Why are the vocals on some records hidden behind the music on my system?

czarivey nailed it as far as I'm concerned.

Assuming everything is connected properly and the MM input is functional, gain is approximately 35 dB on the MM input which is considerably light for a 2.1 mV cartridge, which would probably be optimized with around 44-45 dB of gain.

On the other hand, 68 dB on the MC side is way too high, and more suited to very low output MC's, certainly below .25 mV and more likely to be effective with .1 to .2 mV cartridges.

Get a new cartridge, get a new phono stage, or modify the gain on the existing phono stage.

Most records would probably sound like they were being played through a wet blanket.

scooby2do

The cart. is new with only 100-150 hours on it and I used a Pro-ject cart. alignment tool

I suspect the alignment is off, and suggest you use a gauge which aligns the actual stylus and cantilever using a mirror, such as the WallyTractor.

The cart. is new with only 100-150 hours on it and I used a Pro-ject cart. alignment tool and spent several hours aligning it and getting the azimuth set and used a digital stylus force gauge to set it at 1.3 grams. I just finished playing Fleetwood Mac's Heroes are Hard to Find and there it was , yet earlier this morning I played Billy Joels I am an Innocent Man and it almost sounded 3d with the finger snap 3 ft in front of his voice? I'm not 100% sure what the gain is on the McIntosh C-100 is but it is about 10 yrs old and the 1st owner just used the MC input.

Do you know the phono gain via your MM inputs? It is (remotely) possible that the gain is marginal for a 2.2mV cartridge output, I suppose.  But it would help to have some more details regarding your phono stage; does it have separate MM and MC inputs, as Czarivey suggests?

Other than that, I think you may have no problem; in my experience some cartridges do tend to submerge the vocalist in favor of the instrumentalists, compared to others.  This can actually be a virtue of the cartridge, in the case where you are not listening to a single, stage-center vocal LP.  For example, I found that my Stanton 980LZS tended to paint that sort of picture.  But the Stanton excels at bringing forth internal musical threads within a group of instruments.  It's certainly not broken.  The test for this explanation, of course, is to try another cartridge.

Nothing that you wrote suggests to me that the two channels are necessarily out of phase with each other, but be sure of that, too.  Nothing at all suggests a problem with turntable speed stability; I don't know where that came from.

@scooby2do - Since your CD’s sound fine and some albums sound fine it would appear everything is in in phase.

How old is the cartridge?
--- could just be old age - the suspension of the stylus may be shot

Is the Anti skating set correctly?

Is the stylus worn
--- if it;s worn it could effect phase

Is the stylus/cartridge correctly aligned on the arm?
--- The more advanced stylus types (Contact Line and Shibata) requires a more precise alignment and can cause this issue

I have Optimized Contour Contact Line stylus and it required a Mint Best Protractor to get the best sound

How old is the phono stage?
--- (could be the internal electrolytic caps need replacing is the phono stage is old)

It only takes a small difference in phase between the L/R channels to cause the issues you are descibing.

I do not think the motor would not cause this issue

I’d start with checking Stylus alignment

Then I’d try switching a few IC’s between components in the analogue side of your system to see if they make a difference

As far as room treatments go ...
- the most effective I have tried is a vinyl roller blind behind the listening position. I only had it extended about 15" from the ceiling
- A piece of foam on top of book cases

It seems that the most reverberation issues in my old room occurred close to ceiling level.
The new room has very little (if any) reflected sound issues

Hope you get to the bottom of it

Regards - Steve

Please name a specific album and track that is problematic.

if you place cartridge on its top and you’re facing pins, than bottom left is left earth and top left is left signal. same with right side. to eliminate issues with room treatments, try first headphones and see how things are working for you. some records may be more sensitive to out of phase than the others, but still feel like your cartridge isn't great match.

First off I'm using the MM input due to the 2.12v cart. output, Second the back of the cart. is not color coded like some, but I sure I got that part right. If not wouldn't all records have the same issue?, Third I do have some floor rugs and am using some comforters hung on the wall over a garage door and insulated window shades but no actual room treatments like bass traps etc. A thought though--- would a weak motor cause changes to the platter speed have anything to do with this problem? I have been having to start the platter by hand because the motor doesn't seem to have the torque to spin it up but seems to stay steady after that?

First of all you can use Cardas Test record to check phase and polarity of your system. 

First, why spend all that on gear and not on room treatment?  Try putting soft things on the floor between and around the speakers. That can clear up a lot of mid/treble clutter. This is a free tweak, try it with pillows and blankets before investing. Especially cover hard reflecting surfaces like the tops of entertainment center, sides, and a TV if any.

Second, toe in?

Check to make sure your cartridge is not connected out of phase. Red on red, green, on green, white on white and blue on blue.

what phono input you're using MC or MM? In both cases it's loose-loose.
In case of MC the impedance is too low and MM the input is too low.
The solution is you should either have LOMC <.5mV or HIMM >4mV or outboard phonostage or replace load resistors of your MC input.