Subwoofer choice and "bi-amping" + speaker resistance?

helping · February 15, 2014

Need help figuring out what subwoofer to buy. I've got 150$ in Amazon credit to use, so it would need to be off of Amazon.
After looking for a while through a few pages of results, the only worth while options seem to be:

Dayton 1200 (Most likely option, decent brand, fair price)
Dynamo 300 (could be good, but makes me wonder what I'm actually getting for 130$ if it includes ML name markup)

From a few Google searches, these two seem to be brought up in a few places, but no definitive answer is given.

Alternatives:

Monoprice 12" (not sure how decent a Monoprice sub would be, since it's not something they would traditionally do even as rebadging goes)
Onkyo 10" 230w dynamic :unsure: (Currently least likely option unless I can find some solid evidence this thing is good)

It's going in a 12x12" room so it's not like I need some massive 500w subwoofer. SPL is important, but optimized to sacrifice as little bass quality as possible.

And then the issue of dual wired speakers is worth doing. I bought a pair of Polk Series 2 Monitor 30's and have them connected on a single wire using a jumper to bridge the cone and tweeter. I know since it's from a single amp, it's technically not bi-amping, but the receiver does seem to have the option as the front panel has an "A+B" speaker set option. I have no idea if this would actually [vague idea that it might] yield an improvement by bypassing a jumper and giving the tweeter and speaker their own inputs, I'm assuming these use passive frequency filters.

Now if I bother to go and dual wire them, the Polks are rated at 8 ohm impedance each, then I'm not sure how the ohms would balance out. They should technically be separate, but would each speaker be a separate 4+4 or 8+8? The manual doesn't say anything and I'd rather not go about assuming. It gets complicated between the speaker design and the receiver notation, if each input were to be treated as a separate "speaker",

Bridged, the speakers are rated at 8ohm(? assumption, only information given), then without a jumper each would be 16+16(?) requiring the resistance selector to be switched down. This sounds like the most correct judgement, but I'm still largely uncertain.

A+B terminals (banana plugs)

Impedance selector

oh and if anyone has made it this far, would it be worth while connecting a center channel speaker? I have an old JBL Flix1 center laying around doing nothing but I'm unsure if it's even worth the hassle over two good monitors already in place.

ShearMe · February 15, 2014

Bridged, the speakers are rated at 8ohm(? assumption, only information given), then without a jumper each would be 16+16(?) requiring the resistance selector to be switched down. This sounds like the most correct judgement, but I'm still largely uncertain.

oh and if anyone has made it this far, would it be worth while connecting a center channel speaker? I have an old JBL Flix1 center laying around doing nothing but I'm unsure if it's even worth the hassle over two good monitors already in place.

I'll let the big boys help you with the subwoofer selection, though I'd suggest you get a Polk sub if you've got Polk bookshelf speakers.

You've got the impedance math correct, but I dunno about those assumptions (maybe best to contact Polk about that). If bridged = 8ohms, then unbridged, each speaker's nominal impeadnce is 16ohms.

I don't think 3.1 is any better than 2.1. You already get enough spacial information from 2 well-positioned speakers that the center is rather pointless unless you're adding rears. Then again, this is me talking while sitting at a desk with two bookshelf monitors angled directly at my head. If you're in a big room, the center might be nice if the left and right are in the corners of the room.

helping · February 15, 2014

I'll let the big boys help you with the subwoofer selection, though I'd suggest you get a Polk sub if you've got Polk bookshelf speakers.

You've got the impedance math correct, but I dunno about those assumptions (maybe best to contact Polk about that). If bridged = 8ohms, then unbridged, each speaker's nominal impeadnce is 16ohms.

I don't think 3.1 is any better than 2.1. You already get enough spacial information from 2 well-positioned speakers that the center is rather pointless unless you're adding rears. Then again, this is me talking while sitting at a desk with two bookshelf monitors angled directly at my head. If you're in a big room, the center might be nice if the left and right are in the corners of the room.

I'll probably email them if I can determine a double wired set up is worth doing when only a single amp is used.

I was leaning towards not adding the center since both of the speakers are right next to my face anyway

Unfortunately I don't think much other people on here would know the answers, aside from maybe @MayflowerElectronics or @mr moose

mr moose · February 16, 2014

The A and B terminals is not for bridging or bi wiring. It is simply so you can have main left and right speakers in one room ( A ) and then either a second pair of switchable speakers in the same room or another room ( B ). anything connected to a or b will play the same content and the switch on the front of the amp will only turn on or off the B speakers.

The reason you have impedance's switching is because when you select A and B together it connects the A speakers in parallel with the B speakers so the impedance the amp sees will be half of the speaker impedance, that is why it has a minimum of 8 ohms selectable for A + B (each amp can only handle a 4ohm load)