critique and advise my SQ setup for Rx7

[mslam02 10+ year member]

pics of that RX7, Rotary Fan here

sorry, no more rotary... Swapped in an LS1

Heres a pic from a car show last year, i now have actual hood props, lol

And i guess i didn't really think as much about install as i should have, i knew a good enclosure was key, but i guess i should read more up on that...

 

[Imtjnotu 5,000+ posts]

what amp are u going to use to push the sub?

 

[Bumpin' Goalie 10+ year member]

what amp are u going to use to push the sub?

He's using the 2 unused chan's from the 300/4 bridged.

 

[audioholic 5,000+ posts]

For a SQ system, Id like to see a bit more power on tap for headroom. And Id like to see dedicated midbass drivers in the front stage.

 

[Beerdrnkr 5,000+ posts]

I'm not a fan of those components either. You should get a deck with 3way active capabilities or a processor so you can really dial in the components. Bridge the 300/4 to the components and add a 250/1 or 500/1 to the sub to add headroom and dynamics to your system. Really nice car by the way.

 

[RLJ676 10+ year member]

Awesome car man.

I'd suggest more power as your noise floor is probably pretty high assuming you are not excessively muffled, and with an LS1 I'd hope you're not.

Also, good dampening and noise barrier would be worth it if you really want to hear the music at lower volumes.

Last, due to JL's regulated power supply, you gain nothing by bridging to the rear channel. I like to wring all the power out of what I buy, so I'd consider a different amp. As a matter of fact I was running a 300/4 in my boat w/ L and R on 2 channels and sub bridged, and am replacing it and using it for 4 channel duty in my truck. Any similar price/quality amp will gain you more power in the setup you're looking at. That said, the 300/4 did a reasonable job of creating volume in a boat (limited by current from the 2 battery setup when not running, they are current hogs).

 

[mslam02 10+ year member]

Awesome car man.
I'd suggest more power as your noise floor is probably pretty high assuming you are not excessively muffled, and with an LS1 I'd hope you're not.

Also, good dampening and noise barrier would be worth it if you really want to hear the music at lower volumes.

Last, due to JL's regulated power supply, you gain nothing by bridging to the rear channel. I like to wring all the power out of what I buy, so I'd consider a different amp. As a matter of fact I was running a 300/4 in my boat w/ L and R on 2 channels and sub bridged, and am replacing it and using it for 4 channel duty in my truck. Any similar price/quality amp will gain you more power in the setup you're looking at. That said, the 300/4 did a reasonable job of creating volume in a boat (limited by current from the 2 battery setup when not running, they are current hogs).

Please explain why you say you get nothing from bridging with that amp? the setup you were running - what ohms are those speakers and sub? because with the 300/4, it automatically drops to whatever the lowest ohms are, so say your running 4 ohm speakers and a 2 ohm sub, the sub will run at full power but the speakers power will be cut in half, thus matching ohms rating in the full system is crucial.

 

[audioholic 5,000+ posts]

Please explain why you say you get nothing from bridging with that amp? the setup you were running - what ohms are those speakers and sub? because with the 300/4, it automatically drops to whatever the lowest ohms are, so say your running 4 ohm speakers and a 2 ohm sub, the sub will run at full power but the speakers power will be cut in half, thus matching ohms rating in the full system is crucial.

He's talking about the fact that JL's Slash series of amplifiers have the same output over a range of impedances. But regardless of that, all amplifiers have the same output at 4ohms mono as they would at 2 ohms stereo (bridged mono vs wiring each coil separately).

And, the Slash amps use more than just (strictly) regulated power supplies to achieve what they do.

 

[JimJ 5,000+ posts]

Add another amp, and bi-amp the JLs with the 300/4 unbridged.

Speaker placement/aiming is key...

 

[mslam02 10+ year member]

For a SQ system, Id like to see a bit more power on tap for headroom. And Id like to see dedicated midbass drivers in the front stage.

what size and type of midbass drivers do you recommend?

 

[RLJ676 10+ year member]

Please explain why you say you get nothing from bridging with that amp? the setup you were running - what ohms are those speakers and sub? because with the 300/4, it automatically drops to whatever the lowest ohms are, so say your running 4 ohm speakers and a 2 ohm sub, the sub will run at full power but the speakers power will be cut in half, thus matching ohms rating in the full system is crucial.

Like audioholic said I was referencing when you bridge the JL it doesn't see an increase in power as you do on most amps (same with running 2 ohm stereo vs 4 ohm, no advantage on JL).

As to matching on the system, I'm not sure I follow your intent. It sounds to me like you are concerned with the amp seeing the same loads on all channels? This is not necessary. You could run the front 2 channels at 2 ohms and rear at 4 ohms, no problem (assuming a 2 ohm stable amp of course). An amp doesn't really do anything based on the speakers, it just sees a resistance on that channel, and the current/voltage react accordingly. So channels 1/2 will have no impact on 3/4.

 

[audioholic 5,000+ posts]

what size and type of midbass drivers do you recommend?

8's in the doors for midbass. You can either look into passive 3-way systems with 8's (or 7's), you can run a 2-way passive set off the front two channels and the 8" midbass off the rear 2 channels, or go fully active 3-way and buy 2 more channels of amplification (plus a new sub amp). Of course, once I had 8" midbass, Id be looking at bigger than an 8" subwoofer (10-12"). That, with the mids and tweets in the kick panels, everything aimed right, outputs blended, phases set correctly, etc... and then you have a solid SQ system.

Depending on your dash shape, horns might be an option too. This could/would simplify your front stage down to a 2-way and still be able to utilize a large mid/midbass (horn +8" or 6x9").

Very nice car btw.

 

[RLJ676 10+ year member]

If you are serious about running an active system, or a more custom component setup I'd go read at DIYMA.com.

 

[mslam02 10+ year member]

That all seems way more involved than i want to go...

and to RLJ676, here is the exerpt in the 300/4 manual for what i'm talking about...

"Even though you may have installed zillions of amps in your day, please take the time to read this section! The 300/4v2 is not a typical amplifier and care must be taken to balance the front and rear channel speaker impedances for optimum output from all four channels.

The 300/4v2 employs JL Audio’s exclusive Regulated, Intelligent Power Supply (R.I.P.S.)

design. This sophisticated power supply allows the amplifier to produce its optimum power (300 watts) over a wide range of speaker impedances. unlike conventional amplifiers that require a specific impedance to produce optimum power, the R.I.P.S.-equipped 300/4v2 gives you the

freedom to use a variety of speaker configurations that achieve final impedances between 1.5 – 4 ohms nominal per channel (without sacrificing power output or sound quality).

The operation of the R.I.P.S. circuitry is entirely automatic and adjusts itself every time the amplifier is turned on according to the lowest impedance present at either front or rear channels. There are no user controls to configure. The system operates through three stages of impedance optimization, choosing the stage most appropriate to the actual impedance of the speakers connected to it.

Because the 300/4v2 utilizes a single power supply, it will set itself up based on the lowest impedance present at either the front or rear amplifier channels. For example, if you connect a 2 ohm load to each front channel and a 4 ohm load to each rear channel, the amplifier will adjust itself to deliver 75 watts x 2 to the front 2 ohm loads, but will only deliver half its optimum power (37.5 watts x 2) to the rear 4 ohm loads. If you connect a 4 ohm load to all four channels or a 2 ohm load to all four channels, the amplifier will deliver 75 watts x 4. See, we told you this amp was different... Read on, there is more important information to follow."

 

[Bumpin' Goalie 10+ year member]

If I guess correctly, I believe OP wants a nice sounding system without having to do alot of fab work, and go overboard on his vehicle. I wouldn't think going active and dedicated mids would be needed for him to achieve successful full frequency response. It will be quite possible to sound just fine running passive x-overs and letting the ID8 pick up where the C5's drop off.

OP, correct me if I am wrong. But from what I've gathered, this is more of a daily tunes car than a car that will be audibly tweaked to perfection.