Triticum Agricolam Posted October 4, 2016 Report Share Posted October 4, 2016 currently they're being fed 500 rms each. I'd prefer to keep the port size the same if possible. I'm trying to get a little gain in loudness from a small change if possible just because it's easy and cheap to do. Maybe later on if I'm not satisfied with the gain, I'll consider modifying this box or having another one built. I understand. On a 1000 watts you are probably losing a fair amount of output to port compression. Raising your tuning frequency will most likely exacerbate the problem, but its worth a shot. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
ModestDb Posted October 4, 2016 Author Report Share Posted October 4, 2016 Okay. I'll find my resonant frequency and try to gear the tuning toward that. Would a correct statement be...if I find my resonant frequency, I could tune toward that number without changing port diameter but length..(assuming the port isn't too long to fit in the box, or too short because the diameter isn't wide enough?) Also...to Triticum Agricolam...is that to say that you believe my wattage is too high/low or port diameter is not enough? 4 American Bass VFL 8" at 0.5 ohm Soundstream Tarantula 3000.1D at 0.5 ohm 32 hz ported box designed by Mark at Car Audio Fabrications XS D1200 secondary with Stinger isolator Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted October 4, 2016 Report Share Posted October 4, 2016 You should be able to change your tuning by just changing the port length, like you said. The goal with port area is to have enough so that port compression, which is caused by too high of port velocity, is negatively impacting performance as little as possible. All else being equal things that will raise port velocity are increasing input power, increasing the tuning frequency, and increasing box size. Your combination of input power, tuning frequency, box size, and port area are probably making for some really high port velocities and thus significant output lost to port compression. Getting enough port area for these small, relatively high power subwoofer boxes can be quite a challenge, so your situation isn't an uncommon one. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
ModestDb Posted October 4, 2016 Author Report Share Posted October 4, 2016 You should be able to change your tuning by just changing the port length, like you said. The goal with port area is to have enough so that port compression, which is caused by too high of port velocity, is negatively impacting performance as little as possible. All else being equal things that will raise port velocity are increasing input power, increasing the tuning frequency, and increasing box size. Your combination of input power, tuning frequency, box size, and port area are probably making for some really high port velocities and thus significant output lost to port compression. Getting enough port area for these small, relatively high power subwoofer boxes can be quite a challenge, so your situation isn't an uncommon one. Oh. I see. Thank you for the in depth explanation and it makes sense now. I appreciate your time. I'm going to consider all the factors before I make any changes yet. Do you happen to know if most places who do custom installs, offer services such as testing for resonant frequency or no? 4 American Bass VFL 8" at 0.5 ohm Soundstream Tarantula 3000.1D at 0.5 ohm 32 hz ported box designed by Mark at Car Audio Fabrications XS D1200 secondary with Stinger isolator Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted October 4, 2016 Report Share Posted October 4, 2016 Oh. I see. Thank you for the in depth explanation and it makes sense now. I appreciate your time. I'm going to consider all the factors before I make any changes yet.Do you happen to know if most places who do custom installs, offer services such as testing for resonant frequency or no? No prob, glad I could help! Its really going to vary as to whether a local custom install shop will be able to do the type of testing you are looking for. Your best bet may be to find a local group of people (on facebook, for example) that are into SPL. They could probably help you out or at least point you in the right direction. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
ModestDb Posted October 4, 2016 Author Report Share Posted October 4, 2016 Well I tried several length aero ports. I went from 7.5 inches long to 7 inches to 6.5 inches to 6 inches to 5.5 inches. Each got increasingly quieter on all ranges of bass notes. Low and high notes included. Perhaps I should get some more 2 inch tube and try 8 or 8.5 inch long port. Wouldn't that mean my tuning frequency would be going lower though? By going longer on the port? 4 American Bass VFL 8" at 0.5 ohm Soundstream Tarantula 3000.1D at 0.5 ohm 32 hz ported box designed by Mark at Car Audio Fabrications XS D1200 secondary with Stinger isolator Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted October 4, 2016 Report Share Posted October 4, 2016 Yup, that would make it lower. When you are adjusting your port length you should try to figure out what the tuning frequency by playing sine wave tones while watching cone movement like strangeduck said. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
ModestDb Posted October 4, 2016 Author Report Share Posted October 4, 2016 Yup, that would make it lower. When you are adjusting your port length you should try to figure out what the tuning frequency by playing sine wave tones while watching cone movement like strangeduck said. Okay. Will do tomorrow if I have time. I may just not be able to get any more out of this enclosure and I can accept that. It only cost me 18 bucks to try some ports this time. I might have something else built soon...and just buy 2 more of these 8" VFL subs. 4 of these would probably be pretty loud. I'm getting roof flex now so I can only imagine being a little louder. 4 American Bass VFL 8" at 0.5 ohm Soundstream Tarantula 3000.1D at 0.5 ohm 32 hz ported box designed by Mark at Car Audio Fabrications XS D1200 secondary with Stinger isolator Link to comment Share on other sites More sharing options...
ckeeler11 Posted October 4, 2016 Report Share Posted October 4, 2016 Port diameter is not enough. Low port area causes high port velocities and compression. https://sites.google.com/site/amateuraudio/theory/compression Link to comment Share on other sites More sharing options...
ModestDb Posted October 6, 2016 Author Report Share Posted October 6, 2016 Okay guys. What port diameter would be better than 2 inches, how many and approximately what length? 4 American Bass VFL 8" at 0.5 ohm Soundstream Tarantula 3000.1D at 0.5 ohm 32 hz ported box designed by Mark at Car Audio Fabrications XS D1200 secondary with Stinger isolator Link to comment Share on other sites More sharing options...
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