Members duck995 Posted October 6, 2012 Members Share Posted October 6, 2012 I have 4 JBL PRX635's, and after about 1 1/2 years, two of them have failed. The problem is noticed by loss of higher frequencies (not necessarily highest, I just don't know what frequency range) and significant lower volume level. The first one failed after 8 months from new, the second one (now) after 15 months from new. JBL either fixed or replaced the power module in the first one. I just took the second one for repair today and suspect they will do the same. I love the speakers, but I am losing confidence bidding on jobs. Customers are not really happy when there is a failure. I always keep the levels down so that you rarely see the limiter indicator light. When used outside I have fans on the backs of the speakers. These speakers are only used 8-10 times per year. Does anyone know if there is something weak or poorly designed that causes them to fail? Is there anything a person can do to reduce the chances of failure? Does anyone know if this problem exists in others of the PRX600 line? Thanks! Scott 4 - PRX718s 4 - PRX635 2 - PRX615m 2 -PRX612m Link to comment Share on other sites More sharing options...
Members agedhorse Posted October 6, 2012 Members Share Posted October 6, 2012 I don't think this is common, certainly not your symptoms as I haven't seen one yet. What I would suggest is to have this looked at by a JBL authorized service shop, that way any issues will be repaired correctly. While they may have reolaced the power module, there may also be crossover components associated with the module that have nothing to do with the amp itself. It's also possible that the HF driver was overdriven and the bobbin slightly distorted binding on the pole piece. This was common in a couple of models of their smallest drivers. That's the FIRST place I would look actually. Link to comment Share on other sites More sharing options...
Members duck995 Posted October 7, 2012 Author Members Share Posted October 7, 2012 Thanks AH. Both speakers were handled through the local JBL Authorized service center. They told me that they sent in the amp module to JBL for repair on the first one and they are planning to do the same with this one. I wish that they had looked at some of the possibilities you mentioned. I have been reading on the internet and have found forums where people have discussed problems from heat, however those speakers simply stop working all together. I found a clever solution here:http://www.djmb.net/images/PRX6Fan/PRX6FAN.html Do you think something like this would be beneficial? Thanks - I read many of your posts here and I have learned a lot from you. Scott Link to comment Share on other sites More sharing options...
Members twostone Posted October 7, 2012 Members Share Posted October 7, 2012 Originally Posted by duck995 I found a clever solution here:http://www.djmb.net/images/PRX6Fan/PRX6FAN.html Easier and cheaper http://www.jr.com/lasko/pe/LKO_2004W/ Link to comment Share on other sites More sharing options...
Members agedhorse Posted October 7, 2012 Members Share Posted October 7, 2012 I don't think your problem is related to this at all. It's a cute solution, but most of the issues with any of the powered speakers generally involves direct sunlight on the back plate directly raising the temperature of the heat radiating surface. I've seen it in regular class AB powered speakers as well as class D. Fans are great until the fan stops working and then the speaker will shut down quickly as there is no convection cooling available. Generally if you can avoid the fan the better. I am seeing more and more bad fans in amps that come into the shop for service, sometimes causing catastrophic failures. Most of the PRX thermal "complaints" seem to involve DJ's, beating the speaker to within an inch of it's life, sometimes in the direct sub. Not saying that it's a great design but I think it's received more "press" than it's earned. Link to comment Share on other sites More sharing options...
Members djiceman1575 Posted October 7, 2012 Members Share Posted October 7, 2012 Let us know if you find out what it is. Unfortunately this marks off another point for the JBL's for me. Link to comment Share on other sites More sharing options...
Members Zeromus-X Posted October 7, 2012 Members Share Posted October 7, 2012 I'm using 635s now, after selling my 612s. I have not had any problems with my mains. I've had a problem with one of my 618S-XLFs, as discussed in great detail on this forum, but haven't had any issues since then. Ours have seen about 35 shows if I had to guess, including several corporate events and/or weddings. Link to comment Share on other sites More sharing options...
Members agedhorse Posted October 7, 2012 Members Share Posted October 7, 2012 Originally Posted by djiceman1575 Let us know if you find out what it is. Unfortunately this marks off another point for the JBL's for me. Why does it mark a point off? I can point to a thousand isolated failures due to maiuse or abuse for every product on the market. Without knowing a lot more about this, you have issues a "knee-jerk" reaction IMO. Of course you are entitled to your opoinion but without knowing a lot more about this topic it's just a wild ass reaction. Link to comment Share on other sites More sharing options...
Members ChiroVette Posted October 9, 2012 Members Share Posted October 9, 2012 Originally Posted by agedhorse most of the issues with any of the powered speakers generally involves direct sunlight on the back plate directly raising the temperature of the heat radiating surface. I've seen it in regular class AB powered speakers as well as class D. Fans are great until the fan stops working and then the speaker will shut down quickly as there is no convection cooling available. Generally if you can avoid the fan the better. I am seeing more and more bad fans in amps that come into the shop for service, sometimes causing catastrophic failures.Most of the PRX thermal "complaints" seem to involve DJ's, beating the speaker to within an inch of it's life, sometimes in the direct sub. Not saying that it's a great design but I think it's received more "press" than it's earned. Since I am seriously leaning toward this line of cabs, would this present a problem when playing outdoors in the summer? NY City and Long Island aren't the hottest places in the world, but the hot summer months can get into the nineties and even high nineties. Link to comment Share on other sites More sharing options...
Members BlueGreene Posted October 9, 2012 Members Share Posted October 9, 2012 Hopefully you will be using a rain structure outdoors and at what point, the amp modules would likely only get direct sunlight in the early morning or late evening. I've been a total jerk about having tents, but nobody is spending the coin on the gear but me, so I get to be the ass. Originally Posted by agedhorse Fans are great until the fan stops working and then the speaker will shut down quickly as there is no convection cooling available. Generally if you can avoid the fan the better. I am seeing more and more bad fans in amps that come into the shop for service, sometimes causing catastrophic failures. Is there a design advantage to using fans over a large heat sink? Cost? Most of the PRX thermal "complaints" seem to involve DJ's, beating the speaker to within an inch of it's life, sometimes in the direct sub. Not saying that it's a great design but I think it's received more "press" than it's earned. I assume you mean "in the direct sun" -- being just a key apart. Do any companies that you're aware of design their products to limit safely within the speakers' operational abilities? -- so people could ride the limit lights all night without the systems failing? Link to comment Share on other sites More sharing options...
Members twostone Posted October 9, 2012 Members Share Posted October 9, 2012 Originally Posted by ChiroVette Since I am seriously leaning toward this line of cabs, would this present a problem when playing outdoors in the summer? NY City and Long Island aren't the hottest places in the world, but the hot summer months can get into the nineties and even high nineties. Forgot who posted it but somebody posted about gaff taping some card board used to shade the heat sink fins but never tried it myself. So don't know if it works or not. Link to comment Share on other sites More sharing options...
Members agedhorse Posted October 9, 2012 Members Share Posted October 9, 2012 Originally Posted by BlueGreene Hopefully you will be using a rain structure outdoors and at what point, the amp modules would likely only get direct sunlight in the early morning or late evening. I've been a total jerk about having tents, but nobody is spending the coin on the gear but me, so I get to be the ass. And that's your choice... when it rains or is hot a shell, you can be sure that you are well prepared. Nobody is likely to do this for you without insisting. Originally Posted by BlueGreene Is there a design advantage to using fans over a large heat sink? Cost? It all has to do with power density and the amount of waste heat to get rid of. One of the most attractive things about class D is the ability to greatly reduce the amount of waste heat that has to be dissipated. With well thought out designs and not too high a component density it is entirely possible to do this without fans. When faced with a lot of waste heat (typical of class AB, G, H, or very high power density class D) usually the cost of using a fan is less than additional heatsink and at some point there is no way to do it without a fan. The product size would grow to non-marketable size. Since most of the products I design are of the high power density (high power, small size and weight) I have no choice but to use a fan and I am careful to choose the best and most reliable fan I can that still fits into the budget. Originally Posted by BlueGreene I assume you mean "in the direct sun" -- being just a key apart. Do any companies that you're aware of design their products to limit safely within the speakers' operational abilities? -- so people could ride the limit lights all night without the systems failing? Yes, that is a pretty bad typo. That's what I get for typing fast at FOH in the relative darkness The problem with designing a product like this is that the very people that are likely to do this are also the most cost sensitive customer. There are some sophisticated limiting systems (algorithems) out there that can analyze and integrate over time and when needed squash the shit out of the signal (down to about 1/2 the RMS rating) but it's kind of specialized and when using these kinds of algorithems they tend to limit the performance overall because the designers are often a bit gun-shy and prefer to leave a little "margin" on the table. Since they are all custom written for specific drivers and integrate both average signal as well as frequency specific context, they are costly to write and maintain. Link to comment Share on other sites More sharing options...
Members duck995 Posted November 28, 2012 Author Members Share Posted November 28, 2012 As mentioned in my first post to this thread in early October my 2nd PRX635 died. The authorized repair center sent it in to JBL for repair almost 8 weeks ago. I checked today and he said that the "factory is backed up with repairs" and it will probably be at least 2 more weeks before I get the speaker back. If I get it back by then it will have been out for 2 1/2 months. That is just not acceptable for repair turn-around. I noticed today that the street price on the PRX635 has dropped from $1099 to $919. With the exception of the subs in the 600 series all the 600 speakers are "on sale" with pretty steep price drops. Are they getting ready to discontinue the 600 series to introduce something new? After investing $13,000 on a PRX600 system I have not been especially happy with JBL. They sound better than anything else in the price range, but their reliability and JBL's ability to service customers is questionable. If there are so many speakers being returned for factory repair that they are backed up 2 months, how many speakers are they repairing!? If I had it to do over again, I do not think I would chose JBL. When I was researching what to buy I read numerous reviews that questioned if the Crown amplifiers were a good match with this speaker line. I do not claim to be an expert about any of this, but after having problems with two of the Crown amplifiers I have to wonder. Link to comment Share on other sites More sharing options...
Members OneEng Posted November 28, 2012 Members Share Posted November 28, 2012 I also did extensive research on powered speakers before I bought mine (PRX618S-XLF and DSR112). In all my forum searching and all of the personal contacts in bands locally that use them, I only heard of issues with the 635's. Shortly after I bought my XLF's Z posted his issue with his XLF (go figure), but if you scan the nets, this is rare in the extreme. I know of many people that use the XLF's and the 612m's and have never heard of any issues with them. My personal thought is that there was a design issue with the early 635's that JBL fixed. I also have heard several complaints lately of JBL taking in-excusable amounts of time to repair speakers. This is just hear-say, and AH would likely know more meaningful stats on the repair time for JBL. I am not sure why "crown" amps would not be a good match for JBL speakers. The amps that are in the speakers are not simply crown amps without a case, they are specifically designed for use within the speakers. Unless the design engineers at JBL are simply not any good, I can see no reason to think that the amps were not ideally matched to work with their speakers. Link to comment Share on other sites More sharing options...
Members ChiroVette Posted November 28, 2012 Members Share Posted November 28, 2012 Originally Posted by OneEng My personal thought is that there was a design issue with the early 635's that JBL fixed. This would be great. I am still kind of torn between the 612m's and the 635 for when I buy. I had originally made up my mind in favor of getting 4-5 612m's to use as tops over the 618xlf's and as monitors. I just love the sound of 12" speakers for vocal clarity and upper mid-range and personally feel they "match" better with the 18" subs than the 15's do. Also, if a top or monitor goes down, then I can match with the extras doing double-duty. But there is something VERY ATTRACTIVE (and a little more powerful with the extra horn and extra amp) about the 3-way configuration.So I am not sure whether to go with the 635's or 612's. Link to comment Share on other sites More sharing options...
Members Mutha Goose Posted November 28, 2012 Members Share Posted November 28, 2012 ChiroVette: FWIW Like you I labored over the 635 or 612 decision. In the end I went with the 612s (I have 4 of them). I did this for a few reasons:Weight Configurability (use 2 or 4 depending on application) Clarity etc. I am very happy with the performance. They pair wonderfully with the XLFs. The system is very well balanced and clear. Link to comment Share on other sites More sharing options...
Members Gaffle Posted November 28, 2012 Members Share Posted November 28, 2012 Originally Posted by duck995 ...After investing $13,000 on a PRX600 system I have not been especially happy with JBL. ...If I had it to do over again, I do not think I would chose JBL... $13k... WoW! Did you purchase all of them at one time or at different intervals? Link to comment Share on other sites More sharing options...
Members ChiroVette Posted November 28, 2012 Members Share Posted November 28, 2012 Mutha Goose, I hear you and am VERY GLAD that the choice worked out for you. I think that the fact that it is taking me a little longer than expected to save for my gear (I thought I would have it by now) is working in my favor, because it gives me the opportunity to learn a ton before investing. Things like this "635 Vs 612" for example are things I want to lay to rest before I buy. Another great advantage to the 612, as I said above, is that they can do double duty as tops and monitors if an emergency occurs and a cab goes down. Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 28, 2012 Members Share Posted November 28, 2012 I am far more concerned with their ability to turn repairs around. They sell tens of thousands of these products every year. With the pressure on price, it looks to me like service has taken a hit in their ability to match the labor to the workload. Link to comment Share on other sites More sharing options...
Members sbrett Posted November 28, 2012 Members Share Posted November 28, 2012 We ended up going with the 635s and couldn't be happier. No issues with them yet (after about a year). Our system is one 635 and one 618-XLF per side. As far as weight goes, ya the 635 is heavier than the 612, but it is still a relatively light cabinet. I don't think clarity is a deciding factor between the 635 and 612. They both sound great. 612s are probably better for most folks that will be using them for monitors and mains. We all use in-ears so that wasn't a big consideration for us. Link to comment Share on other sites More sharing options...
Members ChiroVette Posted November 28, 2012 Members Share Posted November 28, 2012 Thanks, scrett. Now I am even more confused. Originally Posted by agedhorse I am far more concerned with their ability to turn repairs around. They sell tens of thousands of these products every year. With the pressure on price, it looks to me like service has taken a hit in their ability to match the labor to the workload. This could be a huge potential problem and a possible selling point for the competing QSC lines, no?Don't get me wrong, I am a huge JBL fanboy. But I am also an adult. And if my fanboy allegiance to JBL causes me to invest upwards of $10K in gear that may or may not have issues and there seems to be some lag time in warranty repair turnaround, I am not sure what to make of that. Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 28, 2012 Members Share Posted November 28, 2012 Originally Posted by ChiroVette This could be a huge potential problem and a possible selling point for the competing QSC lines, no? Absolutely. Link to comment Share on other sites More sharing options...
Members ChiroVette Posted November 28, 2012 Members Share Posted November 28, 2012 Agedhorse, since there are a ton of differing opinions flying around the forum, and you are not only a world class soundman, but a highly specialized tech, I am going to ask you the million dollar question. You ready? Hypothetically, having your knowledge (factoring out passive gear since I am not experienced enough yet) what speakers would you buy if you were looking to get into a system around $10K? And bear in mind that is total budget to include snake, mixer, wires, and other miscellaneous stuff. Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 29, 2012 Members Share Posted November 29, 2012 How important is weight? QSC KW's are a good alterantive to the PRX IMO. Link to comment Share on other sites More sharing options...
Members OneEng Posted November 29, 2012 Members Share Posted November 29, 2012 Originally Posted by agedhorse How important is weight?QSC KW's are a good alterantive to the PRX IMO. Having heard both, I agree from a sound standpoint. I slightly prefer the sound of the XLF over the KW181; however, either would make a very good sounding system.The KW's are much heavier, and cost more.@ChiroVette,You should go listen to these speakers before you buy anything. I would also include the DSR112 tops in your search.I can't comment on Yamaha's warranty policy since I haven't had so much as a hiccup. I do know they have extended their warranty to 5 years (equal to the QSC).I also heard a pair of DXR15's the other day. These are some pretty good sounding speakers as well .... and MUCH more powerful on the bottom end than any 12's I have ever heard. They are priced at the same level as the DSR112's and PRX612m's.On a side note, I have high hopes that with all the Neo mines in the world re-opening to compete with the Chinese mines, we will be seeing the re-emergence of neo based speakers in about 5 years once the price comes back out of the stratosphere Link to comment Share on other sites More sharing options...
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