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?

[PT Sportwagon]

Bass is more feel than hear. so having a sub firing into the interior is a mute point. I have a single 10" Rockford Band pass box in my wifes lincoln Town car. It sits on the side trunk shelf. with the port firing backwards. with 300w PPI A300 sounds good. As Scott said. adding more speakers can cause trouble. I won the 2002 USACi Sound Quility world championship with only 5 speakers. the winningest car in SQ Car audio compitition Richard Clark's Grand National only has 6 speakers with a 1500 watt Amp to each speaker. So less is more as they say.

Tim

[scott_fx]

yeah. to combine what pt sportwagon said and my post. 5 speakers = front mid, front tweeter and sub. no rear speakers.

i never run rear speakers in my builds. best example of this... when you go see a concert... when do they put speakers behind you?

[andrewb70]

I am bringing this thread back up from the dead. I think a lot of you saw the thread regarding my MicroSub experiment. If not, you can see it here:

https://www.pro-touring.com/threads/108649-JL-MicroSub-experiment

After goofing around with the MicroSub, I decided to really take a look with my existing set-up. I discovered that the rear package tray was not exactly solid. The "professionals" that installed the box in the first place, cut out a huge square section right out of the middle, which really weakened the package tray. This isn't so much of an issue, unless there is a 50 pound box with a substantial sub attached to it. I am quite certain that the whole package tray used to move around quite a bit, which isn't exactly ideal. Also, I found that the box itself wasn't well made. Part of it was made of MDF, while another part was made of regular particle board. Also, instead of installing a proper terminal, they simply made a hole in the box, passed the wire through, and called it a day. No silicone...nothing...not even gum.

https://www.pro-touring.com/~andrewb/gtov2/photo207.jpg

On a brighter note, once I pulled the sub, I realize that it was a Diamond Audio M6...and not a M3 as I originally thought. This was the top of the line sub back in the day and has dual 500w 4 ohm voice coils.

https://www.pro-touring.com/~andrewb/gtov2/photo206.jpg

At least they wired it properly for a 2 ohm load. The other good news is that the box is the right size for the driver. Diamond Audio designed these subs to work in fairly small sealed enclosures, around .75 cubic feet. I took some measurements and after a few calculations got .72 cubic feet, after taking the volume of the driver into account. The good news is that with a little TLC, I think I can reuse this box. It is just the right size to fit on top of the hump that GM A-bodies have in the trunk and obviously the volume is right.

So now the questions...

Would it be better to point the driver towards the rear?

Would it be better to point the driver towards the rear seat back?

Any suggestions for anchoring this thing?

I am also quite certain that I am not driving this bad boy with enough power. Right now it is getting 350 watts, and that's just not enough. I bet the driver isn't even broken in.

I did pick up a used Xtant 601 a while back, so I am tempted to use it for the sub.

All comments and suggestions are welcome...

Andrew

[alocker]

Andrew,

Back in the day when my buddies and I were poor, we spent hours tuning our systems to get the most out of them. If your car allowed the sub to face rearward, you got the best overall response. You would think facing the driver forward would be the best but it isn't. We also found and upward facing driver was the least desirable in certain cars. As for anchoring, an "L" bracket screwed to the rear seat divider frame would be a decent way so you don't have to go into the trunk floor.

That thing should hit pretty good even with 350 watts RMS.

[alocker]

Now that I re-re-read the whole thing, just throw the big amp in there and put it any way you want. That's the most fun option by far:)

[andrewb70]

Now that I re-re-read the whole thing, just throw the big amp in there and put it any way you want. That's the most fun option by far:)

Hahaha...Now you're thinking like I am. I first have to see if the 601 eBay special will even work. It arrived with some questionable solder joints on a couple of capacitors. I resoldered them, but it may not even work. The other issue I am having is that both the amps are HUGE! Where in the world am I going to mount them?

Can they go under the rear seat?

Andrew

[alocker]

1/2 the reason you buy an old Xtant is to show it off, it would be a shame to hide it. I also think airflow is more critical for the old a/b class amps. Since I don't know your box dimensions, it's hard to recommend another spot. If the box is short enough, on the bottom of the rear deck is an option. You just have to make sure you leave a small gap for airflow on the bottom of the amp chassis if you mount it upside down.

[andrewb70]

So I had a chance to play around today. I fixed the box by adding a proper terminal box and otherwise making sure that it is sealed up. Then I started playing around with placement. Just about anywhere in the trunk sounded way better than firing through the rear deck. Probably the best was firing backwards, but it was really hard to tell the difference. It definitely hits much harder even with just the same old amp. I did hook up the Xtant 1001x and I think it is dead. It seems to power up, but I wasn't able to make it go boom..boom...

Now I have a dilemma. I can mount the box in the center, just behind the rear seat back, and fire it backwards. The questions is where do I mount the amp?

It used to be attached to the box itself, but with the speaker facing to the rear there is no longer a nice flat spot that is easily accessible.

Ideal?

Andrew

[andrewb70]

What do you guys think about facing the driver towards the bottom of the trunk? I am pretty sure that I can raise it up about 2 inches away from them trunk floor and wedge it in tightly between the floor and the rear package tray. This also solves my amp mount dilemma...

I got the idea from some of the Jeep boxes that are on the market.

Andrew

[alocker]

Almost every home theater sub fires that way and is fine. I would test it to make sure you like the way it sounds.

[andrewb70]

Almost every home theater sub fires that way and is fine. I would test it to make sure you like the way it sounds.

I did a little testing and it certainly felt like it hit harder. It is really hard to judge because things are rattling around and the box itself is not fully secured. I imagine that after I bolt it down and eliminate the rattles it will sound even better.

Andrew

[andrewb70]

In short, FML.

I spent about 6 hours doing this:

https://www.pro-touring.com/~andrewb/gtov2/photo209.jpg

Only to try this afterwards:

https://www.pro-touring.com/~andrewb/gtov2/photo208.jpg

What look like cheap ass 12" Kenwoods totally rocked...If only I had done that first...as I said, FML.

Andrew

[alocker]

Nice. Its all about optimization. We had friends spend a gazillion dollars on high end stuff with custom installs that looked awesome. They always sounded average though. The subs were always mounted to look cool and you could not move them to try different angles. An optimized enclosure with a little tuning can make a huge difference.

[scott_fx]

In short, FML.


What look like cheap ass 12" Kenwoods totally rocked...If only I had done that first...as I said, FML.

Andrew

it probably has to do with the increased distance it gains by having the subs pointing toward the back. try to spin that single sub box you built so it's facing the rear. you may notice some gain as well then you can move it to one side and mount the amp (facing rearward also) on the same plane

[andrewb70]

it probably has to do with the increased distance it gains by having the subs pointing toward the back. try to spin that single sub box you built so it's facing the rear. you may notice some gain as well then you can move it to one side and mount the amp (facing rearward also) on the same plane

Scott,

Thanks for the suggestion.

I really would prefer not to have that giant box back there. I will try my single 10, firing back and see how that works. I may end up building a custom box that fits nicely off to one side. I wish some company would make a molded box that fits nicely up on that shelf. Surely I am not the only person that owns a 68-72 GM A-body that wants a nice compact system that hits hard.

Maybe I should try the MicroSub in the trunk while I am at it...Hmmm...

Andrew

[andrewb70]

I scratched the fiberglass box idea. Instead, I decided that it would be simpler and easier to build a shelf behind the seat that would support the sub on the passenger side and allow for space for the amp on the driver's side.

Here is what I came up with. It isn't super pretty, but it will do the job. The trunk of my car was never meant to be a show piece, it is there to haul crap.

https://www.pro-touring.com/~andrewb/gtov2/photo212.jpg

The shelf is 1/2" MDF and is supported by the hump in the middle and some trimmed down 2x4s on the edges. The 2x4s will be attached to the trunk divider and the sub will be anchored to the bottom of the package tray. Should be pretty solid.

Here you can see where the amp will go.

https://www.pro-touring.com/~andrewb/gtov2/photo213.jpg

There will be ample space all around it for cooling and all the wires will come in from behind and underneath and should look pretty clean.

I even decided that I should make everything a little prettier and wrapped the sub in black felt and I will do the same for the shelf.

https://www.pro-touring.com/~andrewb/gtov2/photo214.jpg

Stay tuned for more, as I just placed an order with Don at Sound Deadener Showdown (http://www.sounddeadenershowdown.com)

This is turning into sub/interior sound deadener redo...

Any comments and suggestions are welcome as always.

Andrew

[scott_fx]

looks good but... do i spy an xtant amp?
I had a 603x... (or was it an x603) back in the day... such a phenomenal amp! I like your setup, i'm pretty sure that's about the same configuration that i'll be using (when my car gets back from the body shop) Did you notice some gains by having your sub aimed towards the rear?

have you thought about turning the amp 90 degrees and flush mounting it?

[andrewb70]

looks good but... do i spy an xtant amp?
I had a 603x... (or was it an x603) back in the day... such a phenomenal amp! I like your setup, i'm pretty sure that's about the same configuration that i'll be using (when my car gets back from the body shop) Did you notice some gains by having your sub aimed towards the rear?

have you thought about turning the amp 90 degrees and flush mounting it?

Scott,

That is indeed an Xtant 603e. I've had it since I first built the car and I bought the amp new. It's probably just broken in...LOL

I like a simple 3 channel set-up and this amp was designed specifically for that. I got everything wrapped up and I am pretty pleased with the results. I am learning that bass response is funny. In my other thread I was experimenting with mounting a JL MicroSub inside the cabin, thinking that printing the bass closer would be better, but clearly that is not the case. For fun I mounted the MicroSub in the trunk and it sounded better than behind the driver's seat. Go figure...

https://www.pro-touring.com/~andrewb/gtov2/photo216.jpg


Andrew

[scott_fx]

Scott,

That is indeed an Xtant 603e. I've had it since I first built the car and I bought the amp new. It's probably just broken in...LOL

I like a simple 3 channel set-up and this amp was designed specifically for that. I got everything wrapped up and I am pretty pleased with the results. I am learning that bass response is funny. In my other thread I was experimenting with mounting a JL MicroSub inside the cabin, thinking that printing the bass closer would be better, but clearly that is not the case. For fun I mounted the MicroSub in the trunk and it sounded better than behind the driver's seat. Go figure...

https://www.pro-touring.com/~andrewb/gtov2/photo216.jpg


Andrew

yeah, I've only had a couple amps that sounded better and i can't say that definitively. the xtant was only 75 watts with passive x-over, the others were 150 wrms and running active.


here is what i was talking considering mounting it flush:
100198

[andrewb70]

The flush mount is definitely sexy, but I just didn't want to bother. My trunk isn't "show" quality, so I think what I have now looks pretty good. The Xtant has a sexy stainless cover and at least the wires are all hidden and neat.

Andrew

[scott_fx]

ah, gotcha. glad it's sounding good!