You are here

Log in or register to post comments
jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Matching Ohms and Bi-Wired Connections?

I just bought a pair of speakers that are 6 ohms. My amplifier has a barrier strip with 4, 8, and 16 ohms. Which output terminal on the amp should I connect to? Also, the speakers have two inputs--high and low frequency for a bi-wired connection. What's that all about? Do I need four speaker wires? Can I drive these speakers with a single amplifier and a single wire (1 pair) connection?

Sorry to be such a newbie!!!

Any advice is greatly appreciated ;-)

Jim

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: Matching Ohms and Bi-Wired Connections?

Try the speakers on each tap separately. Few speakers will have an impedance curve that remains close to the nominal quoted spec. A two, three or four way six Ohm speaker system can very easily be higher and lower than six Ohms at various frequencies. Your ears can determine which tap gives you the best subjective quality of sound. I would tend to opt for a lower than stated match, in other words, a six Ohm speaker on the four Ohm tap. There are, however, reasons why you may or may not prefer this tap with your speakers. Always make your speaker connections with the amplifier powered down and wait a few minutes for the power supply caps to drain.

You can run the speakers with a single cable to each speaker's main terminal set. Make sure the jumpers are in place for both sets of terminals. Replacing the jumpers with either better jumpers or short pieces of your speaker cable is a quick, fairly cheap tweak that many listeners suggest improves their speakers' sound quality. Most shops will have bi-wire cables you can borrow for experimentimentation. Some speakers benefit greatly from bi-wiring and others do not.

http://sound.westhost.com/readers.htm

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

Thanks for the great response. One more question please. Can I connect my old pair, 8--ohm speakers and the new pair--6 ohm speakers to the seperate output terminals on my amplifier for multi-room sound or do I have to have a speaker selector or seperate amps to do that? This forum rocks!!

KBK
KBK's picture
Offline
Last seen: Never ago
Joined: Sep 30 2007 - 12:30pm
Re: Matching Ohms and Bi-Wired Connections?

please tell us what the amp and speakers both are. It is easier to give advice on audio in the light, as opposed to generalities, done in the dark.

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

My amp is a McIntosh MC 2105. The new speakers are Revel Concerta F12s.

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: Matching Ohms and Bi-Wired Connections?

If you add multiple speaker sets connected in parallel, you reduce the load the amplifier sees. That means whatever taps you use probably won't be appropriate for the speaker systems in use. Two eight ohm loads in parallel (what you've done by the suggested connection) will amount to four Ohms and should operate best off the four Ohm tap and not the eight Ohm tap. Your six and eight Ohm speakers will fall beneath four Ohms and would operate best off the four Ohm tap with both speakers demonstrating some quality damage.

As I said speakers don't tend to remain eight, six or four Ohms over their frequency range. Deciding which tap works best is a subjective choice as much as a technical equation.

The negative feedback loop is connected at the 16 Ohm tap of this amplifier. As you move further away from that tap, you alter the amount of NFB and change the operating characteristics of the amplifier. Furthermore, connecting the speakers to a tap that doesn't match their nominal impedance changes the way the amp operates. You will increase distortion and/or lower power output. All the taps are live at any time so they will all feed voltage to the speakers whenever a connection is made to any tap. You could have three sets of speakers connected to this amplifier working each pair off a different output tap and this would work - it would make sound. It's not recommended but it would work.

The goal of the various taps is to most closely approximate the impedance load the amplifier will work into. This will provide the best sound quality overall. In most cases, this one included, I would recommend you do not run various speakers off various taps to achieve multi-room sound. If both speaker sets are going to play at the same time, you should decide which single tap gives the best sound quality for the main speakers. If you want to switch speakers in and out of circuit, then I would suggest a small speaker selector switch wired to one set of terminals. This isn't the best way to get the best sound quality however.

You could wire the two sets of speakers in series which would raise the overall impedance. This would bring the total system impedance closer to working properly off the 16 Ohm tap where the nfb loop is connected. If both pairs aren't meant to play at the same time, however, this arrangement is not your best choice either.

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

Thanks so much for your advice. Some of this is over my head, but you have a great way of explaining things to the novice. You should teach!!

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

Jan et al

Thanks for all your advice. I think I'm set now, but I want to be very careful not to damage my speakers or amplifier.
Would you be so kind as to see if this will work. As you know, I want to drive two pair of speakers. My primary speakers are 6 ohm and the secondary are 8 ohm. I've got a Niles SVC 2 speaker selecter switch. I'm going to connect the speaker wire to the McIntosh at the 4 ohm terminal--out to the Niles and run it as 2 pair of 4 ohm or mixed. Does this make sense? Is the speaker selector switch degrading my sound quality or is it just a power loss?

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: Matching Ohms and Bi-Wired Connections?

That should work well. I can't tell you what you will or will not hear. I would suggest you try your main speakers with and without the Niles box and decide for yourself. In my opinion, a Niles speaker switcher doesn't belong in a decent high end audio system. But we do what we must to make things work. Really, try with and without and decide what you hear. The switch will probably have little real effect on sound quality.

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

Alright, thanks to Jan, I've got my ohms worked out. Now, I would like to try to bi-wire my speakers. I've got a free weekend, and I'd love to try some new connections and speaker placement. However, I've got 14 guage speaker cable, and I'm having trouble connecting the pairs onto a single terminal on my amp. The two wires coupled seem to large. Can you terminate one negative and postive or do all four wires need to connect to the amp?

Thanks yet again--I'm learning a ton and it's fun!!!

Jim

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

Also, does it really matter which colors are paired as long as it is consistant? I've got black and white to negative and red and green to positive.

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: Matching Ohms and Bi-Wired Connections?

By all means be consistent. You don't want to blow up your amplifier. Color is a preference though some people think blue cable insulation sounds better.

Just kidding.

You can jury-rig something that allows you to connect all four 14 A.W.G. conductors to two terminals, one "+" and one ground per channel. Again this is not my preference. Actually, I would tell you to spend some time with your new speakers to get used to what they do before you make any other changes. If you want to play with jumpers, that would be a good first weekend activity. When it comes time to bi-wire you might want to try a smaller guage cable for the high frequency section. There's not much current required for most tweeters so thick cable can sometimes get in the way of the music. Try an 18-20 A.W.G. cable for the top end. If you have the ability to use a good crimping tool, you can try placing both cables for one speaker's "+" and ground connection into spade lugs that will fit the terminal blocks on the Mac.

What are you using for speaker cable? Have you done a proper speaker set up yet? If not, try this, http://www.tnt-audio.com/casse/waspe.html

Get the placement correct and get used to the speakers before you make any other changes. Take your time and enjoy the music.

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

Jan Vigne in 08!! You've been very generous with your advice and patience. A lesser fella might have have dismissed this audio-ignorant new comer. Thank You!

cyclebrain
cyclebrain's picture
Offline
Last seen: 2 years 7 months ago
Joined: Jun 16 2006 - 11:40pm
Re: Matching Ohms and Bi-Wired Connections?

Both the questions by J.Smiley and the responses from Jan have been well thought out and useful.
However I would like to offer some other input.
While Jan's answers regarding speaker loads is correct, I would recommend to J.S. that he not connect two pairs of speakers to his amp. He has a very nice combination of amplifier and speaker and should not risk probable negative audible interaction between them by connecting an additional load. Buy an additional amp to drive the second pair of speakers.

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

Thanks cyclebrain. That's a good idea. Can I connect a seperate amp to my preamp (Mcintosh MX 112)? My preamp has two sets of outputs: one is labeled Main, the other tape. I wouldn't run a second amp from the tape output would I? How would I get the signal to both amps?

cyclebrain
cyclebrain's picture
Offline
Last seen: 2 years 7 months ago
Joined: Jun 16 2006 - 11:40pm
Re: Matching Ohms and Bi-Wired Connections?

Damn, busted me on that one. Yea, just add a additional amp.
Made it sound easy didn't I?
The first question that needs to be answered is, do you want one master volume control or two separate controls for both sets of speakers?
For the one master volume control you would need to connect both amps to the pre amp main output, which could introduce some additional problems with preamp load and amplifier levels.
If you want to have separate level controls (probably the best solution) use the tape out and connect it to an integrated amp. You could use an old reciever if the secondary system is just used as a background system.

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

So an integrated amp gives me the ability to adjust the volume on a secondary system? Could I not just turn the gain up or down a regular amplifier and connect it to the tape out? I like where this is headed. I have to admit that for the short time I've had the speakers, eliminating the speaker switch and running the signal straight from the amp to the speakers is sounding sweet. I'm glued in my chair!!

cyclebrain
cyclebrain's picture
Offline
Last seen: 2 years 7 months ago
Joined: Jun 16 2006 - 11:40pm
Re: Matching Ohms and Bi-Wired Connections?

We might be having a misunderstanding of terms.
Here are the definitions as I use them.
Pre amplifier - switches between different input sources and has a volume control. Connects to a power amp.

Power Amp - has a fixed gain and is driven at its input by a preamp and its output drives a speaker. Most power amps have no controls, only an on/off switch.

Integrated amp - A combination of a preamp and a power amp.

Reciever - An integrated amp with the addition of a tuner.

Does this help?

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

Yes that does help. I should have been more specific. I've got an old Crown D150, which has gain controls, that I could use to drive the secondary system. I guess my question is: As long as both systems are hearing the same source, could I control the volume of the secondary system with the gain controls on my Crown amp? If I'm using the tape out from my preamp to drive the Crown, why would I need a integrated amplifier with a preamp. Sorry to be so dim. This really helps..I appreciate your time.

cyclebrain
cyclebrain's picture
Offline
Last seen: 2 years 7 months ago
Joined: Jun 16 2006 - 11:40pm
Re: Matching Ohms and Bi-Wired Connections?

A Crown D150? Cool. I have one of those too. Well kind of.
I bought all of the parts to one less the chassis from someone that couldn't make it work. Ground loops.
Your idea is valid and obviously you do have a grasp of the concept. It might work and will be dependent on if the gain controls on the Crown have enough range. Give it a try. Connect it to your tape out.

jimsmiley
jimsmiley's picture
Offline
Last seen: Never ago
Joined: Jan 3 2008 - 6:19pm
Re: Matching Ohms and Bi-Wired Connections?

I'll give it a shot. I really like the idea of my primary system being as "pure" as possible. Thanks for all your good advice!! By the way, I've found Crown to be a great company that goes over and beyond my expections for customer service. They may be able to send you a new chassis. I once sent them my amp, and the price for repair was ridiculously low!

  • X
    Enter your Stereophile.com username.
    Enter the password that accompanies your username.
    Loading