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11-20-2010, 08:04 PM
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Bass player | | Join Date: Dec 2009 Location: Downunder Oz | | | PLX-1804 Parallel
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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 |
11-20-2010, 09:33 PM
|  | I Know Nothing | | Join Date: Dec 2003 Location: Columbia River Gorge, WA. | | Quote:
Originally Posted by Growly Lytes  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 ? | Yes. RTFM...  |
11-20-2010, 09:37 PM
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greenboy designs: fEARful, bassic, dually, crazy88 etc | | Join Date: Dec 2000 Location: remote mountain cabin Montana | | | . |
11-20-2010, 09:44 PM
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Bass player | | Join Date: Dec 2009 Location: Downunder Oz | | | Thanks |
11-20-2010, 09:47 PM
| | I Know Nothing | | Join Date: Dec 2003 Location: Columbia River Gorge, WA. | | Quote:
Originally Posted by Growly Lytes Thanks | Just make sure to use balanced connections for the 1-->2 cable if you used a balanced one for the preamp--> 1 cable and you want to keep everything balanced.
Last edited by Passinwind : 11-20-2010 at 10:10 PM.
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11-20-2010, 10:09 PM
| | Registered User | | Join Date: Jul 2004 Location: West Richland, WA | | Quote:
Originally Posted by Growly Lytes 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 | Does this help?  
Joe. |
11-20-2010, 11:59 PM
| | Registered User
Bass player | | Join Date: Dec 2009 Location: Downunder Oz | | | 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 ? |
11-21-2010, 12:17 AM
|  | Total Hyper-Elite Member | | Join Date: May 2000 Location: Groom Lake, NV | | | 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.
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Last edited by Munjibunga : 11-21-2010 at 12:23 AM.
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11-21-2010, 12:19 AM
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Endorsing Artist: SWR Amplifiers | | Join Date: Jun 2004 Location: Sydney, Australia | | | ... "only" 600 watts per side.
I think you'll get by! |
11-21-2010, 01:08 AM
| | Total Hyper-Elite Member | | Join Date: May 2000 Location: Groom Lake, NV | | | Why don't you want to use a Y cable?
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11-21-2010, 03:43 AM
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Bass player | | Join Date: Dec 2009 Location: Downunder Oz | | | 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 |
11-21-2010, 06:47 AM
| | | Quote:
Originally Posted by Lowtonejoe Does this help?
Joe. | What other options are there than doing this, besides the Y cable? Using 2 preamps one for each channel?
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11-21-2010, 09:57 AM
| | Registered User | | Join Date: Jul 2004 Location: West Richland, WA | | Quote:
Originally Posted by monroe55 What other options are there than doing this, besides the Y cable? Using 2 preamps one for each channel? | 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.
Joe. |
11-21-2010, 10:43 AM
| | I Know Nothing | | Join Date: Dec 2003 Location: Columbia River Gorge, WA. | | Quote:
Originally Posted by Munjibunga Why don't you want to use a Y cable? | 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 an Alembic F2B it could be a deal breaker.
Last edited by Passinwind : 11-22-2010 at 09:59 AM.
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11-21-2010, 02:39 PM
| | Registered User | | Join Date: Jul 2004 Location: West Richland, WA | | Quote:
Originally Posted by Passinwind 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. | Sheesh!
Smart guys!   
Joe. |
11-21-2010, 03:11 PM
| | Registered User
Bass player | | Join Date: Dec 2009 Location: Downunder Oz | | Quote:
Originally Posted by Passinwind 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. |
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 ? |
11-21-2010, 04:00 PM
|  | Supporting Member | | Join Date: Nov 2009 Location: San Antonio, TX | | Quote:
Originally Posted by Growly Lytes Then if i jumper the inputs doesnt the same thing happen as using a Y-Cable? | 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.
Last edited by mikeddd : 11-21-2010 at 04:42 PM.
Reason: Clarified question
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11-21-2010, 06:58 PM
| | Registered User
Bass player | | Join Date: Dec 2009 Location: Downunder Oz | | | 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 ! |
11-21-2010, 10:09 PM
| | I Know Nothing | | Join Date: Dec 2003 Location: Columbia River Gorge, WA. | | Quote:
Originally Posted by Growly Lytes So if i get a Y-Cable the amp will reduce the input impedance? | 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. 
Last edited by Passinwind : 11-21-2010 at 10:47 PM.
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11-21-2010, 10:46 PM
| | Total Hyper-Elite Member | | Join Date: May 2000 Location: Groom Lake, NV | | Quote:
Originally Posted by Passinwind 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. | 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.
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