Kyblack76 Posted June 19, 2015 Author Report Share Posted June 19, 2015 I tried to look for dropping below in one of the scientific journals I thought it was in and couldn't find it. I could have been remembering something else dropping below something else, if I was then I'll admit I was wrong. I'll look again if I care this weekend, but for now I'll go with I was wrong. its all good bro..... im also getting learned up good on this...... i dont take the shit personal, i just wanna grow....weed, i just wanna grow some weed. and some knowledge..... SMD SUPER SELLER The Burban Build Blazer Build sold Acura trunk build sold Link to comment Share on other sites More sharing options...
kirill007 Posted June 21, 2015 Report Share Posted June 21, 2015 This is why it can drop below nominal impedance. Nominal impedance is not a accurately calculated value, it's more a average then the lowest impedance. Thinking is the root of all problems... You ALWAYS get what you pay for. Link to comment Share on other sites More sharing options...
Sergeant_Skyrim Posted June 21, 2015 Report Share Posted June 21, 2015 This was quite honestly such a great and very informative read. First and foremost want to say thanks to the people who contributed their expertise and knowledge. so there is no such thing as too much? Only adjustments ive seen to port area...... on every forum, every build... is SHRINKING... i may be the ONLY one that should open the vent.. and even then.. i bet my gain is dick........ im more worried about cooling, and control. Output... fuck... who cares... The thing is when people are SHRINKING their ports, they start off big and work their way down. You want to give yourself as much possible to work with, that way you then shrink until the point where you are no longer getting louder. It's all going to be a fine balance between SPL, bandwidth, cooling, etc. You just have to keep working at it until you find the balance that you are looking for. First wall I ever built in this car for my 2 lvl 6 18s on a dc 9k barely did a 147.x sealed at 40/41hz, with a port area of ~150 sq inches. Rebuilt the wall with about 260-270 sq inches of port and am now doing a 152+ sealed at 40hz (peak higher than that, was just only tone I had available at the time) immediately after dropping the subs in, no changing anything and not even sealed off. Guess what I'm trying to say, if you're thinking of rebuilding then try to give yourself as much usable area at the beginning, that way you can shrink from there. You can always reduce it without having to do much work, just slap more layers of wood in there, however there's no increasing it without cutting something or rebuilding. Again, just want to say this was a really great read and helps explain a few things I've had questions about before...lots of knowledge in here folks Also want to add about the sub moving less around your tuning/peak frequency, I had always heard like some others that the more port area you have the more the sub excurts and the less cone control you had because the more port area you have the more it acts like an IB setup (for example). But after increasing my port area by almost twice as much I can say that around 40 hz (close to peak for both setups) my subs now move less. Like barely moving at all, yet I'm ~5 db louder sealed up. Was interesting to read some of you guys say how that works, makes a little more sense now Build in progress Link to comment Share on other sites More sharing options...
ChevyBoy95 Posted June 21, 2015 Report Share Posted June 21, 2015 This is why it can drop below nominal impedance. Nominal impedance is not a accurately calculated value, it's more a average then the lowest impedance. That is what I always saw was that DCR is a place holder for impedance, and the impedance will never go under the given DCR value, since there is no conversion or anything to get between impedance or DCR Best Score to Date : 160.5 dB Outlaw (47Hz)[4 XM 15's & 2 Taramps Bass 12k's] BL : http://www.stevemeadedesigns.com/board/topic/147800-chevyboy95s-4-15s-7krms-wall-1533-db-on-half-power/YouTube: http://www.youtube.com/hitemwiththeflex/ Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted June 21, 2015 Report Share Posted June 21, 2015 This is why it can drop below nominal impedance. Nominal impedance is not a accurately calculated value, it's more a average then the lowest impedance. That is what I always saw was that DCR is a place holder for impedance, and the impedance will never go under the given DCR value, since there is no conversion or anything to get between impedance or DCR This graph does a good job of highlighting the difference between nominal resistance and DC resistance. Like kirill said, nominal resistance is more of an average number and the sub can go below it, but never below DC resistance. "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...
kirill007 Posted June 21, 2015 Report Share Posted June 21, 2015 This was quite honestly such a great and very informative read. First and foremost want to say thanks to the people who contributed their expertise and knowledge. so there is no such thing as too much? Only adjustments ive seen to port area...... on every forum, every build... is SHRINKING... i may be the ONLY one that should open the vent.. and even then.. i bet my gain is dick........ im more worried about cooling, and control. Output... fuck... who cares... The thing is when people are SHRINKING their ports, they start off big and work their way down. You want to give yourself as much possible to work with, that way you then shrink until the point where you are no longer getting louder. It's all going to be a fine balance between SPL, bandwidth, cooling, etc. You just have to keep working at it until you find the balance that you are looking for. First wall I ever built in this car for my 2 lvl 6 18s on a dc 9k barely did a 147.x sealed at 40/41hz, with a port area of ~150 sq inches. Rebuilt the wall with about 260-270 sq inches of port and am now doing a 152+ sealed at 40hz (peak higher than that, was just only tone I had available at the time) immediately after dropping the subs in, no changing anything and not even sealed off. Guess what I'm trying to say, if you're thinking of rebuilding then try to give yourself as much usable area at the beginning, that way you can shrink from there. You can always reduce it without having to do much work, just slap more layers of wood in there, however there's no increasing it without cutting something or rebuilding. Again, just want to say this was a really great read and helps explain a few things I've had questions about before...lots of knowledge in here folks Also want to add about the sub moving less around your tuning/peak frequency, I had always heard like some others that the more port area you have the more the sub excurts and the less cone control you had because the more port area you have the more it acts like an IB setup (for example). But after increasing my port area by almost twice as much I can say that around 40 hz (close to peak for both setups) my subs now move less. Like barely moving at all, yet I'm ~5 db louder sealed up. Was interesting to read some of you guys say how that works, makes a little more sense now Again one of the reasons, why not to listen to some people. More port area= louder, obviously at a certain point the port area increase vs dB increause percentage will drop. Ported box= helmholtz resonator, the better the waves are combined, the louder. Back wave inverted by 180° + front wave= max efficiency That design obviously means there will be a huge peak at a certain frequency. Everything is a compromise. Thinking is the root of all problems... You ALWAYS get what you pay for. Link to comment Share on other sites More sharing options...
Jessica Posted June 21, 2015 Report Share Posted June 21, 2015 this still has me scratching my head, because one would think at one point it would start acting like a very poorly designed t-line. Rest in peace, walled 87 accord build log 03' Corolla build with AA Mayhem inside. My super random youtube channel and terrible camera work. Wiring comparison by CaptainzPlanetz Wire and fuse guide by Guest SyKo13 Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted June 21, 2015 Report Share Posted June 21, 2015 this still has me scratching my head, because one would think at one point it would start acting like a very poorly designed t-line. You are correct, that's exactly what happens if the port gets to be too long. But that happens because of port length, not port area. Usually with the large enclosures you see people use for SPL purposes, the port is relatively short, so any port resonance issues are going to be at such a high frequency they aren't a problem. Its small, low tuned boxes with lots of port area where it can become an issue. I try to keep ports shorter than 50" for this reason. "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...
Kyblack76 Posted June 22, 2015 Author Report Share Posted June 22, 2015 Good info guys..... hot damn.... I think i may just leave this wall the way it is, and when i rebuild, keep some things in mind appreciate all your help SMD SUPER SELLER The Burban Build Blazer Build sold Acura trunk build sold Link to comment Share on other sites More sharing options...
ChevyBoy95 Posted June 22, 2015 Report Share Posted June 22, 2015 Good info guys..... hot damn.... I think i may just leave this wall the way it is, and when i rebuild, keep some things in mind appreciate all your help im in the same boat... 99% on a rebuild... and hope it turns out. lol Best Score to Date : 160.5 dB Outlaw (47Hz)[4 XM 15's & 2 Taramps Bass 12k's] BL : http://www.stevemeadedesigns.com/board/topic/147800-chevyboy95s-4-15s-7krms-wall-1533-db-on-half-power/YouTube: http://www.youtube.com/hitemwiththeflex/ Link to comment Share on other sites More sharing options...
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