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Infinity Perfect, underwhelming ?


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jdog0411 
Copper - Posts: 150
Copper spacespace
Joined: January 05, 2005
Location: United States
Posted: May 15, 2005 at 1:13 AM / IP Logged  

I spent the entire day completing my box construction and hooking up my new Infinity sub and MTX 421D amp in my Explorer. The sub is a perfect 12 SVC at 4 ohms, and the box I put it in is a 1 cubic foot sealed enclosure stuffed with polyfill and airtight.

I hooked it all up and turned on the system tonight with the amp set at factory settings and tried to play some songs with lots of bass in them, and at first I didn't even think the sub was functioning. It didn't sound like anything was coming from it, and I could feel no vibrations when I touched the woofer. After some fiddling, I turned the gain up on the amp, and added some bass boost, and made sure my crossover was set at around 80hz. I turned up the volujme on the headunit, and there was some bass, but not really what I was expecting. At least I could tell the woofer was functioning, because the cone was vibrating slightly. There was no visible excursion. I was able to get some increased bass response to where there was output from the sub, but I never really got nearly the response I was hoping for. A couple of things I'm thinking are:

the amp is not overly powerful, putting out 210 watts (spec) RMS at 4 ohms at 14 volt DC, and only 150 watts RMS at 12 volt DC. There would be significantly more power if I was running the amp into a 2 ohm load (300 watts RMS at 12 volt DC and 421 watts RMS at 14 volt DC). I'm stuck with a 4 ohm load because my sub is single voice coil. My first question would be, how do I find out how many volts DC I have going to the amp? Maybe I am only seeing 150 watts RMS and the sub is way underpowered. Even if this was the case, others on this forum have told me they have 100 watts or so going to their Perfect subs and it is still putting out high bass output.

I believe I have everything wired correctly, so I don't think that is a problem. It's possible that the sub just doesn't have enough juice going to it and the combination of that and it being in a small sealed enclosure is making it kind of anemic. I want SQ over raw boom, but from what I have heard about the perfects, I just think I should be getting substantially more output from the sub than I am getting. Granted, I haven't played with the amp settings much or even played the sub very much yet, but any ideas or suggestions on what may be holding it back would be appreciated. Thanks!

2004 BMW 325ci.
Alpine CDA-9885
JL 300/4 and 250/1
JL XR 5.25 comps
Infinity Kappa Perfect 12
OhioMike1101 
Silver - Posts: 343
Silver spacespace
Joined: August 22, 2004
Location: United States
Posted: May 15, 2005 at 1:20 AM / IP Logged  
Did you turn the sub on in the deck?  Did you play with the sub settings on the deck?
racer427 
Silver - Posts: 381
Silver spacespace
Joined: August 04, 2004
Location: United States
Posted: May 15, 2005 at 1:30 AM / IP Logged  

First off, you need to get the gains set correctly.

Second, are you using and external crossover or does the headunit have a built in crossover?

Third, what are your pre out's rated at voltage wise?

Chris

Alpine CDA-9833 HU
Diamond Audio M661 Components
MTX Thunder T6.6 Components:rear fill:
Cadence Q400 4 Channel Mains + rears
Thunder 801D Subs
MTX 1004 10's
Dual 4g wire to rear
4g grounds
jdog0411 
Copper - Posts: 150
Copper spacespace
Joined: January 05, 2005
Location: United States
Posted: May 15, 2005 at 1:33 AM / IP Logged  

Yes, from what I know of my deck (Pioneer DEH-7600mp), I have the sub turned on. There are two settings, "rear speakers" which can be full or subwoofer" and "preout" which can be full or subwoofer. I have the rear speaker setting to full because that channel is my rear door speakers, and the pre-out to subwoofer. I believe I have it set ok on the head unit, but anyone familiar with Pioneers, or this unit in particular, please chime in.

I know the box is usually a culprit with a situation like this,  but Infinity recommends a 1 cubic foot sealed enclosure, and that is what I have it in. I just find it odd that it doesn't sound much if any louder than the basslink I had in before. I just wonder if there is something I'm missing. I don't think there are any connection problems, since I am getting output from the sub, just not as much bass as I thought I would get, even on very bassy songs. It almost sounds like half the bass i'm getting is coming from my kappas in the doors.

2004 BMW 325ci.
Alpine CDA-9885
JL 300/4 and 250/1
JL XR 5.25 comps
Infinity Kappa Perfect 12
jdog0411 
Copper - Posts: 150
Copper spacespace
Joined: January 05, 2005
Location: United States
Posted: May 15, 2005 at 1:41 AM / IP Logged  
racer427 wrote:

First off, you need to get the gains set correctly.

Second, are you using and external crossover or does the headunit have a built in crossover?

Third, what are your pre out's rated at voltage wise?

Chris

Hey Chris, I was hoping you would chime in........I finished the install late tonight, so I didn't have much chance to get the gain set on the amp. i will try to do that properly in the morning. The headunit has a high pass filter setting, that I have set to 125 hz, and it also has a "S/W" setting (which I assume is the low pass filter) that I have set to 80hz. The amp also has a continuously variable crossover. It is not graduated, so I don't know exactly what it is set to. Not sure which of the two I should use, I assume I shouldn't be using both.

According to the head unit manual, the pre-out max voltage output level is 2.2 volts.

2004 BMW 325ci.
Alpine CDA-9885
JL 300/4 and 250/1
JL XR 5.25 comps
Infinity Kappa Perfect 12
racer427 
Silver - Posts: 381
Silver spacespace
Joined: August 04, 2004
Location: United States
Posted: May 15, 2005 at 2:03 AM / IP Logged  

Ok, well, there is one problem that I see so far.

In my experience with MTX amps, they usually like to see a higher input voltage. I am in somewhat the same situation with my 801D. My deck has 4 volt preouts though.

First off, turn the crossover on the amp fully clockwise, this will set the internal crossover at 200Hz and use the crossover setting on the deck. You may have the crossover set real low right now on the amp.

Second, as stated before, get the gains set right.

Third, you may want to add a line driver to the system to get the input voltage to the amp a little higher. If you do this though, buy a high quality line driver. The higher quality line drivers tend to reproduce unwanted noise lesser than cheaper ones.

Fourth, set the Bass EQ on the amp around half way, this will give you a little better bass responce out of that amp.

Let us know whats up after you get all this straightened out.

Chris

Alpine CDA-9833 HU
Diamond Audio M661 Components
MTX Thunder T6.6 Components:rear fill:
Cadence Q400 4 Channel Mains + rears
Thunder 801D Subs
MTX 1004 10's
Dual 4g wire to rear
4g grounds
jdog0411 
Copper - Posts: 150
Copper spacespace
Joined: January 05, 2005
Location: United States
Posted: May 15, 2005 at 2:18 AM / IP Logged  

So it looks like optimally I should get a new deck and a DVC sub :-) Man, it seems like I never have the right equipment for what I want to accomplish. Short of getting a deck with higher output pre-outs, where can I find a line driver? I have never heard of them before.

I was reading the manual on my deck, and it does seems there are quite a few sub settings, so I will play around with them tomorrow. I'll get the gain set right and do all of the other things also to see if it makes a difference. I'm considering just getting the DVC version of the sub as an easy way to get a lot more power out of the amp.

2004 BMW 325ci.
Alpine CDA-9885
JL 300/4 and 250/1
JL XR 5.25 comps
Infinity Kappa Perfect 12
racer427 
Silver - Posts: 381
Silver spacespace
Joined: August 04, 2004
Location: United States
Posted: May 15, 2005 at 2:20 AM / IP Logged  

Well, try all of the other things stated before blowing more cash on a new sub. You may find that after tinkering with things a bit, that it will power up just fine.

I am off to bed now after 3 am here, ZZZZZZZZZZZZZZZZZZZ tired as hell. Post tomorrow after you do some tinkering.

Chris

Alpine CDA-9833 HU
Diamond Audio M661 Components
MTX Thunder T6.6 Components:rear fill:
Cadence Q400 4 Channel Mains + rears
Thunder 801D Subs
MTX 1004 10's
Dual 4g wire to rear
4g grounds
racer427 
Silver - Posts: 381
Silver spacespace
Joined: August 04, 2004
Location: United States
Posted: May 15, 2005 at 2:23 AM / IP Logged  

BTW: I have a Infinity Reference 1230 4 ohm sub that is deceided to hook up today in a sealed box and it pounds like mad. So, don't give up, yes, I have a more powerful amp but, you should be able to get some good results out of the amp that you have.

Chris

Alpine CDA-9833 HU
Diamond Audio M661 Components
MTX Thunder T6.6 Components:rear fill:
Cadence Q400 4 Channel Mains + rears
Thunder 801D Subs
MTX 1004 10's
Dual 4g wire to rear
4g grounds
nismo350z 
Member - Posts: 44
Member spacespace
Joined: February 23, 2005
Location: United States
Posted: May 15, 2005 at 10:17 AM / IP Logged  
If I'm not mistaken the 12" perfects come with the Variable Q inserts. What insert do you have in the right now?
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