# Hard Knee House Curve … The Results!



## Orange55 (Jul 20, 2009)

For those of you who have not read the article written by Wayne, it is here http://www.hometheatershack.com/for...target-levels-hard-knee-house-curve-long.html.

In the third line of Wayne’s thread he hit exactly the issue I was facing “The frustration? Well, things never sounded as good as they looked on the screen” but could never seem to work out why, however this article seemed to suggest I was not alone.


*The Issue*
I listen to 2 channel music as much as TV and Movies all through the same system. My mains go down to around 50hz, but start to roll off in the real world at 70hz due to a room mode. I therefore cross over to the sub at this point which due to its positioning is not as affected by the mode as the mains. 

However, overall it has been sounding slow when the sub has been engaged for music and never really having the bass you can feel when watching movies. But the graphs always look good and I am using minimal EQ, calibrated mic etc; so appeared to be doing everything right and I was wondering where I put the second subwoofer to get the feel of the bass.


*The Solution*
Having done lots of reading, including how automated EQ systems set their full range target curve I came across research for the Bruel and Kjaer (B&K) curve. I implemented this and it made a big difference, especially taming the highs which it is surprising how a small tweak really brought them into line.

Next up was the bass as I could hear the integration between mains and sub was flabby to say the least. Enter the Hard Knee House Curve, having made the suitable measurements using my ears for levels rather than sound meter I adjusted the bass area of my house curve to include a dramatic 10db rise in the bass. This figure along was pretty surprising as the (B&K) curve had only a very small increase and I had used a meter to set the levels of all channels to date.

My Sub response peaks are 45Hz and then drops, so I went for a levelling at this frequency, rather than Wayne’s suggested 30Hz. This showed my room has a nasty boost at around 43Hz which caused some annoying booming, which I isolated with a sine signal, nice tip. I then levelled off at 50Hz and bingo the sound sprung into life.

Final part of context, I had my sub installed professionally in our original house before I was introduced to EQ, so therefore assumed the team knew how to get the best from the sub. (How wrong was I)


*The Results*
Amazing … I am gobsmacked that my subwoofer is so good.

Here is the graph which shows it tracking to the curve, which does not look that different from others I have seen on this forum.

*Subwoofer response against Target*








*Overall Measured Curve*








The bass is now tight, fast and precise, did I mention tight, plus I can feel the low regions when they hit and defiantly have no need for a second subwoofer.

The overall sound of the system has far more authority, depth and the bass lines are now clear as day and very detailed. But amazingly with their being far more bass it does not affect the high frequencies, everything is crystal clear no muddiness in sight or should I say ear shot.

I cannot recommend highly enough the impact that a correct High Knee House Curve has on a system. I am just kicking myself that it took so long to go down that route.

Wayne described it has the “Holy Grail of Bass” it is and I am a now convert, so a _*big thanks to Wayne*_ for the article. 

*And Finally...* if you have not tried a Hard Knee House Curve in your system yet, do it today!


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## dougc (Dec 19, 2009)

That's great, and an informative read by Wayne that I somehow missed. I also noticed that once I recently started using REW with miniDSP that the integration almost immediately made the sub channel sound better, more blended with my mains. I had a huge gain at 60hz that I had to tame even though it was recorded as a small spike when measured. The end result was definitely not flat in REW, but more pleasing to my ears.


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## Orange55 (Jul 20, 2009)

On thing I did vary on Wayne's article if applying EQ post the crossover frequency on the sub. This was due to a large boost in the 80Hz region which was clearly audible and the processor crossover didn't take care of it. Went with my hears.


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## xxxx5 (May 14, 2012)

delete 
sorry : wrong thread


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## Orange55 (Jul 20, 2009)

I thought it would be worth adding an update ... after three months and extending listening during the holiday season the effect of the Hard Knee curve still putting a big smile on my face.

The results are truly amazing with such tight and deep bass.


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