Question: “Stereo” out of a mono PA system?

[jazzpiano88]

2 hours ago, SMcD said:

So the 180 button on a DI box wouldn't solve anything, then? Just create a complimentary set of phase cancellation problems?

 

What is that button even good for, then?

I think this is for signals that you want to keep in phase as it was recorded or mic’ed in stereo.  
 

Think of it as mitigating the similar problem of wiring your stereo speakers up out of phase. 

[SMcD]

 

21 minutes ago, jazzpiano88 said:

I think this is for signals that you want to keep in phase as it was recorded or mic’ed in stereo.  
 

 

 

Wait - if I'm reading this right, you're saying it would mitigate phase cancellation on a stereo DP patch. Am I understanding you here, or is my brain failing me at this late hour?

[hrestov]

The flip 180 invert the phase. If you have two mic at the same distance of a source and sum them (for example 2  panoramic mic of a drum at the same distance from the snare) they probably disappear each other. If you flip you sum each other.
 

But piano samples is different. Every single note of piano have 2 distances from the 2 mics. But this distances are different for every note. There isn’t a common rule, so you can adjust the phase generally in one mic and resolve the problem. Because if you adjust the phase in one note it will go out of phase in another note. 

The only possible method for the keyboard company is to record the piano samples with the same distance from the note, so for every note recording move the 2 mics. I don’t think it’s possible. But company sells their keyboard only with a headphones listen by client. So the don’t care too much of mono compatibility. 
 

 

[hrestov]

3 hours ago, cassdad said:

Well, this thread spurred me on to try a little experiment which I did today.  My new Motion Sound KP-612SX has several “outs” (see pic)…. 2 of them being “Left Out” and “Right Out” (both XLR, assumedly for feeding FOH or recording).  Surprisingly, it also has a single 1/4 inch jack Out labeled “Mono Out”.  So I played piano and concurrently recorded 3 tracks into Logic Pro:  Left & Right Outs to tracks 1 & 2, and Mono Out to Track 3.  Then, listening thru headphones, I alternated playing back just tracks 1 & 2, and then just track 3.  (I also played back all 3 tracks at the same time, but no conclusions from that). The stereo of playing back just tracks 1 & 2 was a far, far better piano sound than just playing track 3 (mono).  However, I must say that, the mono (track 3) by itself was not bad….  it was just, well, mono.  But I did not hear any glaring negatives, no severe comb filtering, etc.  It sounded, let’s say “reasonably good” for mono - exactly what I’d expect.

 

I do not know what, if any, processing Motion Sound’s “Mono Out” jack/line has (none mentioned in the manual).  However, I think I can conclude that if I had to only provide the sound person a “mono” out - this would be acceptable.  My 1st preference would still be to provide a left & right XLR and tell them to pan “full left & full right”.

obviously in headphones there is a big difference between mono and stereo samples. But not in the real life. 
You have to listen your registration from a pair of speaker. Try L and R in stereo, than mono L+R, than only R, than only R. The differences will be far less than from headphones. 

[hrestov]

5 hours ago, cassdad said:

What brand / model / Voice are you using?

Yamaha Cp73, Cfx sample. 

[SMcD]

10 hours ago, hrestov said:

The flip 180 invert the phase. If you have two mic at the same distance of a source and sum them (for example 2  panoramic mic of a drum at the same distance from the snare) they probably disappear each other. If you flip you sum each other.
 

But piano samples is different. Every single note of piano have 2 distances from the 2 mics. But this distances are different for every note. There isn’t a common rule, so you can adjust the phase generally in one mic and resolve the problem. Because if you adjust the phase in one note it will go out of phase in another note. 

The only possible method for the keyboard company is to record the piano samples with the same distance from the note, so for every note recording move the 2 mics. I don’t think it’s possible. But company sells their keyboard only with a headphones listen by client. So the don’t care too much of mono compatibility. 
 

 

Thanks for the clarification. Guess there really is no magic bullet, eh?

 

As I mentioned before, I'm making the switch to an IEM soon to better accommodate my single working ear. That leaves three options:

 

1. Sum to mono in my IEM while sending stereo to FOH. This might be the best I can hope for, but I don't love the idea of listening to something fundamentally different than what I'm sending out. As many in this thread have said, it's ideal to have an accurate sense of what it is you're monitoring.
2. Mono for everyone. Not ideal, of course, but at least my Kurzweil PC4 has a few mono piano patches (which, as far as I can tell, are achieved by summing the flagship stereo samples and using EQ/strategic volume boosting on certain layers to compensate for phase cancellation)
3. Same as #2, but with the "right channel only" trick (compensating with EQ as needed)
4. Finding some kind of miracle "smart-summing" solution that allows L+R channels to be combined in a single IEM without phase problems.

I figure if #4 was real, someone would've mentioned it by now. Damn, I miss my left ear.

[Baldwin Funster]

1 hour ago, SMcD said:

Thanks for the clarification. Guess there really is no magic bullet, eh?

 

As I mentioned before, I'm making the switch to an IEM soon to better accommodate my single working ear. That leaves three options:

 

1. Sum to mono in my IEM while sending stereo to FOH. This might be the best I can hope for, but I don't love the idea of listening to something fundamentally different than what I'm sending out. As many in this thread have said, it's ideal to have an accurate sense of what it is you're monitoring.
2. Mono for everyone. Not ideal, of course, but at least my Kurzweil PC4 has a few mono piano patches (which, as far as I can tell, are achieved by summing the flagship stereo samples and using EQ/strategic volume boosting on certain layers to compensate for phase cancellation)
3. Same as #2, but with the "right channel only" trick (compensating with EQ as needed)
4. Finding some kind of miracle "smart-summing" solution that allows L+R channels to be combined in a single IEM without phase problems.

I figure if #4 was real, someone would've mentioned it by now. Damn, I miss my left ear.

Re: #4.

You can adjust the levels of the channels to dial out some of the phase shift. Kind of work the dials back and forth and listen for the phase shift to minimize. It doesn't always get a sound that sounds flat, or even do much at all but it might get you something better than a deeply notched sound.

[Stokely]

14 hours ago, hrestov said:

obviously in headphones there is a big difference between mono and stereo samples. But not in the real life. 
You have to listen your registration from a pair of speaker. Try L and R in stereo, than mono L+R, than only R, than only R. The differences will be far less than from headphones. 

This same thought occurred to me....that I'm hearing things with IEMs a lot more direct and with more clarity than what comes out to the audience.   It's both good and bad, that clarity.  I still think pianos sound worse through a single speaker (I will use my DXR10 in certain situations, namely outdoor ones where I can get away from the drums), but indeed the mono sound bothers me less than it does through the IEMs.  There is "stereo ambience" just by it coming out into the air for one thing.     Another factor--when I'm mono it means we aren't using our PA, and that usually means I'm getting a mono aux from the engineer.  So not only are the keys mono, everything else is dead center stepping on them, so the overall experience is not great.  I *love* stereo in-ear mixes even when all channels are mono, simply because things can be panned apart.

[hrestov]

I don’t use in ear. But I think that, in mono, the lack of a “virtual room” can be unpleasant. So Theoretically if the Foh can give you only a mono signal , you could put it by your own a little reverb/ambient effect, also with a little mixer, maybe the listing could be more enjoyable and create a virtual rooms.

[SMcD]

Okay, here's an idea.

 

Suppose I ran a DP, in stereo, through my Traynor K4 (I find that, even with only one working ear, the 2.1-stereo-in-a-box from the K4 adds a lot of presence and realism to DP's, compared to running them in mono). Then, rather than plugging the DP directly into my IEM mix, I put a single mic in front of the amp and run that as a mono input into the mix.

 

The theory here is that the mic will pick up the L+R coming from the amp, but because they're not directly summed (and the sound waves bounce around the physical world a bit between the amp speakers and the mic), the phase cancellation won't be an issue. In other words, I'm hoping that the mic will pick up the stereo image in the same way that my good ear does.

 

Would such an idea make sense? What kind of sound quality issues might arise?

[cassdad]

31 minutes ago, SMcD said:

Okay, here's an idea.

 

Suppose I ran a DP, in stereo, through my Traynor K4 (I find that, even with only one working ear, the 2.1-stereo-in-a-box from the K4 adds a lot of presence and realism to DP's, compared to running them in mono). Then, rather than plugging the DP directly into my IEM mix, I put a single mic in front of the amp and run that as a mono input into the mix.

 

The theory here is that the mic will pick up the L+R coming from the amp, but because they're not directly summed (and the sound waves bounce around the physical world a bit between the amp speakers and the mic), the phase cancellation won't be an issue. In other words, I'm hoping that the mic will pick up the stereo image in the same way that my good ear does.

 

Would such an idea make sense? What kind of sound quality issues might arise?

Hmmm - I really don’t know, hopefully someone else does.  This raises my fundamental issue in a different way:  Say, for example, on a live stage, one put a single mic several feet away from a real acoustic piano, and then ran that mic signal (which by definition is mono at that point) to a mono PA system.  Is that stereo “summing”, and would there be comb filtering taking place on that mic signal?  I would think not….  so however that works, is how some “conversion” to mono should correctly work - maybe?  Just thinking out loud….

[Baldwin Funster]

The top and bottom of the signal will get shelved and there will be a bump in midrange. But it might be alright in a band mix.

Solo piano? Debatable.

[SMcD]

 

18 minutes ago, Baldwin Funster said:

The top and bottom of the signal will get shelved and there will be a bump in midrange. But it might be alright in a band mix.

Solo piano? Debatable.

 

Yeah, I figure any solo piano situation won't be loud enough to require IEM's so I can just use whatever stereo solution I want, with L + R speakers both suitably close to my good ear.

 

As far as the EQ effects you mention: my experience suggests a single ear does not suffer from this when it gets hit by a stereo signal. I believe this is because of the complex interactions between the L + R soundwaves and the physical matter between the speaker and the ear. Why would the microphone behave differently from the ear in this regard?

[Baldwin Funster]

17 minutes ago, SMcD said:

 

 

Yeah, I figure any solo piano situation won't be loud enough to require IEM's so I can just use whatever stereo solution I want, with L + R speakers both suitably close to my good ear.

 

As far as the EQ effects you mention: my experience suggests a single ear does not suffer from this when it gets hit by a stereo signal. I believe this is because of the complex interactions between the L + R soundwaves and the physical matter between the speaker and the ear. Why would the microphone behave differently from the ear in this regard?

That's what the amp will sound like. Speakers are inefficient in reproducing lows and highs especially when compared to a DI signal.

[SMcD]

Gotcha.

 

Okay, completely imaginary hypothetical here: suppose we had some stereo-in-a-box unit like the K4, but the actual "guts" of it are those of high-end stage monitors. In other words, imagine that we take the kind of monitors that would be suitable for solo DP gigs, and smush them into a box. Would the principle work then?

 

Just trying to better understand what the potential limitations are for this approach. If you heard a stereo DP coming out of some really nice monitors and turned your head so that one ear was facing them, it wouldn't result in the full phase cancellation you get from summing to mono "internally", right? My idea just amounts to replacing the ear with a microphone.

[Baldwin Funster]

1 hour ago, SMcD said:

Gotcha.

 

Okay, completely imaginary hypothetical here: suppose we had some stereo-in-a-box unit like the K4, but the actual "guts" of it are those of high-end stage monitors. In other words, imagine that we take the kind of monitors that would be suitable for solo DP gigs, and smush them into a box. Would the principle work then?

 

Just trying to better understand what the potential limitations are for this approach. If you heard a stereo DP coming out of some really nice monitors and turned your head so that one ear was facing them, it wouldn't result in the full phase cancellation you get from summing to mono "internally", right? My idea just amounts to replacing the ear with a microphone.

It might, it might not.

Too many variables.

Mic placement and tonal coloring.

Quality of mic preamp. Ect ect ect. 

 

It doesn't work to stipulate a magic amp with the perfect speakers or a magic perfect mic or just decree optimizations.

The question you have I believe is can I mic a stereo KB sound in mono

And end up with a mono sound that sounds good. Yeah probably if you have a knack for sound it might work.

[mate stubb]

2 hours ago, SMcD said:

Gotcha.

 

Okay, completely imaginary hypothetical here: suppose we had some stereo-in-a-box unit like the K4, but the actual "guts" of it are those of high-end stage monitors. In other words, imagine that we take the kind of monitors that would be suitable for solo DP gigs, and smush them into a box. Would the principle work then?

 

Just trying to better understand what the potential limitations are for this approach. If you heard a stereo DP coming out of some really nice monitors and turned your head so that one ear was facing them, it wouldn't result in the full phase cancellation you get from summing to mono "internally", right? My idea just amounts to replacing the ear with a microphone.

 

Several times I have set up my pair of TT08a wedges onstage right next to each other, splayed out slightly like a Motion Sound amp. Sounded fine to me!

[Stokely]

Got a wild hair this week and decided to actually work on my rig (trying some ipad attachments, and a couple pedals, and going through patches).   Great success on spiffing up the Nord Stage organ following some advice on the nord forums!   One thing I did was go through my most commonly-used patches, or ones that I recalled having some issues at mono gigs.   I had done this previously with my Modx and found a pretty wide swing between patches that dropped in volume/changed tone, and those that didn't.  To Nord's credit--I was using the "mono" button--the patches generally didn't change tone beyond that general mono-ness.   What they *did* do consistently is drop in apparent volume when going from stereo to mono.  I'm not sure by how much but it was a fair amount.  If that indeed is consistent, no biggie--I have master volume headroom as does our main mixer, and I can gain up by a few db.

I still need to test going through a couple speakers though.  Listening on headphones, patches with widely-panned sounds (which was most of them) might be fooling me into thinking "louder" just because they were "bigger".   And ultimately I'd like to get together with our PA and test this along with testing other things, we just got a new PA mixer so that's something we want to do before gigging it.