4-Channel amps

[1sty]

There could aslo be some flex in the box.
How thick is it?
Some sound deadening material on the inside can help now and again.

Definitly get the pillow stuffing stuff.


Also, to check for air leaks, just push on the subs cone. If it hard to push in and it fires right back out as soon as you let it go, then you have a good seal. If the sub goes in but slowly comes out, then you have a small air leak that most people wouldn't bother with. If the sub pushes in easy and fires right back out, then the seal sucks.

 

[Kid Red]

The box has about 3 layers of fiberglass. It's thick, but I wouldn't go as far as saying it's 'very' thick or anything near 1/4" or anything. I'll pick up some dynamat and that polyfill and check the cone pushing. Thanks.

 

[Kid Red]

I can barely push the sub in, and it kinda grinds when I do. It comes out as soon as I relieve pressure so its hard to gauge fast or slow. I picked up some dynamat stuff and real polyfill and will report back about the affects.

 

[Kid Red]

Just for those wondering, I uploaded all the pics and the tutorial here-
http://www.cardomain.com/ride/2328523

1sty- The Polyfill made a difference, thanks. I'll maybe add a little more to gauge additional affect.

 

[Kid Red]

K, after a few weeks and a bunch of tweaking I'm pretty happy. However, I do have 1 question. Is the ID8 underpowered and how can you tell?

The reason I ask, is everything, all types of music sound perfect at about half volume. Then, once I turn it up past half volume, (I jam at about 3/4 volume) the hard hitting bass notes don't hit as smoothly, and 'boom' sounds tend more to 'bahm' sounds even though the bass tones still carry. At first I thought it was listener position, because I can hear it less the closer I get to the speaker. However, I think that happened at about half volume.

So if the ID8 wants 50w-300w and the Alpine f250 is 40x4 with the 3&4 bridged, what is the ID8 getting? 100w? Or just 50w? And is that at 2 ohm or 4 ohm? Just wondering if I am hearing the ID8's peak performance and tuning it up is showing the Alpine's limits? If so, I need at least another 50w for the ID8 to be really content. It's almost there, maybe a 75x4 would have been a better fit?

 

[1sty]

The alpine is underpowering the sub.
The ID8 wants wants 50-300 which means that in a smaller then reccomended box you want near the 300. In a much larger then reccomended enclosure you can aproach the 50 watt side of the scale. 50 watts is probably all but for only IB setups.

The amp is pumping out 150 watts rms to the sub as it is running a bridged 4 ohm load. Another 50 watts will be theoretically undiscernibly from what you have now. You will need to basicly get to that 300 watt rms figure. Some 75x4 amps can get there but not many and if they can then they are lying about there abilities somewhere.

Also do not consult the alpine website for power rating, they are all screwed up. You have to open up the PDF manual to get the real numbers. Even then pay attention to the THD ratings. For example the website says your amp does 180x1 bridged at .3% THD and the PDF manual gives the ration at 100x1 bridged at .1%THD. Tricky. .3% should be unaudible by the human ear in the bass range so you can probably call it 180 watts.

Just for SG's, if you have the means, try out an MRP-M450 on the sub. That should knock it around NICELY. IF I recall you had a size restriction though right?

Or just get this:
http://www.audio-warehouse.com/web/mdl/TI500.4/detail.asp
(thumb)

 

[chuyler1]

I was sending 775w to a pair of ID8s in my previous install. They can easily take the power. However, they will loose a little low-end when pushed to the limit. It is the downside of 8"s. The upper bass range will always sound fine but as the volume increases they will loose some of the real low end...which you can only truely get with a 15".

Before you go buy a new amp, try playing with the crossover points. Try lowering the front crossover point, lowering the sub crossover point, and raising the gain a little on the subwoofer. Try 50-70Hz for both as a starting point and experiment for a while.

Lowering the crossover point will remove the efficient frequencies that the 8" is playing. Why do you want this? Because that means you will hear more of the lower frequencies where the sub is less efficient.

It's pretty amazing how much crossover points can affect your system. I had my fiance in sit in her car while I turned the knobs on her amp. She didn't exactly understand what I was doing but she knew when to tell me to stop moving the knob.

 

[Kid Red]

Ah, never thought of the xover thing. I have it around 100hz, maybe as low as 80hz, but never lower then that as I thought the sub would add a nice round off to mid bass. Also, the gain is pretty low on the sub channel because that's just where it is to be balanced with the fronts.

I'll play with the xover and gains and see what that does.

1sty- Yea, 10x11 is really the biggest I can go. I'd love to call it a day and get the Alpine PDX-4.150 just don't know if I can justify it.

 

[1sty]

THe other thing that Chuyler just sparked my memory on, is a subsonic filter. If you could get one and have it tuned around 30 hz, that would probably help alot.

 

[Kid Red]

A huh? What? The Alpine supports the tri-way xover- would that do anything?

 

[1sty]

Subsonic filter. It is essentialy a high pass filter that is set very low. So by the Term: Sub-sonic, below the range of hearing. Since most of us will never really hear below 20 hz, a subsonic filter can be used to remove those frequencies so tht the sub is not wasting time trying to reproduce them as it can't anyways as it is an 8" sub in a very small enclosure.

Your amp can not support it. You would need a different amp or expternal crossover.

 

[chuyler1]

Don't worry about it Red. If you had an amp, crossover, or processor that supported it, then I would suggest turning it on to see if it helps. But buying a crossover just for that is a waist. I've played with the one on my amp and it didn't make enough difference for me to leave it on.

 

[Kid Red]

THe Alpine has the subsonic filter, it's engaged when you select low pass filter on the 3 & 4 channels.

I played with the xover and gain and got it a little better. Mostly I have some songs sounding perfect, then some sounds lacking bass and then some songs with the bass getting sloppy on louder volumes. This is mostly from my iPod so in some cases it could be the encoding and original recording. Most songs that suffer from loose bass at higher volume are the older hip hop/bass songs. That could be attributed to those 808 kick drums producing a harder hitting bass note then those of today? I'll keep playing, just hard to be satisfied because when I am, a song comes on that either lacks bass or produces a ton of muddy bass.

Anyone heard of http://earthquakesound.com/TNT.htm ? They have a 4 channel amp, 120w X 4 and would fit my space. I'd have to go with LOCs tho.

 

[1sty]

NEver test or tune with an IPOD, simply put, SQ wise they suck. CD is a bad enough representation of an analog signal then the ipod at best throws away 2/3 of the sampled signal in the hopes of an algorythm rebuilding it.

I can not even count the number of times I have had people tell me that there new system did not sound good and the end result was the IPOD or MP3 player. Examples:

Once at Hearts on Fire in boston, MA. THey had us install a distributed music system and they did not like it as the bass was distorting and poping...amoung other issues. They were using Madonnas Ray of Light as an example of this. It was an MP3 at 320 KBPS. I put in the actual CD and all the issues were gone!

Another time I had a customer that had just installed Boston Pro speakers and a JL 300/2 amp. He said the bass was terrible and not at all like what it had been. After an hour of returing I finanly looked in the deck and found a burt CD. Even though he had a .WAV encoded disc, the tracks were from a 128 KBPS MP3. I put in my recorded copy of the disc, which was all WAV to WAv and again all the problems were gone. I simply gave him my disc and threw his away.

Compresion is compresion and once a part of the music is thrown away it can not be rebuild. Use only CDs. Compression works fine on a completely digital file, a music file really is not all digital. It is simply a weak digital represnetation of an analog signal. This is why super audio CDs are smapled at near 100 khz and not 44 khz like regular CDs. Its also why alot of people like records better then CDs. CDs have a know issue with killing up range harmonics that although we can not direct hear fundamentaly, we can detect them as they interact with the rest of the signal we do hear. From my experiece, MP3s and IPODs have a mjor issue at the exact oppsite end of the spectrum and are terrible in the bass and midbass range and they kill all the impact and detail.


Also, the alpine subsonic filter is very low, far to low to be of much value in your situation. You would need something from 35-45 hz. Like Chylur said though, I would not spend alot of cash for it. If you have a buddy with an amp lying around that can do it, then try it out.

 

[Kid Red]

1sty- Yea, I figured with all my issues, the mp3s might not be the best way. So what, get a few different CDs and use those to tweak the settings?

 

[1sty]

Get the CDs of what you are using on your ipod and compare. See if its a problem with the ipod or atleast teh track on it.

But yes, the best way is to use several different forms of music that you like and all on CD. One major thing to keep in mind that ALOT of people overlook is that you want to use CDs you listen to very often so you are very familiar with the tracks. Otherwise, if you use all new stuff, then you really have no reference to compare it to.

 

[Kid Red]

Just wanted to update- I have the ID8 sounding sweet. Thanks for the CD tip, that made a huge difference trying to tweak it. I also read that if you here the bass localized to lower the hz for the sub. SO I'm at about 65hz or so and have the gain just right. Sounds really good and I have to be really jamming and hear a particular song to get that distorted bass notes. But now I know, it;s the encoding, not my set up.

Thanks guys for all your help.

 

[1sty]

Now you know why I hate MP3's and IPODS.

Its really funny to me to see people dump near $10K into a car or home system to use an IPOD as a source through.

Glad you finaly got it tuned up...good work

 

[Kid Red]

The nature of the beast. It can hold thousands of songs and fit in your pocket and play in your car, in your HT, and in your bedroom then take it to the beach or to a friend's house. Satellite costs $12 a month and doesn't sound that much better. HD radio is really the only option but you need an after market HU and those are ridiculously priced. All we can do is encode better

But again, without you and Chuyler I could never achieved what I have currently. Thanks a million.

 

[1sty]

The nature of the beast. It can hold thousands of songs and fit in your pocket and play in your car, in your HT, and in your bedroom then take it to the beach or to a friend's house. Satellite costs $12 a month and doesn't sound that much better. HD radio is really the only option but you need an after market HU and those are ridiculously priced. All we can do is encode better

Thats why I just travel with my CD case. Its not that big, holds 100 CDs, and is playable in most any home/car/boom box/ or PA system in the world.

By the way, not only do you need the HD aftermarket radio, you need the seperate tuner box as well. I do agree about sat radio though, it sounds like ass.

But again, without you and Chuyler I could never achieved what I have currently. Thanks a million.

No problem, your the kind of student to have.