Ok, so I mounted the Shelter yesterday........

Give it some time to break in. It is sort of quirky on break in, and goes through stages. I had the opposite effect. On my system, it was a little boomy at first.

Also, the VTA needs to be dialed-in correctly. Let it break in for awhile, and if it is still light in the bass, lower the VTA a little to get the bass improvement.

The Shelter is not a bass-weak cartridge. It has plenty of bass.

Hey Oz. I have also heard or read that the 501 was bass shy and like TWL's experience,I found it to be the exact opposite, a bit lumpy on the bottom end ,not really bass heavy just a little too much bloom.Unfortunately... it took a good 40 hours of run in time until it sounded coherent with the midband.AS TWL suggested... try lowering the rear end of the arm and the bottom should fill out a bit, however it will take some time and effort to dial it in correctly.I used George Cardas's burn in record and simply let it play for 5 days continuously.Like all cartridges...[especially moving coils]it is imperative that you run it in with a modulated frequency.You will gradually hear the midrange open up and extend outward further into the frequency extremes.Some like to hear it change as it runs in...ME...[been there,done that]and I'm far to impatient. Best of luck! cheers David.