Connecting a centre speaker

Danem

Danem

Audioholic Intern
I have an amp with the basic 2 wire terminals to each 6 ohm speaker.
Can anyone oblige me with a diagram or text instruction as to how I can replace my speakers with a pair of 8 ohm bi-wire speakers together with a bi-wire centre subwoofer?

All advice appreciated. Thanks. Danem
 
M

markw

Audioholic Overlord
This a very confusing question and think you're laboring under some misconceptions. I'll try to clear them up.

To bi wire a speaker you need two sets of terminals, one for high and one for lows. They are joined by a jumper, which connects them. To bi-wire them you would remover that jumper and run one wire from each speaker terminal to the same channel on the amp.

this process would be the same for all speakers, right, left, center or surround.

There is no need to bi-wire a subwoofer plus it can't be done. You can run one connection to each channel but that subwoofer only handles one limited range.
 
Last edited:
Danem

Danem

Audioholic Intern
Bi-wiring1.gif

The diagram is how I intended connecting a Wharfedale Diamond 220; then thought of splurging on a pair of PSB Imagine Mini speakers. with a subwoofer to attone for their somewhat high frequency bass output. (55hz)
Even if I stay with the Wharfedale's I would like to know how I could wire in a subwoofer.
Your suggestions will help me in this. Thanks in advance, Dan
 
M

markw

Audioholic Overlord
Your diagram is valid for your full range speakers.

What receiver do you have and what subwoofer do you have?
 
Danem

Danem

Audioholic Intern
I do not have the knowledge to know what a receiver is. My amp is a rather dated Denon UPA-F88 (120W)
I have avoided buying a subwoofer until I have some idea of what it would entail. Dan
 
M

markw

Audioholic Overlord
You will need to buy a subwoofer with left and right speaker level inputs.

then, you will connect your amp's speaker outs to the respective inputs on the subwoofer.

Yes, this will result in three wires from each speaker terminal on the amp.
 
Danem

Danem

Audioholic Intern
Thanks. Does that not put the suibwoofer in parallel to the main speakers, thereby lowering their impedance?
 
M

markw

Audioholic Overlord
Good question. The speaker level input of a subwoofer feeds the very, very high impedance input of an amplifier so it will essentially be invisible to the amplifier.
 
Danem

Danem

Audioholic Intern
Phew! the plot thickens. The old story that if my knowledge is like a clearing in the forest, the larger the clearing becomes so does the perimeter of ignorance.

A side issue; if I recall it correctly, putting 2 x 8 ohm resistors in parallel gives a nominal resistance of 4 ohms. Ignoring inductance and capacitance of crossover networks, what would be the nominal resistance (impedance ?) of paralleling an 8ohm speaker with one of 6 ohms? :confused:
 
M

markw

Audioholic Overlord
True, but when you put a 20,000 ohm resistor in parallel with those two 8 ohm loads, what impedance do you wind up with? How much effect do you think it will lower the impedance?

The formula for two resistors in parallel is (r1 X r2/r1 + r2)

If you want to explore this more, check out this site. ...and have your calculator ready.

https://www.swtc.edu/ag_power/electrical/lecture/parallel_circuits.htm

Or, if you want to cheat and simply get the answer without bothering to learn the theory, here ya go.

http://www.sengpielaudio.com/calculator-paralresist.htm

By the way, all my answers assume you'll be using a powered subwoofer, If it's passive (no internal amp) then you DO have cause to be concerned.
 
Last edited:
Danem

Danem

Audioholic Intern
Regarding your question "... but when you put a 20,000 ohm resistor in parallel with those two 8 ohm loads, what impedance do you wind up with?"

One thing for sure is that the combined resistance will always be lower than that of the smallest resistor.
 
M

markw

Audioholic Overlord
h
Regarding your question "... but when you put a 20,000 ohm resistor in parallel with those two 8 ohm loads, what impedance do you wind up with?"

One thing for sure is that the combined resistance will always be lower than that of the smallest resistor.
Oh, a know-it-all, eh?

The question is "by how much".

Did you do the math? Did you bother to even use that calculator I went through the trouble to find for you?

One thing is for sure: Obviously not.

Why should I waste my time spoon feeding someone the answers who is either too lazy to use the tools provided or too stupid to realize they are he answer they seeked.

Have fun. I'm done here.
 
Last edited:
H

herbu

Audioholic Samurai
All advice appreciated.
Apparently not. Mark gave you more than a casual answer. He even found links for you to use. Here is a complete stranger who took his time and knowledge to help you. You blew it.
 
Danem

Danem

Audioholic Intern
"Have fun. I'm done here." Oh no!
For sure I went to the site, and used the calculator, just needed time out to do urgent home repairs.

6x8x20000 = 960000 / 6+8+20000 = 200014
960000 /200014
= 4.799664023518354

Thank you for your assistance.
Best regards, Dan
 
L

Latent

Full Audioholic
The formula he gave you only works for adding 2 parallel resistors and you can't use it for 3 sorry.

You have to break it up into two sections. lets to 6 and 8 in parallel first: (6x8)/(6+8) = 3.428571

Now we pretend this is just a single resistor and cacluate it in parallel with the 20,000 ohm resistor:

(3.428571*20000)/(3.428571+20000)=3.427983

The result of adding the 20,000 ohm in parallel has no real effect as was expected as the resistance only drops by 0.0005 ohm. An insignificant amount.

Here is another formula that makes it easier for multiple resistors and has a form you can just type in the resistor values and get the result:
http://www.1728.org/resistrs.htm
 
Danem

Danem

Audioholic Intern
Thanks for your input; it is good to have the gray matter descaled of the accretion of years. :)
 
newsletter

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top