Mono record sounds like stereo

So I have been playing stereo records for 40 years.  I’ve recently acquired some Verve Japanese reissues. Listening to Metronome All stars tonight and there is clearly separation. I hear horns predominantly on the left and xylophone and drums on the right.  This is on an Ortofon SPU synergy stereo cartridge. Is this normal ?  I’m sorry.  I’m new to Mono.  I bought about 50 verve and Blue notes last week and got some monos on accident.  My system is balanced and the room has extensive treatment so I’m lost !   


Oh dang. It never occurred to me to swap the RCAs as a quick test. I’m going to try that now. TBH I’m not even sure if my Preamp has a mono setting. I’m going to check that as well.    Thank you !

Get a 12" with a removable head-shell so you can easily swap cartridges. I'm not sure it matters which arm hosts the mono. Try both and report back. I have 12" and 9" arms on my main table. 

To be more specific not the whole cable but just the input to each component ,

if anything unplugging and plugging help clean the connections. 


adrianleewelch OP

Definitely, without doubt, put the stereo cartridge on the long arm. Pick an arm with removable headshell if possible, gives you flexibility now and in the future.

Does your 9" have a removable headshell?

My 12.5" long arm is fixed cartridge, used for my MC cartridge. Only change it when worn.

My 9" has both removable headshell and extremely easy arm height adjustment, so it is most flexible. I  have several cartridges I alternate, MC, MM, and now an alternate Mono. And we play my friend's cartridges on it. SUT handles various MC impedances, and has Pass for MM.

I added a 3rd arm for mono, fixed. Limiting, but my 9" arm saves the day regarding flexibility.

My Grado Mono is elliptical, on the 3rd arm. I'm very happy with it. I'm not looking for perfection, or even 'best', just gaining the advantages of playing mono lps with a true mono cartridge.

I just had VAS put a new boron/shibata on an AT33PTG Mono Body. For modern Mono, Haven't used it yet. He played it at his shop, we all were impressed, no comparison here yet.

3 arms: MC, MM, Mono all ready to go in seconds in any listening session.

The compliance of the cartridge and the mass of the tonearm must ’avoid a problem’.

Today’s equipment, I would simply put my existing stereo cartridge (likely high compliance) on my new long arm (likely not too heavy) and expect no problem.

Perhaps, before you buy it, pick an arm you want, tell the members here about it and your cartridge, get their help.

Well I swapped one end of the RCAs and of course it moved the horn section to the opposite speaker.  I played it on my other table and it was balanced left to right so I realized it was the SPU cartridge contributing. I switched the preamp to Mono and it corrected it.  I’m thinking I need to set up that arm again. It’s an SME 3009 unimproved. It was rebuilt by SME last year and has the extra weight system for the SPU. What I forgot is that I added a fluid damper to the arm without readjusting anti skate. I bet it has way too much pull to the outside of the record.  I likely should have backed off on the anti skate when I added the trough. Well at least I know what’s likely happening.  It’s odd though that I never sensed a channel imbalance prior to this.   Adrian