• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

PLX-1804 Parallel

G

Growly Lytes

Dec 4, 2009
1,358
13
Downunder Oz
Disclosures
Bass player
#1
Just an easy question for a couple of PLX-1804 users....
Do any of you jumper channels 1 & 2 to get the same signal coming out of both speaker outputs without a Y-Cable ?
If im correct after you send the mono signal to input 1 you can then use a jumper cable from the unused channel 1 to any of the channel 2 inputs giving a parallel signal out of both speaker outs , is this possible ?
Thanks TB.
Growly
 
#2
Growly Lytes said:
Just an easy question for a couple of PLX-1804 users....
Do any of you jumper channels 1 & 2 to get the same signal coming out of both speaker outputs without a Y-Cable ?
If im correct after you send the mono signal to input 1 you can then use a jumper cable from the unused channel 1 to any of the channel 2 inputs giving a parallel signal out of both speaker outs , is this possible ?
Click to expand...

Yes. RTFM...:cool:
 
  • Like
Reactions: BassmanPaul
#6
Growly Lytes said:
Just an easy question for a couple of PLX-1804 users....
Do any of you jumper channels 1 & 2 to get the same signal coming out of both speaker outputs without a Y-Cable ?
If im correct after you send the mono signal to input 1 you can then use a jumper cable from the unused channel 1 to any of the channel 2 inputs giving a parallel signal out of both speaker outs , is this possible ?
Thanks TB.
Growly
Click to expand...

Does this help?


QSCPLX1804Inputs.jpg




:D

Joe.
 
#7
For Gods Sake, i should have RTFM.
Sorry fellas.Well that means only one thing that im going to get that mother of an amp.I havent heard one bad thing about it. I cant test it so ive got my fingers crossed that it goes good with my cabinets because they are rated higher than the amp.
My two quads are 800watt @ 8ohm & the amp puts out only 600watts @ 8ohm ??
Are any of you powering cabinets that are rated higher than you amp ?
 
#8
600 watts per side = 1,200 watts at 8 ohms. I doubt your cabs would actually handle 800 watts without breaking up. If you're cranking out 600 watts into each of your cabs, I hope you're protecting your hearing. Right now, in my practice room, I'm powering a Berg AE212 (600 watts) and an Eden D-210XST (500 watts) with my little Eden WTX-500, which is giving them a total of 280 watts (due to 8-ohm load ... speakers in series), and it is still very loud at below noon on both gain and volume.

Trust me. It won't be a problem.
 
#11
I actaully would love it if it had a switch just for ease of things & i dont want to pay that much extra for the PLX-3102 just for a switch.Having a jumper cable or a Y-Cable isnt much.I thought maybe that a Y-Cable might degrade the sound by introducing hum or buzz so thats the main reason why i think this i dont know really ?? Ive read that a heap of Tb`ers use Y-Cables into amps that dont have parallel switches & it works fine.
About the watts i quess QSC when they say 600watts a side they mean the real watts.600watts should be enough to power 800watt cab & as you said Munjibunga i dont think the speakers would go that high even though the cabs have 4 BP102 speakers.
Thanks again guys for the reply.
G.L
 
#13
monroe55 said:
What other options are there than doing this, besides the Y cable? Using 2 preamps one for each channel?
Click to expand...

Sure,
you could use 2 preamps but unless you are going stereo or biamping (using x-over) that would be spending way more cash than just using a jumper or y-cable.

The cable run is so incredibly short that any increase in noise would be totally negligible if not balanced and pretty much nonexistent if balanced.

:D

Joe.
 
#16
Passinwind said:
One very valid reason for not wanting to do that is that it'll half the input impedance of the amp. Often times not a big deal, but with something like Alembic F2B it could be a deal breaker.
Click to expand...


So if i get a Y-Cable the amp will reduce the input impendence ? I use two 8ohm cabs so what would be the rms be for each channel if im using a Y-Cable ?
Then if i jumper the inputs doesnt the same thing happen as using a Y-Cable.
This is getting more complicated now.
If i use a Y-Cable or jumper the inputs using 8ohm cabs will the amp still put out 600watts a channel @ 8ohm ?
 
#17
Growly Lytes said:
Then if i jumper the inputs doesnt the same thing happen as using a Y-Cable?
Click to expand...

This is actually a REALLY good question. I pride myself on understanding how all my equipment works. I own two QSC amps; a GX5 which you have to jumper the inputs to use both channels with one signal, and a PLX3602 which has a parallel inputs switch that "jumpers" for you. As far as I know (I have not opened up my QSC amps to look) the XLR and 1/4" inputs on QSC (and any amp for that matter) are hardwired parallel. I.E. the signal you present at either input is present in it's entirety, unbuffered, at the other input. Albiet the XLR input is balanced.

Going by that logic, it IS THE SAME THING as using a Y-cable.

BOB, please chime in and explain why using a Y-cable to feed both channels is different than running a jumper from one input to the other in a QSC amp without a parallel input switch. It would be good for everyone to settle this debate once and for all.
 
#18
Wow i guess you know where im going with this.God i hope Bob can help here.
If using a Y-Cable is going to do something no-good like an input impendence mis-match i would rather do as the o/m says & jumper the inputs so nothing would change.
I think by what you have said above... that maybe when connecting the inputs in parallel via a jumper cable & not a Y-Cable the input impedence will stay the same ?? I hope this is correct !
 
#19
Growly Lytes said:
So if i get a Y-Cable the amp will reduce the input impedance?
Click to expand...

The jumper cable from 1-->2 IS a Y-cable in terms of function, first off. Just a more convenient, cheaper one. Sorry if I didn't make that abundantly clear!

Yes, the input impedance of the amp as seen by the preamp will be halved with either type of cabling. This has nothing to do with your cabs. If your preamp can drive the reduced input impedance of the amp you will still get whatever the power rating of the amp says. If not, you won't. As I mentioned, in some cases like the Alembic F2B and other tube preamps with their outputs fed directly from a common cathode circuit's plate this would matter, in the vast majority of others it will not.

I guess I should also mention that my 1804 works very well indeed for me in bass applications, as well as in PA duty.;)
 
#20
Passinwind said:
The jumper cable from 1-->2 IS a Y-cable in terms of function, first off. Just a more convenient, cheaper one. Sorry if I didn't make that abundantly clear!

Yes, the input impedance of the amp as seen by the preamp will be halved with either type of cabling. This has nothing to do with your cabs. If your preamp can drive the reduced input impedance of the amp you will still get whatever the power rating of the amp says. If not, you won't. As I mentioned, in some cases like the Alembic F2B and other tube preamps with their outputs fed directly from a common cathode circuit's plate this would matter, in the vast majority of others it will not.
Click to expand...

Apparently the kids at QSC don't have any issues with the jumper, which you correctly identified as being topologically identical to a Y cable.
 

Latest posts

Top Bottom
Back