Stereo/Mono switch?

In the old days, lots of preamps and receivers included a stereo/mono switch. What is the difference between playing a mono recording in 'stereo' vs. 'mono'?
It seems like both cases should be the same, i.e., an identical mono signal sent to each speaker. Of course, if this were true they probably wouldn't have made stereo/mono switches...

- joe s

 

I believe the answer is that a mono recording played back thru a stereo pre-amp introduces/adds certain types of distortion. My pre-amp has a mono swith and in the owners manual- a blurb alludes to what I descibed above.

 

So what is one to do if the stereo preamp has no mono/stereo swithch when mono is being played to avoid this distortion?

 

Combining the left & right channel to a mono signal also helps reduce the level of extraneous noise, such as rumble, which is picked up through the cartridge & otherwise amplified by both channels. Mono switching is particularly desirable with older, pre-stereo LPs that tend to be noisier because of the way the grooves were cut.

 

You could rig up another pickup if you have interchangeable ones - there are some specialized mono cartridges about (the cheapest is from Grado) or just use a second one like you have with a shorting wire between the two 'live' contacts at the back pins. These two solutions are not equivalent - a mono cartridge will do a lot more than just 'cancel' out the noise and distortion, it will actually lose it before it gets into the wires.

Personally, a good mono switch has always been on my list for a preamp, and I wouldn't go without one. Especially useful for really worn disks.

Mike

 

The mono button would also come in handy if listening to FM stereo with a weak, hissy signal. Collapse it into mono and the hiss dissapears, also works if you are playing back a recording of it.

 

It sounds like having a mono switch is a must for anyone that listens to older jazz LP`s. I myself have been looking for a preamp with a good phono stage and a mono switch. I`m finding that getting both in one package is hard to come by in newer equipment. I may go the Conrad Johnson route.

 

Of course, if your preamp lacks a stereo/mono switch, and you have a spare tape monitor loop, you can always put back-to-back Y-connectors on the tape jacks, and use your tape monitor switch to do the job.

--Paul Curtis

 

That solution will solve part of the problem but not the worst part. I`ll still have that annoying hiss which a mono switch eliminates totally.

 

Are you sure that you are not confusing the Stereo/Mono switch for the Tuner section. My separate Tuner has this and does reduce the Noise generated from a weak Stereo FM signal but I wonder if, in the case of an Integrated (Tuner, Amp/Preamp) it actually does anything beyond this. May be different for various units.

The reason I even mention this is I think the question has to do with amplification and when I had a PreAmp that provided a Stereo/Mono switch it would not reduce the noise generated from my Tuner which was caused by a weak Stereo signal.

 

I know what you are saying. But that`s not it. If you have ever listened to a mono recording on vinyl while the stereo/mono button is in the stereo mode and then switch it to mono you can hear a better bottom end and less surface noise.
The surface noise is caused by a stereo cartridge trying to extract signal from within the groove walls of the LP that are not there because it`s mono. The "surface noise" is the hiss I refer to and is a better descriptor than "hiss".

 

Gregory,
I was commenting on Phil Elliott's post not the subject in the thread title. Specifically the the remark as it related to FM radio. I was merely pointing out that on some receivers this may not combine the stereo signal to mono in the pre-amp but possibly only switch radio reception from stereo to mono.

So, Regarding the comments relating source playback, whether it be CD or Vinyl, may or may not be switched to mono in the case of the integrated receiver.

 

Oh. Yes, I understand what you are saying now. I have an old Marantz 2225 with a mono switch. When the tuner is playing it cuts the static during weak stereo reception. But when I am listening to a CD or an LP it acts as a mono/stereo switch.

You are right. I guess this could be different with others.

 

Precisely, I just wanted to express that there may be different schemes of the true operation of the Stereo/Mono switch, that may differ from one unit to another.

 

The current issue of The $ensible $ound has an article aboout the need for a mono/stereo switch to listen to mono LPs.

Electrically, it would be very simple to add a box between the phono output (or phono pre-amp output) and the input of the pre-amp or receiver.

The author commented that back in the day, some mono cartridges were actually the stereo models with the L/R outputs jumpered together at the cart, and that other vendors, when stereo came out, included jumpers that the user could install to play back mono LPs.

That was all before my time, but it leads me to think that a mono switch for a phono source is no big deal to build.

I have one mono LP in my collection, a new Sundazed Bob Dylan "The Times They Are A Changin'". The first time played it, I thought I was hearing some distortions that I would not expect with a new LP on a new TT with a new cart.

I may see about building a small mono/stereo box and take a new listen.

BGL

 

BGL
I didn't want to hijack the thread but you bring up an issue I was wondering about.
That is, I have seen some current cartridge manufacturers actually offering mono cartridges in their line-up. I was thinking of starting another thread, asking for Steve's comments and others about Mono Vinyl. I have some coming from Sundazed, have the Hendrix Axis and expect to get more in the future. My thoughts were along the line is a Stereo/Mono switch needed and or would these mono vinyls sound more correct with a Mono cartridge. Do they use a different cutting head on mono...
As if I need to spend more money on this Hobby.

 

These questions you ask Terry are precisely why I`m having a tough time narrowing down my search for a preamp. A switch seems more convenient than changing my headshell every other record. But if that`s what a newly obsessed anal retentive paranoid audiophile as myself has to do, then so be it.

 

There's another discussion going on in another thread right now on this but in researching and going back I wanted to post Steve's solution of making mono work in a system without a mono switch. http://forums.stevehoffman.tv/threa...ords-in-true-mono-how-to-do-it-cheaply.81073/

 

One of the reasons I love my Fisher 500c. It has a phono stereo setting and phono mono setting. Makes a moderate improvement when listening to 60s mono Rock and Jazz

 

All the commentary seems to be about mono records. What about mono cds, such as The Beatles in Mono. Should I switch to Mono when playing mono recordings on CD?

 

Nope. This is just for vinyl.

Some more info on this on the first page of this linked thread. http://forums.stevehoffman.tv/threa...ords-in-true-mono-how-to-do-it-cheaply.81073/

 

Thank you

 

For mono vinyl a monoswitch is obligatory. (no pinch distortion anymore)( less rumble)
For CD or stereovinyl sometimes mono is more earpleasing, added reverb is diminished, more coherent focused sound, espccialy with one loudspeaker.
(one loudspeaker: no combfiltereffect anymore, very easy listening, also for monorecords/CD's.)

Just two T- rca plugs, one side for phono in, other sides to connect a little switch on front of amp with shielded cable.

 

True Hubert jan.
Hell, actually there are many stereo LP's out there that sound better if you INDUCE THE MONO.
For real.