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Old 11-13-2012, 09:00 PM   #1 (permalink)
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Default Need subwoofer help

I'm very dis-satisified with the performance of my sub, it's producing a lot of distortion with many types of bass. I'm looking for some advise to either improve it's performance or what I should replace it with to get better performance. Btw - my idea of performance in a sub is no matter what I throw at it it can accurately reproduce the sound. I could care less if everyone in the Walmart parking lot can here it or not as long as it sounds clear inside the car. I listen to everything from Frank Sinatra to the Beastie Boys, to the Black Keys.

I've got a rockford fosgate shallow loaded enclosure (truck style) in the trunk of my 2006 Subaru Legacy. I need to maintain trunk space for traveling, which is why I chose the shallow enclosure. I'm pushing 500W max to the sub using an Alpine MRP-M500. The sub is aimed toward the front of the car with the ski-bag pass through open to vent the sub to the cab of the car. There is an amp rack seperating the sub from the rest of the trunk. I'm using a Kenwood KOS-V500 head unit to control the whole thing and I have the sub crossover setpoint at 60 hz with a gain set at +2.

I hope I included enough info. If there's anything I left out please ask questions.

Thanks in advance!
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Old 11-13-2012, 10:17 PM   #2 (permalink)
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Is the sub designed to be in a ported box or sealed box? Polarity wired up correctly?
Sure the amp is working correctly? See if someone in your area can analyze the signal on an oscope to make sure the signal isn't clipping.
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Old 11-14-2012, 11:21 AM   #3 (permalink)
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The sub came from the manufacturer in the enclosure. The entire system was installed professionally, BUT I chose the sub and how and where to mount it.
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Old 11-14-2012, 12:23 PM   #4 (permalink)
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Alpine amps aren't known for clean sound. Rather, they're known for hyperbolic claims of power based on peak output and not RMS.

Also, do you have Rockford woofers installed in your enclosure? If so, you're golden there. But if you've got some cheap woofers installed, that would also cause distortion problems.

First, I would recommend replacing your Alpine amp with something from Rockford or Kicker. Don't worry about output numbers. A 40 Watt amp from Rockford or Kicker will stomp all over a "200 Watts!" amp from Alpine. Kicker and Rockford outputs are based on RMS, and not peak like other amps.

Also, what kind of head are you running? Again, if it's something that's not putting out a clean signal, you'll get distortion.

Based on the objectives you listed in your post, you need a head and an amp with very low harmonic distortion. Focus on that rather than peak power output and I think you'll be very happy with the sound you get.
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Old 11-14-2012, 08:08 PM   #5 (permalink)
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Quote:
Originally Posted by Klutch View Post
Alpine amps aren't known for clean sound. Rather, they're known for hyperbolic claims of power based on peak output and not RMS.

Also, do you have Rockford woofers installed in your enclosure? If so, you're golden there. But if you've got some cheap woofers installed, that would also cause distortion problems.

First, I would recommend replacing your Alpine amp with something from Rockford or Kicker. Don't worry about output numbers. A 40 Watt amp from Rockford or Kicker will stomp all over a "200 Watts!" amp from Alpine. Kicker and Rockford outputs are based on RMS, and not peak like other amps.

Also, what kind of head are you running? Again, if it's something that's not putting out a clean signal, you'll get distortion.

Based on the objectives you listed in your post, you need a head and an amp with very low harmonic distortion. Focus on that rather than peak power output and I think you'll be very happy with the sound you get.
Klutch, thanks for the feedback. The sub is RF in a RF enclosure. The Alpine amp is rated at 0.08% THD @ 300W x 1 @ 4ohms (which is what I'm running). The head unit is actually a brain hidden in the trunk controlled by a touch screen. I can't find the THD level of the pre-outs listed anywhere for the head unit.
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Old 11-14-2012, 08:39 PM   #6 (permalink)
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Originally Posted by quik View Post
Klutch, thanks for the feedback. The sub is RF in a RF enclosure. The Alpine amp is rated at 0.08% THD @ 300W x 1 @ 4ohms (which is what I'm running). The head unit is actually a brain hidden in the trunk controlled by a touch screen. I can't find the THD level of the pre-outs listed anywhere for the head unit.
No doubt that 300W is peak output. I'd be interested to know what the RMS output is. That's the true measure of an amp's capability. If the RMS output is pretty low, or the amp simply doesn't do a good job of maintaining a strong output, that could be why you're not getting a good, clean sound.
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Old 11-15-2012, 08:24 AM   #7 (permalink)
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Quote:
Originally Posted by Klutch View Post
No doubt that 300W is peak output. I'd be interested to know what the RMS output is. That's the true measure of an amp's capability. If the RMS output is pretty low, or the amp simply doesn't do a good job of maintaining a strong output, that could be why you're not getting a good, clean sound.
Whoops, sorry. I forgot to include that the 300W is RMS output, not peak.

It sounds like you have some experience with RF subs. I'm using an earlier version of this:

PRIME Loaded Enclosures - R2S-1X10 - Rockford Fosgate®

Are they good subs?
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Old 11-15-2012, 09:34 AM   #8 (permalink)
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Whoops, sorry. I forgot to include that the 300W is RMS output, not peak.

It sounds like you have some experience with RF subs. I'm using an earlier version of this:

PRIME Loaded Enclosures - R2S-1X10 - Rockford Fosgate®

Are they good subs?
300W RMS? Pardon me for being skeptical. But I'm skeptical. I'm not familiar with that particular sub. But I know Rockford makes good hardware. I lived in Phoenix when and where they first started out back on the 70s.
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Old 11-15-2012, 10:18 AM   #9 (permalink)
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Back in the mid '80's I was running a RF Punch 150 pushing two subs wired up for 2 ohms. All this was in a '66 Pontiac Tempest convertible. Built a box out of 3/4 particle board and had it behind the top well.
You could hear that car coming with the top up or down. The headlights would dim with the beat of the music!
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Old 11-15-2012, 10:32 AM   #10 (permalink)
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I think you need a better amp. Get a RF and call them to see what they recommend to push the sub.
I had a RF punch in my old truck. Those subs will thump. But like everything else, you gotta mess with them.
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Old 11-15-2012, 12:54 PM   #11 (permalink)
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From RF website...

Quote:
The R2S-1X10 is a single 10” shallow enclosure with 200 Watts RMS power handling wired to a 2-Ohm load. The enclosure is constructed with 5/8” MDF, covered in high density carpet, and features quick release compression terminals.
Right off the bat, if your amp is actually 300w RMS, you're smoking the speaker. By 50%!
Shallow boxes are cool, but limited in some regards. I think you've got too much amp.
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Old 11-15-2012, 01:32 PM   #12 (permalink)
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I think the sub and enclosure are probably fine for your purposes. With the type of music you listed and the fact that you care more for a clean sound I would have recommend something similar. Here are a few things I noticed in regards to your setup.

1) The Alpine amp isn't bad, but it's a bit to much power for the sub you're using. Even with the gain set minimally you're probably getting some of your problem right here.

2) The RCA pre-outs on the Kenwood controller are 2V. I typically prefer something closer to 5V+. Higher voltage pre-outs are less prone to induced noise and they allow you to turn down the gain on the amp as well. These two factors are often times related to "distortion" issues.

3) What size wiring for power/ground are you using? For that amp it should be at least 8AWG. Also, is any of your wiring running parallel to your RCA connectors?

4) what is the touch screen head unit you're running? I didn't see that listed.
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Old 11-19-2012, 12:06 PM   #13 (permalink)
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Quote:
Originally Posted by TXMAG View Post
I think the sub and enclosure are probably fine for your purposes. With the type of music you listed and the fact that you care more for a clean sound I would have recommend something similar. Here are a few things I noticed in regards to your setup.

1) The Alpine amp isn't bad, but it's a bit to much power for the sub you're using. Even with the gain set minimally you're probably getting some of your problem right here.

2) The RCA pre-outs on the Kenwood controller are 2V. I typically prefer something closer to 5V+. Higher voltage pre-outs are less prone to induced noise and they allow you to turn down the gain on the amp as well. These two factors are often times related to "distortion" issues.

3) What size wiring for power/ground are you using? For that amp it should be at least 8AWG. Also, is any of your wiring running parallel to your RCA connectors?

4) what is the touch screen head unit you're running? I didn't see that listed.
After I read your last post I called up a friend and he and I spent about an hour messing with the gain on the sub amp, the cross over settings, and the tone adjustments on the head unit. I'm happy to report that the sub is much happier now and sounded good during Brian Setzer jam sessions and Gorillas Clint Eastwood.

Thanks for all the posts! Turns out all I needed was a kick in the pants to tune the system right.
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