the home of the turntable

Summing To Mono — Am I doing it wrong?

the thin end of the wedge

Summing To Mono — Am I doing it wrong?

Postby BMRR » 18 Dec 2014 00:00

I've read many posts on many different web sites about the benefits of "summing to mono" when playing mono records, especially older ones. Many of these posts (such as this one) suggest that the easiest and least-expensive way to accomplish this (if your amp/receiver/preamp doesn't have a mono button or you're not using a mono cartridge) is to connect the turntable to two "Y" adapters connected together — one male-to-female, one female-to-male. Most of these posts go on to suggest that doing this results in better audio quality and reduced noise (compared to playing mono records in stereo).

I tried it today for the first time. I do notice that the surface noise of the record is no longer in stereo, and the music seems to be perfectly centered, but I'm not really noticing any other improvements in audio quality... and although the surface noise is now centered, it doesn't seem particularly quieter to me.

Am I doing it wrong, or is this just a case of the technique not living up to the hype?
What do dance clubs and classical radio stations have in common? Technics Direct Drive.™
User avatar
BMRR
long player
long player
contributor
 
Posts: 3378
Images: 10
Joined: 23 Aug 2013 03:48
Location: Maine, USA

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby analogaudio » 18 Dec 2014 00:55

The description you give seems normal for mono, identical signal in both channels = centered phantom image. There should be no other change to sound quality, this is assured by the compatibility between mono and stereo that was chosen when stereo was introduced, mono came first, and stereo discs had to play on mono tonearms.

The thing about noise may depend on how "noise" is understood. If I understand the situation correctly summing left and right to mono cancels any vertical modulation of the groove, what is heard is the horizontal (side to side) groove modulation. This means the vertical component of rumble due to bearing noise and surface noise effectively disappears, leaving only the horizontal wanted signal. The background hiss due to groove surface noise, original recording background noise remain unchanged by the mono arrangement.

I agree there is a lot of "noise" about mono LPs and mono carts right now, perhaps people are overlooking the fundamental compatibility of mono discs played back on stereo carts, which has been present since the origin of stereo.

PS It does make a difference to sound quality if the mono sound is heard via one or two loudspeakers. This arises because of the directional quality of our hearing and the way two identical acoustic sources sum to create a mono phantom image in the middle. There is a slight but measureable change in tonal balance when listening on two speakers. The genuine mono experience is single speaker sound. Turn the balance control all one way.
Ted

Technics SL1600mk2, Ortofon VMS30, modified TEAC AH500 as a preamp, Bryston 4B ST amp, Harbeth M40 speakers, all making musical magic :-)
analogaudio
long player
long player
contributor
 
Posts: 4203
Images: 32
Joined: 06 Feb 2007 23:58
Location: Monroe NY USA

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby Coffee Phil » 18 Dec 2014 05:47

Hi BMRR,

What you describe appears correct.

On a mono Lp or 45 there is nothing in the vertical direction which you want. Summing as you described will largely cancel signals from vertical motion of the stylus. The amount of noise and distortion in the vertical direction will vary depending on the mono record in question. On some the difference is hardly noticeable and on others the difference is vast.

I would not be without the ability to sum the channels, especially for 78s. My mono preamp will sum in phase for lateral cut records or out of phase for vertical cut records such as Edisons and Pathes.

Phil


BMRR wrote:I've read many posts on many different web sites about the benefits of "summing to mono" when playing mono records, especially older ones. Many of these posts (such as this one) suggest that the easiest and least-expensive way to accomplish this (if your amp/receiver/preamp doesn't have a mono button or you're not using a mono cartridge) is to connect the turntable to two "Y" adapters connected together — one male-to-female, one female-to-male. Most of these posts go on to suggest that doing this results in better audio quality and reduced noise (compared to playing mono records in stereo).

I tried it today for the first time. I do notice that the surface noise of the record is no longer in stereo, and the music seems to be perfectly centered, but I'm not really noticing any other improvements in audio quality... and although the surface noise is now centered, it doesn't seem particularly quieter to me.

Am I doing it wrong, or is this just a case of the technique not living up to the hype?
Coffee Phil
long player
long player
 
Posts: 4317
Images: 318
Joined: 20 Sep 2008 08:22
Location: California

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby BMRR » 18 Dec 2014 16:06

Thank you for your replies, Ted and Phil! :)
What do dance clubs and classical radio stations have in common? Technics Direct Drive.™
User avatar
BMRR
long player
long player
contributor
 
Posts: 3378
Images: 10
Joined: 23 Aug 2013 03:48
Location: Maine, USA

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby Tympani1982 » 18 Dec 2014 18:45

I have a similar experience in listening to mono records. My Yamaha preamps have a mono/stereo switch. But I can only hear a very slight difference in overall sound between the two. The difference is so small that I don't really bother to switch to mono most of the time when I listen to my mono records.

I have probably over a thousand mono records. A lot of them are in very clean shape and are noiseless. But a lot of them are somewhat dirty and scratched. I try to ignore the noise and focus on the music.
Tympani1982
member
member
 
Posts: 83
Joined: 02 Sep 2011 18:37
Location: California

Re: Summing To Mono — Am I doing it wrong?

Postby JDJX » 18 Dec 2014 23:21

Some sources don't like the channels combined without some resistance between them...... like in just a "Y" adapter.

This is the resistive stereo to mono mixer I made. It works great.
strero to mono.jpg
strero to mono.jpg (34.11 KiB) Viewed 669 times


All you need is four resisters, four RCA jacks, and a small project box.
resmonoxx1.jpg


Of course, it will attenuate the signal slightly but, it is not enough to be a problem.
In fact, just today I use it to play my mono copy Of the "Dave Brubeck - Time Out" album. :)

BTW... it can even make some of those awful "simulated stereo" albums sound much better.
*Thorens 165 with M97xE
*Lounge Audio phono pre
*NAD C-350 amp
User avatar
JDJX
long player
long player
 
Posts: 2013
Joined: 28 Nov 2013 21:17
Location: Mid Hudson valley..... NY.....In the orginal Orange County

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby howardpgh » 19 Dec 2014 16:18

JDJX
Where does your mono summing device go in the audio chain?
Between the TT and preamp or between preamp and amp input?
howardpgh
member
member
 
Posts: 106
Joined: 22 Nov 2013 22:41

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby Coffee Phil » 19 Dec 2014 17:58

I'm not JDJX, but here is my anwer:

You can do either. The mono switch in most preamps comes after the phono stage so it can also sum other sources such as an FM tuner. The downside of that is that you are depending on gain and phase match of the phono stage for accurate summing. Putting the summing network between the cartridge and phono stage gets the phono stage out of the equation.

Phi


howardpgh wrote:JDJX
Where does your mono summing device go in the audio chain?
Between the TT and preamp or between preamp and amp input?
Coffee Phil
long player
long player
 
Posts: 4317
Images: 318
Joined: 20 Sep 2008 08:22
Location: California

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby JDJX » 19 Dec 2014 19:46

I actually have a multi source switch that is fed to my EQ and that is fed into my integrated amp.
This places the mono mixer between my phono pre and EQ.

My EQ also has two switchable inputs.
So, to avoid switching RCA cables, I also mads a simple A/B switch to accompany my mono mixer.

So, now I just have to toggle the A/B switch and switch inputs on the EQ
to toggle between phono stereo/mono.
It works for me. :)

Putting the summing network between the cartridge and phono stage gets the phono stage out of the equation.

Wont that screw up the cartridge loading going into into the phony pre...... exactly what you do not want?
Doesn't that put it directly in the phono pre equation?
*Thorens 165 with M97xE
*Lounge Audio phono pre
*NAD C-350 amp
User avatar
JDJX
long player
long player
 
Posts: 2013
Joined: 28 Nov 2013 21:17
Location: Mid Hudson valley..... NY.....In the orginal Orange County

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby BMRR » 20 Dec 2014 17:14

Another question: can the Y-adapter method of summing to mono be used to play stereo records in mono? Or would this result in poor audio quality because the vertical part of the groove is being canceled out?
What do dance clubs and classical radio stations have in common? Technics Direct Drive.™
User avatar
BMRR
long player
long player
contributor
 
Posts: 3378
Images: 10
Joined: 23 Aug 2013 03:48
Location: Maine, USA

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby Coffee Phil » 20 Dec 2014 18:40

Hi BMRR,

Think of stereo as the sum of the mono signal (the lateral signal) and the channel difference signal (vertical signal) summed in phase for the right and out of phase for the left. If I understand the operation of the Decca cartridge correctly it does just that. For mono all you want is the lateral signal.

For those "electronically enhanced for stereo" abominations I find summing to mono with my mono preamp makes them more tolerable.

Phil

BMRR wrote:Another question: can the Y-adapter method of summing to mono be used to play stereo records in mono? Or would this result in poor audio quality because the vertical part of the groove is being canceled out?
Coffee Phil
long player
long player
 
Posts: 4317
Images: 318
Joined: 20 Sep 2008 08:22
Location: California

United States of America

Re: Summing To Mono — Am I doing it wrong?

Postby BMRR » 20 Dec 2014 18:42

Thanks!
What do dance clubs and classical radio stations have in common? Technics Direct Drive.™
User avatar
BMRR
long player
long player
contributor
 
Posts: 3378
Images: 10
Joined: 23 Aug 2013 03:48
Location: Maine, USA

United States of America

Return to Cartridges and Preamps