Here is my input on what I have found to be optimum in sound and overall performance (SPL) for both the HDC3 and HDC4.  Now there are several versions of both of these subs and I have tested countless hours with both.  This is my recommendation, it isn't intended to be the end all BEST but will get you really damn close

 

All recommendations are with alum coil D1 subs.  Single sub setup, simply multiply for multi sub setups, works great in my testing. 

 

HDC3 old version (Old Style basket) Stiff suspension

 

1k input power

HDC310 - 2.0 cube net with 18 sq inch port area per cube - tune between 36-41 hz

HDC312 - 3.0 cube net with 18 sq inch port area per cube - tune between 34-39 hz

HDC315 - 5.0 cube net with 18 sq inch port area per cube - tune between 35-40 hz

HDC318 - 6.5 cube net with 18 sq inch port area per cube - tune between 33-38 hz

 

2k input power

HDC310 - 1.5 cube net with 17 sq inch port area per cube - tune between 36-41 hz

HDC312 - 2.5 cube net with 17 sq inch port area per cube - tune between 34-39 hz

HDC315 - 4.0 cube net with 17 sq inch port area per cube - tune between 35-40 hz

HDC318 - 5.5 cube net with 17 sq inch port area per cube - tune between 33-38 hz

 

HDC3 current version

 

1k input power

HDC310 - 1.5 cube net with 17 sq inch port area per cube - tune between 36-41 hz

HDC312 - 2.5 cube net with 17 sq inch port area per cube - tune between 34-39 hz

HDC315 - 4.0 cube net with 17 sq inch port area per cube - tune between 35-40 hz

HDC318 - 5.5 cube net with 17 sq inch port area per cube - tune between 33-38 hz

 

2k input power

HDC310 - 1.25 cube net with 16 sq inch port area per cube - tune between 36-41 hz

HDC312 - 2.25 cube net with 16 sq inch port area per cube - tune between 34-39 hz

HDC315 - 3.75 cube net with 16 sq inch port area per cube - tune between 35-40 hz

HDC318 - 5.25 cube net with 16 sq inch port area per cube - tune between 33-38 hz

 

HDC4 old version (soft suspension)

 

2k input power

HDC412 - 2.75 cube net with 18 sq inch port area per cube - tune between 34-39 hz

HDC415 - 4.5 cube net with 18 sq inch port area per cube - tune between 35-40 hz

HDC418 - 6.0 cube net with 18 sq inch port area per cube - tune between 33-38 hz

 

4k input power

HDC412 - 2.25 cube net with 17 sq inch port area per cube - tune between 34-39 hz

HDC415 - 3.5 cube net with 17 sq inch port area per cube - tune between 35-40 hz

HDC418 - 5.25 cube net with 17 sq inch port area per cube - tune between 33-38 hz

 

HDC4 current version (stiff suspension)

 

2k input power

HDC412 - 3.0 cube net with 18 sq inch port area per cube - tune between 34-39 hz

HDC415 - 5.0 cube net with 18 sq inch port area per cube - tune between 35-40 hz

HDC418 - 6.5 cube net with 18 sq inch port area per cube - tune between 33-38 hz

 

4k input power

HDC412 - 2.25 cube net with 17 sq inch port area per cube - tune between 34-39 hz

HDC415 - 3.75 cube net with 17 sq inch port area per cube - tune between 35-40 hz

HDC418 - 5.5 cube net with 17 sq inch port area per cube - tune between 33-38 hz

 

 

You will notice the HDC3 and HDC4 like the same tuning based on power and suspension.  I have built multiple boxes with different tuning to test how these really performed and these were from my notes on what they really like to get loud.  Hope this is helpful. 

 

My recommendation on Amp match is HDC3 on budget side SQ1200, loud side SQ2200, HDC4 budget side SQ2200, loud side SQ3500. 

 

TEAM SOUNDQUBED - The Black Nasty 160+ db on music daily

Edited May 23, 201411 yr by AMI CUSTOMS

Great write up

Little late, but thanks for the info.  About to start designing an enclosure for (2) HDC3 10's on strapped 2200's.  If I tune at 34-35hz, do you think it's still possible to hit the upper 20's with any kind of authority?  I listen to Dubstep, Decaf, and Hip Hop.  I know 34hz will be great for Dubstep and the rest of my music (probably not Decaf), but I would still like to get low without sacrificing too much "loud", if possible...  I know I will have to give and take in any  situation.  Just looking for optimal tuning... Any thoughts?