maltesechicken

There was an earlier discussion on here about Amplifiers with a common ground for the speaker. I have an old Technics tuner with common grounding for the speakers (I opened it up to see all 4 of the - wires soldered to one point on the inside).

Can someone tell me if this will work . . .
Run a speaker on the left and a speaker on the right. Then, on the common ground return wire a speaker in series. IE the signal goes from left and right speaker to the common ground, through the speaker to the common ground of the Amp.

If this works (and I don't see why it wouldn't) what impedance would the amplifier see if all 3 speakers were 8 ohm? Would it see 12 ohm? or 16 ohm? Or would this not work at all because by placing a speaker on the common ground I would be introducing resistance on the ground were there should not be resistance and then cause the left and right + to start reacting with eachother?

Any theories are welcome.
Any actual knowledge is desired.

Thanks

maltesechicken

Here is my theory:
Since it would be running Series off of the common ground it would get power from both sides - a type of "bridging" perhaps.

My reason: I just moved into a new house and my stereo set-up is different. My main towers are now in the living room. I used to have them with the TV, but ther is no place in the den for the towers. In the den I have 2 shelf speakers.(running off the stereo across the house, and the TV is also wired into that stereo) These bookshelf speakers have an 8" woofer which only does mid-bass. I Have an old 10" CV that I would want to wire in to act as a "sub" so to speak.

This is how I would wire it.
CV in series with the common ground - theorhetically receiving power from both channels. I would place a capacitor (I will use a 330 UF) between the + and - of the sub. This way the higher frequencies will get a free ride and by-pass the sub, while the lower frequencies will have to go through the sub.

Now the Q is: Will all of this theory work out?

So I'm asking the pro's about it before I accidentally fry my amp.

Does my idea with the capacitor make sense? Or will it not work?

[ August 03, 2003, 06:01 PM: Message edited by: maltesechicken ]

pinhead

in order for the amp to be bridgable you must invert the signal to one channel 180 degrees
so to do it you would need a device to do that

maltesechicken

Yup, I know that it isn't bridging.
I still am not sure: Will it get more power than the left or the right independantly?

I'll give 'er a try this weekend when I have some time to play.

maltesechicken

This does work! [img]smile.gif[/img] I connected everything last night and my woofer worked wired in series in the common ground . . . however, when I did it, the shelf speakers started to make a funny noise a bit of a "swishing" noise perhaps - a kind of watery blurring of frequencies . . . yikes.
I placed a 470uf cap between the positive and negative of the sub, and the shishing stopped, and the woofer only puts out mid-bass and bass now.

However, because I heard that swishing, I am wondering if this might be doing a bit of damage to my amp. So, I have ordered a sub amp from solen so I don't wreck my stereo with this experientment.

With this knowledge, I can apply this to an old car HU that I have running in my shop. All 4 speakers use 1 common ground . . . so I could do this and get a sub running off the deck, and if I blow that thing up, I don't really care.