QSC-PLX1804 or QSC-PLX3102 ?

Growly Lytes · #1 11-17-2010, 07:44 PM

TB`ers,

Im trying to find out if my Sansamp RBI or RPM would be able to power the QSC PLX-3102 or the QSC PLX-1804 ?? They both have the same power output @ 8ohms, i have two identical 8ohm 800watt cabs ??
Thing is im not sure if the RBI or RPM would be able to run these amps properly.

The QSC have a 1.2v sensitivity & the Sansamps 1.0v also another thing is my cabinets are rated higher than the amps (QSC 600watt x 2 @ 8ohm & my cabinets are 800watts @ 8ohm)
Does anybody use an RBI or RPM & have a poweramp that has 1.2v sensitivity or higher that works well with the RBI/RPM ??
Thanks TB`ers Keep Rockin

Growly

Gearhead17 · #2 11-17-2010, 09:52 PM

RBI and RPM should push the amps just fine. QSC PLX 3102 is probably the better choice with the bridging capability at 4 ohms (you have two 8 ohm cabs). The 1804 is nice too, cheaper, but no bridging. The speakers will be fine if you don't "match the numbers". Just listen carefully to the speakers and make sure they don't distort or sound funny at high volumes and you will be fine.

badstonebass · #3 11-17-2010, 10:23 PM

My RBI runs any power amp just fine. I used to have the DI and it did just fine as well.

srxplayer · #4 11-17-2010, 10:36 PM

It will drive it just fine. I have driven an 1804 with my Sansamp BDDI so you won't have a problem.

I like the 1804 better because it only weighs 13 lbs and it's only about 11 inches deep. You don't have the bridge mono capability but if I remember correctly you can run a jumper between the channels and get the same output out of both channles with a single input signal. I do this with my GX5.

Munjibunga · #5 11-18-2010, 12:37 AM

Quote:

Originally Posted by srxplayer

It will drive it just fine. I have driven an 1804 with my Sansamp BDDI so you won't have a problem.

I like the 1804 better because it only weighs 13 lbs and it's only about 11 inches deep. You don't have the bridge mono capability but if I remember correctly you can run a jumper between the channels and get the same output out of both channles with a single input signal. I do this with my GX5.

Yeah, I'm a little surprised that QSC didn't put at least a parallel input switch on the 1804. But it's a bare-bones, simple amp, and a Y cable solves that issue. I have a 1602 and a 3402 (they're older), and I like the connectivity and output options. But they weigh 21 pounds.

If it were me, I think I'd go with the 1804 if you don't need the features of the 3102 and don't want to cough up the extra cash.

bobcruz · #6 11-18-2010, 10:55 AM

The 1804 lacks a high pass filter to cut the extreme power-sucking speaker-killing lows. The 3102 has a switchable 33 Hz HPF.

Growly Lytes · #7 11-18-2010, 07:14 PM

Yes thanks guys,
The extra features do catch my intrest more but as i said they put out the same rms @ 8ohms.
So by using a Y-cable i should be able to use the 1804 pumping out the same rms into each cab ?
Do them extra features make that much difference ? The 3102 has filters , bridge & parallel switch modes. What does `Matching The Numbers` mean ?

Gearhead17 · #8 11-18-2010, 07:33 PM

Quote:

Originally Posted by Growly Lytes

What does `Matching The Numbers` mean ?

"Matching the Numbers" means matching the RMS wattage number of the cab with the RMS wattage number for the amp at a given ohm rating.

Growly Lytes · #9 11-19-2010, 05:40 PM

I think by what you guys have told me it wouldnt matter that much apart from the little extra things the 3102 has.I dont use bridge i mostly just use Parallel so a Y-Cable will be needed for the 1804 where the 3102 has a switch.
O.K one big thing i can see in difference is the
`Damping Factor`
>200 -PLX 1804
>400 -PLX 3102
Their cheaper models all have a low damping factor where the expensive ones are more than 400 ??
Does this come into play ?? With the PLX-1804 having >200 DF would it be worse than PLX-3102 having >400 DF ?? I read that it controls the speed of the speaker going back & forth ??

Bob Lee (QSC) · #10 11-19-2010, 06:24 PM

No, damping factor doesn't mean much when you get above 50 or so.

fish slapper · #11 11-19-2010, 07:27 PM

Happy 1804 owner here. I only use one side into a 4 ohm Schro 1210R. I figure if I need to expand I'll get another 4 ohm cab and hook it to the other channel. I have been advised since I use the low-z (mic) input, I can put a cable into the 1/4 phone inputs from one channel to another and the pre will drive both channels. Since the single channel into the Schro is handling my current gigging needs, I personally haven't tested this out.

I don't know about lack of low pass, and damping and all the fancy tech talk, I just know that it's very light, very powerful, and delivers lots of nice tone.

Hope this helps.

Growly Lytes · #12 11-19-2010, 08:43 PM

If you put your signal into channel 1 then jumper the unused channel 1 to any of the channel 2 inputs you can parallel the input signal giving you the same out of both speaker outputs, i think this is correct ?? That would mean no Y-Cables needed for parallel ?
Please chime in once more Bob for these two questions !
1. Would my Sansamp RBI power the PLX 1804 to full power also ? The amps input sensitivity is 1.2vrms where the Sansamp is 1.0vrms
2. Can i jumper the inputs to give me the same signal via both outputs ?
Thank you guys
Growly.

Bob Lee (QSC) · #13 11-20-2010, 12:28 AM

Quote:

Originally Posted by fish slapper

I have been advised since I use the low-z (mic) input

PLX amps have high-Z inputs with both XLR and 1/4" input jacks. They don't have mic inputs.

Growly Lytes · #14 11-20-2010, 12:39 AM

Quote:

Originally Posted by Bob Lee (QSC)

PLX amps have high-Z inputs with both XLR and 1/4" input jacks. They don't have mic inputs.

Yo Bob what about the jumper cable from channel 1 to channel 2 is it possible to have the same signal coming out of both inputs without a Y-Cable ?

**mikeddd** · #15 11-20-2010, 05:22 AM

Quote:

Originally Posted by Growly Lytes

Yo Bob what about the jumper cable from channel 1 to channel 2 is it possible to have the same signal coming out of both inputs without a Y-Cable ?

Yes. I've done this with my GX5 and it works great. Here's a thought. If money is not too much of an issue, I would get the 4-ohm bridge-capable amp. If it should happen that your RBI cannot drive the poweramp to satisfactory levels with an 8-ohm load, you can parallel your two cabs on the bigger amp for a 4-ohm load. The greater output wattage should/could make up for the fact that the amp's front end isn't being driven to max. I don't have scientific numbers/theory to back that up, but it makes sense to me.

Growly Lytes · #16 11-20-2010, 05:57 AM

Appanently the RBI can drive the PLX-1804 & PLX-3102 all the way if it has to but im not to sure ??
My cabinets are 800watts & i can only afford the PLX-3102 as far as money is concerned.Now the caper is that the PLX-1804 has the exact same power rating @ 8ohms so i imagine that it will be cheaper for me to get that seeing i wont get any more watts if i go with the PLX-3102, do you see where im going ?? They both put out the same rms @ 8ohms & i have 2 8ohm cabs.
Now is the PLX-1804 enough to power two 800watt 8ohm cabinets ??

**mikeddd** · #17 11-20-2010, 06:45 AM

The PLX1804 is rated 600 WPC @ 8 ohms. Assuming your RBI can push the amp properly, you'll be very happy with 1200 watts into those two cabs. Though I've never used a RBI/RPI into a poweramp setup, I was looking into it. Those who do so seem to be very happy. The RBI is designed to be used exactly in this way, so I think you'll be good to go.

Bob Lee (QSC) · #18 11-22-2010, 10:19 AM

Quote:

Originally Posted by Growly Lytes

Yo Bob what about the jumper cable from channel 1 to channel 2 is it possible to have the same signal coming out of both inputs without a Y-Cable ?

A jumper cable or y cable will allow you to put the same signal into both inputs, if that's what you're asking.