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2012ScionTC
08-26-2012, 04:07 PM
I have a JL 10W6 with a 500/1 amp, recently built a custom enclosure with 1.89 cubic ft internal vol and tuned it to 31hz. It sounds really good but I'm wondering if I can improve on it and flatten the curve on the graph out a bit to get a little more SQ. Looking for a bit of advice.

Box is 38W x 13H x 10D, Port height 11.5 length 22.75 width 1.5 then 2.0 at port opening (L shaped port).

Looking at the graph in Winisd at +2 db 60hz +3 50hz +4 at 40hz peak, then the curve goes down to +0 at 30hz and drops off.

The sub according to JL is 28.5 hz FS.

In building another box (I have enough materials) some questions.

1. Is it okay to tune the box lower to 28 to flatten the curve and not have such a high peak 40hz, +4db seems a bit high to me.

2. Using a longer port with the same size enclosure to get to 28hz will drop my internal vol to around 1.5 or 1.6. Is my current 1.8 internal vol box too big for the sub and would I be better off at 1.5 or 1.6?

3. Is it safe to tune the box for the 10W6 to 28hz with subsonic filter set to 20hz? Looking at Winisd graphs at 28 hz I have a flatter curve with +3db at the peak across a broader freq range.

4. Port width, 1.5 (jl site recommends) but I have been told to go larger to avoid port noise. 1.75, 2.0? Recommends?

Thanks.

fasfocus00
08-26-2012, 04:11 PM
are you only basing your "curve" on a computer program compared to an RTA that would tell you what is actually going on, if so maybe you should do that before saying you need to flatten the curve considering that most listeners prefer to have frequencies below 100hz 4-8 db above all other frequencies.

kushy_dreams
08-26-2012, 04:16 PM
Win isd doesn't figure in cabin gain, so even if it does model up perfectly flat, it will won't be flat when you put it in the car.

2012ScionTC
08-26-2012, 05:01 PM
I agree with the cabin gain, unfortunately don't have tools at my disposal such at an RTA or other method. Just looking at software and listening to it. The enclosure I built sounds incredible with most music but just wondering if tuning lower etc would give better sound quality. Unfortunately I don't have anything to compare mine to but like I said I have enough materials to build another box and just wondering if I can improve on it and was looking for feedback on the questions I listed above. Once I build the 2nd box I can compare them to see which I like better in the car. I'm also going to build a sealed as well and listen to that.

The car is of course a scion tc hatchback, 130 sq ft of sound deadening, full job.

Julian
08-26-2012, 05:13 PM
Tuning is a fairly arbitrary number -- There are a lot more important factors that will play a role in the FR. Even though WinISD doesn't account for cabin gain, but it can give you a fairly good idea what the FR will be. What are you trying to do? I'm not sure you understand what flattening the FR will do. It will lead to an overall consistent loudness from x Freq to X freq. What are you exactly missing?

2012ScionTC
08-26-2012, 05:25 PM
Not really missing anything, just wondering if I can improve on what I already have as far as SQ. Note my questions on the initial post. I'm just considering tuning the box lower which will flatten the curve a bit in search of improved sound quality. I've heard a flatter curve will give you better sound quality and am researching building another box. If it doesn't work out then I just scrap it and stay with what I have. I'm looking for input that's all.

1. Is it okay to tune the box lower to 28 to flatten the curve and not have such a high peak 40hz, +4db seems a bit high to me.

2. Using a longer port with the same size enclosure to get to 28hz will drop my internal vol to around 1.5 or 1.6. Is my current 1.8 internal vol box too big for the sub and would I be better off at 1.5 or 1.6?

3. Is it safe to tune the box for the 10W6 to 28hz with subsonic filter set to 20hz? Looking at Winisd graphs at 28 hz I have a flatter curve with +3db at the peak across a broader freq range.

4. Port width, 1.5 (jl site recommends) but I have been told to go larger to avoid port noise. 1.75, 2.0? Recommends?

Julian
08-26-2012, 05:30 PM
If you tune lower, your upper end will go away. Now say you increase your overall tuning and make your enclosure slightly larger you will be able to drop well below your tuning of your enclosure while maintaining a good FR.
Model it in winSD and see what happens :)

fasfocus00
08-26-2012, 05:30 PM
seems like you asking for jesus to appear, you keep saying sound quality and sound better. what are you basing this off of? you clearly think that building another box tuned to a lower frequency will solve the issue that you have in your head, i say just do it.

pro-rabbit
08-26-2012, 05:31 PM
When you alter your tuning you have to alter the enclosure. Once you alter the tuning you are taking away or adding net volume(raising tuning adding volume, lowering tuning taking away volume). I would try and do a 2" wide port and drop the height of it to keep a similar port area to what you have now if that is working for your application.

The net volume will also play roll in your response.

Bringing down your tuning should help to smooth out that bump you're getting, but then again your cabin gain may be the cause and if that is the case you will need to use an EQ to get the bump out.

2012ScionTC
08-26-2012, 05:44 PM
Good suggestions in regards to tuning and box size, that's what I was looking for am modeling it now in winisd to see the differences compared to my current enclosure.

In regards to Jesus, haven't seen him post up yet... ; )