Axiom Home Page Forums General Discussion Technical Questions Stereo to Mono

If I wanted to put a single speaker like my VP150 in another room by itself, is there a device that would change two stereo outputs to a mono output?

Good question Doug, one that I'm sure someone will answer.

Hey by the way, if you get a chance, it would be cool if you could post your Emotiva visit thoughts to our board as well. I've spent a lot of time on the phone visiting with Lonnie lately, even today. I have no doubt that they are a great company providing top of the line products, and their experience/knowledge, well that is obvious.

ps: to bad you didn't have your 80's with you so they could shut them down.

You don't need a device.

Connect the left channel (+) to the VP150 (+).

Connect the right channel (-) to the VP150 (-).

What you should hear is the sum of the left and right channels (unless there's something unique about your amp).

Hi Mojo and Bugbitten,

Do NOT connect the output of your amplifier's or AV receiver's left and right channel speaker outputs in that fashion. You could damage or blow out one or the other (or both) amplifier channels.

If you both amp outputs to the VP150, the left channel amplifier would be driving not only the VP150, but also routing its output power back into the output section of the right channel amplifier and vice-versa. Not a good idea!

The way to do this is to use the pre-outs (low-level) for the left and right channels. Get an adaptor with left and right RCA female input jacks and a single female (or male) output jack, then connect the combined (mono) low-level signal into one of the unused amplifier pre-amp inputs. The amplified output of that channel would then be mono. In some respects, the pre-outs should be buffered so there is no interaction of the left channel preamp with the right.

But at least you won't damage the power amplifiers this way.

Regards,

Does that still work with modern amps ? My recollection was that the -ve terminal (black) on most amps was "ground" these days, so the -ve of right would be the same as -ve of left and so you would only get the left channel.

After reading Alan's post, we should go back to the drawing board.

I used the configuration that I suggested successfully when I was a teen with my Kenwood stereo amp and cheap, Realistic speakers. It was, I thought, a good way to get the centre image that my left and right speakers couldn't muster. Maybe I was just lucky but it appeared to work.

So I just tried this on my wife's Sony book-shelf system. I used my old no-name brand center channel speaker. I cranked the volume and it appears to work. I'll let it play for a while and see what happens. It's been playing ten minutes already.

Alan, can you comment on what equivalent impedance each channel would see when driving this configuration?

However Alan's pre-amp suggestion is shrewd and will work if you have a channel to spare and are willing to play in multi-channel mode.

Ohhh how I miss my old Optimus speakers. Actually I still have the bookshelf versions, just miss the mains with the monster woofers.

My wife's Sony is still alive...unfortunately:D.

And it looks like bridgman's right. My suggestion for the center channel yields only the left channel.

I did discover however that if I connect the left and right channel positives to the center channel I get the algebraic difference of the two channels.

oh my I just went back in time to my childhood. They did have 15" woofers and were Mach something. I was thinking Mach 1's, but now that I see that picture, they might have been 111's.

You guys were obviously rich as teens. Mine had one driver, a tweeter that wasn't even electrically connected and doubled as bongo drums for parties .

I still have my 80's Pioneer 4-way CS-60 loudspeakers with turbo bass 12" woofer and selecter buttons for tone control of the ribbon tweets, they are still like brand new.

Yeah, but how do they sound?

In 1986, I bought myself a used pair of Bose 601 Series IIs. Until a month-and-half ago, I was still using them as my main speakers. Only one driver still had foam on it. Shortly after my Axiom system was dialed in, me and a few friends lit a nice fire in the backyard. Those Boses sure smell nice when they are being cremated .

In 1982 I was 13, and bought my first pair of speakers - a set of Audio Pulse 3-ways. (I have no idea of the model) They had 12" woofers and all my buddies were like "HOLY CRAP, MAN!!! THOSE THINGS ARE HUGE!!!"

The year before, my parents bought me a Technics all-in-one stereo, that was actually quite nice. It had a turntable, cassette deck, tuner, and a whopping 12 watts per channel!

That just didn't cut it, sooooo, I bought a 50 watt/ch car amp from Radio Shack. Stole my dads 12 volt power supply and hooked it all up. I tell you, I was really the big man on campus then! The rumours and legend they built were rampant. I was diming lights, and breaking windows. When I started high school, kids that came from other schools would approach me and say, "Hey, you're that guy with the killer stereo, aren't you?" It was hilarious.

Fast forward - When I got my first set of M80's in the early 2000's, I gave the speakers to my brother-in-law. He has never used them, and they are still sitting at my mother-in-laws house. The foam surrounds are shot, of course.

Thing is, looking back - those speakers sounded like crap. Didn't know it at the time though.

They actually sound very good, just like new. I pampered them in college.

Doug, it isn't entirely clear what setup you're proposing for that other room. If you're going to use an inexpensive stereo receiver, for example, you can simply set it to mono and drive it from one channel(both are identical in mono, of course)wired to the VP150.

Mojo,

I think each channel would "see" roughly the same nominal impedance (6 ohms) of the VP150, although this becomes complicated by the fact that each channel's amplifier is connected to the output section of the other channel.

The output impedance of most transistor amplifiers is essentially zero ohms, but amplifiers were never designed to be connected to each other in this fashion. Perhaps JohnK would comment.

Regards,

Well, as I indicated, I'm still not sure exactly what Doug plans to do, but as John B. indicated, it would only be the left channel(positive connected)that would be driving the speaker if that proposed wiring was used. That being the case, it seems to me that the left channel would be driving the impedance of the speaker(the nominal 6 ohms of the VP150, as Alan pointed out)and this wouldn't be changed in any way.

Maybe Doug can try the +ve from each channel (my other suggestion). I didn't fry my wife's Sony with any of these methods so he probably won't fry his.

Do you guys think all that time when I was a teen I was listening to the left channel thinking it was centre ? Or perhaps the two channels were isolated back then.

Okay Doug, that clarifies the matter a bit; you don't want to use a stereo receiver, but instead a mono amp. Sure, Zone 2 preouts can send the same(or for that matter different)program material from your 3805 to the VP150 in another room, but it's not a good idea to do it with just a Y-connection. The left channel sound, for example, doesn't know that it's supposed to follow just the branch into the amplifier, so it also runs up the other leg of the Y into the right channel pre-out. Here's a discussion of the matter, with suggested circuitry.

Thanks.

Soooooo, never mind, maybe another pair of M3s.

have you ever thought about returning your VP150 (that is boxed) for an exchange for M22s or something? Sheesh!

-Hutz

well, since it is un-used, I am sure that Axiom would trade you up if you bought something more expensive than a pair of M3s (such as M22s which are more than a VP150).

You never know until you try

I used the speaker for a year before changing to the M3 centers.