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len armstrong



Joined: 28/01/13
Posts: 3
Loc: Cumbria
PA system
      #1030901 - 28/01/13 07:39 PM
Hi all Newbie here
i would like some help to create a way forward in improving my present rather old system
Firstly I gig with one other guy mainly smallish venues country folk blues etc and i put on various open mikes. so power aint the highest priority. Here is my set up
yamaha powered amp emx500-12
pair of peavey prosys 15 speakers
monitor
laney combo bass amp
backingt tape deck
and smartphone
some questions and some photos
channel 2 on the amp is very noisy 1 has a bit of noise as does 7 the rest are silent even on max volume and gain so any ideas as to how/if i could clean up the 3 i have done all the checks and found the only thing to silence them is putting a blank jack in the I/O input.
Now to the reall nitty gritty i have attached some photos for your perusal
Most of the drivers in here have had some repairs at some time so i ma replacing them
I have already replace the 3 way passive crossovers
as you will see these cabs have three inputs a bi amp lo switching jack
1/4" jack bi amp hi
and an xlr bi amp hi
ok so my bquestion how should the inputs from the input the panel be connected to the xover cos im not sure i have it right.
and using the figures can someone give me some decent quality replacement drivers that would work with this sytem that would make me a happy bunny the speakers at present are 150 rms but the amp is much bigger so i would like to be able to use a little more of its power. I love working this stuff out and hate throwing away so it would be great to make these old cabs punch above there weight a little and keep them off the tip. I am learning loads about frequencies and drivers and eager to get better i have no qualms about opening things up and heating up the solder station so if anyone fancies giving me a helping hand into this new domain bring it on
cheers Len sorry abou the long post but thought id get as much info in as poss see photos when i work out how to upload them


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Sam Spoons
active member


Joined: 23/01/03
Posts: 1428
Loc: Manchester UK
Re: PA system new [Re: len armstrong]
      #1030923 - 28/01/13 08:46 PM
Ok, as far as I can work out, the XLR on the back of your Peaveys is in parallel with the top jack socket. This allows two connector choices for full range operation (i.e. signal going via the xover to all drivers). If you plug something into the lower jack socket I suspect it will send signal to the either the LF driver plus the MF but not to the horn or the LF only, you would then need to send an additional signal to the horn only via one of the upper connectors (or possible the split is LF and MH + HF). Either way you need to use one of the Full Range upper connectors to run them from your Yamaha EMX. Without a circuit diagram it's impossible to tell how to wire the LF switching jack but I'll bet the xover (but you have changed that haven't you?) is labeled for which connections go where. However, without two power amps it's academic, just connect the speaker outputs of your desk to the Hi/FR upper connectors and you'll be fine. BTW, if the switched LF jack bypasses the xover you'd need an active xover to bi-amp the speakers but I doubt that's the case.

Regarding the power output of the amp relating to the power handling of the speakers, they are 8 ohm speakers and the amp produces 500 watts RMS into 4 ohms and 325 into 8 ohms, this is reasonably close to optimum, the recommended relationship is for the amp to have 1.5-2.0 times the rated RMS power of the speaker (to allow headroom for loud transients without them distorting). If the drivers are working I'd stick with them, alternatives will compromise the design, possibly to the detriment of the overall sound.

Regarding noisy inputs, you probably have a fault in the pre-amps on those channels, get a good amp tech to look at it. (when you put a jack into the insert I/O jack you disconnect the pre-amp from the rest of the channel strip). The cause is most likely a failing component or a dry joint on in the pre-amp but it may be worth buying a tin of DeOxit first though and giving the connectors a squirt, sometimes the switch contacts on the insert jacks get dirty and this can occasionally generate some noise.

Good luck

Edited by Sam Spoons (28/01/13 08:49 PM)


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len armstrong



Joined: 28/01/13
Posts: 3
Loc: Cumbria
Re: PA system new [Re: len armstrong]
      #1030957 - 29/01/13 01:51 AM
Sam thats awesome and all without the photos which i was going to upload but found out were way too big.
I do have to replace the drivers one 15" i have had to patch up one horn wasnt working and i had to solder a link and one midrange 8" is also patched so i thought i would replace them all over time. any advice !!!!
i am going to have a good look through this forum cos if all the answers are as quick and concise then i am at the right place, who knows i might one day answer someone elses question lol

right click and show in new tab


Edited by len armstrong (29/01/13 01:54 AM)


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Sam Spoons
active member


Joined: 23/01/03
Posts: 1428
Loc: Manchester UK
Re: PA system new [Re: len armstrong]
      #1031008 - 29/01/13 12:44 PM
Glad to help Len. The limiting factors for power will probably be the xover and the horn drivers first followed by the mid and low drivers.TBH it probably isn't worth spending too much replacing the drivers with better quality ones, (I do know where you're coming from, I don't like to see serviceable gear scrapped) I'd keep it simple and replace like with like as far as possible .


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len armstrong



Joined: 28/01/13
Posts: 3
Loc: Cumbria
Re: PA system new [Re: len armstrong]
      #1031084 - 29/01/13 08:32 PM
cheers Sam i understand problem is the only driver that has any detail is the tweeter at 150w 8 ohm
cant identify the mid or the woofer whether its full range or sub


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Sam Spoons
active member


Joined: 23/01/03
Posts: 1428
Loc: Manchester UK
Re: PA system new [Re: len armstrong]
      #1031108 - 30/01/13 12:29 AM
Most likely what defines the mid and LF drivers as 'sub', or 'low mid' or 'high mid' etc is the crossover. A typical 15" PA driver will probably have a frequency response of 40-3500 Hz (within certain limits) so it could act as a 'sub' or a 'low/mid' or even a 'mid' driver, that's not to say it'll do each job optimally but the job it's doing is defined by the frequencies the xover sends it. In the absence of accurate information on the precise speaker characteristics I'd replace the faulty drivers with general purpose PA speakers of roughly the same power handling and size.


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