HDC4 15 Wall Help

[Triticum Agricolam]

10 hours ago, AlexwiththeCanyon said:

To decrease on port noise and other things. He has a whole write up about it and also a port calculator. Although, I've always done pretty good on the 12-17 per cube rule of thumb. 

Yup, that right.  In addition to decreasing port noise, larger port area also decreases port compression, which is the real nasty thing we are trying to avoid.  Port compression raises impedance and robs you of output,  it can easily rob you over more than half your amp power.  The nasty thing about it is you usually can't even tell when you have it because you can't hear the output you don't get (it can be measured with an SPL meter though if you know how to do it).  When you fix the problem by adding more port area you sure notice a big difference though.  This is why I don't like the "12-17 sq in per cube" rule of thumb.  It doesn't account for input power.  That rule of thumb work great when you are tuned to the low 30's and are running around 400 watts per cubic foot of input power, but when you go much above that it isn't enough.  

[Mr DeeBeez]

9 minutes ago, Triticum Agricolam said:

Yup, that right.  In addition to decreasing port noise, larger port area also decreases port compression, which is the real nasty thing we are trying to avoid.  Port compression raises impedance and robs you of output,  it can easily rob you over more than half your amp power.  The nasty thing about it is you usually can't even tell when you have it because you can't hear the output you don't get (it can be measured with an SPL meter though if you know how to do it).  When you fix the problem by adding more port area you sure notice a big difference though.  This is why I don't like the "12-17 sq in per cube" rule of thumb.  It doesn't account for input power.  That rule of thumb work great when you are tuned to the low 30's and are running around 400 watts per cubic foot of input power, but when you go much above that it isn't enough.  

Thanks for clarifying. I think I am going to go with the box that you designed. But how do you think they will preform in a box that small on just one 3500 @ 1ohm? It may be 6 months or more till they are on two 3500s. 

[Triticum Agricolam]

37 minutes ago, Mr DeeBeez said:

Thanks for clarifying. I think I am going to go with the box that you designed. But how do you think they will preform in a box that small on just one 3500 @ 1ohm? It may be 6 months or more till they are on two 3500s. 

It will work just fine,  the difference in output between a 7.5 cu ft box and a 10 cu ft box is only about 1 dB and only right around tuning, you will never hear the difference between the design I posted and a larger box.  

[Mr DeeBeez]

Awesome. Thank you very much!

[Mr DeeBeez]

11 hours ago, Triticum Agricolam said:

It will work just fine,  the difference in output between a 7.5 cu ft box and a 10 cu ft box is only about 1 dB and only right around tuning, you will never hear the difference between the design I posted and a larger box.  

What side of the box would you recommend having the port? Drivers side or passengers side