I love it how Paul always tries to simplify his answers as much as he can for us dummies.😮

@Natan9000

4 ай бұрын

And I still don’t get it. 🙈

I would definitely watch that series if you ever had the time to do it

I remember hearing a 3 channel Left-Center-Right demo at the Klipsch factory in Hope, AK in the early 1970's. As I recall the center channel was run 3db lower in level than the 2 side speakers placed on the long wall of the room. They referenced the original Bell Labs stereo testing from the 1930's. Two Klipsch horns and a Belle Klipsch center channel. Most impressive. A number of preamps of that era had a mono output with separate level control for just this setup.

@glenncurry3041

4 ай бұрын

Are you sure it was the Belle? Klipsch was famous for the room placement of Corner Horns often being too far apart to get good center channel. So he invented the heresy of a center fill channel speaker and called it.... the Heresy! It had reduced fidelity to complement instead of compete. The Belle was designed as a full range speaker in the 70's. So yes perhaps it could be used as center fill. But that was not the intent. And it was not around to do the '30's test. That was the Heresy.

@marksulloway5669

4 ай бұрын

I am sure, it was the Belle - a fancy version of the La Scalla - and just as large with different proportions.

@glenncurry3041

4 ай бұрын

@@marksulloway5669 Interesting. Because I know the Heresy center was pushed in Audio shops. But Paul always did what he wanted!

Paul's answer is what we expect coming from an electrical engineer: he's worried about impedances and such in a circuit. However, when it comes acoustics and even more so psychoacoustics the issue about making "mono" from two stereo channels it that the resulting signal will not be the same as if one had simply placed a single microphone midway between the stereo microphones. Paul did mention "phase" near the end and the problem of cancellation, but he ignored that these kind of cancellations are always going to happen from two channels recorded, as the complexity of the sound is such there will be signal that is always out of phase on one channel from the other.

@maidsandmuses

4 ай бұрын

True but a single mono microphone recording also "suffers" from phase cancellations. Place a mono microphone in the wrong position and gone are some specific notes produced by a double bass, or a church organ. In fact you _will_ get phase cancellations with a mono microphone no matter where you place it, but nevertheless microphone placement is key as to how noticeable/objectionable these cancellations will be in the end result. The only good way to create a mono channel is to record and mix appropriately specifically with a mono channel reproduction in mind. Averaging two stereo channels as an afterthought is suboptimal, but so is using a single mono microphone. I the end, mono, stereo, and multi-channel recordings are all compromises.

Thanks for your time; sharing your experience with us. ❤

Interesting. I'll try that. I have a The Fisher mono Hi-Fi tube preamp. Now, it is very common to have stereo recordings where a given instrument is in one channel and totally absent from the other. In this case, when listening in stereo, we can hear it very distinctively. But if you join the two channels, it may "sink" and sound much lower than the background. I guess the best way of summing up stereo to mono is to acquire a mono edition propperly remixed from the original tapes.

Ages ago (early sixties) when I first started playing with live recording one of the setups I commonly used was the classic crossed mics (Blumlein Pair) for early stereo, and a third identical mic aimed straight ahead for a mono signal. I was never quite happy with the "summed" "mono" signal from the two crossed mics, as they always seemed to me to lose something, especially in the high end when summed. YMMV. 😉

A totally different and much easier way of converting a stereo signal to mono (besides just using a Stereo/Mono switch that may be present on a preamp, integrated amp, or receiver) is to have the signal in a digital format (like WAV, FLAC, MP3, etc.) that's compatible with software like Audacity (PC freeware), or convert it to such a format (e.g., through an A/D converter, which a PC's sound card or motherboard may include), and sum the left and right channels to mono mathematically and virtually instantly with the click of a mouse. Or feed each channel's analog signal into a mixer [very simple inexpensive ones exist] and "pan" them both to the center (assuming it's a stereo mixer) and the output will be the summed mono version of the 2 channels. Either such method will achieve the same result as Paul's cut/resistor/splice/solder method. As others have stated, this is not necessarily exactly the same as if the original performance had been recorded with a single center-positioned microphone, but for most recordings, it may be indistinguishable. As Paul said, it will depend on the phase differences between the two channels. Usually, all of the voices and instruments across the original stereo mix image will simply be smooshed together. BUT if there were any unusual strong phase differences between the same voice or instrument in the original two channels, they will partially or even totally cancel out and disappear. This can happen with some early stereo mixes from the 60s when they were still learning how to best use the technology, or purposely experimenting with it. E.g., there's one George Harrison Beatles' song that has his voice 180 degrees out of phase in the two stereo channels. When summed to mono, instead of the typical result of the vocal ending up sounding the same as the stereo mix (in the middle phantom channel between the two stereo speakers), it will virtually if not totally disappear. Yet another approach would be to feed the stereo signals into a home theater processor/receiver set to a Dolby Surround mode (or similar) and listen to only the center channel, which I think would produce pretty much the same result (but different sometimes for the surround channel outputs, which we're not talking about here, because Dolby Surround applied some different frequency filtering to those channels). Dolby with "logic steering" processing did even more "weird" signal stuff to "enhance" channel separation, which probably also affected the center channel in some ways some of the time.

@stimpy1226

4 ай бұрын

Class dismissed

Thanks Paul Sir.

I wish you could do a drawing (diagram). I know it is pretty simple but it would help the feeble minded people that don't understand what you are saying.

@stimpy1226

4 ай бұрын

Guess what… That’s the way these explanations should be done.

Mono audio is great! I do not get all that stereo stuff.

When I first made a mono recording I just ran two stereo speakers and placed a high end mic in the middle .. worked a treat 🥹..! Inverting summing amplifiers with their virtual earths are really the only way to really ... But who listens to mono 😀😂

@cliff4693

4 ай бұрын

I have one Adam monitor speaker for background music listening and feed it mono. Why buy 2?

Perhaps what also needs to be covered is that summing stereo to mono is not the same as a mono recording! If you think of each instrument, vocalist, ... as it's own mono mic'd source if you just record it or all other sources to one mono track, that is Monaural. However in stereo recordings each source might be fed in different ratios to both channels. So if a source is mixed to same levels in both channels and then passively added as described, it's ratio would be greater in the mono mix compared to a source which is only in one channel. As compared to an active mixer that would keep the output level of a common source the same.

It seems Paul is defaulting to an application whereby you get a center channel in a stereo set up. I am not sure that was the intend of the question. I think it was about getting pure mono out of stereo. It gets interesting when you want to get mono from a stereo LP. Using a mono cartridge is not the right way. Shorting the coils out to each other is done but not ideal, the cartridge will survive but it is not guaranteed to give the best sound. So where in the chain of amplification to make it mono? I believe the best way to do so is to put the coils of the cartridge in series. It could be tricky with some turn tables / cartridges and a piece of cake with others. It would be an interesting experiment.

Er... actually no! I thought I understood mono perfectly well until you started explaining it. You quickly lost me and now I'm just confused. (Probably lucky I'm not an engineer! 😮)

Just like a few other methods Paul's resistor bridge effectively generates the _average_ of the left and right channels. A more fundamental question is whether _averaging_ both channels is the right way to go. Paul already hinted at the problems phase cancellation can cause. E.g. the phase cancellations encountered when mixing two stereo channels into one will be _different_ from the phase cancellations encountered when using a mono microphone setup vs. a multi-microphone setup. There is no wrong or right, just different end results and it is up to the recording and mixing engineers to make sure it sounds good. The _averaging_ method is likely to undo some of the good work the sound engineers put in over and above just losing the stereo effect.

Does the "sub out" on an amp sum the base from both channels? If so, how do you connect a single sub to mono block amps?

DO THE OP-AMP BENCH VIDEOS!!!

Or you can just put your stereo speakers right next to each other and sum acoustically.

Only summing problem I have is lack of money😂😂😂

@romangaslan7947

4 ай бұрын

True this!😮

@stimpy1226

4 ай бұрын

That’s a good one😉

What’s that big check in the background?

@JD-mm4ub

4 ай бұрын

It’s a $10,000.00 check to Music Cares.

LawnGuyLand!!!

I have used 10k resistors for summing on a number of occasions. However, I don't cut and splice cables to make the connections. There are much more elegant ways...

Or you could use one channel hot lead as the ground and the other as a normal hot lead. The normal ground wires join these together. This produces an interesting effect which is mono, but I've only done this with the signals coming directly from a turntable magnetic cartridge. I take no responsibility if someone tries this with the output of their amplifier and their house burns down. 😁

I have some brain cells 😵‍💫 I think

I live a two channel existence. Something goes in one ear and out the other. I retain next to nothing…

is not the simple explantation, that we have two ears?

Why don’t you draw this on a whiteboard or a sheet of paper? It would be much more easy to understand for us.

Just get a whiteboard and give a class so you can put what you’re saying up on the board. You’re pre-recording these videos so you can even set up your whiteboard explanation in advance. then you can be our instructor and stand up in front of the board with the pointer or your finger and you’ll be ready to go

But I'm rich in experience

How to sum stereo to mono ? Ans: with an Op-amp.

First!

@spacemissing

4 ай бұрын

Being first is OK, but making it your only point is too stupid for words.

@funny0000000

4 ай бұрын

@@spacemissing It is not my only point. I left a second comment.

@davidstevens7809

4 ай бұрын

You need opamps used as buffers. You float the ground and derive a diff channel. The signal between the center of the diff center and true ground is summed mono.. haha. Am I hired yet.?

@davidstevens7809

4 ай бұрын

Have chris read what i said..he will tell you im correct..mixed mono isnt summed mono. So far as y jackin the preamp outputs..its usually no problem to get mixed mono because the output has coupling caps

@davidstevens7809

4 ай бұрын

If not a 22uf 50v cap on each signal isolates them..

Wrong. Thats mixed mono..not summed mono. Pauls not always correct.

@hugobloemers4425

4 ай бұрын

If you feed two signals with a resister in to an amplifier you get the sum of them. This is very easy to measure and prove with DC signals. I don't think Paul is wrong here, it is a direct summing amp. Also, mixed mono, what is that even? Probably the same as a mono signal where the left and right channels are summed. So yeah, Paul is right on this one.

@kc9scott

4 ай бұрын

If you just use two resistors, you get the average of the two channels. The only difference between an average and a sum is the gain factor of 2. As far as sound quality, they're the same. And if you then take that mono signal and play it using left and right amps/speakers, that makes back the factor of 2, giving the same overall volume as the original stereo signal.

@davidstevens7809

4 ай бұрын

@@kc9scott but not the same equal flat responce..