Can a volume of .48cf provide the same level of output as .65cf?
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Bronze Member Username: InvictuzSeattle, Wa Usa Post Number: 54 Registered: Jan-05 | Question: Is a .48 enclosure with a cubic foot of fiber/poly padding going to sound as good as a .65 enclosure? Problem: I have two dual chamber (.50 volume per chamber) enclosures housing four MTX 81044a DVC 10" subs. The recommended sealed enclosure is .65 in volume per chamber. Attempted Solution: Last night I spent five hours on one box beginning with a complete strip down to the wood. I thoroughly resealed every seam with a ketatone (?sp) sealant. After sealant dried for 24 hours I covered every sealed seam with a non-reflective/conductive duct-tape. I took the cloth material that was covering the outside of the box (a grey wool like fabric) and lined the inside of the box with it. I purchased 1.7cf of pillow stuffing material (a fiber/poly blend) and added enough to come up to but not touch the sub (I pressed it down several times). I covered the exterior with a black pleather material. One box is done. Finishing other tonight. Root Cause: When installing my stereo I chose to go with a prefab box until I teach myself fiberglass and box design. I was told a dual .71 volume per chamber sealed box from Subzero was the best choice by the sales rep known as "I have the same (insert product here) in my car" while shopping at a local discount stereo warehouse in Seattle. Based on the MTX data sheet (which I had with me) it appeared this was a good choice so I bought two to house four subs. Over the next year several people questioned my (original) "one amp for one sub" configuration. I had difficulty explaining the benefit of four independent power supplies during deep/fast bass lines over a single power supply. Several people I respect for their knowledge of car audio (including a few on this site) finally persuaded me that a single amp for four subs was better than four amps for four subs (only two people agreed with my original config. Both are SPL competitors still using HCA amps...) After searching for a replacement for my four RF 301m's I decided on the Orion 2500d Immediately I could hear a less than ideal difference in bass. Even after dropping from a 2ohm load (RF 301m) to a 1.3ohm (Orion 2500d) load and the additional 1300w RMS the bass had less impact. It was loud (maybe even slightly louder) but it didn't give you the same quality that made you feel the break beats My first assumption was that the amp settings required adjustment. After a month of trial and error I still did not have a bass that I was happy with when compared to the RF amps It was during this time I discovered I was misled about my sub enclosures. The enclosures actually only had a volume of .50 per chamber. Damn lying sale rep! Take way the volume the subs take up inside the enclosure (huge magnet) and I am below any suggested size from MTX. Suggestions and/or thoughts are welcome and appreciated! Current Equipment*: Alpine 9833 deck Orion 2500d (subs) Rockford Fosgate 301x (two) Rockford Fosgate 1 farad capacitors (four) 4 way fused distribution block (aka 4way block) 2 way fused distribution block (aka 2way block) 250amp fuse at battery MTX 81044 DVC 10" subs (four) Infinity 6000cs components (two pair) Subzero dual chamber/sub sealed enclosure<br> Current Configuration*: Signal wiring: 4 volt from Alpine front output to RF 301x # 1 4 volt from Alpine rear output to RF 301x # 2 4 volt from Alpine sub output to Orion 2500d Power Wiring: RF Capacitors are wired as two sets: Cap 1 and 2 equal Cap Set 1 Cap 3 and 4 equal Cap Set 2 0 gauge from battery positive to 4way block 0 gauge from battery negative to ground 4 gauge from alternator to battery 4 gauge from alternator to ground 4 gauge from 4way block pre-fuse out to 2way block 4 gauge from 4way block to Cap Set 1 positive 4 gauge from 4way block to Cap Set 2 positive 4 gauge from Cap Set 1 positive to Orion positive input #1 4 gauge from Cap Set 2 positive to Orion positive input #2 4 gauge from Cap Set 1 negative to ground 4 gauge from Cap Set 2 negative to ground 4 gauge from Orion negative input #1 to ground 4 gauge from Orion negative input #2 to ground 8 gauge from 2way block to first RF 301x amps positive input 8 gauge from 2way block to second RF 301x amps positive input 8 gauge from first RF 301x amps negative input to ground 8 gauge from second RF 301x amps negative input to ground Speaker wiring: MTX 81044 Ohm wiring (1.3 ohm): 2 subs are configured as MTX Set 1 2 subs are configured as MTX Set 2 Coils are wired in series Subs are wired in parallel 12 gauge from MTX Set 1 to Orion positive speaker input #1 12 gauge from MTX Set 2 to Orion positive speaker input #2 12 gauge from both RF 301x to Infinity 6000CS<br> *= Original equipment/configuration (only differences listed): Rockford Fosgate 301m Mono block amplifier (four) 4 gauge from 4way block to Cap #1 positive 4 gauge from 4way block to Cap #2 positive 4 gauge from 4way block to Cap #3 positive 4 gauge from 4way block to Cap #4 positive 4 gauge from Cap #1 to RF 301m #1 4 gauge from Cap #2 to RF 301m #2 4 gauge from Cap #3 to RF 301m #3 4 gauge from Cap #4 to RF 301m #4 4 gauge from RF 301m to MTX 81044 #1 positive 4 gauge from RF 301m to MTX 81044 #2 positive 4 gauge from RF 301m to MTX 81044 #3 positive 4 gauge from RF 301m to MTX 81044 #4 positive Each MTX 81044 was wired to present 2ohm load in this configuration. Again suggestions and/or thoughts are welcome and appreciated! |
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Gold Member Username: InsearchofbassPost Number: 3038 Registered: Jun-04 | ok this is right up my alley since ive been around the mtx 8000 10's first of all the sealed box just doesnt cut it from what others have told me and after i modeled it on a computer program for subs sure enough my suspesions were right adjusting this persons enclosure size to after sub displacement volume. I have heard this single voice coil sub in mtx's recomended 1 cf ported gross box size tuned to 37 hz which mtx recommends and the sub sounded very pleasing from an sq point of view and the spl was aprox 130 db running 800 rms out of my mtx 81000d. Now one thing i did notice is that the mtx amp needed alot of gain and bass boost to do this and my car was bad for spl as well with this box. As far as the multiple amp combo I would agree that one to each sub would be better than 1 total amp and i have personally heard the difference doing it that way. I feel that just the reserve capacity alone on four amps would be greater than one big amp. So your results are not suprising to me. experimenting with placement might be one possible solution to your sound characteristics with your 10's and you might gather a couple of db in the process. |
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Silver Member Username: AlpineuserWinchester, TN Post Number: 604 Registered: Mar-05 | sorry A.D.D set in and i couldnt read that. |
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Gold Member Username: InsearchofbassPost Number: 3042 Registered: Jun-04 | They have meds for that. |
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Silver Member Username: AlpineuserWinchester, TN Post Number: 607 Registered: Mar-05 | yea they make me h0rny |
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Gold Member Username: InsearchofbassPost Number: 3044 Registered: Jun-04 | sounds like a problem |
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Silver Member Username: CheapskatePost Number: 169 Registered: Mar-04 | lowering cabinet volume usually increases deepest bass volume. the smaller the box... the higher the resonant frequency. smaller boxes ten to roll the bass off, but also tighten it up too as the smaller airspace tries to pull the woofer back harder. that's a rule of thumb answer. the ACTUAL answer depends on any woofer's thiele small parameters. different woofers will have different outputs in the same box, mostly due to their resonant frequency. it's POSSIBLE that you could actually get more output from a smaller box if the Q emphasizes the woofer's resonant frequency, but generally... bigger airspace = deeper bass extension & smaller airspace = a tighter airspring holding the woofer. the same thing also applies to ported woofers too. larger airspaces have lower resonant frequencies. if you blow across a 16 oz. soda bottle, then across a 2-3 liter bottle... the bigger bottle will resonate deeper. getting deep bass is all about moving air. |
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Silver Member Username: Daddy_phat_sackPost Number: 268 Registered: May-05 | i bet that took an hour to type..... id do it if i wasnt so fukin lazy.... lol |
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Bronze Member Username: InvictuzSeattle, Wa Usa Post Number: 58 Registered: Jan-05 | UPDATE: When finishing the second box i also decided to drop back to a 2ohm load as the 81044 has a 400w RMS and the Orion 2500d puts out 1700w RMS @ 2ohm. Sean i did play with placement for about two months. First: i had each enclosure places against the side walls (each box had one sub near the rear of the back seat and one sub close to the liftgate) with the subs facing the ceiling. The enclosures have a slight angle on the sub panel. So you could draw a straight line from the center of the sub outwards and that line would intersect with the line from the sub across from it about 4"s above the roof of my jeep. Then I put both enclosures parallel with the liftgate. Finally I built a shelf about 7" from the floor and placed them parallel with the liftgate (the amps and caps sit under the shelf) which is how they currently sit. The MTX engineer I have been working with suggested the .65 cf enclosure. (the spec sheet that came with the subs indicates an ideal size being .63; either way substantially more volume than I have) Budget I have not noticed deeper bass (but it has only been a few hours) . I have noticed what I can only describe as a more controlled sound. Brandon Yeah the original write up did take some time...now I just cut an paste from my cardomain page or previous post when I was researching amps in Jan. I am still hoping some can answer my question regarding a padded volume versus a slightly larger non-padded volume. Will the benefit of a larger sealed chamber justify the cost or would i simply be wasting money? |
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Bronze Member Username: InvictuzSeattle, Wa Usa Post Number: 63 Registered: Jan-05 | is there a definitive answer to this question: If you add 1cf poly/fiber fill to an enclosure with .50cf in volume will it sound as good as an eclosure with .65cf? |
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Gold Member Username: CarguyPost Number: 3400 Registered: Nov-04 | Your first choice is to have proper box size. If that's not possible, then pollyfill is your next logical choice. It will improve the sound. |
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Bronze Member Username: InvictuzSeattle, Wa Usa Post Number: 65 Registered: Jan-05 | I am willing to replace the boxes if it will make a noticable diffence. My concern that i will not hear any difference between the larger enclosure versus the smaller but padded enclosure... Will the diffence be noticable? |
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Gold Member Username: CarguyPost Number: 3401 Registered: Nov-04 | In theory, it's suppose to be the same, however, you can never be sure unless you test it. I don't think you'll notice that much of a difference. The purpose of pollyfill is to fool the sub into thinking it has a larger box. |
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Bronze Member Username: InvictuzSeattle, Wa Usa Post Number: 68 Registered: Jan-05 | good info! thanks... last night i began looking into building my own box (for the third time in a year)... i am considering adding two more subs (they have been sitting NIB in garage for a year)... ...which leads me to my next question: Should i stay with sealed enclosures with six 10s on an Orion 2500d? |
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Gold Member Username: InsearchofbassPost Number: 3058 Registered: Jun-04 | ok from what i remember reading with a .50cf box minus the subs displacement which is .08 i think that brings you down to .42 cf for the sub. With a box this small youll have to put sparing amounts of poly loosely inside id say less than half a pound to half a pound in each box which will bring you to as much as .60 cf each sub. Another idea i had for you will sound strange but if your game try it for me. This will require no modifications to your prefab boxes take a piece of wood and place it on each side of the boxes preferably mdf and place two of the subs firing left and right then put a top piece and bottom piece and screw the pieces of wood together as if it was a box and have about three inches from your vehicles walls. Do the same with the next set of woofers and have about 3 inches from your vehicles walls again. Also place the boxes at the centered postion of this enclosure back to back of each other. This would give you a bandpass effect with corner loading. And it may sound better than you think if my hunch is right. |
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Bronze Member Username: InvictuzSeattle, Wa Usa Post Number: 70 Registered: Jan-05 | Sean: I based the fill on Tom Nousaines article on padding enclosures... earlier today i was looking at single reflex band pass numbers when the t81044 is used While it did offered higher db, it did so when tuned to a high 74hz... I am willing to give your suggestion a shot...give me the weekend to get back to you. Couple of questions: can you send the direction (with as much detail as possible) to me via email (included with this post) use the word "bandpass" in the subject line for filtering. based on these dimensions can you provide a the size and steps to implement this design: Each box is: 30" wide, 13" in height and 11.8" top / 8.3" bottom in depth. thanks again...i will give this a shot over the weekend. |
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Gold Member Username: InsearchofbassPost Number: 3060 Registered: Jun-04 | Thats the same article i read to understand what I told you as well. http://web.archive.org/web/20020808224043/integra.cyberglobe.net/caraudio/resour ces/fiberfill/ |
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Silver Member Username: Koz1031Monticello, In United states Post Number: 394 Registered: Jul-04 | you could also invert the subs to gain the .08 airspace that they take up and add extra poly. it seems to work on some subs but not oon others. if you try this remember to invert the wiring also. |
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Gold Member Username: InsearchofbassPost Number: 3064 Registered: Jun-04 | good point koz i didnt think of that and yes this suggested idea im giving Invictuz is from our discussion we had the other day thanks to you sharing some things |
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Bronze Member Username: InvictuzSeattle, Wa Usa Post Number: 74 Registered: Jan-05 | Sean/Koz, Can you send me your suggestion via email to  a simple list of suggestion materials and size scale or simply the measurements based on a box: 30" wide, 13" in height and 11.8" top / 8.3" bottom in depth thanks again for taking the time to answer... I will give this a shot on saturday... |
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