JB-I

Pb82 Ronin

I don't know if I would do that. Just the safety aspect of it all. Not being able to see through the rear view mirror, and the weight of it possibly flopping around during a collision or aggressive driving. Or worst case, you do crash and it breaks free and smashes you in the back of the head.

02BlownZ06

It would probably work OK, but my prediction in a car audio environment (and this is based on a good bit of experience) is that to get the most musically accurate bass that will hit plenty low enough is to go sealed and make sure the enclosure airspace is 20% give or take, larger than what the manufacturer specs at. With the enclosure you are describing, I think one 10 with an airspace of .90 cf (and will be less when you take out the displacement of the woofer) would sound great. You could use the other 10" hole for a passive radiator if you really want to use that enclosure. Just my .02, but every time I have done a sealed enclosure for the airspace specced for the sub or tried to go on the small side, it sounded terrible. No bottom end with preponderance of mid-low bass in the undesirable 100 to 125 HZ range that you can't EQ out.

02BlownZ06

This is pretty much it. A car audio environment is different. Hell, back in the day in high school in the 80's, you started with a pair of 6 x 9's in the rear deck, a new am/fm cassette deck with a power booster/equalizer (LOL) combo and you thought you had something. I grew up listening to music with it coming from behind me while tooling down main street with glasspack mufflers rumbling and a budweiser between the legs. A luxury was to add front speakers and then eventually go outboard amps. I was one of the first in my hometown to add a subwoofer behind the rear seat in an infinite baffle situation. That was state of the art back then. Eventually, car audio became about the soundstage being up front but retaining rear speakers for fill. I, to this day, like this arrangement over all others in a car audio environment, assuming the system is set up right with the right gear. This will smoke the doors off any system that is fronts only to my ears, anyway. Now in a home stereo (audiophile caliber) setting, I prefer a left and right channel right in front of you for critical listening where you can close your eyes and imaging is good enough that you can sense the position of the instruments and vocalists and it doesn't sound like two speakers in front of you but a complete sound stage. I just view the two environments differently and at the end of the day it is what you like. If you like fronts only go for it, but in my c5 it sounds remarkably better with fronts and rears. With my head unit I can switch off the rears and compare and it is night meet day.

daverulz

On the amp rack, I don't think he's proposing that it will interfere with the rear window. To me this sounds like an OK idea if aesthetics are important. Also it puts the amps in an area where they can get fresh air regardless of the position of the top. I would think top up the amp rack should be no problem, but top down you might see a reduction in bass, how much would be blocked by the rack is debatable. Generally, bass finds a way into the cabin. Just make sure everything is bolted down and secure and there should be no concern.

On the topic of rears/no rears. The general advice on audio forums is to get the fronts right first, and then if you feel like you're missing something to add the rear fill. Properly executed rear fill presents a more "spacious" sound. That being said, I've done just fronts in almost every car I've had. I prefer the sound stage in front of me, and not getting dragged to the back by unnecessary speakers. The right way to do rear fill is with a bandpassed left minus right, right minus left signal with A LOT of delay. This is complex, and hard to get "right" It's not as easy as just putting some speakers with an amp in a hole. You need to have processing too. I am willing to bet that 99% of people have never heard a system with appropriate rear fill, they've just heard "more" as noted above. Take into consideration that you drive a convertible, with a big motor, and It is just more of a reason to spare the expense. A pair of 5.25's is not going to add much benefit to the overall sound in your car. Instead, bridge the extra channels onto your midbasses. More power to the low frequency drivers up front will do much more for the sound than the rear speakers.

You're only kinda grasping what that spec is. That spec is the f3 of that configuration. f3 is the point at which the frequency response is 3db down. Your frequency response does not cut off at this point. It simply starts to roll off at this point. You will get frequency response well below this and often the car works with you to naturally boost these frequencies. Of course with the top down you have that working against you. That being said, the difference between the f3 for the enclosures you mention is negligible. Punchy bass (ie kick drum) is in the 50-100hz range. Don't under-estimate the value of the midbasses in getting "punch" if that's what you're after, again I'll point to my suggestion to put more power on your midbasses.

daverulz

Another note - if you're doing sound deadening please read up on https://www.sounddeadenershowdown.com/

Don's techniques will prevent you from wasting money or energy on the wrong types of treatments. Even if you don't use his products.

TheProsecutor

I bought most of my damping from https://www.sounddeadenershowdown.com/

JB-I

TheProsecutor

Since you are focused on running the JL Audio line of amplifiers, this is what I would do.
1. Purchase the VX800/8i.
2. Channels 1 and 2 - tweeters, 75 watts.
3. Channels 3 and 4 - midranges, 75 watts.
4. Channels 5 and 6 - bridged into the left woofer, 200 watts at 4 ohms bridged.
5. Channels 7 and 8 - bridged into the right woofer, 200 watts at 4 ohms bridged.
6. Purchase the VX600/1i
7. Bridge the amp at 2 ohms for 300watts per subwoofer.
You will have lots of headroom.

TheProsecutor

This is what I am doing.
1. Purchase a Mosconi AS 100.4
2. Channels 1 and 2 - tweeters, 100 watts.
3. Channels 3 and 4 - midranges, 100 watts.
4. Purchase a Mosconi AS 200.4
5. Channels 5 and 6 - woofers, 200 watts.
6. Channels 7 and 8 - subwoofers, 500 watts per subwoofer.
7. Purchase a Helix DSP.2
Why is this better?
Slightly better amps, slightly more power, but double the size of the amplifiers, because A/B class sound cleaner than class D amplifiers, about 1/2 the cost.

JB-I

Thanks for the response. That is what I was thinking! With the convertible its pretty tight between the waterfall and folded down convertible top so two small amps is what it needs to be. I still am deciding on whether to just build the vertical amp rack under the tonneau lid or lay the amps down under the folded soft top. I wanted an aesthetic factor as well as SQ. But I'm still not sure if blocking the passthroughs behind the seats will decrease the bass? Again I will put some mesh openings on each side of the amps so hopefully it will help with bass and it is certainly not perfectly sealed from floor to tonneau lid so there will be lots of air gaps around the amp rack. What are peoples opinion on how this would affect bass from the trunk. Also I had a great conversation with Marc @vettenuts and am now considering two corner boxes. He said they are larger in volume than the standard coupe boxes because they have to stand up the subwoofers more to fit the convert. They have around ~.7 cu.ft. instead of the .45 cu.ft. of the sub thump center console box (which appears to have a center divider to create two separate .45 chambers). I need to make a decision so I can get things on order this week! Finally, I will probably just leave the rear speakers for now and connect them directly to the HU and see if adding a little vol from them improves the overall sound. But I will only concentrate on tuning the front sound stage without them till i get it right and then fade in a little to see if it adds anything.


Concept design for vertical amp rack behind C5 seats under tonneau lid.

TheProsecutor

Let me also suggest that two 10" subwoofers are overkill. One should be enough. The second subwoofer increases the volume at most 6db. I am considering selling my subs and enclosure. I would go with the Focal P25F or Image Dynamics IDQ10 or Arc Audio 10D2 in a 1.0 cu. ft. box.

JB-I

daverulz

Those amps are by all accounts amazing. You won't be disappointed and the built in DSP is freaking sweet. 5 watts difference is nothing. You would not be able to perceive it That is not a problem. But I highly recommend getting the 8 channel and bridging for your midbasses. Your midbasses can handle a lot more power when they are properly crossed over. This is an apples to oranges comparison, but it proves a point: I ran Dayton RS 7"s which are rated for about 50 watts off of 200 watts each in my old car. And I can say going from 50-80 watts per side to 200 was a night and day difference in sound - as you would expect with WAY MORE power. I ran them from 63-320 hz with no distortion or damage to the speakers The midbass region is very important to getting the kick and snap that you are after! I would say this is even more important than your subs.

I like your amp rack idea, and I don't think you're going to have output problems with a pair of 10s off of 600 watts. I agree with getting enclosures with more volume, as that will bring the QTC down and make them less boomy. Maybe start with just a simple plywood or MDF board for the amps laying down. Then make a simple plywood or MDFbaffle in the shape of your amp rack to see if you have output problems. Shouldn't take long, and would let you know if your showy (and really tasteful I might add) amp rack is worth pursuing.

Also, the rears off of HU power are not going to be able to keep up with the front. There is no harm in hooking them up, but as I said before, don't waste too much time with them

Pb82 Ronin

What sub did you plan on running?

JB-I

Pb82 Ronin

They going to face the rear behind each amp? That would make a stable enough platform for me to feel comfortable riding in front of it. LOL! That's a serious setup you're running. Looking forward to your impressions of ease of tuning when using the DSP feature in the amps .The lack of feedback on the web has made me hold off on buying 2 of them for my setup. The ONLY thing I need now is DSP. But I need a warm and fuzzy that using the amps is just as effective as using a $3-500 external DSP. Keep up the good work man.

daverulz

Looking at your rendering, why not make the area that supports the focal logo out of perforated aluminum like something here. Then there will be no problem wit h bass venting through. You could back-light it and it would look sick also

JB-I

JB-I