2 Speaker system to 1 stereo speaker

[jassdhali]

Hi Guys,

I currently have a hi fi in the bedroom with a left & right speaker.
To de-clutter/remodel the room I am thinking of putting in a single stereo speaker in the ceiling.
Can anyone suggest a way of making the 2 speaker (mono) signal convert into a single stereo output for the ceiling speaker.

I have read about using a summing mixer - 2 10k Ohms resistor on both outputs, then the resistor outputs are bound together to feed the stereo speaker.
Is this a method anyone has used?

Many thanks

Jass

 

[Gees]

Hi Guys,

I currently have a hi fi in the bedroom with a left & right speaker.
To de-clutter/remodel the room I am thinking of putting in a single stereo speaker in the ceiling.
Can anyone suggest a way of making the 2 speaker (mono) signal convert into a single stereo output for the ceiling speaker.

I have read about using a summing mixer - 2 10k Ohms resistor on both outputs, then the resistor outputs are bound together to feed the stereo speaker.
Is this a method anyone has used?

Many thanks


Jass

Singe stereo speaker ???????????????

 

[OwainDIYer]

I have read about using a summing mixer - 2 10k Ohms resistor on both outputs, then the resistor outputs are bound together to feed the stereo speaker.
Is this a method anyone has used?

Yes, at line level, but not at loudspeaker level.

Couldn't you use two speakers, one for each channel?

 

[Lucid]

What you're planning isn't the best idea.

You'd be better off with a simple Speaker Source Switch.

This will allow you to connect the speaker wires from both stereo systems to a box that then acts as a simple "A or B" switch. It will route through one Hi-Fi signal at a time but not both together. (In logic terms, it's a NAND switch) This means that the power from one Hi-Fi goes to the speaker and not to the speaker and the other system. You'll also preserve the "stereo" element of the signal rather than reducing to two monos.

There's a used one of these on Ebay right now for just £15. I'd say that's perfect timing. Here's a LINK

 

[Lucid]

Singe stereo speaker ???????????????

Well, single rather than singe; but yes, these things do exist.

It's a ceiling speaker with a crossover and audio filter circuit. The bass gets filtered off to a mono woofer. The high frequency left and right signals remain intact and are fed to a pair of tweeters. Here's an example of a good quality version Bluecube CXC 650-S @ £299

 

[jassdhali]

Thanks for your replies guys.

Lucid - I would still have one channel not feeding a stereo speaker so the sound wouldn't be the best.

Gees - single stereo speakers were new to me too

OwainDIYer - I may have to use this setup. Unfortunately I have bought 2 stereo speakers already, so will have to use one for each channel.
If I had known this before I could have spent less money on 2 mono speakers. My fault lol.

Thanks again

 

[Lucid]

Lucid - I would still have one channel not feeding a stereo speaker so the sound wouldn't be the best.

Ah, for some reason when I read the OP I thought you were trying to connect two Hi-Fi's to one stereo speaker. My apologies.

So, what you've done is purchase x2 in-ceiling stereo speakers. Is that right?

If so, then the answer is simple. Drive one input on each speaker. Leave the other input disconnected. The speakers will act as plain 8 Ohm mono speakers just as if you'd bought a regular pair of in-ceilings.

An inceiling stereo (if properly designed) should provide the amp with the same load as 2x 8 Ohm speakers (ie 8 Ohms per channel: 8 Ohms for left, 8 Ohms for right).

Summing the left and right inputs on the speaker will create either a 16 Ohm load or a 4 Ohm load for the amp depending whether you wire in series (16 Ohm) or parallel (4 Ohm). At 16 Ohm you'll lose some level but the amp should cope. At 4 Ohm you risk the speaker sucking more current than the amp can supply. That'll be a problem and could result in you blowing the amp's output transistors and possibly frying a voice coil or two as well.

Try running the speakers single channel. You won't be losing anything and you'll keep the amp happy.

If you really must drive both channels on both speakers then look for an impedance matching speaker selector. Decent ones of these include passive transformers that balance the speaker load so that the amp still 'sees' 8 ohms per channel. You will lose some level via this though.

 

[JBR]

Singe stereo speaker ???????????????

Well, single rather than singe; but yes, these things do exist.

It's a ceiling speaker with a crossover and audio filter circuit. The bass gets filtered off to a mono woofer. The high frequency left and right signals remain intact and are fed to a pair of tweeters. Here's an example of a good quality version Bluecube CXC 650-S @ £299

I really can't see how that speaker could pretend to produce stereophonic sounds, as there is virtually no separation between the two tweeters.
Has anyone any direct experience of them?

 

[Lucid]

Yes, I install them quite regularly.

If you're comparing them to conventional bookshelf/stand-mount/floor-standing speakers then I can see your point, but what you're missing is how the application changes the requirements.

This isn't "sit down and listen seriously to precision stereo imaging" Hi-Fi. It's about good quality sound reproduction in a variety of different and sometimes challenging spaces.

A good example would be an en suite bathroom. The space might not be large enough to allow or warrant installing a stereo pair of in-ceiling speakers. Also, it might not be possible to generate a mono signal from the source equipment being used; and driving just one channel from an amp in to a single mono speaker wouldn't be satisfactory too when most source material is stereo. So a single point stereo speaker allows for the use of conventional source electronics without compromising the signal integrity or risking invalidating warranties with Heath Robinson summing circuits.

 

[JBR]

Yes, I install them quite regularly.

If you're comparing them to conventional bookshelf/stand-mount/floor-standing speakers then I can see your point, but what you're missing is how the application changes the requirements.

This isn't "sit down and listen seriously to precision stereo imaging" Hi-Fi. It's about good quality sound reproduction in a variety of different and sometimes challenging spaces.

A good example would be an en suite bathroom. The space might not be large enough to allow or warrant installing a stereo pair of in-ceiling speakers. Also, it might not be possible to generate a mono signal from the source equipment being used; and driving just one channel from an amp in to a single mono speaker wouldn't be satisfactory too when most source material is stereo. So a single point stereo speaker allows for the use of conventional source electronics without compromising the signal integrity or risking invalidating warranties with Heath Robinson summing circuits.

Thanks, I take your point about the need for correct wiring.
I suppose, what I was really asking was whether this two-tweeter speaker sounds any better than a single high quality 'normal' speaker.

As for options, I used to have an amplifier (Rotel RA840B - now in amplifier heaven, I'm afraid) that had a 'mono' button that, I think, combined the two stereo signals. The sound was quite good although, admittedly, no longer stereo.

 

[Lucid]

I suppose, what I was really asking was whether this two-tweeter speaker sounds any better than a single high quality 'normal' speaker.

I think you're still missing the point. You wouldn't buy two of these to run as a stereo pair (despite that being exactly the mistake that jassdhali made). It's not two tweeters for the left channel and two tweeters for the right channel in place of a single tweeter/woofer conventional stereo pair. So your question whether two tweeters sound better than a single tweeter in a conventional in-ceiling speaker really doesn't make sense.

The top end frequencies remain channel separated. There's the left channel and the right channel. There's one tweeter for each channel. The two tweeters are in close proximity because they have to be housed in the single speaker basket; but they're still acting the same way as two individual speakers for the treble. Bass is omni-directional (in theory). So the bass goes in this speaker from the L & R channels and gets summed to mono because there's one woofer.

As for options, I used to have an amplifier (Rotel RA840B - now in amplifier heaven, I'm afraid) that had a 'mono' button that, I think, combined the two stereo signals. The sound was quite good although, admittedly, no longer stereo.

There are all sorts of solutions available to me also to make mono if required. However, there's a growing trend for people doing DIY to think about AV. One part of that trend is multiroom music. This is where music is streamed from either a house library file system called a NAS drive, or it is streamed live from the web either as internet radio, cloud storage or an on-line media service such as Napster or Spotify. Music can then be played on one/some/all of the house media players. It can be played in-sync (party mode) or multiple streams played; one per user. These systems are often driven by Sonos media players. Their amp product is stereo. I've also come across folk using the inexpensive T-amps as a budget solution, or re-tasking an old AV receiver, or making full use of the 2nd and 3rd zone audio capabilities of mid range and high-end AV receivers. It's common that those solutions are stereo only.

 

[JBR]

I suppose, what I was really asking was whether this two-tweeter speaker sounds any better than a single high quality 'normal' speaker.

I think you're still missing the point. You wouldn't buy two of these to run as a stereo pair (despite that being exactly the mistake that jassdhali made). It's not two tweeters for the left channel and two tweeters for the right channel in place of a single tweeter/woofer conventional stereo pair. So your question whether two tweeters sound better than a single tweeter in a conventional in-ceiling speaker really doesn't make sense.

The top end frequencies remain channel separated. There's the left channel and the right channel. There's one tweeter for each channel. The two tweeters are in close proximity because they have to be housed in the single speaker basket; but they're still acting the same way as two individual speakers for the treble. Bass is omni-directional (in theory). So the bass goes in this speaker from the L & R channels and gets summed to mono because there's one woofer.

I'm afraid I'm not making myself clearly understood.

Yes, I understand that this two-tweeter unit is designed to replace two separate speakers, and I understand that there is no need for two low-frequency units. This is evidenced by the current trend to have separate high-frequency speakers (sometimes several with TV systems) yet only a single sub-woofer.

Yes, I understand that the concept relies on two tweeters in close proximity (necessarily so because they are housed in a single unit), yet providing separate left and right stereo sounds.

My argument is that I doubt whether such a (single, two-tweeter) speaker unit would produce stereo sound because of the lack of separation. Yes, the two (left and right) sounds would still be present, but would emanate from practically the same source. My understanding is that good stereophonic reproduction of sound relies on left and right sound sources being at the points of two angles of an equilateral triangle, the listener being at the third angle.

I have not heard one of these speakers, but I'm certain that what I would hear would not be a convincing spread of sound (of, say, a symphony orchestra) laid out before me, as I would hear from two widely separated speakers. To clarify: the violins might appear to be on my left, the cellos and double basses on my right, and the woodwind in the centre (simplified, of course). With the single (two-tweeter) speaker, all of the instruments would be in the middle!

On those grounds, I was suggesting that, provided both left and right sound signals were present, a single traditional speaker would sound the same as these two-tweeter speakers. The only way to be sure would be to experience each of the two systems in comparison at first hand, of course.

 

[Lucid]

<SNIP>My argument is that I doubt whether such a (single, two-tweeter) speaker unit would produce stereo sound because of the lack of separation. Yes, the two (left and right) sounds would still be present, but would emanate from practically the same source. My understanding is that good stereophonic reproduction of sound relies on left and right sound sources being at the points of two angles of an equilateral triangle, the listener being at the third angle.</SNIP>

This has already been addressed. Look at my post (posted: Tue Feb 24, 2015 11:42) in reply to when you first raised the question.

what you're missing is how the application changes the requirements.

This isn't "sit down and listen seriously to precision stereo imaging "Hi-Fi. It's about good quality sound reproduction in a variety of different and sometimes challenging spaces.

<SNIP>I have not heard one of these speakers, but I'm certain that what I would hear would not be a convincing spread of sound (of, say, a symphony orchestra) laid out before me, as I would hear from two widely separated speakers.</SNIP>

You do realise that these speakers are installed in the ceiling, right? When was the last time the LSO played a concert where the orchestra was dangling from the roof?!

You're barking up the wrong tree trying to apply pure Hi-Fi principles to in-ceiling speakers such as this. In-ceiling speakers do a different job to conventional Hi-Fi speakers. The speakers point down from the ceiling and fire at the floor. They disperse sound in to the room from above, not in front. They fill a room with music, and as ceiling speakers go then these Bluecubes do a damned good job, but any thought of having the sort of 3D holographic imaging you'd get from a very well set-up pair of conventional Hi-Fi speakers is just absurd. But think about it: How good would conventional bookshelf speakers sound in the same position (i.e. with their backs glued to the ceiling and the drivers pointing down at the floor.)