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A not-so-serious measurement of Genelec Three + KEF KC62 bedroom (untreated) system

timiark

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So, long story short, I think I had figured out the end-game setup in my small 3x3 bedroom. Since there isn't a lot of measurement specifically for KEF KC62, I'd believe it would be interesting to post some actual numbers and curves here. Still, bare in mind that my room is not treated so dips and peaks are expected. (and some nasty THD peaks)

Setup: Equalizer APO + Topping EX5 + XLR to Genelec G Three + RCA to KEF KC62
Speaker config: -10dB sensitivity, everything else being the same as out-of-the-box, no crossover.
Sub config: 80% volume, crossover at 40Hz (roll off at a speed of 24dB/octave), 'room' EQ mode, manual mode.

For raw measurement, I turned on all three of them, sub is switched to 0 degree phase shift.
raw.jpg


For another raw measurement, I switched the sub to 180 degree phase shift. You can see the phase shifting actually works to fill the dip around 70-90Hz.
raw+180inv.jpg


So, previously I also have some channel imbalance problems, the L and R channel is not balanced at lower bass area, which is super annoying. The figure below shows the measurement of L and R G3, no sub. Green is L, blue is R.
G3 LR Imbalance.jpg


Next, with the sub turned on, the L and R channel basically matched. I think it is because I am placing my sub below the R speaker.
G3K62 LR balance.jpg


Finally, with some EQ that REW has designed, I am using 1/6 smoothing here.
cal+180inv.jpg


THD:
The white line is THD and the peak around 60Hz is 17%. The sub stays around 2%-5% on other frequency tho. I am currently figuring out what is going on at that area. (mostly likely related to my room mode being 58Hz)
cal+180inv distortion.jpg


Then, spectrum of decaying:
cal+180inv spectrum decay.jpg

The sub bass area is not optimized indeed, but currently I don't have too much ways to tackle this problem, or room for those treatment.

For your information, this is what my room and placing looks like:
1661575941252.png

There is a closet on the bottom left cornor and a bed on the bottom right cornor. This is why my LR channel is not reasonably balanced.

Conclusions:
I've being spending some hours into this speaker system building and tried some terrible mini sub. I had auditioned other proper sub like REL T5x and T7x. My opinion about KEF is that as long as you are fine with their somewhat exaggerating marketing, KC62 is the choice for a small bedroom. I did not try SVS micro 3000 because it is a bit larger and I don't like the look. Also, since I actually got this KC62 as a second hand, I only paid the price of micro 3000 for KC62, which is better than buying a brand new micro 3000, at least to me.

About the loudness issue of KC62, yes it's true, it cannot be super loud. But since I mainly listen around 75-85dB... I don't really care about that. And, can you feel slam on your chest from this tiny sub? I think no. But the bass is indeed textured and speedy. It adds loads of warmness to my G3 and it surprisingly kind of solved my channel imbalance issue...

If I have other choices, I'd probably try 7040A or 7050C. But given those two are not necessarily better than KC62 if take size into consideration. I would probably use my current setup for a long time.

Hope this could be helpful for your bedroom system planning. If you have further suggestions or questions about pairing Genelec G 3 (8030C) with this mini sub (kc62), I will do the best I can to improve/answer.
 

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ernestcarl

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It looks like the summed response could be better. Try looking at the actual phase curves between your mains and sub using REW’s ‘alignment tool’ found in the All SPL tab options. Do the phase curves overlap with each other correctly/optimally? If not, time delay and/or xo EQ may need to be adjusted. How about the impulse and/step response… is the sub’s start time close to the mains when overlayed? For this to make sense, correct ‘timing reference’ must be set up beforehand.

Search for “alignment tool” in the forums and you should find examples of how its used. It may be a little bit over your head right now, but it’s really quite an invaluable tool when setting up a sub, IMHO.
 
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timiark

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It looks like the summed response could be better. Try looking at the actual phase curves between your mains and sub using REW’s ‘alignment tool’ found in the All SPL tab options. Do the phase curves overlap with each other correctly/optimally? If not, time delay and/or xo EQ may need to be adjusted. How about the impulse and/step response… is the sub’s start time close to the mains when overlayed? For this to make sense, correct ‘timing reference’ must be set up beforehand.

Search for “alignment tool” in the forums and you should find examples of how its used. It may be a little bit over your head right now, but it’s really quite an invaluable tool when setting up a sub, IMHO.
I checked the alignment tool and played around with it for a while. I found the optimal results I could achieve is basically the 180 degree inverse switch could do. Therefore, it terms of timing alignment, I currently cannot go any further than that, no to mention I am not using something like a minidsp to manage a single channel.

I might get a miniDSP in near future, but current it doesn't sound wrong to me.
cal+180inv IR.jpg
 

YSC

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it looked nice and I am sure IRL it sounded fantastic (my 8030 and 7040A did similarly but down only to 30hz not 20.

but thing is your measurement scale is rather zoomed out so plus the 1/6 smoothing it hides any potential issue. interested to see how it looked if it's 50db scale and 1/48
 
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timiark

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it looked nice and I am sure IRL it sounded fantastic (my 8030 and 7040A did similarly but down only to 30hz not 20.

but thing is your measurement scale is rather zoomed out so plus the 1/6 smoothing it hides any potential issue. interested to see how it looked if it's 50db scale and 1/48

Raw:
raw1.jpg

With sub inverted for 180 degree.
raw2.jpg

Calibrated:
cal1.jpg

There is indeed huge dips with high Q. I usually cannot sense them therefore I think it makes sense to smooth more. Still, I am well aware those dips and I had tried fixing them. But as you might have already known, fixing cancellation is hard. (or impossible in my case)

I originally considered about 7040A, but it is constantly out of stock here in Singapore and it is priced 1245 SGD while this second hand KC62 is 1720 SGD. (paid 50% more for another 10Hz of extension makes sense to me)

Let me know if you want to see more graphs, I will post them when I have time for measuring.
 
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YSC

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Raw:
View attachment 226971
With sub inverted for 180 degree.
View attachment 226972
Calibrated:
View attachment 226973
There is indeed huge dips with high Q. I usually cannot sense them therefore I think it makes sense to smooth more. Still, I am well aware those dips and I had tried fixing them. But as you might have already known, fixing cancellation is hard. (or impossible in my case)

I originally considered about 7040A, but it is constantly out of stock here in Singapore and it is priced 1245 SGD while this second hand KC62 is 1720 SGD. (paid 50% more for another 10Hz of extension makes sense to me)
The extension actually makes sense, in my case it was like 3.5 times more for the kc62 vs7040, plus the 7040 gives me more legroom.

I wonders why changing 180’degrees phase don’t seem to do anything on the FR for good?
 

YSC

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The L+R depression in mids looks like the effect of comb filtering where I used mine on desk having similar issue, any L and Rbseparate measurement?
 
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timiark

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The extension actually makes sense, in my case it was like 3.5 times more for the kc62 vs7040, plus the 7040 gives me more legroom.

I wonders why changing 180’degrees phase don’t seem to do anything on the FR for good?
Legroom: decent enough for me. But surely 7040A should be better on that. (but if I want more bass and go for 7050C... then it does not have the advantage anymore)
1661615438670.jpeg


180 degree phase shift is doing some job at the 80-90Hz area. I probably overlap too much curves that you might not notice that. Still, without further channel management, inverse 180 degree does make some slight differences and make that 90hz dip not so deep.
 
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timiark

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The L+R depression in mids looks like the effect of comb filtering where I used mine on desk having similar issue, any L and Rbseparate measurement?
This is actually the 4th figure in the original post.
Here is the zoomed and less smoothed version:
LR48.jpg

I had noctied the comb fitering but it might be something I got to live with for now... since it is all for my desktop entertainment system.

More, because my room is not symmetric, you can see those channel imbalance for sure. Furthremore, my ears actually have some hearing capability differences... my left ear is slightly more sensitive to bass and it always makes the soundfield I could feel a bit twisted... (sadly, I cannot purchased another pair of ears... LoL)
 

ernestcarl

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Raw:
View attachment 226971
With sub inverted for 180 degree.
View attachment 226972
Calibrated:
View attachment 226973
There is indeed huge dips with high Q. I usually cannot sense them therefore I think it makes sense to smooth more. Still, I am well aware those dips and I had tried fixing them. But as you might have already known, fixing cancellation is hard. (or impossible in my case)

I originally considered about 7040A, but it is constantly out of stock here in Singapore and it is priced 1245 SGD while this second hand KC62 is 1720 SGD. (paid 50% more for another 10Hz of extension makes sense to me)

Let me know if you want to see more graphs, I will post them when I have time for measuring.

People often use a sub(s) to offset limitations in their mains setup. The way you have things arranged in your room, other than the deeper extension it offers, the frequency response of the sub doesn't particularly help in mitigating the weakness' of the mains magnitude frequency response due to room modes and/or boundary interference -- i.e. they're almost identical in the location of major peaks and dips.

I might get a miniDSP in near future, but current it doesn't sound wrong to me.

A miniDSP will increase the flexibility in where you can position the sub and what xo EQ combinations you can apply, but if you do not have much wiggle room in your room setup/arrangement it may not be that important of an addition.
 

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  • ALIGNMENT TOOL IMPULSE RESPONSE.png
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  • ALIGNMENT TOOL IR STEP RESPONSE.png
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timiark

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People often use a sub(s) to offset limitations in their mains setup. The way you have things arranged in your room, other than the deeper extension it offers, the frequency response of the sub doesn't particularly help in mitigating the weakness' of the mains magnitude frequency response due to room modes and/or boundary interference -- i.e. they're almost identical in the location of major peaks and dips.



A miniDSP will increase the flexibility in where you can position the sub and what xo EQ combinations you can apply, but if you do not have much wiggle room in your room setup/arrangement it may not be that important of an addition.
Yes I am aware that room modes are not to be fixed with just another sound source.
I'll probably consider about that, if price suits. Currently it is roughly crovssovering around 100Hz despite I did not specifically set the xover for G3. There is indeed some over emphasize arond 60-80Hz, but mostly EQ-able.

I wonder what would be consider a decent RT60 time in a small bedroom, though for sub bass I really cannot do too much about that. (I read it requires very tick treatment foams, traps, which is not practical to place in a small room)
 

ernestcarl

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Yes I am aware that room modes are not to be fixed with just another sound source.
I'll probably consider about that, if price suits. Currently it is roughly crovssovering around 100Hz despite I did not specifically set the xover for G3. There is indeed some over emphasize arond 60-80Hz, but mostly EQ-able.

I wonder what would be consider a decent RT60 time in a small bedroom, though for sub bass I really cannot do too much about that. (I read it requires very tick treatment foams, traps, which is not practical to place in a small room)

I don't think the RT60 in a small bedroom is going to be very useful to look at... rather study the reflection-decay characteristics from other available visualization plots instead -- e.g. IR, spectral decay, waterfall, and spectrograms. Look at how serious pro studios deal with the region below 150 Hz or so -- it simply is not possible to implement a solution like theirs. Think about the size of the wavelengths...

1661861145197.png


With enough specialized diaphragmatic absorbers and covering enough surface area in the room, you may still be able to reduce the decay noticeably, however, the LF magnitude response isn't going to be flattened by all that much.

Your subwoofer, on the other hand, is small enough to move around all over the room -- including the height axis. I would endeavor to find a spot where it fills in 30-100 Hz region the most to complement the mains rather than replicate the same linearity issues. *and, If all else fails, there's always EQ (even though not best/perfect solution) to fall back to.
 
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timiark

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I don't think the RT60 in a small bedroom is going to be very useful to look at... rather study the reflection-decay characteristics from other available visualization plots instead -- e.g. IR, spectral decay, waterfall, and spectrograms. Look at how serious pro studios deal with the region below 150 Hz or so -- it simply is not possible to implement a solution like theirs. Think about the size of the wavelengths...

View attachment 227620

With enough specialized diaphragmatic absorbers and covering enough surface area in the room, you may still be able to reduce the decay noticeably, however, the LF magnitude response isn't going to be flattened by all that much.

Your subwoofer, on the other hand, is small enough to move around all over the room -- including the height axis. I would endeavor to find a spot where it fills in 30-100 Hz region the most to complement the mains rather than replicate the same linearity issues. *and, If all else fails, there's always EQ (even though not best/perfect solution) to fall back to.
I had previously posted my spectrum decay plot as well as IR, I will appreciate that if you could check them and comment on what to look at. (I am not 100% sure about how to interpert those plots desipte it is obvious I have some decaying issues below 50Hz)

IR wise, there is a reflection that could be seem by I have few idea whether it comes from ceiling, desk, or wall. (anyway I could debug this and find the source?)

To save your time:
1661864832158.png

1661864846338.png


About the sub, I am looking for a KW1 unit to make the sub wireless so I can place it wherever I want. (according to RoomSim, it seems like a good idea to place the sub behind me so I won't have a huge dip around 44Hz)

My current setp be like:
1661864961945.png

1661865318345.png




Ideally, according to RoomSim, this looks better:
1661864931774.png

1661865299695.png


EDIT: I posted the sim for wrong room dimensions, corrected.
 
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