Hey Everyone. It's been a while 🙂
I have a pair of uni-q drivers who's midrange units seem a note apart. One is too high pitched, forward and lacks air. The other has an almost dark quality I find very appealing. I have heard dark as a description in reviews, and it sounds very good. The other... well quite cheap really. I can only weigh up the sound between them as I got them used, and have heard no others.
After every component on the crossover was swapped out. Cabling. Electronics. I pulled the units out and put them on the table with just a capacitor on a speaker wire I moved between them. Sure enough, about a note apart regardless of sine wave frequency fed to them, or white noise.. voices.. So I swapped them over to be sure it wasn't my table. Put stickers on and did the switcheroo so I could blind test. There is no small difference between them. It's a note. My phone registers this higher frequency unit a couple of db higher.
Sounds like little else to look at? So I sent both off to Kef to be sure of which one they thought sounded right, before I bought another. My first reply was they work. I think it was a 9v battery test. They then had more serious testing done and some artifact in the lower regions showed that was unlikely to ever be heard.
I'm now stumped. They seem to think I should buy more, but that these are fine. Is there anybody that can test these properly in the UK, that perhaps has such a uni-q themselves to give an authoritative view? I'm going to get them back and suspect an issue in the voicecoil area. I understand from the pics there is a chamber of damping material so perhaps it's in contact, or the coil just needs a little shellac. Might a gain in higher frequency noise come from such things?
I'm a bit lost. I got the kefs as my 50th present. eBay so typically broken. 3 months in, I'm yet to enjoy them. I think I need a second opinion.
I have a pair of uni-q drivers who's midrange units seem a note apart. One is too high pitched, forward and lacks air. The other has an almost dark quality I find very appealing. I have heard dark as a description in reviews, and it sounds very good. The other... well quite cheap really. I can only weigh up the sound between them as I got them used, and have heard no others.
After every component on the crossover was swapped out. Cabling. Electronics. I pulled the units out and put them on the table with just a capacitor on a speaker wire I moved between them. Sure enough, about a note apart regardless of sine wave frequency fed to them, or white noise.. voices.. So I swapped them over to be sure it wasn't my table. Put stickers on and did the switcheroo so I could blind test. There is no small difference between them. It's a note. My phone registers this higher frequency unit a couple of db higher.
Sounds like little else to look at? So I sent both off to Kef to be sure of which one they thought sounded right, before I bought another. My first reply was they work. I think it was a 9v battery test. They then had more serious testing done and some artifact in the lower regions showed that was unlikely to ever be heard.
I'm now stumped. They seem to think I should buy more, but that these are fine. Is there anybody that can test these properly in the UK, that perhaps has such a uni-q themselves to give an authoritative view? I'm going to get them back and suspect an issue in the voicecoil area. I understand from the pics there is a chamber of damping material so perhaps it's in contact, or the coil just needs a little shellac. Might a gain in higher frequency noise come from such things?
I'm a bit lost. I got the kefs as my 50th present. eBay so typically broken. 3 months in, I'm yet to enjoy them. I think I need a second opinion.
I guess quality control could be questioned. I weighed the wadding in each midrange enclosure. One had double the weight in it, and both seemed slightly different types. This is more critical than you might imagine, as the unit fills the enclosure so tightly, the screws tighten as the wadding gets compressed at the back. One was worryingly tight, hence I stopped and weighed them. Also, the terminal posts at the back present a spade connection for the internal wiring. The female was so loose on one that gravity would of let it fall off, had the cable not been supported. I had read here of people having them fixed, so thank you to whoever pointed me to this issue.
The uni-q has no pole piece, as the tweeter lives on a stalk that passes through the vc former to the back plate of the magnet assembly. It's where it passes through the vc it's just a plastic stalk. Here I believe it's thinned out to get damping in there. The advertising pics are drawings that don't offer much information, but the blurb about the later R series speaks of it.
I know after the first round of testing, they did more in response to my own efforts being quite methodical. This next line of testing has included things such as impedance curve I'm told. I will get a print out when they are returned. It's been a free service which is really quite nice of them, but what I really want, is them listening to. To find if a replacement will sound the same. To ears, not a computer.
The uni-q has no pole piece, as the tweeter lives on a stalk that passes through the vc former to the back plate of the magnet assembly. It's where it passes through the vc it's just a plastic stalk. Here I believe it's thinned out to get damping in there. The advertising pics are drawings that don't offer much information, but the blurb about the later R series speaks of it.
I know after the first round of testing, they did more in response to my own efforts being quite methodical. This next line of testing has included things such as impedance curve I'm told. I will get a print out when they are returned. It's been a free service which is really quite nice of them, but what I really want, is them listening to. To find if a replacement will sound the same. To ears, not a computer.
It is also about the passive parts of the filter if the crossover development was good enough.
Lythics caps have drift after few years and sometimes a good filter must be precise at 100 nF in the high pass and low pass caps...not noticable on a frequency plot but very herable.
Often theu use Solen first cheap range. If Solen cap have a lot of contrast between notes with a sort of good dynamic behavior between 2 notes, they are a little harsh for the high pass position...fatiguing.
Recaping is worthing it with full new film caps everywhere and eventually new resisptor is too worthing it...halas as the lythics as drifted you must refind the precise values that are never the ones marked on body caps.
People spend crazy money on expensive dacs but still have lythics in their loodspeakers with low resolution caps than simplify or at least has a veil or simply do not make justice to the drivers.
At least my own experience and my two cents
Lythics caps have drift after few years and sometimes a good filter must be precise at 100 nF in the high pass and low pass caps...not noticable on a frequency plot but very herable.
Often theu use Solen first cheap range. If Solen cap have a lot of contrast between notes with a sort of good dynamic behavior between 2 notes, they are a little harsh for the high pass position...fatiguing.
Recaping is worthing it with full new film caps everywhere and eventually new resisptor is too worthing it...halas as the lythics as drifted you must refind the precise values that are never the ones marked on body caps.
People spend crazy money on expensive dacs but still have lythics in their loodspeakers with low resolution caps than simplify or at least has a veil or simply do not make justice to the drivers.
At least my own experience and my two cents
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I might re-cap at some point, but for now I just need them to work. The drivers don't match, without any crossover at all to mess with my findings. Just sat on the table.
You are in UK, you might try to call Kef directly as an advice you received from Diyaudio community ? 😉
No. If there is such a differznce and the speakers not used for a party there is a serious quality controll and so something upon the comon guaranty. At least in europeans laws. A serious company like Kef should listen that. Up to you to describe your problem with the rigth words.
They have been at Kef for 6 weeks.
I need a second opinion. A fresh opinion. Not directed by me.
I feel one is the best I have personally heard. The other is a £100 bookshelf I don't want. I'm not hearing some tiny difference, I'm hearing a totally different speaker. So different the problem must be extreme. They say they test alright, like new.
I'm in Nottingham. If anyone locally owns some R - series and could listen, I will get Kef to send them over to them, not return them to me. I'm not just trusting them to 'anyone' though. I would rather pay someone, but finding such a person is near impossible.
Kef have said they test like new, and said they can offer me a good price on replacements. However, why replace them with something the same, if it's true they are fine. I need to hear agreement that one is wrong, and a description of how bad it sounds that's in line with my findings. Or I'm just wasting money. The agreement of friends is all well and good, but a solid identification of the issue is what I really need, before spending £270 on some speakers that cost me £800. I should just sell them with Kefs certification, and spend longer auditioning some more.
One really does sound good. I want that sound from two of them. Friends hear the difference, but have the attention span of children, so think both sound alright (but not as good as an mp3 on their phone.. you know?)
I might have to see if the headphone jack on my phone can drive them with a tone. Make a change-over lead and visit some hifi shops with them.
I need a second opinion. A fresh opinion. Not directed by me.
I feel one is the best I have personally heard. The other is a £100 bookshelf I don't want. I'm not hearing some tiny difference, I'm hearing a totally different speaker. So different the problem must be extreme. They say they test alright, like new.
I'm in Nottingham. If anyone locally owns some R - series and could listen, I will get Kef to send them over to them, not return them to me. I'm not just trusting them to 'anyone' though. I would rather pay someone, but finding such a person is near impossible.
Kef have said they test like new, and said they can offer me a good price on replacements. However, why replace them with something the same, if it's true they are fine. I need to hear agreement that one is wrong, and a description of how bad it sounds that's in line with my findings. Or I'm just wasting money. The agreement of friends is all well and good, but a solid identification of the issue is what I really need, before spending £270 on some speakers that cost me £800. I should just sell them with Kefs certification, and spend longer auditioning some more.
One really does sound good. I want that sound from two of them. Friends hear the difference, but have the attention span of children, so think both sound alright (but not as good as an mp3 on their phone.. you know?)
I might have to see if the headphone jack on my phone can drive them with a tone. Make a change-over lead and visit some hifi shops with them.
What about a picking up a microphone like a UMIK-1 and performing your own measurements with REW? If I was going to tear the driver apart I'd want more than just my ears to assess the impact of any physical changes made to the driver.
Otherwise I'd seek out an independent speaker repair shop if you don't want to invest in measurement equipment.
Otherwise I'd seek out an independent speaker repair shop if you don't want to invest in measurement equipment.
I think you just nudged my brain along. Wilmslow Audio moved up to Leicester some years ago. I have good history with them as a parts supplier. 40 miles.. an hour each way, and £80 on diesel by next week 🙂
Testing to a good standard has been done really. I need them listening to. That's what matters. Perhaps then some testing can better pinpoint the issue, but I just need some agreement on which one is shot, before I go buying more of them.
Testing to a good standard has been done really. I need them listening to. That's what matters. Perhaps then some testing can better pinpoint the issue, but I just need some agreement on which one is shot, before I go buying more of them.
I thought I better update this, as it's not going any further.
Kef did a third round of testing. This time finding a fault in the lower mid, I probably wouldn't here. Again, I said that can't be it, just listen to them
Kef had tested someone else's speakers.
4th round of testing, yes I'm right, there is a faulty tweeter. Really sorry. We are usually better than this. Have two on the house.
I declined. Interesting as this was, they were in for the midrange to be tested. The chart provided, were a tweeter. They tried to blame me this time, so I told them to check any mail or call made, and actually listen to me telling them to put a tone through the midrange.
This time things looked better. Two new uni-q units were sent out. From different batches, that didn't sound or look the same. They were all 'we test them' but I have seen their idea of testing, so simply asked if there was one from the better batch available to buy. There was.
I call up, order the one I need, and as I need a new bass unit, order two due to the aging issues often reported. A bronzing due to poor processing. I was very clear, asking for two from the same box. I went over it 3 times. That I was buying a uni-q because one was sent from the wrong box, I wanted to buy two from the same box. Nope. One nicely packed, and one from a different batch that didn't have the original packaging. There is no way they had just fetched it, tested it, and put it back in it's box. If one had the right packaging, and one had different types, actually taped together to make them bin enough.
Kef were an absolute joke. Andy the managers is nearing 30 years service, but we might have 15 years left of him still. Their factory reconditioned stuff that comes up quite often, should be considered after second hand ones.
Wilmslow Audio were happy to help with my request for independent testing. With 5 uni-q units here, I managed to pair up two new one's though. While another new one pairs with one of my old units. While one is just rubbish. Though tests fine except for a 2nd harmonic wobble in the tweeter about 2khz. I have fitted both bass. One to each cab, as they are less faded than the originals. I just hope they age together.
I stripped the bad uni-q driver, but couldn't see any problems. I think it's likely the spider isn't so stiff, after somebody has sat on it. Causing excursion beyond reason. That's just a guess though. There was also stuffing in the magnet. Right at the back/bottom of the gap. Not inside the former, but into the magnet/backplate area. It goes in then an interference fit part that seals it away from service. It did seem the entire chamber wasn't full, and that this fluff may of been compacted back a bit. Making a cavity where you don't want one.
I put it back together. Wondering if the magnet itself could be poor. There are spares available there in that uni-q, but I don't know what
Kef did a third round of testing. This time finding a fault in the lower mid, I probably wouldn't here. Again, I said that can't be it, just listen to them
Kef had tested someone else's speakers.
4th round of testing, yes I'm right, there is a faulty tweeter. Really sorry. We are usually better than this. Have two on the house.
I declined. Interesting as this was, they were in for the midrange to be tested. The chart provided, were a tweeter. They tried to blame me this time, so I told them to check any mail or call made, and actually listen to me telling them to put a tone through the midrange.
This time things looked better. Two new uni-q units were sent out. From different batches, that didn't sound or look the same. They were all 'we test them' but I have seen their idea of testing, so simply asked if there was one from the better batch available to buy. There was.
I call up, order the one I need, and as I need a new bass unit, order two due to the aging issues often reported. A bronzing due to poor processing. I was very clear, asking for two from the same box. I went over it 3 times. That I was buying a uni-q because one was sent from the wrong box, I wanted to buy two from the same box. Nope. One nicely packed, and one from a different batch that didn't have the original packaging. There is no way they had just fetched it, tested it, and put it back in it's box. If one had the right packaging, and one had different types, actually taped together to make them bin enough.
Kef were an absolute joke. Andy the managers is nearing 30 years service, but we might have 15 years left of him still. Their factory reconditioned stuff that comes up quite often, should be considered after second hand ones.
Wilmslow Audio were happy to help with my request for independent testing. With 5 uni-q units here, I managed to pair up two new one's though. While another new one pairs with one of my old units. While one is just rubbish. Though tests fine except for a 2nd harmonic wobble in the tweeter about 2khz. I have fitted both bass. One to each cab, as they are less faded than the originals. I just hope they age together.
I stripped the bad uni-q driver, but couldn't see any problems. I think it's likely the spider isn't so stiff, after somebody has sat on it. Causing excursion beyond reason. That's just a guess though. There was also stuffing in the magnet. Right at the back/bottom of the gap. Not inside the former, but into the magnet/backplate area. It goes in then an interference fit part that seals it away from service. It did seem the entire chamber wasn't full, and that this fluff may of been compacted back a bit. Making a cavity where you don't want one.
I put it back together. Wondering if the magnet itself could be poor. There are spares available there in that uni-q, but I don't know what
As a KEF owner I am encouraged by the available parts, support and service provided for a no longer manufactured middle of the range speaker. Not sure I wholly understand the origin of your dissatisfaction. Given the speakers were second hand and you have stripped them as may the previous owner/s if they were faulty the origin of faults is likely to be uncertain.
I do not understand your description of the fault. If you send the same sine wave to two different drivers they will play the same frequency/note. One may be louder than the other and one may distort more than the other but the frequency/note will be the same. Perhaps it is to do with terminology.
Measuring the drivers is the most reliable way to determine faults and examine things like differences due to tolerances. Listening is nowhere near as useful a diagnostic tool but is obviously a useful and important check. It is good that this has now been done and your issue resolved? It is also good to see Wilmslow Audio providing satisfactory service since they went through a poor patch a few years ago prior to changing hands as can be seen by browsing some of the threads on this forum from a few years back.
The serial numbers on the drivers is likely to be a more reliable way to identify batches rather than the packaging. My replacement pair of coaxials differ by 5 in the last digit and seem fine. Given the drivers ceased to be manufactured a few years ago they are likely to have been on shelves and possibly used for one or two things over the years.
I do not understand your description of the fault. If you send the same sine wave to two different drivers they will play the same frequency/note. One may be louder than the other and one may distort more than the other but the frequency/note will be the same. Perhaps it is to do with terminology.
Measuring the drivers is the most reliable way to determine faults and examine things like differences due to tolerances. Listening is nowhere near as useful a diagnostic tool but is obviously a useful and important check. It is good that this has now been done and your issue resolved? It is also good to see Wilmslow Audio providing satisfactory service since they went through a poor patch a few years ago prior to changing hands as can be seen by browsing some of the threads on this forum from a few years back.
The serial numbers on the drivers is likely to be a more reliable way to identify batches rather than the packaging. My replacement pair of coaxials differ by 5 in the last digit and seem fine. Given the drivers ceased to be manufactured a few years ago they are likely to have been on shelves and possibly used for one or two things over the years.