Members MrJoshua Posted January 27, 2010 Members Share Posted January 27, 2010 I have a Peavey SP-15M passive monitor, which gets powered with one side of a QSC RMX-2450 most of the time or one side of an RMX-850. I've been getting a lot of distortion on the high end with it lately, and I think I've blown the horn. What troubleshooting techniques would you recommend to trace down the exact problem before I simply begin replacing parts? I've used it on both sides of the amp with the same problem, while another identical monitor sounds fine on either side. Different cable, same. So I'm certain that the problem lies in the monitor itself. Should I simply replace the compression driver? Put a new diaphragm in it? Or are there procedures I can go through to verify exactly what the problem is first? I'm familiar with basic electrical troubleshooting techniques; just not sure how to test these components, exactly. Thanks very much. Link to comment Share on other sites More sharing options...
Members gspointer Posted January 27, 2010 Members Share Posted January 27, 2010 freq sweep. Link to comment Share on other sites More sharing options...
Members dboomer Posted January 27, 2010 Members Share Posted January 27, 2010 I'd pop it open, pull one wire off the HF driver and measure the resistance ... should be about 5-6 ohms. If it's 0 or really high then it's blown. If it's still making sound then it's likely some foreign matter has fallen in or it's been knocked around. You'll have to replace the entire driver as they don't sell the diaphragm by itself. It may seem counter-intuative but since they buy the drivers in 10s of thousands and would buy the diaphragms in the 100's it was cheaper to just include the entire unit than pay to box up the diaphragm by itself. Such is modern manufacturing. I believe that unit has a couple of SK-3 light bulbs in it. You could swap those out and see if that fixes it. Link to comment Share on other sites More sharing options...
Members RoadRanger Posted January 27, 2010 Members Share Posted January 27, 2010 That box uses an RX22 driver - the diaphragm is available for about 1/2 the cost of a new driver. Link to comment Share on other sites More sharing options...
Members Gordon Sound Posted January 27, 2010 Members Share Posted January 27, 2010 You could also swap the driver from the good box and see if it goes away, Does it do it at all levels? Link to comment Share on other sites More sharing options...
Members dboomer Posted January 27, 2010 Members Share Posted January 27, 2010 That box uses an RX22 driver - the diaphragm is available for about 1/2 the cost of a new driver. Oops ... my bad. See how quickly you can forget:rolleyes: Link to comment Share on other sites More sharing options...
Members RoadRanger Posted January 27, 2010 Members Share Posted January 27, 2010 Oops ... my bad. See how quickly you can forget:rolleyes:Yah, you wuz thinkin' 'bout the PV/PR boxes with their disposable RX14 drivers. Actually there are aftermarket diaphragms available for those but none from Peavey. Link to comment Share on other sites More sharing options...
Members MrJoshua Posted January 28, 2010 Author Members Share Posted January 28, 2010 You could also swap the driver from the good box and see if it goes away, Does it do it at all levels? I'm not 100% sure what levels it does and doesn't do it at as when I went out to the trailer to grab it I realized two things: 1. I had forgotten to mark which of the two identical monitors it was, and 2. When you want to work on an item at home, it's NOT a good idea to put it on the trailer waaaaay up near the front where you have to pull almost everything else off the trailer before you can get to it. I'm running sound tomorrow. I'm going to use setup as a time to track down which monitor it is and mark it with some tape. Then I'll yank that monitor off the stage and put one of the spares in its place, and that monitor will go on the back of my truck instead of in the trailer so I'll be able to bring it inside to work on it when I get it home. Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 28, 2010 Members Share Posted January 28, 2010 A bad driver may not have a different DC resistance reading, it may be that the bobbin has blistered or distorted due to heat and is rubbing on the pole piece. Could also be that the bobbin attachment to the diaphram is damaged. Any of these require a new diaphram. Not a big deal. Link to comment Share on other sites More sharing options...
Members MrJoshua Posted January 28, 2010 Author Members Share Posted January 28, 2010 Any suggestions on places to buy replacement diaphragms? Figure I'll buy two so I'll have a spare on-hand. I've looked around on the web but I don't know anything about most of the suppliers and I'd rather buy from someone reputable as opposed to just going with the lowest listed price (although saving money is nice too, of course). Link to comment Share on other sites More sharing options...
Members RoadRanger Posted January 28, 2010 Members Share Posted January 28, 2010 http://www.northernsound.net Link to comment Share on other sites More sharing options...
Members MrJoshua Posted January 29, 2010 Author Members Share Posted January 29, 2010 Cheaper than Parts Express ... thanks! I appreciate the input, everyone. Link to comment Share on other sites More sharing options...
Members Dogoth Posted January 31, 2010 Members Share Posted January 31, 2010 When you go to rebuild it, do a couple of things before you just plunk a new diaghphram in there. Firstly (as has been stated) foreign matter can get into the gap and cause rubbing/wear problems. Take a piece of masking tape, fold it inside out (so it's all sticky on the outside and run it around inside the gap a couple of time. Then inspect closly with a flashlight. I do this as a matter of course, just in case I missed something. Other tape can work but masking seems to be the best as it's sticky enough yet won't leave any residual adhesive behind (a VERY bad thing). Sometimes the foreign material is ferrous metal slivers and can be difficult to remove from the magnet. MAKE SURE IT's CLEAN! Secondly check the gap for uniformity. It's rare but I have seen drivers that have been dropped and the center piece shifts making the gap narrower on one side than the other (the dia might just fit but it will wear out in no time and you'll just waste your money. As I said, it's rare but if this is the case, you pretty much have to replace the whole driver. Just a couple of extra tricks to know. At one time Peavey used to provide a piece of masking tape and instructions with their diaghphrams (now THAT'S CUSTOMER SERVICE :>) Link to comment Share on other sites More sharing options...
Members Unalaska Posted January 31, 2010 Members Share Posted January 31, 2010 One of the 22xt's was 6dB down at least because it had been dropped and the gap was pinching the voice coil. When I pulled the diaphram off it was pinched so badd it ripped the VC off. Both went to the trash... The 22xt may not be the best 1" driver but finding parts is really easy. I really like the fact peavey parts are so available and robust too. Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 31, 2010 Members Share Posted January 31, 2010 I use console tape, and rather than fold it over I do each side seperately. I then check very carefully. Just got some JBL's in the shop, both had the horn broken off from the drivers. One was an SRX-4700 series which I have never seen broken before. That's a FRC composite horn and is very strong. The cabinet must have taken a heck of a fall. Drivers and cabinet were ok surprisingly. The other was an MP-415 and that mount is moulded into the entire baffle. May not be economically repairable. Link to comment Share on other sites More sharing options...
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