I have two of the Monoprice 12" subs for the home theater. Got them a few years ago and I'm surprised the police haven't showed despite living in the boonies. Very impressive. I recently tried one on Houdini...the 12" was just too much, plus it's huge. I had noticed Monoprice came out with a slimline active 8" ported. Much better cosmetically. Acoustically?...spot on for a pin. $100 with shipping Hooked it up to AS a couple of days ago. Wow, what a difference. I made simple circuit (just a resistive voltage divider) to run into the sub's "line in" since I tapped off of the AS woofer (that is still connected). That way I could set the sub volume independently from the Stern woofer.

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Monk,

A little hard to understand your drawing, but we'll work thru it. A few questions:

1) The outside of the RCA connector is ground. The center is the signal. Which speaker wire did you attach to the RCA ground in your 3 drawings?

2) What game is this for? (Sorry if you mentioned, didn't search thru the thread). I'd like to look at the schematics.

3) Got a DMM (multi-meter)?

Added another question:
4) Any chance you have a home AV receiver for your TV setup? if so, have you tried the sub woofer output of that to the monoprice sub?

Monk,

So the yellow/black on the speaker. That's the ground. That will go to to the copper 'shield' of the wire (ends up going to the outer part of the RCA connector). This is the 'exposed' wire you mentioned when you stripped off the outer jacket.

The yellow wire on the speaker. That's the hot side. That goes to the red center wire you described above (ends up going to the center pin of the RCA connector).

I've quickly skimmed thru the thread to try to catch up, but it sort of bounces around. Maybe you already did what I mentioned above. But those are the correct connections. Next step we will unhook you wire use to connect the sub and verify you have it wired correctly. I think you are using alligator clips on the cab speaker end?

Keep in mind, the line-in inputs are low level. There's a chance you could damage the sub if the cabinet sub setting is too high. Turn the Sub volume control almost all the way down. On a scale of 0 to 10, set it to 1 or 2. And turn down the cabinet volume too. I added resistors to my setup to keep the line level low and and to create a high impedance. More on that later, if needed.

Hang in there!

Monk,

No kidding on the wires. I saw the same thing when I modified mine. It was like working with thread. LOL.

No reason you can't use some speaker wire. The shielding helps prevent noise from getting picked on the center lead. But the levels you are working with are plenty high enough to not be an issue. Plus I think you likely would have a short distance to run anyways, so not important. Speaker wire will work fine, and be easier to work with.

Any chance you can round up some small speaker wire? Not the 12 or 14ga fat stuff, but something more reasonable to deal with, like 18-20 ga? Solder some clips on one end, you can get some RCA connectors (no wire), and just solder the wires on. Then use that to hook it up, after we use the multi-meter to make sure it is OK. Like this:

I'll see if I can find one on Amazon or eBay if you don't want to make.
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That was a lot easier when Radio Shack was still around. Fry's maybe? I don't have one in my neck of the woods, but I've seen posts over the years mentioning you can get some stuff there for DIY.

This will get you most of the way...just add clips. There are cheaper ones, but this has the red/black wire - so easier on you end to not get confused.

https://www.amazon.com/dp/B00OC8UO2A/ref=psdc_3236443011_t1_B00PIYARAQ
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Once we get somewhat in the ballpark, there's a couple of other things we should do to help make it a little bit safer on the electronics. But you will still be able to reuse the cable we've been discussing.

boust,

I agree completely, and that's where my post above yours was headed. Plus if one side of the amp was grounded, and an individual accidentally swapped the leads to the sub, that could be a big issue there too. I was just going to suggest just some high value resistors (i.e. 1K) on both sides of the speaker leads (and one line to line) so that the the amp always sees a high impedance. But your suggestion of an transformer is good since it's goes from balanced to unbalanced (balun). Just wanted to sort out the wiring first.

I finally had a sec to look at the Amazon link. Rather nice for $8. I think I might get one to play with. I actually 3d print a little box, wires come out to the cab speaker, then a RCA cable for attaching to the sub. Then I add the resistors inside the box to make it a 'pseudo' balun and to to provide attenuation for a line-in level. Don't mind tinkering, but $8 and pretty decent specs - I might nab one.

Monk - You should follow boust's suggestion and get one too. This sort of where I was going, but mine was more DIY. I suspect you've done enough DIY on this project already and would rather hook it up and be done, and enjoy some thumping bass while playing.

Monk - I'm reposting boust's comment as a reminder. I still think it would be prudent to purchase the Amazon product. A safer and more appropriate way to hook it up.