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Newbie speaker wiring question

S

SpaceNoodle

New Member
So this is probably really simple for most of you. I have a 1970s Hitachi SR-703 receiver that is rated at 8 ohms. The receiver has A & B channels for speaker inputs (2 speakers each) that can be used at the same time. Can I hook up five speakers rated at 4 ohms and a sub rated at 3 ohms? I know I won't get true surround sound, but just looking to run audio to all four corners of the room plus a centre and sub. I've read a bit about parallel vs series but am confused as to which option my receiver can handle. Thanks in advance!
 
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Yes, you will send that amp to the cemetery real quick with all that.

You could series wire the 4 ohms speakers to get by, and omit the sub for now.
speaker_power_handling_series_speaker_wiring.svg

Do this for each left and right. The speakers will then add up to 8 ohms and the amplifier will be safe.

You could implement a powered subwoofer with high level inputs on channel B later.
 
Sounds pretty risky to me.
Really risky actually.

Five 4 ohm speakers unless wired in series (they would be in parallel if wired off a/b) , and a 3 ohm passive sub (a powered sub would add no load to the receiver), maybe post video if/when it blows up.

I agree with Wes, get something designed for that kind of load and use.
 
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SpaceNoodle said:
I know I won't get true surround sound, but just looking to run audio to all four corners of the room plus a centre and sub
Click to expand...

If you're using a powered sub, its speaker-level inputs don't present a load to the amp feeding them, no worries there.

I'll let others figure out the best actual connection four the four corner speakers. However that ends up, you'll be running two pairs (both right speakers, both left speakers), with the two speakers in each pair connected in series.

The tricky part will be the center channel. The crudest approach would be to derive the sum of the left and right channels (Left+Right). And the crudest way to do that is electromechanically with a dual voice coil speaker, Left into one voice coil, Right into the other. But I doubt your center speaker has that provision. You could mix the two channels via some series resistors(20 ohm 50 watt might be ballpark), then send the mix to the center channel speaker's + terminal, its - terminal to the amp's common - terminal for the other speakers.

Keep in mind that deriving a *true* center channel signal from two-channel source material is far from arbitrary. There are a couple of proprietary processes that do this well.

Also keep in mind that unless *all* the speakers are the exact same distance from your listening position, you'll end up with timing and phasing issues. How noticeable depends on how much the difference in distance.

With your setup, you also won't be able to do much to integrate your subwoofer. You certainly won't be able to high-pass your main speakers, or time-align the sub to them.

When all is said and done, you're trying to make a silk purse out of a sow's ear. Your Sansui might be terrific at 2-channel, but for what you're attempting you want a 5.1 AVR. It would include everything you need, that's what it was designed to do.
 
I'm also guessing the sub might be a powered one that has it's own amp. Line out to that won't affect your amp much. 4 x 4 ohms on a 40 watt amp is asking a lot, if you are going to play it loud. I did see a write-up at https://stereonomono.blogspot.com/2014/04/hitachi-sr-703.html that showed a rating for 4 ohm loads at 60 watts per channel, and that makes me think you might be OK running this way. I still wouldn't crank it really loud unless I wanted to fry the amp so I could just buy something newer.
 
Get a budget AVR and enjoy true surround sound in all its glory. If you blow up the old receiver you'd have to buy something new anyway. Go to local goodwill type of store for a cheap AVR. Or, just run two speakers in stereo. The sound created by two speakers will, in fact, travel to all four corners of the room! :thumbsup:
 
Same as others have stated if you like the sound of your hitachi in stereo just keep it for that purpose and buy a cheap surround receiver for movies. That’s what I do. You’ll have multiple stereo setups before you know it. I have several vintage receivers i like to baby. There’s 2 that I have that says 4 ohm is not much of a problem but only one set of speakers.
 
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First off, that receiver is rated at 8 ohms and is only two channels.

You don't want to run even one pair of 4 ohm speaker on that receiver much less two pairs. That would be a 2 ohm load. And implementing that 5th speaker and 3 ohm sub will just lower the impedance even more and add to that danger.

If you do that, get long sticks, marshmallows and invite a few friends.
 
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