Simple inexpensive way to make your small soundroom sound bigger

I

indieGuerilla

Member
Hello everyone, If you have a small soundroom or screening room I have a little trick that can help out and make it sound larger. This actually makes the soundstage in your listening area sound larger than it really is. In some cases it can make the sound from your speakers sound like it is coming from outside the confines of your listening room.

A few companys in the past actually sold stereo systems that utilized this technique.

If you have an amplifier or preamp with a digital sound processor built in then this trick isnt needed for you. You most likely have a feature (or two) that widens your soundstage built in. Some amps and home theater systems have a feature that is actually called "WIDE". That feature just enhances stereo seperation.

This simple method of enhancing your stereo seperation does the same thing, (for the most part).

I hope I can explain this so the folks who understand how a speaker makes sound arent bored and those who dont arent confused. If you dont understand anything or have questions just ask and I will help you figure it out.

If you have an amp or stereo with outputs for two different pairs of speakers then it is real easy. It is even better if you can adjust the volume and tone qualitys for each pair independantly.

For those of you with outputs for two pairs of speakers just simply wire the main pair of speakers correctly. When I say correctly I mean red wire to red terminal, or + to + and - to - (positive outputs from your amp to positive inputs of your speakers) and of the same for the negative terminals . Now wire a second pair of speakers incorrectly or out of phase. This means red amp outputs to black speaker inputs, and black amp outputs to red speaker inputs. Take the smaller speaker that is wired up to the left amp outputs of your amp and place it near the large speaker on the right side of your room.
Take the other smaller speaker and wire it up out of phase as well and place it near the large speaker on the left side of your room.
And thats it. Why this works is the sound that is to be heard dominantly from the left side of the soundstage is canceled (or reduced) by the out of phase speaker that it is set beside.
I know I am not explaining it very clear so here is another way to explain it.

Lets say you are playing back a conversation between a man and a woman. The mans voice was recorded with a mic on the left and the womans voice recorded with a mic on the right. But some of the mans voice was picked up by the mic on the right side, and some of the womans voice was recorded by the mic on the left. The small out of phase speaker cancels that little bit that was intended for the speaker on the other side.

Now if you have only one pair of speaker outputs it is a little harder. You would essentially take a pair of speaker leads and tap into the right side speaker and take those leads and hook it to an out of phase speaker on the other side of the room. The tricky part here is that when you hook more than one speaker to one amp output you change the load that is drawn from the amp. Depending on how you wire it you can increase, decrease, or leave the load unchanged. By changing the impedance of the speaker system that you connect to your amp you can potentially overload it and cause damage. Some amps automatically detect an unsafe load and switch off. If you dont understand the whole amp load and speaker impedance thing I dont recomend trying the second method.

The picture shows how to wire the first method. Notice the red wires are conected to the black terminals of the smaller speakers. and vice versa.

Try different placement of the smaller speakers and see how it affects your soundstage. I recomend trying facking the smaller speakers facing the fronts of the larger speakers. This just helps in the soundwave cancelling procces.

Everybody seems to know a guy who has the awesome stereo or a room full of different speakers. Maybe you know someone who builds custom speakers. Those folks can most likely help with this or help to explain it clearer than I have. Anyway, Let me know what you think of this info. If it goes over well or there is some interest I may post some plans for sub boxes, studio monitors, and some other audio projects. Thanks for looking, IG
 

Attachments

  • ESS.jpg
    ESS.jpg
    125 KB · Views: 0
Another variation: wire second set of small speakers in series from speaker out 2L+ to R+ out of phase reative to each other. This sends the difference signal to back speakers.

2L+ to RearL+, RearL- to RearR-, RearR+ to 2R+

These difference speakers are located to the sides back of the room.
 
This last one can be dangerous to some amps. We used to do this in theatre setups every once in awhile. It is a bit unpredictable where things end up coming from but it is a huge sound. However some amps do not like this wiring set up. The Samson amps for one used to blow up with this wiring, never figured out exactly why but after two blown amps in a week we stopped using the Samson's for this setup. That's the only brand I know has problems but I have heard that there are others. The problem seems to be that you are shorting out the + connectors through the speakers. Why this blows some amps and seems to have no effect on others???
 
I don't know why you would want to create such a non-standard playback system in a production room, if that's what you mean. If you use the setup to mix audio for a film for example, and it's a 2-channel stereo mix, then you're inviting disaster because everyone else will be playing your mix back on *conventional* in-phase speakers, which won't replicate the sound you thought you created. Your system will be, for all intents and purposes, the *only* place your mix sounds "right". The other side of that coin is that everywhere else, you can bet on it sounding "wrong". This is the worst of all possible scenarios.

Putting an out of phase, channel reversed speaker on top of another will randomly cancel certain frequencies and boost others in an unpredictable way, depending on the particular speakers in question, their locations and the program material. Again, this is an invitation to hell.

What you want is the most neutral mixing environment possible, so the decisions you make regarding the sound have the best chance of translating similarly in the largest number of possible environments. Adding any kind of sonic "gimmick" to make it sound cooler only on your system (and this includes any kind of stereo-field enhancing DSP like you also referred to), works directly against that goal.

Sorry to be blatantly flashing my cred here, but I've made a career for many years as an audio engineer/scoring mixer, and what you're suggesting would be a big mistake.
 
I wouldnt recommend using this for your mixing room either Ted. It is a way that makes your system sound "cooler" As you have stated, but it isnt really any different than using a digital sound proccessor, tone controls, or even adjusting the balance to make the soundstage larger. This is easy to try and the first method I mentioned is free of risk. I just thought I would share the idea because some folks out there may listen to movies or music in a very small room. Some rooms are so small that you cant really enjoy the stereo effect the way that you or I may have intended it. And again I wouldnt want to mix, edit, or analize any audio in a condition that wasnt truly flat and unaltered from the way it was captured. I thought of posting a method similar to this one that allows greater stereo seperation during recording. It can be benificial to those with one single stereo mic versus multiple single channel mics. Ill probably post it later though. If folks arent interested they most certainly dont have to try it. I just am not a video guru and wanted to share in any way I could. I value this forum and everyones opinion so thanks all for your input. IG
 
I assumed you were only suggesting this as an interesting effect for playback, or I also would be objecting. In theatre it was used just to make certain cues "more interesting". Music became almost disorienting because of the strange movements in the space (the second method - I think the first would probably be more predictable).

I don't however think it mimics the wider setting on some of the playback systems and it certainly doesn't give you what the mixers intended, but then my 2" mono TV speakers wont either so...

If you've been around here for any time you know I'm not a big fan of surround on low budget projects, but what the user does after it's in their hands is their business. Most home systems are so totally out of spec that it's pretty much a toss up if your tracks are going to play back anywhere close to what you intended no mater what set up they have. The only real potential down side to the above mentioned configurations is that they will tend to suppress the center and that could make dialog harder to understand. But really most systems in most houses are asymmetric, out of tune and badly placed. Some are even miss-wired.
Of course there is also the point that movies are not supposed to be very wide. It's not a video game. Well I guess in some cases it is a video game. But usually you want people focused on the screen not off to the side or behind themselves. So it is a very rare (big budget) film that mixes much to the surrounds and of course hard L & R are still behind the screen.
 
Yes , this would only be recomended for playback and only if the system had two speakers for listening, Just one left and one right. No front, rear, center etc. IG
 
That out-of-phase-difference-back-signal setup I descried really works only with cleanly miked classical stereo signals. AB stereo organ music is awesome, you can really get that cathedral space behind you. Cheap.

Articifial multitrack stereo gives strange inconsistant effects.
 
I'm wondering why this would endanger an amp? If it's a TRUE 4 channel amp then the amp doesn't see phase. The individual speakers are simply DC resistors inserted in a DC signal. An 8 ohm speaker is an 8 ohm resistor. The phase is determined by the speaker, not the amp... (relatively speaking). You can wire up all your speakers with the red to black and it will operate exactly as if you wired it up red to red. Of course on many amps you can switch phase AT THE AMP... and that is different, but for a conventional amp I don't see why this would be any problem.

That said... a 4 channel receiver which specifies minimum ohm requirements... or an amp that you KNOW shares the load across multiple speakers (as in (2) 8 ohm speakers on the right channel equals a 4 ohm load)... okay now THAT would probably blow the amp if you wire the same channel with a pair out of phase... even if it appears that the amp is 4 seperate channels, you need to check to see that it genuinely is... what was blowing those Samson amps was that the speaker pair wired out of phase was sending the same hot DC signal back on itself... and the amps lasted a couple weeks because the DC signal probably needed a couple things to happen before it was enough to blow the amp... one is minimum ohms (speakers have nominal ohm ratings and they change with power and frequency)... and the other factor was adequate power.

Those amps probably had some sort of cap system to handle normal back EMF (electro-magnetic force)... but eventually a low ohm load (from fluctuating impedence) combined with high power in the bass register... well that eventually blew out the protection caps and let the full DC circuit complete... and that blew the amps.

Bottom line... make sure you have a GENUINE 4 CHANNELS... or use 2 seperate 2 channel amps and split the line-level signal off the RCA inputs. In either of those cases you can get away with this indefinitely.

Any of that make sense?
 
Matt,
In the second scenario you have the + sides of two amps facing each other through two speakers. So what I figured was happening was they were each "pushing" and the amp with the weaker signal at any given point would get a reverse current flow through the amp. My assumptions were that some amps were more tolerant of this or that they were reverse polarity protected and so were not at risk.

The first scenario just reverses phase and as you pointed out should be no problem.
 
MattinSTL, You are correct. THere is no damage using a true 4 channel amp. I used to sell pro audio and make some wild systems and I dont recall any problems doing this with even two channel amps and designing the phase cancelling speakers into the main speaker cabinets. Thanks for backing me up on this. IG
 
I've built a crap-load of speakers in my day and one of the design ideas that I always liked was a planar design where you can use the same drivers on the front and back of the enclosure (for the upper mid-bass through 20khz)... you wire the drivers on the front of the face normally... and on the back of the face they are + to - so that you have a thin projection plane where the voice-coils of the drivers are nearly in the same plane (because of the depth of the cone into the enclosure)... the benefit is that the speaker surfaces are moving in the same direction all the time and you can tune that particular part of the enclosure accurately (.7 tuning) in HALF the volume... then you just have the sub through mid-bass in a seperate enclosure (even within the same tower) and wire that normally. You will get a vastly more open sounding speaker.

This is ZERO problem for ANY amp... because what's happening here is as you are saying IG... that each speaker component is still operating as a simple DC resistor and it doesn't care how you wire it... it's only motion through current that starts at one end of the wound voice-coil or the other... it's still the SAME exact passing of electricity.

Where the problem comes in is when you use TWO DIFFERENT output feeds of the amp to do the same thing... because then you are sending the same electrical current that is fed by the amp, back into itself... it's not a function of speaker phase, etc. It's because the "phase" issue is really an electricity issue from the amp, not the speakers.

Think of it like a Barger Bag Light or one of the other high powered lights that use multiple cords to plug the light in... you can flip the halogen bulb over within the fixture however you want... the light doesn't care... and doesn't KNOW which way the bulb is facing (or phase)... but as soon as you flip over one of the rails of power the HOUSE knows that you just sent "hot" back onto itself and the fuse blows... or the house burns down.


EDIT: Hey I just re-read this after reading your post again... I think I'm basically adding to what you said, so forgive me if I sound like "repeaterguy"... he is all over several of the forums and that's the last guy I want to be. ("repeaterguy" is the guy who posts last on a thread and basically repeats the answers that have already been given, but he changes the wording just enough to come across like it's his own original knowledge... of course repeaterguy may actually know what he's talking about, but it's irritating to answer a question and then have repeaterguy come along and get credit for pretty much the same answer.) For the record, repeaterguy can be anybody.
 
Last edited:
Matt,

No worries, actually having it said two ways may make it clear why it can be a problem, so maybe we just saved someone's amp. The puzzling part to me was why it ever worked. But in fact on most of the amps at the theatre it wasn't a problem. We had a designer who loved this configuration so we actually used it a fair amount at one point.
 
You must log in or register to reply here.
Back
Top