Bass from two sets of speakers cancelling each other out!

[admin_exported]

Hello hi-fi crew.

I'm currently running two pairs of bookshelf speakers through a CA 740A. The speakers are MS Mezzo 2s and Tannoy DC6s, and are placed in the same end of a room but on different bookshelves, one above the other. I run both sets of speakers at the same time which I really like except....I've noticed when both sets of speakers are on that the bass seems to disappear. The Mezzo 2s have a stronger bass when played on their own but the Tannoys aint too bad either.

I know when setting up subs you have an option to change the phase so that the sub augments the speakers and doesn't cancel out the bass. I'm worried that the two sets of speakers may be out of phase with each other and I may not be able to change this.

Any ideas???

 

[ear]

that doesnt make sense.

sometimes I run 2 or 3 pairs and ive never noticed it.

 

[Anonymous]

Well its definately happening on my system! I agree it doesn't make sense though, surely the amp sends the signal in the same phase on both sets of speakers. Its a mystery to me but I bet someone out there can help...

 

[MattSPL]

The positioning of them or some other factor must be making them run out of phase with each other. Try reversing the polarity on 1 pair.

 

[Anonymous]

Speakers have different phase responses, so it's very possible that they would cancel even if you put them together.

I suggest not running them together due to comb-filtering effects. But if you really want to run both, try playing with the distances between them, and the relative polarity (you can invert the polarity on one set)

 

[Andrew Everard]

Cidershed,

Two pairs of speakers at different heights running simultaneously? That must sound truly horrendous!

 

[Anonymous]

Can you biwire both of them? Remove the connectors and run wires to one speakers treble only and to the other to the bass only. This might give better results.

Alternatively sell both speakers and buy a better pair!

 

[Andrew Everard]

angelface59:Can you biwire both of them? Remove the connectors and run wires to one speakers treble only and to the other to the bass only. This might give better results.

Then again, could sound even more horrible, with either an overblown midband or a suck-out in that region.

angelface59:Alternatively sell both speakers and buy a better pair!

Gets my vote...

 

[Anonymous]

Thank you for the replies folks. As a matter of fact they don't sound horrendous when played together at all! The Mezzo 2s are quite bright and fast while the DC6s are more neutral and, in addition to my Rel Stampede sub sound great together, though when the sub is on it's hiding this bass problem (though obviously not entirely).

Its handy running the two sets of speakers as I can switch to the DC6s for AV use, and click the Mezzos in when I want to crank the music up. And the combination works well to my ears Andrew so don't judge what you ain't heard!

Anyway, I was interested to hear about the possibility of reversing the polarity on one set of speakers. How do I do that? Many thanks.

 

[The_Lhc]

You swap the positive and negatives over on one set of speakers, however my suspicion is that you've already done this accidentally on at least one speaker.

 

[Anonymous]

So I'd run one set of speakers with amp+ to speaker - and amp- to speaker +. Is that right? (sorry I'm a bit thick hehe)

 

[The_Lhc]

Yes but it would be well worth checking you haven't already done that by mistake. If you've only done it on one speaker and you swap both of that pair over you'll end up with the same result.

 

[Anonymous]

Problem solved! Both sets were wired up correctly but reversing the polarity on the Tannoys has given me the bass back, fantastic. Thanks for your help folks, I can turn the sub down now....

 

[MattSPL]

Also be aware of the phase reverse function on your sub.

I have my Strata 5 in the corner to the left of my left speaker.
With my old PMC DB1i's, the phase of the sub had to be set at Zero.
With the scm19's its set at 180. Speakers in approximately the same position.

One speaker may favour the sub to be in phase and the other may favour reverse phase.

 

[Anonymous]

Hi Matt. Good point, I'll play around with it. Nice set up, though I'm a little concerned about that lamp...

 

[Andrew Everard]

Cidershed:And the combination works well to my ears Andrew so don't judge what you ain't heard!

If you're happy, I'm happy, but I know enough about the characteristics of those speakers to know that what you're hearing with them both running ain't anywhere like the way the music is supposed to sound.

 

[MattSPL]

I have little blobs of trusty blue tac around the base of the lamp so its nice and secure.

 

[Anonymous]

Thats odd, 'cos I can hear the Mezzo 2s on the own, the DC6s on their own and a combination of the two. In my opinion on my CA740 combination, the Mezzos are fast and detailed but a little bright while the DC6s are more neutral but a liitle lacking in energy and clarity (better for AV use). However, the sound when switched on together is really nice, fills the room and blends the characteristics of both speakers very nicely.

So I'm not bothered what they are 'supposed' to sound like. I know what they REALLY sound like to my ears in my room with my equipment, and thats what matters. Shame you didn't help me find the problem like other contributors and only saw fit to criticize the set up without actually hearing it. Still, like me, you obviously have stuff to learn, thats the point of this forum right?

 

[Andrew Everard]

Indeed: today I have learned that all I thought I knew about soundstaging, driver integration and tonal neutrality is wrong. Oh well - that's 20 years of my life I'll never get back...

But to return to your original question, yes, the problems you have are due to the characteristics of the two speakers clashing, and while you can try using the bass from one and the treble from the other, or wiring one out of phase and the other in phase, or indeed turning one pair so they're facing the wall and the other facing into the room, the best solution will be a single pair of speakers able to suit all of your needs.

 

[Anonymous]

In your opinon. Problem is, what is the 'best solution' for one person is not the 'best solution' for another. Otherwise we'd all be robots.

Anyway, thanks to the others for the solution to my current problem. May the journey continue...

 

[The_Lhc]

To be fair to Andrew, what you're doing IS a bizarre idea, I don't think I've ever heard of somebody running two different sets of speakers together like that before, not in the same room at any rate.

 

[Andrew Everard]

Cidershed:Otherwise we'd all be robots.

Danger, Will Robinson! Danger!! Godwin's Law event probability increasing...

 

[Anonymous]

When I started out on this crazy hobby, the thing that made me go up the food chain was when I placed a pair of Monitor Audio BR2's on top of a pair of Celestion 551's. With both speakers being run from a Harmon Kardon HK620 it sounded pretty nice. Room filling sound but the coherence wasn't all that good. Then I thought, if that combination could sound as good as it does, why not get a better pair of speakers.

In my uni days I ran 4 speakers off an old technics seperates with one speaker in each corner. No, the soundstage, imaging ect wasn't there but it sounded good wherever you were in the room, and at times, there was a lot of people in that room.

I would say both opinions are right.

If it sounds good, to your ears.............

But could it sound better????????

Would I go back to more than 2 speakers? Pro's and cons to each but, I'll be sticking to 2 from now on.

Lee