95Honda

This is what I am getting at, the truly balanced signal components do not pass those signals on RCAs. They use connections and cabling specifically designed for differential transmission. DC won't induce noise, correct. Any AC component that is also on your DC cable (alternator ripple, ignition harmonics) can be induced on to your signal cables, but it is normally so low in magnitude, it never gets anywhere...

I would also like to see a car audio source with RCAs and identical phase inverted signals on the outer shell and inner pin... Just don't see it happening, but I could be wrong...

The original PDX amps were confirmed by werewolf to have differential inputs per the service manual back in the ECA days. The designers at JL and JBL are pretty smart cookies....from the posts from Manville and Andy, respectively, I would readily believe the amps they indicate to have differential inputs truly do. Seems like of all of the things to falsely advertise, differential inputs would be a bad choice given the first time someone tries to drive it with a balanced signal and the amp goes pop, there would be a lot of liability there. From what I found skimming threads a while back some BMW systems use balanced line level signal transmission and people have been splicing in directly to the OEM system by using amps with differential inputs. Yeah, I just don't see the logic here. It is pointless to have differential inputs driven by a single ended source. I can cause a myriad of problems. That is why I wonder if it is some kind of modified/quasi balanced circuit. RCAs were never intended to be a part of a balanced signal chain. This is why I think there is some BS going on here. All circuits are differential at some point in a push-pull amp, anywhere past the splitter/inverter is balanced, there can be some creativity in how this is described to the customer.

I have read about some companies claiming differential balanced inputs on RCA's, but it just doesn't make any sense. You just can't exploit the benefit of differential transmission with an RCA connector, never mind the fact that most sources are not balanced, so that actually makes things worse if you truly have a balanced amplifier input. My guess is they may be running some kind of quasi-balanced input, I just don't see the reasoning behind true differential balanced signal on single ended connectors, with single ended sources. I think it is more off an attempt to float the input cutting down on ground loops than differential operation... All truly balanced equipment I have dealt with has truly balanced I/O connectors, be it XLR, Phoenix or barrier strips, never RCAs... I would have to see a schematic of the amplifier to see if it is truly balanced, but that is pretty tough to get sometimes, so I will probably keep my BS flag up on this one until shown otherwise...

This is primarily due to the fact that the attributes needed to ensure retard-high thermal ratings kill efficiency... It is a double edged sword...

The rating has no correlation to output level...

For sh*ts and grins, can you please explain why you thought the RMS rating had to do with output? I am not going to be a prick and try and tell you your dumb or something stupid like that, I am just curious as to why people are always saying this...

The RMS rating is the thermal power limit of the voice coil. It isn't a power requirement, it isn't a figure to match amplifiers to, it isn't going to tell you how load a subwoofer will be in the slightest. It is the most useless specification given by a manufacturer. All the RMS rating tells you is how much power you can continuously ask a voice coil to handle before parts begin thermal breakdown.

They don't even need to be fed the same signal, actually...

There is no correlation between the RMS rating and output levels in any way whatsoever... At all...

Show me the schematic of an amplifier that has true differential inputs on an RCA connector... The only car audio amplifiers I have installed that had differential inputs were Butlers, and they had XLR connectors, of course... Some Adcom and Macintosh gear ran differential signal I/O, but again, on XLR connectors...

My RMS statement is for any line of woofers...

Nothing you did will help you in any way. Setting a gain at a fixed frequency only works at that frequency, with that test tone, on that CD, at that battery voltage, at that exact settings of everything in your chain. If you change anything, which you already have, everything is null and void. You simply cannot set gain to prevent driver damage under any circumstances whatsoever. You need to use your senses to tell you if you are damaging anything...

There is no such thing as under-powering. If you ever over-powered them, they would fail. So you never over-powered them...

Don't buy any German equipment, it is all extremely over-priced, even if you can use a VAT form. You can get everything for the stateside price via APO shipping, as long as each item is under 75 pounds... Praktiker an Toom both sell 3/4" (19mm) MDF. I bought probably 20 sheets while I was there. I just got back from 4 years there and was ordering monthly, I sold a lot of gear to the Germans... Don't buy any German stuff(!)

The RMS rating has nothing whatsoever to do with how much power a driver needs, how loud it will get or how it will sound. In fact, it is the most meaningless spec you get when you buy a driver. It also has nothing to do with matching up an amplifier. All it the RMS rating tells you is what power level it takes to drive the voice coil into thermal failure.

Again, the "order" refers to the roll-off, not the actual physical configuration of the enclosure. 4th order refers to the alignment attenuating roughly 24 decibels per each octave on the bottom end (and the top on a band-pass). You need to fully understand this before you press ahead designing anything for yourself.

All it takes is one little spot, and then all down hill from there... Hopefully you get this sorted out...

Honestly, the part where the big hole is has signs of something (from your car) rubbing there. Once that happens, the rest tears itself apart easily. I have seen this a ton of times...

The amp is a single channel. I has a few extra places to stick wires, but there aren't any extra channels. you can't bridged, strap or do anything else with a single amplifier. They put what looks like extra channels there to make it easier for you to get a bunch of wires hooked up without cramming them into a single set of holes. Do not buy CCA ever. It is a marketing gimmick. It is lower performing (greatly) to the same awg copper. Additionally, aluminum in any form is inferior to copper in all aspects electrical. The amount of copper plating on the individual strands is there for color appearance more than anything... Buy welding cable, it is better quality to price ratio than any car audio branded cable. You don't need to fuse the - side, one fuse blows in the circuit, the whole circuit stops current flow.

I run all of mine inside the walls and use decent looking gang plates where they go in/out...

Ok, lol that isn't silver wire... Polyfill is used to change the Qtc of a sealed enclosure (make the woofer behave as if it is in a bigger box), it doesn't do the same thing to vented enclosures. You don't need to add any fill to a vented anclosure that only operates over the bottom 2 octaves. Use one of the suggested FI alignments or have someone help you with your box design.

You can't "ohm it out to see what the amp is seeing". You can measure the DCR with a DMM, but this will be lower than the box impedance 95% of the time and doesn't give you any real idea of the load your amplifier will be presented... You need test equipment in addition to a DMM to measure impedance. There is no such thing as impedance rise. You are using pure silver speaker wire? What gauge? Last time I used solid silver it was Kimber Kable and was over $100 a foot...

Class Ds pretty much perform similarly, buy what you can afford. Honestly, there isn't a huge difference in quality from amp to amp these days. There is no such thing as dirty power, underrated or overrated. The amplifiers put out a certain power before clipping, and that is usually pretty close to what they are supposed to do. When brand X makes a 1500.1 class D amp that puts out 1774 watts, it isn't overrated, it is a 1774 watt amplifier into the given load it was tested with. All class Ds have similar distortion and efficiency, there isn't huge differences in their topology from manufacturer to manufacturer. The more expensive amps have *only potentially* better quality parts than the cheaper ones. They may also have better QC to cut down on failures. Clipping doesn't hurt anything, it never has and never will. If it did, every speaker would blow if you listen to popular music, because it all has heavy clipping in one form or another... I have done exhaustive *objective* tests with this, more so than anyone on this board. You can destroy any subwoofer made with a 1900 WRMS class D amp if you try hard enough. Gain settings have nothing to do with, or will ever limit, total output power.

If they are operating above the resonance point of the enclosure they will never cancel each other no matter the difference in power if they are in phase electrically. If one is getting 1 watt and the other is getting 100 watts of an identical signal, then you will get 101 watts worth of output. This is how output sums above resonance, regardless of individual power and even cone size... Your problems are caused by something other than the drivers receiving different power levels.