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Rackmount Power Amps

#65
Mark Corradetti said:
sweet ! can you recommend a specific one? each cab is 6 ohm and rated at 600 w...thanks in advance !
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Actually, one of QSC's models that was just mentioned might work great for you and they're fairly lightweight (13 lbs).
The PLX2 1804 will give you 900W at 4 ohms per channel. I'm thinking you're probably going to get 750W at 6 ohms.
It's quite okay to go over the rated power for your cabs with clean power. Just make sure to be careful with turning up the gain knob on your preamps.

You could probably save some money and pick up at QSC PLX 2402, 3002, or 3402 used. They're all around 21 lbs I believe.
The 2402 will give you less power output per channel at 6 ohms than the new PLX2 1804, but the 3002 will give you about the same. The 3402 will give you a bit more.

Any of these amps are rock solid and great. You may need to really turn up some of your preamps if they don't have very hot outputs. Again, be careful with how much you turn the gain knobs.

Good luck!
 
#66
bassballs27 said:
Actually, one of QSC's models that was just mentioned might work great for you and they're fairly lightweight (13 lbs).
The PLX2 1804 will give you 900W at 4 ohms per channel. I'm thinking you're probably going to get 750W at 6 ohms.
It's quite okay to go over the rated power for your cabs with clean power. Just make sure to be careful with turning up the gain knob on your preamps.

You could probably save some money and pick up at QSC PLX 2402, 3002, or 3402 used. They're all around 21 lbs I believe.
The 2402 will give you less power output per channel at 6 ohms than the new PLX2 1804, but the 3002 will give you about the same. The 3402 will give you a bit more.

Any of these amps are rock solid and great. You may need to really turn up some of your preamps if they don't have very hot outputs. Again, be careful with how much you turn the gain knobs.
Click to expand...

1804s are old news these days, there are plenty of used ones out there. And yes, you need a real preamp with pro sound level output unless you get one with the gain mod, or have that done.
 
#69
Mark Corradetti said:
man....these 3402's are like 3400w!! isn't that too much?
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No, that's the bridged power at 4 ohms.

Since you'd be running that amp in stereo at 6 ohms per channel.
Each channel is rated at 700W at 8 ohms and 1100W at 4 ohms. Since 6 ohms is between that, my assumption is that you be getting about 900W going to each cab.
That's a conservative amount of power to use with your cabs if you're careful.

You could probably get away with using one cab and one channel for mid sized gigs……and then take out both cabs for a big show if you decide on the 3402.

I guess the 3402 will work just like the PLX2 1804 for you at the end of the day for you.
You might want to look for the PLX2 1804 used just like Passinwind mentioned.
 
#72
Mark Corradetti said:
My cabs are Phil Jones 12b's.....12 5 inch drivers in each cab. I'm really pleased with them overall. Check them out...[Invalid or Expired Link Removed]
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Cool, I know what PJB's thing is about. Just wanted to make sure you weren't measuring DC resistance rather than spec'ing nominal impedance. Link Removed
 
#73
Whenever using amps with significantly more power than the speaker is rated for, caution is always recommended.
 
#74
Passinwind said:
Cool, I know what PJB's thing is about. Just wanted to make sure you weren't measuring DC resistance rather than spec'ing nominal impedance. Link Removed
Click to expand...
bassballs27 said:
No, that's the bridged power at 4 ohms.

Since you'd be running that amp in stereo at 6 ohms per channel.
Each channel is rated at 700W at 8 ohms and 1100W at 4 ohms. Since 6 ohms is between that, my assumption is that you be getting about 900W going to each cab.
That's a conservative amount of power to use with your cabs if you're careful.

You could probably get away with using one cab and one channel for mid sized gigs……and then take out both cabs for a big show if you decide on the 3402.

I guess the 3402 will work just like the PLX2 1804 for you at the end of the day for you.
You might want to look for the PLX2 1804 used just like Passinwind mentioned.
Click to expand...

Very interesting. So the preamp goes into the channel 1 input and then I'm all set, right?
 
#75
Passinwind said:
1804s are old news these days, there are plenty of used ones out there. And yes, you need a real preamp with pro sound level output unless you get one with the gain mod, or have that done.
Click to expand...

Some inside info: The GX7 is essentially a rework of the PLX1804 and could save you some money.
 
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#77
Bob Lee (QSC) said:
Some inside info: The GX7 is essentially a rework of the PLX1804 and could save you some money.
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That's a dang good looking amp I may have to check into one of these. A lot of power for what I do though. For a while I used the PLX 1804 with a MM2 preamp and a 4x10 GIII and 1X15 GIII what a powerhouse for a rig.

Bob what is a good 1,000 watts bridged QSC amp that is lightweight these days?

I'm looking for an old Trace GP12 SMX Pre and a power amp to move back to a possible non micro rig.
 
#79
Hmmm…..a little more off topic……but still talking in the same realm.
I think I should be looking at Input Sensitivity of any power amp that I decide to go with (or may it's just flat out keep the PLX2402) and see how it matches the Output Impedance of the Aguilar DB680.

Normal Output Impedance of the DB680 is 1 k ohm. My guess that this is the unbalanced output impedance.
Balanced is the standard 600 ohms.
I believe there is a selector switch to adjust the output (0, +2, and +4). I believe these are dB.
[Invalid or Expired Link Removed]

So, bringing back the old PLX series specs…..

Input sensitivity at 4 ohms - PLX 1602 - 1.1v (+3.2dBu), PLX 2402 - 1.3v (+4.6dBu), PLX 3002 - 1.5v (+5.7dBu) and PLX 3402 - 1.7V (+6.6dBu)

So, technically, the DB680 can't drive the 3002 or 3402 to it's full potential?

Maybe I'd be better off with a pair of 1602's operating in bridged mode?

-Chris
 
#80
bassballs27 said:
I had all the limiters and filters on…
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that's another thing i like about the PLXs for bass, that nice little control bank on the back!

the 30Hz filter is just right for keeping a deep low end while not letting your speakers jump around and uselessly suck up all the amp power, while the limiter control lets you decide whether or not to use it. i've read where many pro sound guys recommend taking the limiter off for PA sub duty because the amp basically becomes more powerful and a little transient clip here and there doesn't bother sub speakers so much. i've been following that logic for bass guitar, even though my 3002 doesn't get close to the clip lights without me being already way too loud :D

i tried the 50Hz filter but that seemed to emasculate the bass tone a bit too much, where i was turning up the low end on my pre until it made a mess of the stage mix while still not having the deepness i wanted.

so channel 1 is 30Hz on, limiter off for my bass, then the other channel (which often ends up doing monitor wedge duty) is set for 50Hz, limiter on.

as cool as the new stuff like the GX7 is for the money (USA-made and everything) the lack of these options on the back panel makes me lean towards the older stuff for bass guitar.
 

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