Unexpected disappointing performance of KEF Q300 :(

[john_k_antony]

John, you are right. in fact i see no issues with using a 150w amp with your speakers. WRT to overexurcison, you can hear it as well as see it. In most cases. as you raise the volume you will hear the sound hardening and compressing before you overdrive the woofer ( and there is a sound technical reason why that happens). you need to watch out for that.


WRT to crossover see my previous post.

80dB is not loud. but if you want 80dB of 20hz bass from the bookshelf - it is waaaay too loud. you are asking a bit much from your speakers.
1. you want them clear,
2. you want them small,
3. you want them cheap (WRT to the average spend of a hifi fan)
4. and you want deep bass.

if that were all possible in 1 speaker, then forum members are less than wise to buy their multi lakh speakers, right?

. pls do not blame the speakers.

Kapvin,

80db was for the total sound out put, not just the bass frequency. I think for bass frequencies < 80Hz, it would be 50db or so at my volume level. I measured bass SPL by just running my Sub and measured the SPL at the same listening position setting the cross over in the AVR to 100Hz. So my Sub was doing everything below 100Hz. The AVR was playing at the same volume level of 73.

I never wanted deep bass from Q300 and I know that it can't create deep bass. This was proved to me in the audition. I got Q300 for its mid range clarity and I know that it will work well for me in the dialog parts and with Indian movies with lots of music in it. And I must say that Q300 ROCKS as a center channel for dialog clarity. I just wanted them to do anything above 80Hz. I have my Sub to do everything below 80Hz.

I used Pure Direct mode as I felt Denon sounded pretty bad in the normal mode where it does DSP. Pire Direct was sounding pretty balanced for me.

Thanks,
John.

 

[john_k_antony]

Update - 12-Oct-2013

Today ProFx service engineer visited my home and replaced both the faulty drivers FREE OF COST . I was very honest with what has happened and they didn't ask any questions. They replaced Uni-Q driver for both the L and R channel speakers. After doing that the service engineer did the following settings

1. Did a factory reset on Denon and erased all the Audyssey settings.

2. Set the cross over frequency to 120Hz and marked all the speakers are "Large". However, I later changed the cross over frequency to 100Hz and marked all the speakers to "Small". I made sure that with this setting and speakers are not excurting crazy. They are all excurting normally with the same volume level that produced 85db SPL (overall) at my listening position. Tested with various inputs and everything looks fine.

3. Set the channel level for all channels to 0db and I tested the SLP at the listening position using my SLP meter with the test tone. 0db channel level is creating a very balanced sound stage.

Here are the picture of the replacement drivers ProFx got.

Finally, I would really like to appreciate the EXCELLENT service back up from ProFx. I am so impressed. Very professional service. They really boosted my confidence that they will listen to my problems and help me in case of any issue.

Thanks for all your support.

Thanks,
John.

 

[john_k_antony]

RESOLVED : Unexpected disappointing performance of KEF Q300

Mods,

I wouldn't mind changing the thread title to "RESOLVED : Unexpected disappointing performance of KEF Q300 "

Thanks,
John.

 

[elangoas]

Congrats John... Glad to know that Pro FX replaced free of cost, and i believe that you were lucky....

Great job by Pro FX.:thumbsup: to keep an enthusiast happy...

 

[ketansethi1987]

I also have the same question regarding X-over. A good speaker with proper X-over design should be rolling off frequencies that are not capable of reproducing by the drivers. I assume that is the basics of the X-over design in any "well-designed" speakers. I am really surprised that KEF Q300's X-over failed here. I am not sure if the X-over was faulty in the first place, as in manufacturing defect.

Thanks,
John.

I also believe the xover is at fault. It should not have allowed the speakers to vibrate so vigorously. I am using small 3 inch satellite speakers with 10 inch subs having a locally made crossover in between to control the frequencies and the satellites never show any over excursion or distortion which they do when they are directly connected to the amp...and I am connecting the satellites to the mid range out and not using the highest frequency range as my amp is a bright one.

BUT it might also be possible that the amp is not powerful enough to push the woofers and the satellites to the limit and I always turn down the volume as and when the distortion is heard so that there is no damage to any component.

Really confused on this...anyways point is you heard the sound distorting so you should have turned the volume down without thinking where the distortion is coming from.

Really happy to know that your drivers got replaced without any issues and finally all problems have been solved.

A great thread!!!!

 

[john_k_antony]

Thanks dude . I am much more than happy .

ProFx service engineer told me that ProFx has to bear the cost for the replacement drivers now as KEF takes a long time to respond to these kind of replacements, even under warranty and its a pain to deal with these guys now. He said they had a similar issue with Q300 from a customer in Mumbai.

OT: While discussing about various things, he asked me to check out the new Polk TSx series. He said they are very sweet in mid-range, where Polk used to lack before. He said very good value for money. Will checkout next time I visit their showroom .

-John.

 

[john_k_antony]

Really confused on this...anyways point is you heard the sound distorting so you should have turned the volume down without thinking where the distortion is coming from.

To be very honest, I never expected that the speakers are causing the distortion in the first place. The actual distortion sound was like some loose ends vibrating. I was initially thinking that the sound absorbing panels are vibrating and making that distorting sound when I first heard it. I am stupid . Because more distortion was coming from the right side of the room and I just re fixed some absorbing panels on the same side a day before. Then I opened the dust cover of the speaker to see them moving so vigorously. I immediately stopped the amp, but by then the damage was made .

Anyway, I am very lucky that my problem was addressed in the best possible way by ProFx.

I will never buy expensive electronics stuff from non-dealers or abroad after this experience .

Thanks,
John.

 

[denom]

John,
I don't think its to do with ProFX being professional, its more to do with the Q300's having some kind of fault which has been highlighted in other cases as well. Something not right...

Would advise you to be careful in future.

Regards

 

[john_k_antony]

Sure Denom,

I realize that now. Will be very careful till I do my next upgrade . This experience is tempting me to save for a better Amp and Speaker upgrade for my HT setup. Might be another 2yrs down the line .

I also feel that there is something not right with Q300 as I found another strange issue with the drive cones excurting, not vigorously, but significantly when I play from LP. The volume was very low, still it was moving "freely" and the ProFx engineer was also confused with this behavior. This was not seen when playing CD. Strange right ? Any way I will not be playing my LPs through my Denon + Q300, but was just testing my newly acquired Technics SL-Q33.

Now my hunt is on for completing my 2 channel setup

Thanks,
John.

 

[ketansethi1987]

you can use them with LPs just remember to turn the volume down whenever you hear distortion or turn down the bass if there is an option to do so

 

[john_k_antony]

you can use them with LPs just remember to turn the volume down whenever you hear distortion or turn down the bass if there is an option to do so

The cross over is set at 100Hz in Denon for both 2 channel and surround modes. So I am protecting the speakers from playing low frequencies though they are rated to go all the way down to 42Hz.

Yes I am keeping a watch on the volume and the amount of excursion. Planning to keep the dust cover off the speakers from now on .

-John.

 

[Nishanth]

This is a very curious case, the specs on paper say that the Q300 should be able to handle anything from the Denon AVR. I wonder if it was a defective piece or if its a flaw with the speaker design

John, Thanks for sharing your experience with PROFX. Your experience has built some trust in me about their after sales service

 

[john_k_antony]

This is a very curious case, the specs on paper say that the Q300 should be able to handle anything from the Denon AVR. I wonder if it was a defective piece or if its a flaw with the speaker design

John, Thanks for sharing your experience with PROFX. Your experience has built some trust in me about their after sales service

I strongly feel that design and drivers of Q300 are not 100% capable of performing to the specs on the paper when driven little harder. This is purely my opinion from my experience. There are lots of other FMs here think different way . As a safe bet, if you are using Q300, either listen to it at a low volume if you want it to do bass down from 100Hz to 42Hz or if you want them to sing louder, don't feed any low frequency less than 100Hz. Use a Subwoofer. I think its better NOT let the Q300 sing loud in either case.

Having said all this, their mid-range clarity is very hard to beat in that price range.

I think they are best suited with Stereo amps rated at 50w/ch in a comparatively smaller room of area 150-200sft or so.

Again these are purely my opinion from my experience.

Other lesson learned is NEVER believe the specs on the paper. You have to drive them harder during audition to see what they are capable of and shortcomings. I guess we all should include some extreme cases in our auditions along with our favorite music .

Thanks,
John.

 

[john_k_antony]

Just thought of giving this update. I think it is already known to many of you.

It is very unsafe to feed any frequency less than 120Hz to KEF Q300 at a moderate high volume. Forget about loud, even at moderate high volumes, if you feed any frequency less than 120Hz to KEF Q300, it is almost certain that the drivers will be damaged.

Other sad thing is that, my experiment failed. I tried the experiment of using KEF Q300 as HT speakers. And from my experience, KEF Q300 is an ABSOLUTELY NON-HT speakers. They should NEVER be used for HT applications, though KEF says I can use them as main speakers for HT.

KEF Q300 is best suited for 2 channel stereo with a moderately powered stereo amp rated at 50-70w/ch and play them at moderate volumes.

I started saving for the following upgdade now - Pioneer SC LX87 + Jamo D600 5.1 package. Both are THX Ultra-2 rated and I am already impressed with Jama D500, which is a younger brother of D600.

Till I upgrade, I will use KEFs very very carefully.

Thanks,
John.

 

[Staxxx]

Just curious...where did you find the D600 (5.2 package) in Bangalore please and at what price? Thanks.

 

[john_k_antony]

Just curious...where did you find the D600 (5.2 package) in Bangalore please and at what price? Thanks.

Cinebels (Cinebels: Home Theatres, Speakers, Projectors, AV Receivers Bangalore, Chennai, Delhi, Mumbai & Hyderabad). You can contact Mr Leanardo at Cinebels, Phoenix mall. They have D500 setup in Phoenix mall and D600 in their main showroom near millers road. I was seriously looking at D600 before I took KEFs. But was not able to afford them now. I think the 5.1 was around 3.75L and 5.2 was around 5L. The 15" sub woofer is the most expensive of the lot. This quote was given when GBP was at 80 . It would have gone up by 20-25% now!

Other reason I didnt go with them now was that they are 4Ohm speakers and I had to do an amp upgrade also to drive them. The amp options was also limited that could drive all the 5 channels at 4Ohm. I found some models of Onkyo and Pioneer LX87 to do the job. Since I am not a big fan of Onkyo, I was looking at Pioneer.

Thanks,
John.

 

[musicbee]

Don't know if the D500 is in the same price range as the D600 (quoted above) but if so you should consider other brands.

I recently auditioned Martin Logan Motion 40 home theater package along with some Jamo home theater package and the Martin Longan's performance was way higher than the Jamo's though interestingly both were priced in the same region of 2.5L to 2.75L. I don't remember the exact prices (did not make a note of them) but I can call and get the approximate prices and the exact HT packages if you want more details.

PS - Maybe it was not the Jamo D series on demo... if so my apologies in advance.

 

[john_k_antony]

I have heard Martin Logan recently for my 2 channel setup and was not very impressed when compared to some other speaker, well costing double the cost though. I didn't like the guitar sound from Martin Logan for couple of songs I heard. So I let it pass.

I realize that for my HT, I need more quantity than quality for HT use. For stereo , obviously I am behind the quality.

I have some budget that I saved my Stereo setup upgrade (AMP + Speakers). I am seriously wondering if I should use that money for an HT upgrade than upgrading my current Stereo setup. For Stereo, I think I can still live with my older KEF iQ7 and AP power amp. I am actually falling in love with my existing combo as it suddenly started sounding good in my acoustically treated dedicated HT room. I am thinking of selling my entire current HT setup and upgrade the HT amp and speakers with the money I get from sale and my savings.

I have a 4 year old Denon 2310 is perfect condition and 2 months old 2 pairs of KEF Q300 and 2 pairs of KEF Q100. I will not put them up for sale now. Will play around for a little while before I make a decision.

But the BIG worry is that, back in my mind, I am always thinking whether a sudden sound sequence will damage my speakers. So I tend to listen to movies in a low volume and not enjoying it 100% .

After setting the cross over frequency at 120Hz, as few of you guys pointed out, I am not fully leveraging the sonic capabilities of KEF Q300 that I have bought them for.

-John.

 

[john_k_antony]

I am checking out other options as well. This time, I want to get the following right.

1. Will look for speakers rated at 90db sensitivity or higher.
2. Look for more powerful amp and play the amp at 40-50% of the max level. I learned that running a powerful amp in lower level is much easier on speakers than running a low wattage amp at the higher level. The latter has a good chance of ripping apart your speakers as most of the budget amps go crazy and cause lots of distortion when cranked up. I see that running my Denon 2310 at 75-80% of max level can create distortion and damage the KEF Q300 again.

I think if I get speakers with 90db or more sensitivity that can handle 100-120w of power paired to a more powerful amp that can deliver 150-175w of power will be good enough for my needs. That means I can play the setup in a good loudness level by letting the amp play at a level 40-50% of its max capacity.

What do you guys think? I can start my shortlist based on the above specs as a starting point and then start the audition.

Thanks,
John.

 

[Audio_Freek]

I have a 4 year old Denon 2310 is perfect condition and 2 months old 2 pairs of KEF Q300 and 2 pairs of KEF Q100. I will not put them up for sale now. Will play around for a little while before I make a decision.

But the BIG worry is that, back in my mind, I am always thinking whether a sudden sound sequence will damage my speakers. So I tend to listen to movies in a low volume and not enjoying it 100% .

After setting the cross over frequency at 120Hz, as few of you guys pointed out, I am not fully leveraging the sonic capabilities of KEF Q300 that I have bought them for.

-John.

John,

Please give me a message in case you have idea to sell KEF Q300 :licklips:I dont know i became mad for this speakers,and currently i dont have budget to own them as new.

Its some thing like,you feel the girl whom you love might be loving someone,but you have a feel that they both are friends,Though you have clearly mentioned that KEFq300 are not the HT speakers, i still have love.

Then Kefq300 should be best for the Music i think so as no Low Freq hit Hard at sudden and damage the drives or the wallet.Just a give a try with IQ7 for HT and Kef300 for Movies,:indifferent14:, Might be sounding funny.

I have Blown an Amp some years before while turning the volume up and the distorting Hit the Capacitors, then i just thrown it away, as the Repairing cost was almost to what i had Paidhyeah:

But its better to change a setup for HT, You cant be cautious always on the Volume control and what the use of having HT? Enjoy and not being watcful as we are not the mechanics .

Some time the heaven turns to hell too at sudden