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Peavey Hisys

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Category: General
Forum Name: General Forum
Forum Description: Open Discussion / Questions
Printed Date: 25 September 2023 at 9:30pm
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Topic: Peavey Hisys
Posted By: Strathmore
Subject: Peavey Hisys
Date Posted: 27 June 2011 at 1:55pm
Hi. I have just bought a pair of Peavey Hisys 2XT and a pair of hisys 115XT. Both run at 4 ohms.
I want to buy a powered mixer to run them for live bands.
Can anyone advise what ohm amp I would need?
Much obliged.

Posted By: soulray2
Date Posted: 27 June 2011 at 2:20pm
Unless there is a passive crossover built into the Peavey subs, you're going to need 2 amps & a crossover for them. What connections are on the back of your cabs, that will tell you?

"Moderation in all things, particularly moderation!"

Posted By: studio45
Date Posted: 27 June 2011 at 2:34pm
You'll need an amp that is capable of powering a 2 ohm load. Two 4 ohm loads in parallel = 2 ohms.

You might be misunderstanding the way amps are rated here: the phrase "what ohm?" is not correct, rather "What impedance rating will the amp need to have?"
As well as a wattage figure to indicate amp power there is a minimum impedance figure the amp can safely drive into. 
As the impedance goes down (as you hook up more speakers in parallel) the circuit is approaching a short circuit and more and more current flows to achieve the same voltage. There is a limit to how much current can flow as it is directly correlated to heat generation in the output devices. 
In addition, too low an impedance at the output can cause an amp to break into spurious radio frequency oscillation which will quickly overheat and damage it (and probably the speakers) 
Some amps will let you load them right down to 1/2 ohm and simply cycle on and off as they overheat, cool down, overheat again etc. Some will whistle themselves to death and let the magic smoke out of everything in the circuit, some will simply go bang right away.
I believe you'd be quite happy with one of the Behringer Europower or QSC RMX series. They might not be a good choice for continuous 2 ohm high average power sub operation but 2 ohm full range, at correspondingly lower average power, will probably be OK. 
Other than that, you'll generally be after something with big fans and good heatsinking, made to deal with heat generation properly. Also, use the thickest cables you can. A 2 ohm rig will really suffer if you string it up with bell wire. 4mm minimum IMO.

Studio45 - Box Builder Commotion Soundsystem -Mobile PA

Posted By: studio45
Date Posted: 27 June 2011 at 2:36pm
@Soulray the Peavey Hisys stuff has all the crossovers built in. Horrible crossovers, but they are there.

Studio45 - Box Builder Commotion Soundsystem -Mobile PA

Posted By: Jasonstry
Date Posted: 27 June 2011 at 4:26pm
And it isn't a 2 Ohm Load as the boxes aren't covering the same frequencies and a single amp doesn't "know" that the crossover is there.  It sees a 4 Ohm load up to the crossover point and a 4 Ohm load above the crossover point so, except for some anomalies around the crossover point, the amp just sees a 4 Ohm load.

Posted By: Strathmore
Date Posted: 27 June 2011 at 5:47pm
Thanks everyone for getting in touch.
Have been on the phone to Peavey today and Andy is right, the speakers need to be run with a 4 ohm amp.
Thanks again.

Posted By: studio45
Date Posted: 27 June 2011 at 6:33pm
Ah yes, right you are. However I would not bet on the actual total load being 4 ohms or more at all frequencies. Probably not enough to trouble a non-2 ohm stable amp, though. On their own the Hisys boxes run all the way down, connected through the sub there is a highpass filter in circuit, not sure if there is an overlap or not.

Studio45 - Box Builder Commotion Soundsystem -Mobile PA

Posted By: Jez_3phaze
Date Posted: 27 June 2011 at 8:26pm

The section (operation and cable wiring) may be useful!      

Rgards .....J

Posted By: mitchiemasha
Date Posted: 03 July 2011 at 8:13pm
Originally posted by Jasonstry Jasonstry wrote:

And it isn't a 2 Ohm Load as the boxes aren't covering the same frequencies and a single amp doesn't "know" that the crossover is there.  It sees a 4 Ohm load up to the crossover point and a 4 Ohm load above the crossover point so, except for some anomalies around the crossover point, the amp just sees a 4 Ohm load.
Was thinking about this last week due to a project I was working on. I was unsure of the effect on ohmage load with a passive crossover. I couldn't come to a final conclusion but thank you, I think I've grasped it now.
I've always avoided passive crossovers in subs etc due to only achieving half the power from your system.
1 of the first things I learned down my local PA shop was that using the passive cross over with say a 2x 400w amp @ 4ohm (ingnoring the tripple power rating rule) feeding 2 400w 4ohm subs and 2 400w 4ohm mid/tops you would get a split of the 400w between your speakers and not an actual 800w of power. I'd never realised that this was due to the passive not dropping the circuit down to 2 ohms until now..
If the passive wasn't there the power available would double as the ohmage has halfed. This gives you 800w a side @ 2 ohms. I'd not thought about this in reverse. If the passive is there and the ohmage dropped I would get the correct split of 400w bass and 400w mid/tops. I already know this is not true I only get the 400w full range then split. So of course the ohmage at the cross over must stay the same.
Simply using a 2x800w 4 ohms (still ignoring the tripple power rule, trying to keep this simple) with the passive wouldn't get the full 400w per speaker. The peavey passive cross over is designed for 400w of full range signal which it divides into what ever ratio of bass and mid/tops to the speakers. Better speaker builds like the massive cross overs in the logic bins I used to have may handle this differently. They will no doubt be designed to take a power rating much higher than stated and divide it acordingly. I may be wrong on this though... 
The best soultion will always be.
Using an active cross over and 2 2x400w (ignoring tripple power rule) amps would feed 400w to my subs and 400w to my mid/tops.
Note for OP: If you are new to audio the tripple power rule is about using amplifiers tripple the rated power of the speaker. This is due to music having high crest factors. Over compressed music will have lower crest factors so most people stick to using amplifiers double the rated power of the speaker.
Having an amp with matched values means you will be driving the amp into clipping to get the needed power out of your system. This can cause more damage than using a larger amp and actualy over powering your system.

Posted By: grazzeee
Date Posted: 06 July 2011 at 12:00pm
mackies all the way!

Posted By: mitchiemasha
Date Posted: 06 July 2011 at 10:29pm
Originally posted by grazzeee grazzeee wrote:

mackies all the way!
Well thats helpful and to be honest they aint that much better than peavey.

Posted By: kedwardsleisure
Date Posted: 06 July 2011 at 11:13pm
The Peaveys are engineered as a package to be used with 2 bins and 2 tops and a 4-ohm capable amp complete with correct link leads. They were sold this way and are voiced as such. You'll be fine!

Just pay attention to the speakon pin wiring because some HiSys cabs have full range in on pair 1 and high pass out on pair 2, and others have seperate FR ins and HP out sockets.

If you get it wrong it might give a 2R load.... seen it, taken the blame for not repairing an amp properly, advised the customer and had the apology in due course.


North Staffordshire

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