Second opinions....

[andrewb70]

I am getting my car ready for a road trip in June, and one of the things that I would like to address is my stereo. The main problem is that I pretty much loose all bass while driving. I realize that this is a common problem, but I feel like the equipment I have should produce more of a low end impact, even when not going down the road. My equipment is not super high end, but it seems to be very decent by all accounts. Here is the breakdown:

iPhone 3Gs
HRT iStreamer (DAC)
JL CL-RLC (sent a 7.5V signal to the amp and acts as the preamp)
Xtant 603e 3 channel amp (150w to the fronts, 300w to the sub)
Boston Acoustics 6.5 Pro 2 way in the front mounted in kick panels
Diamond Audio M5 10" sub (from year 2000) mounted in a sealed .6 cubic foot sealed box. (500w RMS)

The sub box is attached to the bottom of the package tray and fires up at the rear window. After doing some reading, I realize this is not the best option, but I would like to see if I can improve the sound without redoing the box. I have fiddled with the gains and I am pretty happy with the sound while parked, but as I said, as son as I go down the road, the bass is gone. I have a decent amount of sound insulation in the car and my exhaust is not very loud.

In my frustration, I bought a used Xtant 1001e on eBay and it should be here in a few days. I figure throwing more power at the sub might be a first step. I am open to ideas and suggestions.

Andrew

[alocker]

Few things first.

Is the sub free air right now (no enclosure behind sub)? Edit, nevermind, I see that its sealed. Have you considered facing it rearward?
How do you have the amp and speakers wired? I looked up the specs on that amp and your numbers stated are in the 2 ohm load. So, to confirm that you are wired that way, your sub is a dual 4 ohm voice coil model correct?

[JustJohn]

He has a 0.6ft^3 sealed box...

Odd that you lose bass while moving. Do you hear the same effect just sitting still and turning up the volume? 300W to a sealed air sub should be very clean, but not likely to be the resonant boom you hear from ported bass boxes. The first thing I would look at is speaker phase. Try reversing the +/- cables on your sub and see if you hear a difference.

[andrewb70]

Few things first.

Is the sub free air right now (no enclosure behind sub)? Edit, nevermind, I see that its sealed. Have you considered facing it rearward?
How do you have the amp and speakers wired? I looked up the specs on that amp and your numbers stated are in the 2 ohm load. So, to confirm that you are wired that way, your sub is a dual 4 ohm voice coil model correct?

Keep in mind that I am going off memory here, but I believe that the sub has dual 4 ohm voice coils and is wired for 2 ohm operation. I can't imagine that it is anything else because when I got the parts, 12 years ago, I knew that the amp was 2 ohm stable. However, this is definitely something that I need to double check.

I have considered facing it backwards, but that would mean a lot of work, and I am lazy. LOL....I am trying to see if anything else can be done because removing that box would be a major pain in the rear.

Andrew

[andrewb70]

He has a 0.6ft^3 sealed box...

Odd that you lose bass while moving. Do you hear the same effect just sitting still and turning up the volume? 300W to a sealed air sub should be very clean, but not likely to be the resonant boom you hear from ported bass boxes. The first thing I would look at is speaker phase. Try reversing the +/- cables on your sub and see if you hear a difference.

Reversing the polarity is a good idea. I haven't tried that, but it is an easy thing to do.

I also downloaded a bunch of tuning tones and am considering getting a db meter to see what frequency is problematic. The problem does not occur while parked. The stereo is loud and clear and the bass levels are good. It doesn't hit super hard, but I am not looking for ghetto bass.

Andrew

[alocker]

I'm not NVH expert but I assume some resonant chassis frequencies are cancelling out some of the bass. I have also found an up firing sub is never the optimal setup but we will attempt to perform a miracle here without moving the box;)

Reversing the polarity is worth a try but also check how it's wired. It would be pretty hard not to wire it correctly considering its a DVC sub to a single channel. Maybe only one coil got wired by accident.

[andrewb70]

I'm not NVH expert but I assume some resonant chassis frequencies are cancelling out some of the bass. I have also found an up firing sub is never the optimal setup but we will attempt to perform a miracle here without moving the box;)

Reversing the polarity is worth a try but also check how it's wired. It would be pretty hard not to wire it correctly considering its a DVC sub to a single channel. Maybe only one coil got wired by accident.

I think you are right about the resonant chassis frequencies.

I secretly want someone to tell me that I made the right decision by buying the 1000 watt amp...LOL

Andrew

[rfalker1]

You made the right decision.. more power is always key.

But one time I had an issue that stemmed from a broken box. (even though it does not seem like the issue). But good luck anyway with issue andrew!!!

[GrabberGT]

duplicate post

[GrabberGT]

I've got 1000 watt running to a Kicker 12" L5. Incredible bass but unless I REALLY crank it up while driving, it gets lost in the road and exhaust noise.

[andrewb70]

You made the right decision.. more power is always key.

But one time I had an issue that stemmed from a broken box. (even though it does not seem like the issue). But good luck anyway with issue andrew!!!

I will inspect the box for any issues or potential leaks.

Andrew

[hifi875]

Its a resonant frequency issue. With your exhaust. Could look at a resonator (s) to move the resonant frequency or get rid of it.

[andrewb70]

So I had a chance to play with the stereo a little bit today. I relocated the tweeters off the top of the pillars, down low on the kick panel, by the main driver. This really balanced the system and eliminated the ultra bright highs that I was experiencing. I really thought that having the tweeters up high was a good idea, but every where I read, the suggestion was to keep the sound source at the same point. I also played around with the gains on the amp. The sub channel is turned all the way up, while the fronts are only about 1/4 up. This gave a nice balance, and I think it also told me that I need more power to the sub. The system actually sounds pretty nice when not driving.

I also wanted to play around with the crossover frequency for the sub. Right now it is set to 90Hz. The Xtant amp uses little SIP modules to change the frequency. I bought some 150Hz SIPs on eBay, but as luck would have it, they were damaged in shipping. The seller will be sending me a new set. I think crossing over the sub at the higher frequency will help bump output at the 100-150Hz range, which seems to be the trouble spot.

If the weather clears up tomorrow, I plan on taking the car to a local audio shop that seems to have a good reputation and see what they have to say. I may contract them to install the new sub amp that I got.

Andrew

[MonzaRacer]

First of all your subs crossing point should be LOWER inside a box. I ran 2 Blaupunkt 10" Pro Componenents (100w RMS @ 4ohm) free air fired into my rear seat through the seat divider and use 6.4 mHz inductor coils. my regualr speakers were 6x9 4 ways. Also my system used a Marantz BP750 amp setup, 90W per channel.
I had plenty of bass and my 402 and 3" ex made some serious reverb and I still heard it over my car. bass is under 100 hz. I personally hate built in crossovers, and prefer to use caps and coils.

[andrewb70]

I just wanted to give you guys an update and also ask a few more questions.

I finally got the 150hz SIPs for my amp and this really helped. My sub is only 10" and is in a sealed box, so it has good response even at 150hz. This really added more bass overall without sounding boomy. I contacted Diamond Audio and they confirmed that I can go to 150Hz given my configuration.

I am still considering installing the second amp just for the sub. This will leave the sub channel on my first amp open.

What do you guys think about me adding coaxial 6x9s in the rear deck and running them mono from the sub channel of the first amp? I can easily run 2 4ohm 6x9 and wire them to run ohm load to the amp, which it can handle. The only down side is that it will be mono...

Andrew

[alocker]

If running mono, I would delete the tweets out of the 6x9 and they would work great for a mid-bass driver. Worst case scenario is they sound bad and you disconnect them.

[andrewb70]

If running mono, I would delete the tweets out of the 6x9 and they would work great for a mid-bass driver. Worst case scenario is they sound bad and you disconnect them.

HOw about these boys?

http://cdtstore.com/6x9_series/es_0690gold.htm

I can run the mono channel as "low pass" and cross it over at...what...1000Hz? Or maybe even as "band pass" between 50Hz and 1000Hz?

Andrew

[alocker]

The band pass may work but one thing to consider is the 2 ohm load. Not sure if it matters on midbass but your THD goes up at a 2 ohm load. Might want to look into that before you make your final decision.

[scott_fx]

I'd look into your wiring. what gauge are you using and is your ground solid? You could be starving your amp.... but that should also be the case when you're not driving... but i'd still check it with a dmm to make sure. How efficient is your sub? and did you set your gains correctly? that could be a big issue. i can't see polarity being an issue unless you have more then one sub, there aren't any other drivers canceling the frequencies here. Also try to isolate the issue. First unplug your highs and see if the condition still exists. if it does then try it with a different source (ipod hooked up directly to the amp will work in a pinch). Lets rule out the head unit first.

as far as adding more speakers...don't! you're just adding more points of sound that will create deadspots. most people that compete professionally in sq competitions will do so with tweeters, mids and a single sub or two. more speakers just complicate things and often times degrade the sound quality. Before you add more stuff.. fix what's wrong.

[avewhtboy]

Hey Andrew, I am know pro, I just know what sounds good to me, with that said, I never liked the sound from a closed subwoofer box as opposed to a ported box. I have read/heard that ported boxes sound is "sloppy" verse the sealed boxes, but the ported boxes have fuller sound to me, maybe that's what is missing.

Maybe ask the pros just to wire in a ported 10" box set in your trunk to see if that is more of the sound you are looking for?