Impious

Keep an eye out for a Rockford Fosgate RFX-8240. It's a rebadged Denon and can normally be found for $250 or so when they come back up for sale. I can't recall which Denon model it is off hand, but it was one of the better models and had an MSRP of $900-$1k. The RFX-8250 was a slightly "upgraded" model, but they are normally in the $500+ range now (MSRP was something like $1300). They were blown out by desertaudio on ebay as well as sounddomain a few years ago at ridiculous prices, and as a result still go pretty cheap (albeit not blowout cheap anymore) when they come up for sale. Neither are a Z1, but still quality Denon decks that have "Rockford" screened on the face.

The RCA knob is more than likely a simple attenuator. So all it can do is turn the volume "down", but can never turn it "up" past the original level being output from the headunit (that's assuming it doesn't offer any sort of bass boost circuitry...most of them don't). Without knowing what amp you have, I have no idea what the knob actually controls. If it's a remote gain control, then those are usually basically the same thing....an attenuator that can only turn the volume "down" but not "up". However, if it controls the bass boost or something of that sort, then you could be in trouble using it. If they are both just attenuators, then there's nothing really wrong with just leaving them both installed. It'd be a little redundant to leave them both in, but sometimes it's a bigger PITA to remove something from a system than it's worth due to having to rewire. If they are both just attenuators, then you can basically continue doing what you're doing, leave one all the way up and use the other one as the control.

It's basically a matter of relative source levels. Some headunits offer source level adjustment, others don't. With all of the things a CarPC can offer, I'm sure there's probably some sort of input loudness/volume control software that would be available or built into certain programs.

It won't

It would be helpful to know what you already know and what you don't. Or, what exactly it is you need to know. There can be entire books written on the specifics of enclosure design and the physics of how they work and why. And after all, this sounds like a business class not an engineering class. At some point even the business people say "go ask the engineers".

Yes, for gain setting ACV is correct. But I would try to find a way to verify the ACV readings of the electrical system. If they really are outside of the normal range (~1V), you may have a problem that needs fixed......so it might have been a lucky mistake.

You have the DMM on the wrong setting. Battery and your car's electrical system is DC voltage, you have the DMM set to ACV. Although I'm not sure why it's showing 30V AC, that's more than a bit out of the norm. Your alternator produces AC voltage which is then rectified into DC voltage. You may have an issue with your alternators rectifier? That or your DMM is freaking out. The rectifiers don't completely remove the AC ripple, so I wouldn't have been surprised if it had read a volt or two of AC.....but 30V has be a bit confused. I would imagine you would be having serious problems with the vehicle if the electronics were getting hit with 30V AC.

Sounds like a good alternative

All of the amplifiers are sufficient to power your subwoofers and of good build quality. If you want a little more versatility, the Sundown does offer 1ohm stability which neither of the other amplifiers offer, and a little more power output at that lower impedance. But for anything 2ohm or above, I'd just stick with the least expensive option. How do you know that? I just recently had to contact JBL's customer service, there were no deficiencies in the service they provided. What is your experience with the CS of Pioneer and JBL to determine the CS from Sundown is vastly superior? I picked up the phone, called JBL and had my issue resolved in under 10 minutes. Sundown on the other hand has explicitly stated they often can't reach the phones in time (a phone number is not even published on their website) so the best method to contact them is via email , which normally means you are waiting much longer than 10 minutes for a response. How is that "far better" than the service I received from JBL in under 10 minutes?

Or you could simply save $100, not buy that, and just set the amplifiers settings to match

It won't burst into flames and explode if you run the "normal" Qts driver in a sealed enclosure, but the "normal" Qts drivers really don't have the parameters to excel in sealed enclosure performance.....the parameters are really more geared a little more towards ported enclosures. I don't know exactly how high the High Qts option actually raises the Qts, but if your intention is to run them in sealed enclosure, I'd probably recommend it since they specifically offer it as an option for that purpose and with it's "stock" parameters, it's not as ideally suited for sealed enclosures. If you were going to simply use them in a sealed enclosure for a period of time but plan to use them more permanently in a ported enclosure, then you would be okay using the normal driver in a sealed enclosure.

There are no negative side effects to the subwoofer or sound quality as long as the amplifiers' settings are all matched (which in reality isn't all that difficult; people make it out to be much worse than it really is). The settings between the two amplifiers would actually have to be significantly different before you'd breach the realm of audibility, so minor deviations aren't really that important. And before anyone asks; No, the subwoofer would not be damaged by the settings being slightly different. There would be zero difference to the subwoofer between running one amp per voice coil, a strapped pair of amplifiers, or a single amplifier to both coils. The sub doesn't know or care. It just responds to a voltage. If the voltage is the same, the result will be the same. It would also possibly be a little better from an amplifier perspective to run two separate amps @ 2ohms compared to a single amp @ 1ohm. Typically efficiency will be a little higher @ 2ohm than 1ohm and you won't be running the components as close to their limits @ 2ohm. This could decrease heat within the amplifiers, decrease the current drawn from the electrical system and improve amplifier longevity. It's hard to compare these differences between two different amplifiers without all of the variables being known, so this last paragraph is just a generality but something to think about.

It would be a HUGE asset to the SSA community for Don to have his own dedicated forum. He is the primary source of accurate and informative input regarding sound deadening and noise control.

The number of responses you've received is a direct result of the quality of the question asked and information provided. For starters, please read the Noob Posting Guidelines With the lack of information you provided, anything we say will simply be a shot in the dark. I don't know if I need to suggest a $100 5.25" 2-way component set or the $7000 Rainbow Platinum 3-way component set. We don't know what size speakers you are looking for, your budget, your goals for these speakers and setup as far as output and sound quality, which speakers you plan to replace (both front and rear or just front?), how you will be powering the speakers, if you are powering them from an external amplifier what amplifier and how much power you would be using, how you plan to install the speakers (stock location w/ no modifications, stock locations w/ modifications possible, kickpanels, etc), what music you plan on listening to, what your sound preferences are, how much experience you have w/ past products and what you like/didn't like about them, etc. It's sort of like I Robot.....In order to receive a response, you must first ask the right question.

So, you come here and ask two questions that directly relate to build quality (one of which potentially impacts performance)....and then go on to say that build quality is good? You're much nicer than myself......LOL....strike one, maybe an oversight.....two strikes in the same set of speakers? -1 on QC IMO. As to your questions; 1) Yes, I would recommend finding a way to secure the xover board. Help safeguard the components from being rattling loose a connection or solder joint. 2) If there is no obstruction to the cone movement, it won't pose an actual problem. However, you may be able to recenter it yourself if you know how they are attached. IIRC aren't those supposed to be able to converted into coaxials? If so, it should be pretty easy to remove the phase plug and recenter it if that's the issue. The other issue may be a mis-centered backplate which is throwing off the centering of the entire pole piece.....in which case, I'd be sending an email to the company about supplying a replacement driver.

Thanks for taking the time to benefit the community here on SSA

Personally, I'd just wait rather than jerry-rig it. When people are impatient and start trying to make something work is usually when mistakes are made and things start getting damaged. If you're impatient, you could always just grab the necessary speaker wire locally.

I'm pretty sure I just managed to catch a bag of popcorn on fire.....literally, on fire. Entire kitchen is filled with smoke, almost have to stop, drop & roll to make it through the room without coughing. Worst part: I don't want popcorn anymore It sounded soooo good, until I melted the shit to my microwave and filled my kitchen with the not-so-sweet smell of burnt fucking corn. Dammit!

What if that load stays the same, but two crossovers are paralleled from the amp?? If I'm understanding your question correctly, what you're describing won't have any effect on the passive crossovers but it will affect the load your amp sees. To the OP: I guess I don't really understand what you are trying to do. As 98GMC basically asked, what exactly are you trying to do here?

The short story is yes, measuring the input side of the passive crossover is not going to give you an accurate representation of the attached speaker load. Also, your plan to connect 2 pair of speakers to 1 passive crossover is not a good plan. Changing the impedance of the load the crossover is connected to is going to change the crossover frequency (among some other things depending on what circuits the passive crossover includes) which is going to seriously affect performance in a negative way. If you connect the tweeters in such a way that causes the crossover frequency decreases you now run the risk of blowing both tweeters. Passive crossovers are designed to operate with a specific load attached to them.....you do not want to change that load or negative things will happen.

Fi suggests always using a SSF. Fi suggests that because they are the ones who have to repair the drivers after some kid tries to play a 15hz tone through their sub in a box tuned to 40hz with 2.5kw on a 1kw rated driver because it impresses their friends and makes the sub move a lot.

More for your money, the float voltage of a Xs is around 13.4v on the other hand a Kinetik is around 12.4. When buying a battery from say amazon you have to factor in the shipping costs.. You may see the 150 price tag then they don't tell you the shipping is 100 dollars +. I would disagree with your statements. XS power are good batteries, but so are Kinetik. I don't know why, but the XS Power supporters seem to spend a lot of time trying to put down Kinetik's products, but you don't really see the reverse being true. I don't know the float voltage of a XS, but since I had to take my DMM back out to my garage anyways I checked the rest voltage of my 3 or 4 year old HC1800 (that I've never recharged/reconditioned during that time) and it was sitting at 12.9V. Not that float voltage is really an indicator of how well the battery will perform under load anyways. But it seems you are hellbent on "proving" XS Powers superior, apparently even if that means you need to give out inaccurate info.....so I'm not sure I'd trust your XS numbers either. Posting a picture of a swelled Kinetik doesn't prove anything other than abusing a battery will damage it. XS Power batteries will swell when abused aswell, as will any other brand. I'd say it looks more like someone is riding XS pretty hard......

Great prices