You haven't given us enough information to attempt to help you, really. We totally disagree with your assessment of "thin" in comparison to the S90 but that could simply be a matter of opinion. Here's what we can tell you.

First, "thin" is a description best fixed by adjustments to your sound system. If you play the S90 and the CP4 Stage through headphones you will conclude that neither is considered any where's near a description of "thin". Thin is a description of the sound in a system that is deficient in the mids and lows, neither the S90 nor the sounds of CP4 Stage would be considered thin when played through a properly balanced sound system. Try a good pair of headphones to eliminate your current sound system (to us the obvious culprit, because we DO NOT consider the CP4 Stage's natural sound as "thin")

If you specifically want my help with this issue, and not sure why you have singled me out, but thank you for your confidence. I highly recommend you compare apples to apples wherever possible. Having personally compared the piano in all recent Yamaha synthesizers to the CP4 Stage, I think it is just you getting used to a new favorite sound ... Well perhaps not favorite yet, you are realizing perhaps you need to change something in your sound reproduction setup; you are describing it as "thin" - it is not a "thin" sound in my opinion. Not saying that you are not getting a thin sound, that is obviously what you hear... I pray it is not a hearing issue, but in reality you cannot just rule that out. Let's deal with sound system 101 issues... If truly it is hearing, I can't really help you there.

Are you playing it back in stereo?
Nothing causes a "thin" sound like summing a stereo signal into a single mono speaker. You get cancellation that winds up giving you a boxy sound devoid of definition in high end and low end. This common mistake made by CP4 Stage owners means you are not taking advantage of the majority of pianos sampled in true stereo. Try the mono piano Voices (provided for those still living in the pre-1950's world on mono music) .... Do they also sound "thin" through your sound system?

If you are playing in mono, how many cables are you connecting to your system?
The correct answer should be one. If you use two cables make sure you connect to a true stereo system with the left channel panned hard left to the left speaker, and the right channel panned hard right to the right speaker. Best setup!

If you are not playing in stereo, use headphones to avoid the "thin" sound.
Whenever possible Play in stereo, life is stereo, music is stereo, the CP4 Stage will put life back in your music if you play it through a quality stereo sound system, anything less, well, you get what you deserve! (which unfortunately is not optimum sound quality. Sound is always at the mercy of the weakest link in the chain).

When you have guests over to your place and you put on some music to entertain, do you play it for them through one speaker or do you break out your stereo sound system? If you answered, "stereo, of course" you understand the passion I have for stereo. It's the minimum for how you should listen to music, if it is at all important to you.

Let us know what you are playing through. We KNOW for certain the CP4 Stage is not "thin" by nature. That we KNOW... What we don't know is what you are doing to its sound output. However, if it is thin to you in headphones as well, then let's proceed to a repair recommendation.

Thanks bad mister for your reply. I play in stereo when there is adequate equipment available. At home i have a Yamaha Pa ?12sx and sv 12 cabs...always instereo at home. You are probably correct in "training my ears" for the newer sounds after the s90. I will continue to play and listen. If there are any favorite internal settings you like, please share. Have a wonderful holiday season...

The CP4 Stage is so flexible, I am at a point where I'm still discovering what it can do. The perspective is very much from a personal 'need to accomplish' basis. The combinations of sounds is always predicated on a specific requirement... What the song you're performing requires from the keyboardist.

If you layer marimba and flute split with synth brass, it might seem a strange combination ... Unless your requirement is to cover Toto's song "Africa" ... If you get my meaning. But with two FC7s, an FC3 and an FC5 ... I'm finding more to like. This is why someone else's Performance setups always are things to learn from... Because you wind up changing them to suit your own individual needs

Beyond the Piano and E. Piano modeling functions, the CP4 Stage has a weath of sounds for the on stage player who needs to cover a variety of parts and functions within the band. Once you get a handle on assigning the controllers, the sky's the limit.

I spend a lot of time discussing with end users specific requirements, for specific songs, etc. And what that allows me to discover is that there is no one setup that will make everyone happy, but almost anything is possible. It's worth the time to dig in and and discover !

While stereo certainly works great––especially on certain sounds––many gigging musicians can't afford (or don't want) the luxury of stereo. Some would argue that, in the context of a stage, an acoustic piano never was a stereo instrument.

I'm all about travelling light and turning up at a gig with just the CP4, and a Bose L1c is terrific. I would challenge anybody to describe that sound as thin. In fact, I played it through this setup yesterday to some friends, and their first response was: "It's very rich". Of course, as Bad Mister says, it's important that you use the mono patch if you're going to be playing mono. I have set the mono version of each sound to be the "favourite" when I select the bank button.

Aside from some issues with sample stretching, I couldn't be happier with the sound of the CP4. I would describe it as "fat". 🙂

I'm really sorry to say that as a Yamaha user and one who has purchased many Yamaha instruments over the last 35years I don't think what ever you do with the CP4 you will achieve what you were hoping for. I was really impressed by the build quality and appearance of the instrument and thought it really stood out. The studio style monitor speakers in the store were perfectly positioned to my ears brought out the sound quality and I was happy and quite exited to make the purchase. I know Yamaha are genuine people with a real expertise in piano design and manufacture. I thought the sounds would on stage be a real improvement on the 14year old Clavinova CLP150 in my lounge.

However when I put the CP4 through my gigging rig it was a different story. I sounded thin and lifeless. I could not believe what my ears were telling me. I must have been finally going deaf! I A/B 'd it with the old Clavinova on exactly the same amp and settings and it sang out beautifully! Then I put in an even older Technics which although not technically perfect sang out with character and 'vibe' . I must say I was pretty gutted and thought 'it must be me' . I went with my instincts and returned it for a more expensive red keyboard. I will still be using my 2 TX7s and the Motif ES rack. They can blow the house down.

Just my 2 cents
I had S90 from 2003 to 2005 and since 2005 I own a S90ES. In the meantime, on November 2013 I bought also CP4.
When I moved from S90 Classic to S90ES, it seemed to me a great step ahead in piano timbre. I remember also a F#3 (or F#4) on the S90 that sounded a little dull and this made me quite nervous, because it was an often used note in the middle of the keyboard.
I find CP4's CFX piano timbre very well "defined and precise", if compared to the S90ES's one, but not "thin". Perhaps S90ES 53MB piano is more "in front", while the CFX is more airy and, expecially if played through headphones, it seems to be a little far from the keyboard. I guess it depends from the miking techniques.
To sum uo, I find CP4 a wonderful instrument, both for its hammered keyboard, acoustic and piano sounds and its master keyboard capabilities. Perhaps the supplementary sounds might be numerically less but better quality.

I have had an S90 in the past. The CP4 sounds better to my ears. It's so difficult to know how other's perceive "thin". So many factors to consider. Andy had the best info on this. He A/Bd several boards on the same sound system and decided to go back to the red board. I did the same thing and decided to stick with the CP4. It's all in the ears of the beholder! I do know this: The older I get, the louder I seem to need things and the brighter I tend to mix things. I think at some point we all start doing this and the result can be a thin sound. Too much high end content and not enough lows and mids. Its unreal how bright we think we want things. Piano players are so afraid of getting drowned out by guitars we make our patches cut too much. Sometimes I'll go play a real piano, a bright one, and realize I have been over-doing it. The piano sound of the CP4, right out of the box is pretty much spot-on. One thing that is fun to play with is the damper-resonance. Sometimes I can get a little high-end content there without over-eq-ing the heck out of the main piano sound.