Q's for the car audio experts

[scottmandue]

I asked this before but have a few more questions..

My current setup (in my 1996 Miata) is:

New Kenwood head unit (don't remember model) I know kenwood isn't the best out there but they are not junk either (I hope, this is my first experience with them and I am on a tight budget)

And some MB Quart ONX116 6.5" 2-WAY COAXIAL coaxial in the doors.

I know these are not top of the line components and they sound OK but I am searching for ways to tweak the system for better sound (yes I know how to mess with the EQ and have it sounding as best as it can).

I can best describe the sound as thin and a little harsh.

First question, It was recommended I get the cups/baffles that fit behind the speakers in the doors and I did, is that a good idea?

Second, my wife has some fiber fill batting, will stuffing some of that in the doors help? Would stuffing some of that in the cups/baffles help?

Last time I asked this question it was recommended I add a power amp because the anemic Kenwood head puts out 40 Watts max which is 15-20 RMS (speakers rated at 100+ watts) so I am looking into installing a power amp (going to be a bit of a project, need to install power-amp in trunk thus run preamp wires to trunk the speaker wires from trunk to dash then to doors.)

Third, what about sub-woofers? I am told installing a sub in the trunk will just get me the boom-boom I don't need/want (I'm a jazz and classic rock guy) other options are install a sub box in the passenger foot well, that looks like the best sounding option, however I hate to sacrifice foot room in an already tiny car. Another option is to install a pair of small woofers in the deck behind the seats (pointing upwards), but because storage is at a premium in such a small car I have a very handy deck bag there.

There is zero room under and behind the seats in the cab, however I think I might be able to cut a speaker (8 or 10 inch) into the bulkhead behind the drivers seat between the trunk/cab. Unfortunately I have been told unless you seal the trunk completely (not practical) or have the sub in a sealed box it will sound horrible. Is there anything such as a “free air” sub that doesn’t need a box?

Thanks!

[Gogar]

Is this a 911 or your Miata?

I have a kenwood head and two-piece Quarts in my doors in my 1972.

IMO YES you will experience a little better low-low mids if you put a baffle behind the speaker. Don't put any batting 'inside' the baffle. Don't put any in the door either, you're just sort of spinning your wheels.

For a speaker to work 'best', it needs a sealed chamber behind it, or a chamber that has a port (like you see so often) that is tuned to accentuate the deficiencies of the speaker and round out the sound. (super-over simplifying.)

If you can create a seal behind the speaker, that's great. At that point you will need more power.

If it's a '83 or older 911 you could put a sub under the drivers seat. I put one of those Kenwood powered subs under my driver's seat in my SC and it's not amazing but it adds a little thump and is fun.

If it's '84 911 and up and you don't have anything under the pass seat (?) and you have manual seats you could toss the little Kenwood sub under there.

If it's the Miata check if you have clearance under the seat and you could just put a little butt-thumper thing (like the Kenwood) under there and see if it's enough for you.



I find every stereo mod I've done to my 911s to be fun, but pointless in the end.

[imcarthur]

Originally Posted by scottmandue

First question, It was recommended I get the cups/baffles that fit behind the speakers in the doors and I did, is that a good idea?

Yes. It will help the driver pressurize the airspace which makes it do its job better.

Originally Posted by scottmandue

Second, my wife has some fiber fill batting, will stuffing some of that in the doors help? Would stuffing some of that in the cups/baffles help?

Think of the door cavity as a speaker box. As Jeremy said, the most important thing is seal it as tight as you can. Fiber fill will not make a big difference. Dynamat (or similar) on the inside of the door would but that can be a pita. Worth it though.

Originally Posted by scottmandue

Third, what about sub-woofers? I am told installing a sub in the trunk will just get me the boom-boom I don't need/want (I'm a jazz and classic rock guy) other options are install a sub box in the passenger foot well, that looks like the best sounding option, however I hate to sacrifice foot room in an already tiny car. Another option is to install a pair of small woofers in the deck behind the seats (pointing upwards), but because storage is at a premium in such a small car I have a very handy deck bag there.

There is zero room under and behind the seats in the cab, however I think I might be able to cut a speaker (8 or 10 inch) into the bulkhead behind the drivers seat between the trunk/cab. Unfortunately I have been told unless you seal the trunk completely (not practical) or have the sub in a sealed box it will sound horrible. Is there anything such as a “free air” sub that doesn’t need a box?

No, a sub needs a box. It needs a volume of air to pressurize. many people do cheat & use the trunk air volume but you need big drivers for anything remotely satisfying.

Ian

[RWebb]

get a big, clean amp - you would not believe the power needed in a NOISY automotive environment

put sound deadener on at least 1/4 of the surface of every body panel that does nt already have it - esp. the doors where the speakers are

remove the vapor barriers on the doors and use the thermal conforming stuff that Cascade Audio sells - their web site has pics of how to do it and how to use plastic tubing for the cable, wire and rods feeds thru the material - it is a water barrier so don't worry about the old vapor barrier & it seals the doors too

various other panels should get "MLV" on top of the deadener - a heavy layer of vinyl that is floated on top of the deadener by sitting on a layer of closed cell foam

find all open 'tubes' - channels in the unit body such as are formed for the A and B pillars etc. and stuff closed cell foam in them to block sound transmission

track down any other noise sources and deal with them too

this, together with the other posts, will give you as high a quality audio env. as you can achieve without laboratory measurement equipment and skills

[scottmandue]

Yes, it is for the Miata.

Zero room under the seats, I had to remove them to put on seat covers.

I sealed the doors and speakers with duct tape (not the cheap kind you get at Home Depot, the heavy duty industrial type).

I did install the cup/baffle things behind the speakers.

Good to hear I don't need to reopen the door panels, they are not much fun to remove.

The Quart speakers get good reviews so I don't think they are the problem (however they are rated at 100-200 watts so I am guessing not very efficient).

Thanks for the validation, I will go forward with the amp install project and see how that sounds. Pretty sure I can install that in a day with just pulling out some carpet and running a bunch of wires.

[scottmandue]

Originally Posted by RWebb

get a big, clean amp - you would not believe the power needed in a NOISY automotive environment

remove the vapor barriers on the doors and use the thermal conforming stuff that Cascade Audio sells - their web site has pics of how to do it and how to use plastic tubing for the cable, wire and rods feeds thru the material - it is a water barrier so don't worry about the old vapor barrier & it seals the doors too

various other panels should get "MLV" on top of the deadener - a heavy layer of vinyl that is floated on top of the deadener by sitting on a layer of closed cell foam

this, together with the other posts, will give you as high a quality audio env. as you can achieve without laboratory measurement equipment and skills

Will proceed with the "big, clean amp", if I want further improvement I will look into Cascade Audio stuff, thanks for the heads up.

Speaking of an Amp, what would you guys recommend (that doesn't cost an arm and a leg... something in the $200 range... sorry but the McIntosh is out )?

In my previous post the soundstream was highly recommended... but there is a lot of stuff in their lineup... then I was told to buy used because the new line isn't as good? I would prefer to buy new.

[Aragorn]

From what I remember some miatas came with headrest speakers.

Seat Headrest Speakers - MX-5 Miata Forum

Maybe that could help a little. Find if you car has this option (or at least the holes in the seat foam) and see if installing a few speakers in the headrest helps with the volume and sound quality. Just a thought.

[RWebb]

used Soundstream - those amps have a good rep.

the amp will cost more; but is a lot less DIY labor for you; also this is all going to add wt.

[scottmandue]

Originally Posted by Aragorn

From what I remember some miatas came with headrest speakers.

Seat Headrest Speakers - MX-5 Miata Forum

Maybe that could help a little. Find if you car has this option (or at least the holes in the seat foam) and see if installing a few speakers in the headrest helps with the volume and sound quality. Just a thought.

Thanks and you are correct but ufortunatly no, my seats do not have the headrest speakers.

The pros/cons of the headrest speakers are a hot topic over on Miata.net but the point is moot for me.

[scottmandue]

Originally Posted by RWebb

used Soundstream - those amps have a good rep.

the amp will cost more; but is a lot less DIY labor for you; also this is all going to add wt.

Are the Rockford Fosgate amps overrated?

[RANDY P]

Get some serious amplification, and flip polarities on ONE midrange, and ONE midrange only. (I use passenger side)

Yes, listen to it out of phase, it may restore bottom end.

Buy a brand name amp. Alpine, soundstream (they are all very similar, just physical differences) or a Fosgate.

Worse comes to worst- slam a 10" tube in the trunk. Use a 4 channel to run everything.... Placement of amp? Somewhere along left or RH side of trunk.

Amazon.com: Bazooka BT1014 10-Inch 4-Ohm Bass Tube: Car Electronics

PS- the old soundstream amps sound great, but they aren't real reliable nor are they good at noise rejection. I used to sell them, and at one time had the MC300, MC140 and D60II in my car. What a pain in the ass to keep the system quiet. Be careful with them

If it wasn't for the fact they were cheap I wouldn't have run them. WIth that being said I'm about to slam a reference 405 and a 15" and separates in my new BMW...

[Cajundaddy]

It's a Miata roadster with a pretty high (approx. 95db on the highway) noise floor to overcome. It will never sound as good as the same system in a Lexus with a 75db noise floor. Tuned enclosures behind the speakers will make the most out of their bass response. Check with MB Quart for enclosure dimensions for your speakers.

For truly great sound on the highway, I don't think speakers/amps/subs will get you there. A ragtop roadster is simply the wrong listening environment. My choice is in ear monitors on long trips. No flack from the CHP so far.

[herr_oberst]

Originally Posted by Gogar

I find every stereo mod I've done to my 911s to be fun, but pointless in the end.

Amen, brother.

[imcarthur]

Originally Posted by Cajundaddy

For truly great sound on the highway, I don't think speakers/amps/subs will get you there. A ragtop roadster is simply the wrong listening environment.

I respectfully disagree. I have a '75mph top down on freeway' system in my cab. No, it doesn't image, it isn't like an audiophile system at home - it's more like a mobile ghetto blaster. And yes, I can hear it over the music of the engine - if I want to.

Ian

[scottmandue]

Originally Posted by RANDY P

Get some serious amplification,

Buy a brand name amp. Alpine, soundstream (they are all very similar, just physical differences) or a Fosgate.

Worse comes to worst- slam a 10" tube in the trunk. Use a 4 channel to run everything.... Placement of amp? Somewhere along left or RH side of trunk.

Amazon.com: Bazooka BT1014 10-Inch 4-Ohm Bass Tube: Car Electronics

PS- the old soundstream amps sound great, but they aren't real reliable nor are they good at noise rejection. I used to sell them, and at one time had the MC300, MC140 and D60II in my car. What a pain in the ass to keep the system quiet. Be careful with them

If it wasn't for the fact they were cheap I wouldn't have run them.

Randy, I have looked at a bazooka... but I am going for the power amp first...

What do you think of Soundstream Rubicon amplifiers?

Are you sayin Fosgate is a good option in power amps?

Thanks

[imcarthur]

Get an affordable Class A/B 2 channel amplifier. If you want to do a sub, amplify it separately if space & budget allow. Ignore all specs except the 4Ω two channel figure. A sub amp can be Class D & the more power, the better.

Ian

[Steve Carlton]

Easy fix- install this:

[Cajundaddy]

Originally Posted by imcarthur

I respectfully disagree. I have a '75mph top down on freeway' system in my cab. No, it doesn't image, it isn't like an audiophile system at home - it's more like a mobile ghetto blaster. And yes, I can hear it over the music of the engine - if I want to.

Ian

Haha, A mobile ghetto blaster is a perfect analogy Ian. I think I must borrow that phrase.

Yes, this result is certainly possible with enough sound pressure level.

[scottmandue]

Originally Posted by imcarthur

Get an affordable Class A/B 2 channel amplifier. If you want to do a sub, amplify it separately if space & budget allow. Ignore all specs except the 4Ω two channel figure. A sub amp can be Class D & the more power, the better.

Ian

Exactly!

Sub to come later (maybe) and will have a seperate amp.

What is a boosred rail amp?

Rockford Fosgate PBR300X2
300W RMS 2-Channel Class BR Punch Boosted Rail Amplifier

Leaning towards this:

Soundstream RUB2.450
450 Watts RMS 2-Channel Rubicon Series A/B Class Amplifier
•Power output:
◦RMS Power @ 4 ohms: 130 watts x 2
◦RMS Power @ 2 ohms: 225 watts x 2
◦RMS Power @ 4 ohms bridged: 450 watts x 1
•THD 0.015%
•Signal-to-noise ratio: 105dB
•Damping factor: >250
•Signal sensitivity: 0.2V-6V
•50Hz Bass Boost: 6 or 12dB
•35Hz Subsonic Filter
•Infinitely variable crossovers w/ multipliers (High/Full/Band/Low)
•Mosfet PWM power supply
•IDI intelligent distress indicator for thermal, short, & impedance protection
•Turn on/off delay

Hard to chose when I think I have found an amp then I hear bad things about the manufacture.

Thanks again,

[imcarthur]

Originally Posted by scottmandue

What is a boosted rail amp?

I don't understand the tech but they skip a transformer in the power supply by 'boosting' the 12V supply to 24V via a capacitor array. Stick to a conventional amp like the Soundstream.

Ian