KEF KC62 Subwoofer Owners Thread

PascalF

Standard Member
No, I haven’t heard back either. But I have an update: Unexpected Standby doesn’t happen in MANUAL mode! I left my two in this input mode for 3-4 days, and they didn’t drop to standby once. Then, back to LFE mode, and voila, Standby, from which they can only be woken with a strong 30Hz tone (from REW). I notice from measurement that MANUAL gives more dB’s, so I am currently experimenting with a signal voltage of 1.1V in LFE mode (1V wasn’t enough).
I’m getting close to sending these back, and I do wonder if the KF92 has similar design faults.

just a silly thought: would these issues disappear when using kef’s wireless module?
 

JohnnyZeroSix

Standard Member
It’s not a certainty, but I should imagine that relative signal level still applies to the wireless module. I think that the reason that KC62 forums are not snowed under with complaints from people using it with AV amps, is that those are designed for true LFE signals of over 1V (up to 4V on peaks). In this sense we cannot blame KEF for designing trigger levels around that fact (perhaps a little more tolerance wouldn’t have gone amiss!). Fortunately I can increase the voltage from my 2-channel preout, which defaults to a mere 0.5V otherwise.

I’m still irked by the mild hum from LFE in a quiet room, which does seem a little more audible when it’s right next to mains wiring! Hum is not exactly uncommon in the subwoofer world, though.
 

PascalF

Standard Member
FYI - i have chased my local KEF dealer who had a chat with sales: they were not aware of the issues (they are now) and will pass these on to engineering. Will check again with them by next week on the status of the issues.
 

JohnnyZeroSix

Standard Member
'Standby' for Update...
I have been having positive results with a 1.3V output setting from my pre-amp. No Standby's for 2 days. Now, my Devialet amp declares that setting to be a maximum voltage... so I'm guessing I could safely go up to 2V to ensure the KC62's continued "attention". (When did subwoofers start acting like teenagers?).
My sympathies go out to those unable to adjust sub output level; they will have to stick with MANUAL input mode for a stress-free experience.
Personally, I have found that an LFE 3rd-order slope (rather than the KEF's internal 4th-order) integrates best with the low-end acoustical roll-off of my speakers.
 

Govnah

Standard Member
Loud pop from KEF KC62 from line-out to amp w/ LS50 Metas attached.....

KEF KC62 Line-Out issue or something else?

My setup consists of the following:

ADI-2 DAC RCA ----> KEF KC62 SW (RCA Input and LPF 80) ----> KEF KC62 (RCA Output and HPF 80) ----> Parasound A21 (Auto Sensing Enabled) ---- > KEF LS50 Meta

KEF KC62 volume @ 1000 O'Clock, Mode Manual, and Ground Lift Off.

The problem occurs when I stop the audio signal, the LS50 Metas will pop, ~10 minutes after the audio signal is stopped.

I have swapped all RCAs, power-cords, speaker cables, and moved the KC62 to another room/setup (different preamp, amp, and speakers) and same issue....

Thanks
 

JohnnyZeroSix

Standard Member
My two did this when chain-linked in series, and it always frightened the life out of me. Unfortunately it’s unavoidable with some combinations of electronics. Only option is to pursue the avoidance of Standby. To be clear, the sub propagates this noise to its outputs when falling into Standby.
 

Govnah

Standard Member
Thanks for the reply...

To avoid standby on the KC62 I assume I would have to power-cycle the SW on and off either by the switch on the SW or use some type of smart plug and enable/disable power to the SW?????

Any other suggestions?
 

PascalF

Standard Member
How about Kef getting this fixed? Please report this to the shop where you bought it and ask what Kef engineering is planning to do about this.
I've done the same with previous issues everyone encountered and i am expecting a response next week. Of course i am realistic and every product has it;s issues - but i do expect the vendor to clarify whether this is a design fault and whether this can/will be fixed.
 

Govnah

Standard Member
How about Kef getting this fixed? Please report this to the shop where you bought it and ask what Kef engineering is planning to do about this.
I've done the same with previous issues everyone encountered and i am expecting a response next week. Of course i am realistic and every product has it;s issues - but i do expect the vendor to clarify whether this is a design fault and whether this can/will be fixed.

I do have a request into KEF and engaging w/ Fred. Not to impressed with their support. Fred is in the process of engaging their engineers and I am waiting on a reply or replacement.

I will update this tread for others that may have a similar issue.
 

PascalF

Standard Member
I do have a request into KEF and engaging w/ Fred. Not to impressed with their support. Fred is in the process of engaging their engineers and I am waiting on a reply or replacement.

I will update this tread for others that may have a similar issue.
Super - i'll do the same. Let's see what they come up with. Do you think they will come up with revised electronics?
 

Govnah

Standard Member
That's a good question and don't know what they will do. I replaced my previous sub and LS50s w/ the KC62 and Metas, the DAC and preamp are the same and didn't have this issue. I really hope they are able to address the issue, possibly maybe just a bad KC62...

To add some clarity to my setup, see p.13 of the KC62 manual.
 

PascalF

Standard Member
That's a good question and don't know what they will do. I replaced my previous sub and LS50s w/ the KC62 and Metas, the DAC and preamp are the same and didn't have this issue. I really hope they are able to address the issue, possibly maybe just a bad KC62...

To add some clarity to my setup, see p.13 of the KC62 manual.
If i am reading this right johnnyzerosix seems to have the same problem?
 

Govnah

Standard Member
No, different issue, but I wouldn't be surprised I would be experiencing the same issue over LFE.
 
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JohnnyZeroSix

Standard Member
I got a frightening whump into my second KC62 when the first one (in the chain) dropped into Standby. Again, that’s not unusual with some equipment. I have now unlinked them so I’m not using the outputs of either sub. This is of course a separate annoying issue from the over-enthusiastic Standby problem.
 

Govnah

Standard Member
So question, the "whump" I am experiencing from the line-outs on KC62 to the Metas, is that something to be concerned with i.e., damage to the speakers/Metas?
 

PascalF

Standard Member
All,

I have received an answer from Kef - see below. The email address i used was [email protected]

Thank you for contacting us. Our offices were closed from April 2nd to April 5th, and we apologise for the inconvenience the delay in our response may have caused. We also apologise if your previous email has not been replied to. We will look into this to understand what caused the delay.

With regard to the below queries, we can provide a general response, but each case would need to be examined individually. If you do own a KC62 subwoofer or know someone who does, that presents the issues described in your message, please send us a short video of the issue it is presenting and of how it is connected to the other equipment (speakers, amplifier etc.), so that we can further look into the possible cause(/s).


  1. The lowpass filter in manual mode helps to supress any high frequency noise fed into the subwoofer input from connected equipment. This filter is disabled in LFE mode. The level of noise can be minimised by making sure there is a healthy signal level fed into the subwoofer, for example by dropping the volume on the subwoofer and increasing the volume on the connected source device, such as an AV receiver. Please note, however, that our engineers are currently looking into this to provide improvements on future products.
  2. Please note that the KC62 Subwoofer will start. However, the subwoofer may not immediately come out of standby if the low frequency signal level is very low. In this instance, it would be beneficial for us to have further evidence of the issue, such as a short video of the issue (i.e. the TV turning on, but without waking up the KC62) and the way the equipment is set up and set, so that we can further investigate the problem.
  3. We have investigated this issue further and can confirm that the labelled frequency points are correct. The Frequency, however, will change gradually step by step and there may be a very slight delay between changing the frequency and this being registered by the DSP. However, if this is not the case, we are happy to receive a supporting video that shows the behaviour of the KC62, so that we can investigate this further.
  4. When the KC62 subwoofer is powered on, an orange LED will light up. Once it receives audio input, the LED will turn white. The start-up time may take a bit longer, as the set will need to fully check the whole system, ensure it is all working properly and check for an audio signal. After this process, it will start up. The start-up will assume there is a two-channel input. If they sense it is single channel (after 2-3 seconds), then +6dB will add in. That is why you may have a feeling of a two-step process in the bass. If your input is two-channel in, then the powerful bass will start right away.
  5. This issue has been identified in our early production models and has since been fixed. Any affected users will indeed have to invert the polarity of the 2nd subwoofer to correct this.

We hope this information helps but, as stated previously, this is a general response. We encourage anyone having issues with their products to contact us directly, so that we can investigate the specific cases individually.

Kind regards,
KEF
 

JohnnyZeroSix

Standard Member
Quite a decent response, confirming some of my suspicions about 2-channel connection and irrational response to frequency setting, and even acknowledging my output inversion finding! I like that they admit to the latter, rather than secretly fixing it, but of course I now suffer from early adoption. People who plug active speakers into those outputs will really have to watch out for that and not assume 0' phase when placed right next to their speakers..
 

PascalF

Standard Member
Quite a decent response, confirming some of my suspicions about 2-channel connection and irrational response to frequency setting, and even acknowledging my output inversion finding! I like that they admit to the latter, rather than secretly fixing it, but of course I now suffer from early adoption. People who plug active speakers into those outputs will really have to watch out for that and not assume 0' phase when placed right next to their speakers..
Yes - i really happy with this response - very mature and this is also imho in line with their customers expectations.
As a result of their response i have decided to order the KC62 (of course i will ask for the newer production run).
 

PatSurf70

Novice Member
Seems they have adjusted the KEF App.

Overview of new setting:
Subwoofer out:
  • How many subwoofers are you using: None-One-Two
  • Subwoofer channel: Mono - Stereo
  • Subwoofer Model: Custom-KC62-KF92-All other KEF Subwoofers...
  • High-pass freq (70 with KC62)
  • Low-pass freq (45 with KC62)
  • Subgain
  • Are you using a KW-1: Yes-No

After selecting the subwoofer model you get a popup to put the subwoofer volume to 3 o;clock (75% volume - 15:15) and connect via LFE.

Good to know i tested 3 weeks with all possible setting due to the standby issue i has with my LS50W mkII and KC62. Had one KC62 connected to the left speaker (not the primary one) and i could not get the KC62 out of standby with settings below gain 3 o'clock combined with volumes below 38. Only 3 o'clock will not fix the standby issue with LS50W2.
What helped was to max both high and low pass and when you saw the KC62 turn active i slided back to 70-40. But after some time it went in standby again.

Sent the KC62 back and ill wait till hardware is fixed in next version.

Could it also be a LS50W2 issue? To less signal to Subwoofer?
 

PascalF

Standard Member
Seems they have adjusted the KEF App.

Overview of new setting:
Subwoofer out:
  • How many subwoofers are you using: None-One-Two
  • Subwoofer channel: Mono - Stereo
  • Subwoofer Model: Custom-KC62-KF92-All other KEF Subwoofers...
  • High-pass freq (70 with KC62)
  • Low-pass freq (45 with KC62)
  • Subgain
  • Are you using a KW-1: Yes-No

After selecting the subwoofer model you get a popup to put the subwoofer volume to 3 o;clock (75% volume - 15:15) and connect via LFE.

Good to know i tested 3 weeks with all possible setting due to the standby issue i has with my LS50W mkII and KC62. Had one KC62 connected to the left speaker (not the primary one) and i could not get the KC62 out of standby with settings below gain 3 o'clock combined with volumes below 38. Only 3 o'clock will not fix the standby issue with LS50W2.
What helped was to max both high and low pass and when you saw the KC62 turn active i slided back to 70-40. But after some time it went in standby again.

Sent the KC62 back and ill wait till hardware is fixed in next version.

Could it also be a LS50W2 issue? To less signal to Subwoofer?
What would be interesting to know is whether you have a model from the first production run (with the inverted polarity) or a later production batch.

I'm about to pull the trigger on the kc62 (i also have LS50w2's) but if these issue exists i rather wait. Also rather strange that you cannot adjust low-pass freq afterwards without running into standby issues again....

Would you be so kind to check with Kef - using your kc62 serial - to get this confirmed and ask whether later serials numbers have this issue fixed (and If so, from which starting serial number)?

Edit: i've just send a message to Kef customer support about this.
Edit2: i really want to start ordering the subs, but these issues keep holding me off...i really hope Kef hurries up as i don't want to deal with these issue in a few years from now.
Edit3: these issue are getting really frustrating....
 
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Govnah

Standard Member
Still no resolution on my issue, here is the latest reply from KEF:

The engineering team will be investigating the KC62 to make sure it is not sending a signal out after going into standby. If for some reason this is happening in the KC62 you could experience the noise you have described. That would also mean it would happen in a new unit.

Before we move forward with getting you a replacement unit let's wait for confirmation from engineering.

Thank you,


If this is by design I will be requesting a refund...
 

PascalF

Standard Member
Still no resolution on my issue, here is the latest reply from KEF:

The engineering team will be investigating the KC62 to make sure it is not sending a signal out after going into standby. If for some reason this is happening in the KC62 you could experience the noise you have described. That would also mean it would happen in a new unit.

Before we move forward with getting you a replacement unit let's wait for confirmation from engineering.

Thank you,


If this is by design I will be requesting a refund...
My guess is that these are production issues and that the kc62 has been rushed to the market a bit too fast (also see the polarity issue).

What i suggest is that we open a sepate topic containing a table with all known kc62 issues and fixes (and from which serial number this has been fixed) in order to keep track of things...

Personally i can’t wait until this has all been fixed - really want a kc62...
 
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Conrad.

Moderator
Google Docs is probably your best bet.
 

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