silvermetal Posted March 27, 2013 Share Posted March 27, 2013 I was just given a set of KEF Q50s for free because they are somewhat broken. They are not producing mid to high frequencies. The volume is also slightly decreased. This problem is happening identically in both speakers. I have tried them on a couple different amps and they still have the same problem. At first I was thinking that the tweeters could be blown, but wouldn't I hear some sort of crackle like it was trying to produce noise? I was also thinking that blown tweeters wouldn't decrease the overall volume, so I have somewhat ruled out blown tweeters as the cause. Now I am assuming it is probably a crossover problem. Would the crossover from a q30 speaker work for a q50 speaker. The reason I am asking if the q30 crossover would work is because I cannot find any q50 crossovers but there are some q30 crossovers available which look very similar. Here is a back to back comparison of the specs for both speakers. The only difference I could see is the q50 frequency response is down to 45hz compared to the q30 which is at 50hz. I am not to sure what individual jobs the crossover over performs which is why I am asking for help. Specification: Q30 System type: Two-way, floor standingEnclosure type: ReflexDimensions (H x W x D): 700 x 190 x 301mm (27.5 x 7.5 x 11.85 inches)Weight: 9.3kg (20.5 lbs)Nominal impedance: 6 ohmsAmplifier requirements: 10-125WFrequency response: 50Hz to 20kHz +/-3.0dBSensitivity: 88dB at 1m for 2.83VFinish: Grey, Black Ash or MahoganySystem: SP3175Drive units: B160 bass/midrange unit (SP1322), NT19 tweeter (SP1352)Crossover network: SP2208System: SP3229Drive units: B160 bass/midrange unit (SP1322), NT19 tweeter (SP1352)Crossover network: SP2239Specification: Q50 System type: 2½-way, floor standingEnclosure type: ReflexDimensions (H x W x D): 800 x 190 x 301mm (31.5 x 7.5 x 11.85 inches)Weight: 11kg (24.3 lbs)Nominal impedance: 6 ohmsAmplifier requirements: 10-125WFrequency response: 45Hz to 20kHz +/-3.0dBSensitivity: 89dB at 1m for 2.83VFinish: Grey, Black Ash or MahoganySystem: SP3174Drive units: B160 bass unit (SP1334), B160 bass/midrange unit (SP1335), NT19 tweeter (SP1352)Crossover network: SP2207System: SP3265 (Q50S – 1996)Drive units: B160 bass unit (SP1334), B160 bass/midrange unit (SP1393), NT19 tweeter (SP1367)Crossover network: SP2272 If anyone could please help me out I would greatly appreciate it. Quote Link to comment Share on other sites More sharing options...
slinch Posted March 27, 2013 Share Posted March 27, 2013 A crossover is a filter that splits the signal from your amp and sends only specific frequency band to each driver. Since Q30 has two drivers, meaning only one crossover cut, and Q50 has three drivers - two crossover cuts - it's really not easily "interchangable". So the sound will come out, but it will be far from optimal if you use Q30's crossovers. You also have to know how to connect the extra driver without creating a heavier load for your amp. But honestly I just don't see a scenario where the crossovers would be at fault (short of them missing a piece or two, or disconnected wires), and a blown driver can just as easily produce zero sound. It can however seriously damage your amp, so it's not something worth tinkering with. If you don't have the knowledge to find the problem with measuring equipment, you're way better off taking them to someone who does, because so many things can go wrong this point forward. Quote Link to comment Share on other sites More sharing options...
silvermetal Posted March 27, 2013 Author Share Posted March 27, 2013 Okay thanks for all the input. I did not notice that that q30 only had the two drivers. I thought it was like the q50 but smaller. What do you think is a fair price for stereo repair labor an hour? I spoke with a man at one shop and he said they charge $85 up front for an estimate and if they can fix it that is applied to the first hour. This sounded a little steep to me. Especially if they find out that the speakers cannot be fixed. Then I am just out the $85 completely. With your experiences what have you found is a fair price for speaker repair? I am not opposed to paying an upfront fee, but I don't feel like $85 is fair. Edit* I would really like to get these fixed if possible because I heard they are pretty solid little speakers when working properly. I got them for free so I would be willing to spend some money on getting them fixed. What do you think a good amount would be to spend without wasting money would be? Basically what would you say the speakers are actually worth today? Quote Link to comment Share on other sites More sharing options...
slinch Posted March 27, 2013 Share Posted March 27, 2013 Honestly, I think $85 just to get an opinion is extortionate. It's 30 minutes of work at most to figure out exactly what's wrong with it. And not a really tough job as well. I cannot really say what these would be worth, as I haven't come across them, but judging by the age and the class their successors are in I'd say around $150. Now paying $85 in total to get them working would be a fine deal, but paying this much up front without knowing what's wrong is not really worth it. If the tweeters are blown, you're looking at $50 in materials easily, if it's a problem with the crossovers, you can potentially sqeeze through with $10. But first you have to find someone who will take a look at them for free or maybe something like $20, and doesn't charge $50 or more an hour. Quote Link to comment Share on other sites More sharing options...
ajxd Posted March 27, 2013 Share Posted March 27, 2013 As someone who used to work in audio repair... I never charged for estimates/diagnosis. I agree with Slinch, may not be worth it. Those are older speakers... from the early 90s I think... Quote Link to comment Share on other sites More sharing options...
silvermetal Posted March 27, 2013 Author Share Posted March 27, 2013 Thanks for the response. I took them to a guy that repairs speakers out of his home. He helped me test the tweeters by running a frequency while bypassing the crossover. Turns out both tweeters are blown. Even more bad news is that these tweeters are special because they sit in the middle of the mid and are apparently around $80 a piece. So I would have been looking at $160 plus labor to have them installed. That would have not been worth it considering I got the speakers for free. I ended up taking them to a stereo repair shop that sells refurbished equipment and traded them in for $40 store credit or labor. Quote Link to comment Share on other sites More sharing options...
slinch Posted March 28, 2013 Share Posted March 28, 2013 Probably the best thing you could have done with them in this case. Quote Link to comment Share on other sites More sharing options...
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