total sound quality, spl not the issue

[tcguy85 10+ year member]

Given the OP's requirements, I can't see why introducing a peak in the system's response is desirable in any way.

since when does ported always mean peaky? my setup is not peaky at all. winisd maps out an almost completely flat response.

or am i wrong and this looks peaky?

 

[Ptown_TSxxx 10+ year member]

winsid

 

[tcguy85 10+ year member]

winsid
yes obviously there is cabin gain and every car creates different response but this gives you a good idea. at least i know it has somewhat flat response. and this just proves that not all ported boxes create a large peak. that slight peak you see in that graph is a .3 db gain, it's nothing. it's completely flat until 38hz, then is SLOWLY starts to roll off to -3db at 28 hz. so it's +/-3db from over 200hz down to 28hz before cabin gain.

 

[2004alpinewhite 10+ year member]

Well the intent here is basically just trying to push the sound into the front of the vehicle... With the way my car is made, being a convertible.. the whole trunk is sealed off... if you fold down the seats there is nothing but solid steel.. The sound just dies when it hits it... So the thought was to place a port through the 9x8 hole that is in the center of the metal slab to get sound into the front cab.. I just took some measurements and realized that I have less room than I previously though.. So my thought is basically that I can use ten inch subwoofers, which will obviously drop off sooner than a 12.. If I tune the box at the right frequency, I should be able to get the most out of the bottom end of the subs... And since I have the audiocontrol dqs (sexiest piece of equipment EVER) I should be able to get rid of any peaks that occur.. I am actually floating between two different ideas right now.. Possibly either 2 tens which are in a ported isobaric chamber leading into the cab OR I may possibly be able to fit 4 eights in two separate isobaric chambers.. Anyone here used isobaric chambers lately? I realize this isn't a frequently used approach, but with my space constraints (along with a lot of room needed for amps and other equipment) I think it may be my best option?

 

[2004alpinewhite 10+ year member]

This is what I had in mind when I said 4 8's by the way.. Would only require the airspace for little more than one vented 8, but would be able to offer the output in excess of 2 ported, probably closer to 3.. I know they say you get the same output from 2 drivers in isobaric as you do from 1 in regular configuration, but I have found that there is a definite addition from personal experiences..

 

[JimJ 5,000+ posts]

If you want the sound in the front of the vehicle...start there //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

How do you have your midbasses installed? You have the makings of a pretty nice front stage there, so it'd be a shame to be losing midbass and have a sub that pulls the stage back //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[2004alpinewhite 10+ year member]

If you want the sound in the front of the vehicle...start there //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
How do you have your midbasses installed? You have the makings of a pretty nice front stage there, so it'd be a shame to be losing midbass and have a sub that pulls the stage back //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

This is very true... I actually was out in my car searching for any possible mounting location up front for any size sub, wether its small in diameter or very shallow.. there's really no hope up front for fitting any sort of sub.. I am going to have the 6.5s from the es-643 set in the doors, which will have to be modded slightly to fit but that's ok.. I'll probably throw on a nice layer of sound deadener or two in the door panel and reinforce it with some fiberglass.. If all shit hits the fan once I get into it, I may end up fabricating something to attach to the door and just shave out the inside of the pannel to make room.. Either way.. I've used the speakers in my last vehicle, and while they do get some midbass its not a lot.. The high end is freaking crystal clear though for sure, and they'll still punch to pull the sound to the front of the cab.. I will also have all of these time aligned so that the subs will be firing inline with the front soundstaging.. I definately hear your concerns about making mud out of the soundstage though... Also though... I have only ran these components with their passive 3-way crossover in the past, so once I go active and actually mess with the cross points I may be able to get a little more out of them.. I may be able to get a little bit lower end out of the 4"s, to reduce the distortion in the 6.5"s at higher levels.. But everything being said... what would you recommend in order to preserve the staging? My last vehicle was a land rover, so I only had 1 ten in the back and it was more than enough (being completely open air). I had an amazing stage presence in my land rover, and I am definately trying to take it even one step further this time.. My main concern is just getting the clean bass up-front.. Because the subs HAVE to be in the rear, and with the top down it makes sound travel very difficult.. (I'm sure this is self evident.. being that the roof essentially folds down into space BETWEEN the trunk and the ears of the passengers).. If I buy anything over an 8, it will have to be mounted facing upward, because there is only about 10" of space vertically.. There is actually the possibility for mounting an 8 incher IN the center of the backseat.. There is an 8.5 x 9.25 hole to enable skis to fit into the vehicle.. I could mount a single 8 in that hole.. But it would have to be one ****ing hell of an 8! cause I still need to feel the bass you know? But I definately need the sound quality as well.. Does anyone know anything about he actual sound QUALITY of the w7? I know its obviously one beast of an 8, but aside from being able to pound does it hit crisp and clean? AND do you think that one 8 would be enough low end to satisfy my thirst?? I do not need pounding bass, but I need to have enough there to be able to get a flat response out of my system all the way down to 20hz.. This is my ultimate goal.. A flat response from 20 - 20,000 (dont think i'm completely naive and think it's attainable.. But hey, if you dont shoot for the best where will you end up, right?) ..

 

[BrianChia 10+ year member]

The Dayton Reference HF sub is THE lowest distortion subwoofer available under $200--as far as SQ goes, you will not find anything better for the price; probably not for twice the price either. I would start with any sub in that series. For a flat response, I'd recommend a sealed enclosure with active EQ. A vented box is certainly feasible but in a car you should be able to EQ a flat response to 20hz more easily with a sealed setup.

 

[helotaxi 5,000+ posts]

yes obviously there is cabin gain and every car creates different response but this gives you a good idea. at least i know it has somewhat flat response. and this just proves that not all ported boxes create a large peak. that slight peak you see in that graph is a .3 db gain, it's nothing. it's completely flat until 38hz, then is SLOWLY starts to roll off to -3db at 28 hz. so it's +/-3db from over 200hz down to 28hz before cabin gain.

Once you add cabin gain to that response curve you end up with a big peak at the corner freq. Cabin gain is usually best modeled with a 6dB / octave rise starting around 100Hz and increasing as freq decreases. Think the inverse of a sealed box's response on the bottom end since they typically roll off at around 6/dB / octave. Now throw the ported response in there and the cabin starts to boost well before the box starts to roll off and when the box does roll off, it's twice as steep. Sounds like a big response peak to me.

 

[tcguy85 10+ year member]

Once you add cabin gain to that response curve you end up with a big peak at the corner freq. Cabin gain is usually best modeled with a 6dB / octave rise starting around 100Hz and increasing as freq decreases. Think the inverse of a sealed box's response on the bottom end since they typically roll off at around 6/dB / octave. Now throw the ported response in there and the cabin starts to boost well before the box starts to roll off and when the box does roll off, it's twice as steep. Sounds like a big response peak to me.

well whatever..... it sounds great to me so i'm sticking with it.

 

[audioholic 5,000+ posts]

well whatever..... it sounds great to me so i'm sticking with it.

No, not whatever, he is exactly right, and you have shown your lack of experience. You boast about your flat freq response, and then show a modeled graph of out-of-car response as proof. Sure, standing out in the middle of a corn field, that would have a rather flat response. But, in your car, its not flat.

 

[Electrodynamic 10+ year member]

No, not whatever, he is exactly right, and you have shown your lack of experience. You boast about your flat freq response, and then show a modeled graph of out-of-car response as proof. Sure, standing out in the middle of a corn field, that would have a rather flat response. But, in your car, its not flat.

Right. In the perfectly designed subwoofer system (and I mean the box and the sub together - not just the speaker alone) the bottom end would yield a perfectly flat response.

...if that's what you're into.

There are a LOT of people that like an exaggerated low-end and there are considerably fewer people who like a perfectly flat response. The great thing about this industry is that there are enough people who like both types that it keeps every system different from the other. Not to mention the plethora of subwoofers out there that work in both sealed and vented alignments so the end user can have whatever they want with a single speaker.

But anyway, is a ported alignment typically flat? No. It is easier to avoid peaks and keep your overall sub-stage response curve flat with a sealed alignment. But that doesn't mean that its how you prefer your subwoofer to sound.

The Mag's in the Integra had a very flat response curve, but I wanted to port them SO BADLY on numerous occasions because it was so much more fun to pound the bejesus out of yourself when listening to ported Mag's or BM's. (Yes, Hoss, that was a reference to your truck)

 

[Immacomputer 10+ year member]

Once you add cabin gain to that response curve you end up with a big peak at the corner freq. Cabin gain is usually best modeled with a 6dB / octave rise starting around 100Hz and increasing as freq decreases.

But cabin gain is rarely ever just a pure 6dB/octave slope. The transfer function in my car is pretty weak from 60-100hz and then from 35-45hz it peaks pretty high with 20-30hz having not too much of a gain. I've measured my transfer function with a sealed and ported enclosure and I got very similar results.

Basically, I get a peaky response, sealed or ported, unless I tune real low. The closest I have come was with my IDQ ported tuned to 30hz. Its only problem was the 25-35hz area where is really lacked output. Sealing my av12 also had the same problem with low end and there was a noticeable peak from 38-45hz.

 

[Electrodynamic 10+ year member]

But cabin gain is rarely ever just a pure 6dB/octave slope. The transfer function in my car is pretty weak from 60-100hz and then from 35-45hz it peaks pretty high with 20-30hz having not too much of a gain. I've measured my transfer function with a sealed and ported enclosure and I got very similar results.
Basically, I get a peaky response, sealed or ported, unless I tune real low. The closest I have come was with my IDQ ported tuned to 30hz. Its only problem was the 25-35hz area where is really lacked output. Sealing my av12 also had the same problem with low end and there was a noticeable peak from 38-45hz.

Good point - transfer function does differ from vehicle to vehicle and it's also dependent upon where you place your subwoofer and what direction it's firing.

 

[audioholic 5,000+ posts]

If we want to get technical, transfer function shouldn't really change with speaker placement/aim, but wave interferance (constructive and destructive) will, which will of course alter system frequency response as well. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

edit: On second thought, aiming will also alter amplitude of the transfer function just not the frequency, which makes what Electrodynamic said true. (ie: aiming at plastic interior panels versus aiming at a reinforced steel panel)