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Help with KEF Q400. (1 Viewer)

Boy_Narf

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Dean
Hello Everyone,


I'll start out by saying I'm not an audiophile. I run a set of 80's pioneer fronts, and a cheap Samsung receiver. Here is a pic of my setup:


67KaYkjb60_Q7K1KlbRRJYB-6sPX1hmJWZltnloRK-1Gu0t990QSa-MAY5JFN1Ah8VNnLuQILFlRxyUeXvL6r9uKnXKF5KssoPtSoWymZHmtGu3S9xA9XfwU2nW959JeAw0-gyCcmjbz3835gJY2HKqlELNe7d7a_P6n9VS4AU8bx379EZtM6Qsd7BGEyw2NbZAphs1AdceFfGdlYqe9ShbEVR5YafYaAGVF2nDJq8p_Y4kIDcULAWtbV7t6tYM2GwrH3HOAh-isxAgytrzNZraedIZrt-4BJ-kkotU6JKAoySUsh8sq4KKq_w4huYCqCvT76V3UC0T89DtVZqo9GEToiR73WcnzJs-3UZhvv-7ynNZVyPynN_tqwJd7Vk1Awb52avf5KJE82ueEQbiufFVVwE9CLi7ZVaZjUpmZIyn5H4sioGHebUu6r1PaGq3RADP9R8fsZUr2IKPz41eX1O4YtKz8UV3xHO6k4oq47QqOoSk2DcECtv4TGJnclT6Y8clhM63Ddv4EWZsrNt8AMxVoxC7iGRMCoJ22nw=w840-h621-no



So I used to run a Polk audio PSW125 but earlier this week the amp died. I emailed support and they want almost as much as a new sub to replace the amp. I decided it was time to get a new sub. I headed down to my local Visions as they are having a grand opening sale. I was planning to get the PSW505 as it was 50% off, but it sounded horrible. The sales guy suggested the KEF Q400B as it is his #1 selling sub. I was sceptical but it wiped the floor with the other subs. It was able to hit notes the other speakers couldn't even pick up, not to mention how small it is. So I went back the next day and bought the Q400. It was almost 50% off so I think I got a good deal. That being said I'm left a bit disappointed.


1. Poor separation. When the bass really kicks in, the bass and kick drum loose all of their separation. I don't remember having this issue with my Polk. (10" vs 12"???)


2. Sloppy response. I fired up a dub step track today to test the response of the driver. During the faster wub wub parts it couldn't keep up and sounded like a single note. The sub was visually keeping up, but the sound did not match. (room positioning???)


3. Low volume. I followed the steps in the manual during my set-up. Receiver crossover at 80 hz, sub xover at 140, level at the 7th tick, and sub volume on the receiver to taste. It's the same config as my old sub, with the exception of sub volume. I need to max the receiver sub volume to get it up to an audible level. I have left the sub level at 7 as suggested. Going to mess with this a bit more later.


4. Deep notes are there, but hardly audible. (10"vs 12"???)


5. The KEF rattles the lights in the kitchen two rooms away, but isn't all that loud in my living room. (room positioning???) The Polk used to live in the back left corner of the room (the young lady got some new furniture and of course the sub had to go). I was never happy with this position, but it was the only place for it. As you can see in the picture I have the Q400 to the right of my front speaker. Suggestions on where it should live?


6. One positive thing though is that with the exact same amp/xover settings, voices no longer creep into the sub. It seems to be filtering better than the Polk.


Like I said I didn't notice any of these issues with my old sub. It had way too much volume on tap. I usually had to keep it at 50% or less with receiver sub volume at 0 and it would overpower the mains. Now here are the differences as I see it.


a. 10" vs 12"

b. 200 watts vs 150 watts

c. sealed enclosure vs bottom ported

d. not broken in yet? Controversial subject I know, but could be a factor.


Now coming from a cheap entry level sub to something priced at nearly 1K CAD I was expecting to be blown away. I tried looking for reviews but there isn't much on this little guy. Is this even a decent sub? or do people generally avoid it for some of the reasons above?


This could all also be due to my home theatre noobery. If anyone has advise on how I should be positioning it, or tuning my system I would really appreciate it.


Thanks guys,


P.S. I tried hooking up my Polk today for a direct comparison but it won't power on any more.
 

Boy_Narf

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Dean
Hey,


Thanks for the quick reply. I'll fire up some hip-hop before I head to work tomorrow.
 

Boy_Narf

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Messages
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Dean
Ed83-vuE_T4tG9Iae4-h3LMLPsBq5fWQvtju81Ery-2OCQ4jcNJVLEEhlmG1-32w4nKBbiDN0nm_6SxuucO3jXSLovuEIxFjyv_xEGc39QlR0BPNeO0rXiAoXQa0gvfRLGjRyoy52wvwygscpqCGRvBGQvK96SyhqrGqT0nSBh3QN0lMwuuzrd19iSev95vStXFu4kjKR5-fFKMm3Z130qxeCinWg580NsCgR6ftFQv8D7rwUPGsCJ8LK5kFXtuiSd9PyAKYSeUsB9Olo1hLwBVp37XUat-upKlnyRLHJPAxqLPrtbh3W4MRCDUj09JQvtV7KCMlrCUMtAmjjWrsYqjYUaEHsHND2mf-bmTizdt2ET8mC61j3kpv63JtUL42c3nQwh4434yjU_XL86KgnNBLQ6vrQ8_ejj5chcRQ5ccV77qTuSomTFP85FJclA3029pTofhlWBjFjw7fO0pQhpt_lgYIsvHFEdmuGHMV18x5I19sKtmH_g2AmjlPJdtxMDJk9wPH2Pff9w4dvOZqRlyPBpsAUBxAReTsOw=w819-h460-no



Above is my living room layout. Not optimal for a home theatre I know that, but it's all I have to work with. So I tried moving the sub back to it's original position (A). It sounds damn good when sitting right next to it, but is completely lost sitting everywhere else (couldn't even tell it was on). With the sub in position (B) it sounds good sitting on the south side of the couch but gets lost when moving to a different seat. When sitting on the chair it sounds like there are phasing/cancellation issues. I tried switching the sub to 180, but it lost all of the low end.


So...


Where should I put his darn sub? Way back in the day I had the Polk sitting in location E, and it seemed pretty good no matter where I was sitting. After we got some new furniture, I had to move the sub to location A. It was also difficult to hear in the chair, but seemed to have more sound dispersion. This little guy sure is directional. Almost as bad as my Orange cabs!


Thanks everyone,


P.S. I emailed KEF support and they suggested I had it in the wrong position, or that I need to angle it more?
 

Jason Charlton

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It's very difficult (perhaps impossible) with any single sub to get good performance in all locations in a room. The sub crawl method that Sam mentioned can be used to find both the best placement for a single listening position, or the best overall compromise for multiple listening positions.


Most of the time, we position the sub to provide optimal performance for the primary listening position, leaving all other listening positions compromised to varying degrees (I can't see your pictures, so I don't know how far apart your two listening positions are).


One way to improve subwoofer performance over a larger area is to add a second (identical) subwoofer that can be positioned in a complimentary location to the first subwoofer (the optimal positions for both likely being different than if there were only 1 subwoofer).


Not sure if that's an option for you...


Edit: Actually, since you are still on the fence as to whether or not this is the right sub for you, I would pick a spot where it sounds at least OK for one listening position, then leave it there for a while to let it break in. If after a few weeks of heavy use, the performance has improved, then you'll know whether or not you should take additional steps to make it work in your room.


If you're still not wowed by the sub, then I would consider returning it and looking for something else.
 

Boy_Narf

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Dean
Are my pictures broken?


Like I said above I never had a problem with placing a sub woofer. I always just put it where there was room. I guess it's possible my old polk had better sound dispersion. I believe it was bottom ported, and the cab is at least twice as big. I wish it was working so I could hook it up and compare.


I will say that this KEF sub is much cleaner, and goes much deeper, but it is not as loud and just isn't filling up the room like the old sub did. I'm going to re-arrange some furniture while the young lady isn't home and see how it sounds in the other corner.
 

Jason Charlton

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Boy_Narf said:
Are my pictures broken?

They aren't showing up for me - just this:
Screen Shot 2015-10-22 at 12.16.00 PM.png



Maybe it's my browser, not sure if it's happening to anyone else...

Boy_Narf said:
I always just put it where there was room.

Then you've gotten lucky. Subwoofer performance can vary widely based on its placement within a room. Though it is a bit odd that a position that worked for one sub would be so bad for another.


It's also possible that if your previous sub was ported and the new sub is sealed that you're not used to the differences between the two. Ported subs tend to be boomier than sealed, and they do take more power to produce the same SPL as a ported sub.


Good luck.
 

Boy_Narf

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Dean
Hey,


Yea I'm familiar with the ported vs sealed debate. I'm a car audio enthusiast, and a bass player.


The old sub is almost twice as big in a ported box, which is why there would be a bit more sound dispersion. It was also extremely boom as it was impossible to dial out deep voices in movies or TV. I have a feeling POLK has an exaggerated EQ to make things sound more um... bassy? This KEF seems very flat in comparison.


This morning I have set the EQ to +6 at 40hz, it really helps to bring out the lower notes that were inaudible before. I also moved the gain up a few notches and changed my sub level from +10 back to 0. It's sounding better for sure. I'm still not happy with the room placement, as in certain places the sub sounds great (2 rooms over), but from my listening position it sounds sloppy. Will be crawling shortly here as per the suggestion above.


Guess I'm just missing that boomy low mid bass that the POLK was boosting. I tried the crossover at 100hz, but it makes my mains sound quite thin (doesn't blend as well either). Thanks to my cheap receiver I can't adjust the crossovers individually. The speakers have to be set to small in order for the LFE to have an output. Pretty dumb design decision IMO. The fronts have 15" woofers with built in cross overs so they should be fine to handle lower frequencies.


Thanks guys, I'll report back after a bunch more location testing.
 

Boy_Narf

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Hey Guys,


So I've settled on the original placement. It seems to be the best sounding location for all seats in my room. Also not sure if it's all in my head, or if I've gotten used to it, but seems that the sub has opened up a bit and is able to push out the deep notes with a bit more volume. After listening for about a week, I have decided that It defiantly sounds better than my old sub. It seems to bring out the proper low end, where as the POLK and it's exaggerated EQ caused everything to sound boomy, including voices, and explosions. This little sub actually rumbles the room, as it has a much lower frequency response.


Thanks for all of the help.
 

Boy_Narf

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Dean
Well that didn't last long. The young lady finally noticed the sub in the living room and of course it had to move to the old location under the coffee table hah.

Nice well it lasted. Hah.
 

Jay_Cat

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I'm in the same situation as Boy_Narf, but have different feelings on the results. I had a Polk Audio PSW125 that I got in a HT package with other Polk speakers. I have never liked the PSW125. Either no bass is produced or an over abundance of bass is produced. I turned the sub volume way down, but still never liked the results - no bass or too much bass. There never seem to be a middle ground in the amount of bass produced. Besides being bloated, the bass notes were ill defined. A month after the warranty expired, the sub started to produce on and off booming sounds, even when there was no signal going to it. Unplugging the RCA cable, from the receiver to the sub, did not change the situation. About a month later, the sub started to produce a continuous humming sound that was even more annoying than the previous noise.

After going without a sub for a month, I saved up enough money to get a replacement. Visions had the KEF Q400 at more than 50% off, due to it being a discontinued model. Since it was the only sub on sale and at my price range I bought it with a bit of hesitation - will the KEF sub match my Polk Audio speakers?

Without even properly breaking in the sub, I can say that the KEF is superior to the Polk. I have put the new sub in the exact same location (rear corner) as the Polk. The KEF produces bass that is cleaner, more detailed and with volume levels that matches the movies. There is absolutely none of the all of a sudden big booming bass that comes out of no where, that the Polk produced. What's most surprising is that the KEF sub blends in better with the other Polk speakers. To be sure, that was a pleasant surprise.

Essentially, the difference between the Polk PSW125 and the KEF Q400, in my eyes (ears?), is quantity vs quality. If all you want is a sub that gives the largest boom, then go with the Polk. If you want quality sound, then the KEF is a better choice. I play a lot of music though my stereo system, so the KEF suits me better. It's just a matter of taste and priorities.
 

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