Does Box Shape Matter?

[mossman]

If the alternator is being current-starved, I would expect to see that in the form of a voltage drop measurable with your multimeter. A clamp-style meter will allow you to observe the difference in current going through the circuit with ignition off/engine running.

I quickly measured it a week ago when I noticed the issue, but I'll measure again. I recall the voltage not dropping much.

A smaller enclosure will sound "punchy" in the form of increased upper bass energy, but does so at the expense of lower bass energy...it will need more power to reach maximum output down low compared to a larger enclosure (which is generally more efficient). With small adjustments in enclosure volume, the differences in efficiency are also small.

Honestly, the IDQ10 has a little too much lower bass energy. It wants to rattle my car to pieces when played below 50 Hz. I find myself constantly adjusting the bass knob. Hip hop songs are overwhelming and rock isn't loud enough. This isn't what I want. I primarily want tight, punchy, and higher response, but also want it to sound good when playing hip-hop or reggae, but not overwhelming. This is why I'm thinking maybe two 8's is the way to go. One IDQ8 in a 0.53 sealed enclosure sounded really good to me, but I wanted more kick, which is why I went with the IDQ10. I have more kick now, but it's too damn loud when the lower notes hit. Maybe I just need some EQ to tame the lower and boost the higher? My Audio Control DQDX has a 7-band EQ on the sub channel.

Does your vehicle's head unit have a speed-sensitive volume circuit? The RNS-510 head unit in my VW had that, and I found that to be annoying and turned it off in the settings.

It does, but I have it turned off. And I can be sitting stationery at idle, turn the engine off, and the sub gets at least 6dB louder.

[mossman]

...also wanted to mention that my IDQ8 blended better with my 6.5" components. So much so that it was difficult to perceive the transition. With the IDQ10, it's very noticeable.

And I'm assuming it is always better to modify the enclosure to get a flat response as opposed to using EQ?

[basicxj]

Originally Posted by mossman Honestly, the IDQ10 has a little too much lower bass energy. It wants to rattle my car to pieces when played below 50 Hz. I find myself constantly adjusting the bass knob. Hip hop songs are overwhelming and rock isn't loud enough. This isn't what I want. I primarily want tight, punchy, and higher response, but also want it to sound good when playing hip-hop or reggae, but not overwhelming. This is why I'm thinking maybe two 8's is the way to go. One IDQ8 in a 0.53 sealed enclosure sounded really good to me, but I wanted more kick, which is why I went with the IDQ10. I have more kick now, but it's too damn loud when the lower notes hit. Maybe I just need some EQ to tame the lower and boost the higher? My Audio Control DQDX has a 7-band EQ on the sub channel.

The idea that an 8" will be punchy and a 10" will be boomy (all other factors being equal) is a myth perpetuated on the internet. Enclosure and cone size will have more effect on the response curve of a given sub.

With that said, the larger sub will be slightly louder per watt of input power and will play lower more effortlessly- a good thing- I would experiment like we discussed to adjust the response of the 10 before doing anything drastic, and then level match by turning down the gain so output of the woofer is better balanced with output of your mids. Making the enclosure smaller will also roll off some of those lower frequencies. As for blending, try reversing polarity of the woofer- this will often bring the bass more "up front" but keep in mind that in many recordings audio engineers don't pay the most attention to whether the lowest frequencies are "in phase" or not and you may have to toggle phase back and forth as phase varies from song to song...I could do that from my head unit with two clicks, so for you it may pay to set it for the majority of music you play rather than to tweak it so frequently.

What I did with my compact enclosure was to add a few db's of parametric EQ to frequencies where the enclosure rolled off (40hz to 20hz) to normalize the response a bit while retaining the kick of the upper frequencies for a more consistent response curve rather than a peak up high. I measured with an RTA app and felt the experiment was a success in getting the best of both worlds with a good SQ 12" woofer (my Polk SR 124, which needed less help down low than my JL Audio 10W6v2).

Originally Posted by mossman It does, but I have it turned off. And I can be sitting stationery at idle, turn the engine off, and the sub gets at least 6dB louder.

If you were being current starved, you actually have less current with the ignition off than with engine running- just sayin' .

Does the sub get quieter with engine running if you turn on high beams and defrost?

[mossman]

The idea that an 8" will be punchy and a 10" will be boomy (all other factors being equal) is a myth perpetuated on the internet. Enclosure and cone size will have more effect on the response curve of a given sub.

What I was getting at is I know I like the response of the IDQ8 in the sealed enclosure, but I want more kick. Will adding a second IDQ8 give me the kick I want? Moreso than a single 10?

If you were being current starved, you actually have less current with the ignition off than with engine running- just sayin'.

My assumption is with the car on, the other systems in the vehicle are using up the available current, including that delivered by the battery. Then with the car off, the full capacity of the battery is available.

Does the sub get quieter with engine running if you turn on high beams and defrost?

Nothing noticeable. But when the engine is shut off, it is very noticeable.

[mossman]

Try throwing something inside the enclosure to displace some air and adjust the woofer's response...a phone book, a brick, something you can measure the displacement of and subtract from the enclosure's known volume to get an idea of what the final volume is and how it affects what you are hearing.

Bags of sand okay?

I should also mention that I lined the interior of the box with 1/2" thick polyfill batting. Could this be the reason for the increased bass 50Hz and below--since polyfill lowers Qtc?

[mossman]

I stuffed as many of my daughter's building blocks inside the enclosure and brought the volume down 0.28 cubic ft to a net of 0.82 cubic ft. It sounds much better now. The lows are no longer overwhelming and it is hitting the high notes like the IDQ8 did. Guess I'm building a smaller enclosure! First I'm going to enlarge the hole from the ported enclosure I built for the IDQ8, block off the port, and install the IDQ10 so I can see what it sounds like with a 0.6 cubic ft enclosure (minimum recommended by ID), then make a decision what volume to go with. I'll likely split the difference and go with 0.85 cubic ft.

[mossman]

I put the 0.6 cubic ft test enclosure in today and it gave me more high end like I wanted but killed a lot of bottom end, as expected. So I think I'll go with a 0.8 cubic ft sealed enclosure as a happy medium, lined with polyfill batting. I guess I should throw some polyfill in the 0.6 box first to see what effect it has actually.

[SPL_Krayzie112]

Originally Posted by mossman Box is finished and I hooked up the sub (IDQ10) yesterday. It is undoubtedly louder, extends lower, and hits harder than the IDQ8, but I have lost some response on the higher end of the spectrum. My test discs don't have enough granularity for me to give exact numbers, but it seems that the response drops off rapidly after 50 Hz. Below that it booms, but above sounds weak. Should I try going with the smallest recommended enclosure volume to see if that will restore the 50 to 80 Hz range? If I had to compare the two, I'd say that I prefer the IDQ8 over the IDQ10 when in their respective enclosures. However, I do like the added kick/punch that the 10" has. So if I can get the IDQ10 to reach higher like the IDQ8 does, I would be happy with that. Reminder that I have my IDQ10 in a sealed 1.1 cubic ft enclosure and the smallest recommended enclosure size is 0.6 cubic ft, which is what I am considering trying next. I am using a Sundown 100.4 amp to deliver up to 320W rms. Additionally, I believe my alternator needs to be upgraded because the sub gets significantly louder when I turn the engine off. IDQ10 frequency response (yellow line = 0.6 ft^3, green = 1.1 ft^3): http://i64.tinypic.com/oqy805.png ...or should I go with two IDQ8's since I prefer their frequency response. Will the combined surface area of two 8's give me more kick/punch than a single 10? If so, that may be the winning combination for me.

Break the subs in first...they will sound ¨easier¨ after the break in period. Try some Bass Mekanik material to break those ****ers in...

[SPL_Krayzie112]

Originally Posted by mossman I put the 0.6 cubic ft test enclosure in today and it gave me more high end like I wanted but killed a lot of bottom end, as expected. So I think I'll go with a 0.8 cubic ft sealed enclosure as a happy medium, lined with polyfill batting. I guess I should throw some polyfill in the 0.6 box first to see what effect it has actually.

Yeah...I was gonna suggest that...if you have extra resources, go straight for the purpose-built sound deadener they have around the internet...

http://www.roxul.com/products/reside...39;n'sound

http://www.homedepot.com/b/Building-...P_PRC_MODE%7C0

http://www.soundproofcow.com/product...ng-insulation/

http://www.audimutesoundproofing.com/

[basicxj]

Originally Posted by mossman I put the 0.6 cubic ft test enclosure in today and it gave me more high end like I wanted but killed a lot of bottom end, as expected. So I think I'll go with a 0.8 cubic ft sealed enclosure as a happy medium, lined with polyfill batting. I guess I should throw some polyfill in the 0.6 box first to see what effect it has actually.

Do try adding a few db's of EQ on frequencies at and below the point bass starts to roll off in the smaller enclosure.

Originally Posted by SPL_Krayzie112 Yeah...I was gonna suggest that...if you have extra resources, go straight for the purpose-built sound deadener they have around the internet... http://www.roxul.com/products/reside...39;n'sound http://www.homedepot.com/b/Building-...P_PRC_MODE%7C0 http://www.soundproofcow.com/product...ng-insulation/ http://www.audimutesoundproofing.com/

Polyfill is better for inside the box, sound deadener is better for panels that vibrate outside the box.

One works by damping the air inside the enclosure and tricking the woofer into "seeing" a larger air space than is actually there, while the other lowers the resonant frequency a panel vibrates at by adding mass...if the enclosure is made of MDF, it is acoustically inert and won't vibrate in an audible way with the frequencies produced by the subwoofer on/in the enclosure- it may help some with plastic enclosures (like some vehicle specific loaded boxes and OEM sub enclosures).

[mossman]

I'll add some polyfill tomorrow and drive around for a week to see if I like it or not. As of now, I don't really like the smaller enclosure, but that may be because the sub needs more power now that there is more spring pressure.

I hate to say it, but I think the 10 may be a little too much. It sounds good, but after a while it starts to tax the ears. I'm contemplating trying out two 8's. I still have the IDQ8 and a JL 8w3v3, so I'd just need to throw together an enclosure.

[basicxj]

Originally Posted by mossman I'll add some polyfill tomorrow and drive around for a week to see if I like it or not. As of now, I don't really like the smaller enclosure, but that may be because the sub needs more power now that there is more spring pressure. I hate to say it, but I think the 10 may be a little too much. It sounds good, but after a while it starts to tax the ears. I'm contemplating trying out two 8's. I still have the IDQ8 and a JL 8w3v3, so I'd just need to throw together an enclosure.

Don't mix and match subs- if you decide on a pair of 8's, use identical woofers. You want pairs of woofers to work 100% in unison.

If the 10 is too much, reduce gain to level match.

[mossman]

Originally Posted by basicxj Don't mix and match subs- if you decide on a pair of 8's, use identical woofers. You want pairs of woofers to work 100% in unison. If the 10 is too much, reduce gain to level match.

It would only be temporary to get an idea of what two 8's would sound like.

I think it may just be a power and gain thing with the smaller box. I have to crank the bass knob up and increase the volume to give the sub enough presence, but then my highs are a little too loud. I can't really explain it. It's like the 10 is choking and wants a larger enclosure, but then it's too f'ing loud with the larger enclosure, but if I turn the gain down, it isn't loud enough in the right places. I may just need to accept that I'm not going to get the bass kick I want and focus more on a balanced system that sounds good. Basically what the 8" sub was giving me, only it wasn't quite enough, which is why I'm thinking two 8's may satisfy.

[basicxj]

Originally Posted by mossman It would only be temporary to get an idea of what two 8's would sound like. I think it may just be a power and gain thing with the smaller box. I have to crank the bass knob up and increase the volume to give the sub enough presence, but then my highs are a little too loud. Things just don't sound as musical with the 10. I can't really explain it. It's like the 10 is choking and wants a larger enclosure, but then it's too f'ing loud, but if I turn the gain down, it isn't loud enough in the right places.

Some time with some test tones, sine sweeps and a measuring device (like an RTA app on a smart phone) and then some well-recorded tracks you know well from listening on a reference system should sort that out .

[basicxj]

Sometimes we have preconceptions of what is possible with a piece of equipment, but some experiments may change our minds (if we care to have that happen).