plus, isn't the driver rated 1000 watts RMS?

It is I believe, but it is considered to be a conservative rating IIRC.

**Bradley** · **11-06-07, 10:32 PM**

Ack... why is that Crown rated from (only) 22 Hz to 22 kHz?

If that's truly the case, and you can't do a simple mod to "fix" it, I'll take a pass on that one. The QSC has great specs:

http://www.qscaudio.com/products/amp...ifications.htm

Can probably get a new one for $600 delivered and sell one or both of the RMX amps I have.

**WillyD** · **11-06-07, 10:43 PM**

What? You think its some brickwall at 22Hz? It is the +/- point for the top and bottom end. Every amp manufacturer does this. Even the QSC you're looking at has it: 20 Hz-20 kHz, -0.5 dB

In neither case does it mean the amps don't go below 20Hz, it just means the FR is guaranteed to be within a +/- .5 or 1dB deviation at/below 20Hz. You'd have to mod the QSC as well if you want flat to DC.

**warnerwh** · **11-06-07, 11:25 PM**

I'm new to pro audio amps and am wondering why spend more than what the Behringer costs? I buy quality whenever I can but in this case I don't see what you gain by using a Crown, QSC or Crest. Being as so many people are happy with the Behringer amps they must be reliable. Other Behringer components I have work fine.

Wish I'd never have sold the DEQ 2496 with mike but it worked perfectly for 2 years and I happen to know alot of people in high end audio like them, like me. I knew I'd regret it.

**Bradley** · **11-07-07, 12:16 AM**

Quote:

WillyD wrote:

What? You think its some brickwall at 22Hz? It is the +/- point for the top and bottom end. Every amp manufacturer does this. Even the QSC you're looking at has it: 20 Hz-20 kHz, -0.5 dB

In neither case does it mean the amps don't go below 20Hz, it just means the FR is guaranteed to be within a +/- .5 or 1dB deviation at/below 20Hz. You'd have to mod the QSC as well if you want flat to DC.

Ok... now you are just being funny. I'm not stupid and I don't expect it to be flat to DC. If you actually read the QSC specs you'll see they state the -3 dB points, both high and low, and I think in the case of the PLX it is 6 Hz, and 5 Hz for the RMX.

**WillyD** · **11-07-07, 01:17 AM**

Yes, I was. Only because I was confused as to why you were acting like the spec'd low-end FR of the Crown is so horrible, when I see no reason to suspect it is. But forget it, get the QSC.

**Bradley** · **11-07-07, 01:22 AM**

"Odd" is the word that comes to mind, not horrible.

**WillyD** · **11-07-07, 01:26 AM**

Quote:

Bradley wrote:

"Odd" is the word that comes to mind, not horrible.

Odd because it is 22Hz and not 20Hz or odd because the +/- 3dB point isn't present? It appears that is a common thing for Crown to omit from their specs, but it hasn't stopped anyone else from using them (CE4000, K2 but we know it has a highpass at 8Hz, XTi lineup).

**Bradley** · **11-07-07, 10:06 AM**

Mostly because it was specified as 22 to 22kHz, instead of 20 to 20kHz like "everbody" else does. The -3 dB points would be nice to have also. Probably nothing to worry about for the sake of driving a subwoofer, though. If low frequency response is limited, it is probably being done intentionally with a simple RC HPF. So I'd think that in the worst case scenario you'd only have to change some capacitors (and/or resistors) in the amp to get the lowest frequencies to pass.

The Crown is an interesting option. $569 with free shipping is a pretty good deal. I guess that's because it has been discontinued and is now on clearance?

**John N** · **11-07-07, 10:40 AM**

Quote:

Bradley wrote:

Why the PLX over the more affordable RMX? I know the PLX series weigh a lot less, but for the HT, you obviously aren't going to be hauling it around from gig to gig (as it was designed for).

From what I've read, the PLX is a better sounding and higher quality amp (tighter low end for subs)

When I went from a Parasound hca 1500a (205/ch) to the used QSC PLX 1602 (300/ch), it woke up my pair of VMPS original subs.

**WillyD** · **11-07-07, 12:06 PM**

Quote:

Bradley wrote:

Mostly because it was specified as 22 to 22kHz, instead of 20 to 20kHz like "everbody" else does. The -3 dB points would be nice to have also. Probably nothing to worry about for the sake of driving a subwoofer, though. If low frequency response is limited, it is probably being done intentionally with a simple RC HPF. So I'd think that in the worst case scenario you'd only have to change some capacitors (and/or resistors) in the amp to get the lowest frequencies to pass.

The Crown is an interesting option. $569 with free shipping is a pretty good deal. I guess that's because it has been discontinued and is now on clearance?

I think I might contact Crown about the -3dB points, because I am curious as well. Assuming they are comparable to the QSCs, it is definitely a solid deal. Yeah, the XS lineup was discontinued. $570 for a new one with free shipping and a good 3yr warranty isn't bad.

edit: Just sent David Glass an email. We'll see what he has to say.

**Bradley** · **11-07-07, 12:32 PM**

Quote:

John N wrote:

From what I've read, the PLX is a better sounding and higher quality amp (tighter low end for subs)

When I went from a Parasound hca 1500a (205/ch) to the used QSC PLX 1602 (300/ch), it woke up my pair of VMPS original subs.

More power always helps plus the QSC might have better damping factor and flatter low end response.

Edit: OK, scratch that. Looks like the Parasound has excellent FR down low and super high damping factor. Go figure. Were/are your subs 8 ohms? You ever try bridging the Parasound?

HCA 1500A SPECIFICATIONS

Continuous Power Output - Stereo:
205 Watts RMS x 2, 20 Hz-20 kHz, 8 Ω, both channels driven
315 watts RMS x 2, 20 Hz - 20 kHz, 4 Ω, both channels driven
Continuous Power Output - Mono:
630 watts RMS, 20 Hz - 20 kHz, 8 Ω
Current Capacity:
60 amperes peak per channel
Slew Rate:
> 130 V/µsecond
Frequency Response:
5 Hz - 100 kHz, +0/-3 dB at 1 watt
Total Harmonic Distortion:
< 0.03% at full power; < 0.01 % typical levels
IM Distortion:
< 0.03 %
TIM:
unmeasurable
Dynamic Headroom:
> 1.5 dB
Interchannel Crosstalk:
> 80 dB at 1 kHz; > 60 dB at 20 kHz
Input Impedance:
33 k Ω
Input Sensitivity:
1 V for 28.28 V, THX Reference Level; 1.2 V for full output
S/N Ratio:
> 110 dB, input shorted, IHF A-weighted
Damping Factor:
> 800 at 20 Hz
Power Consumption:
500 watts

**Bradley** · **11-07-07, 12:44 PM**

Quote:

WillyD wrote:

I think I might contact Crown about the -3dB points, because I am curious as well. Assuming they are comparable to the QSCs, it is definitely a solid deal. Yeah, the XS lineup was discontinued. $570 for a new one with free shipping and a good 3yr warranty isn't bad.

edit: Just sent David Glass an email. We'll see what he has to say.

Cool. Keep me posted, 'cause that's a lotta amp for the money. And hurry up, because they'll probably sell out pretty fast at that price.

I still like the QSC PLX 1804, but another 200 watts per channel (into 4 ohms) and somewhat lower price certainly is tempting.

**John N** · **11-07-07, 01:00 PM**

Quote:

Bradley wrote:

Edit: OK, scratch that. Looks like the Parasound has excellent FR down low and super high damping factor. Go figure. Were/are your subs 8 ohms? You ever try bridging the Parasound?

Never bridged the parasound (it is used now for my mains now ) they don't recommend it unless the speaker is 8 ohms. I think the subs are 8 ohm? (just replaced the woofers and passives with the mega woofers)

The PLX is rated 300/8 ohms 500/ 4 ohms so it has a good amount of headroom. I could bridge the PLX too. I think the subs would like a little more juice

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