Turntable, where is my bass???

Hi, I've noticed a clearly diminished low frequency output with my analog gear lately but cannot put it in precise timely relation with a particular event since I have mainly been playing newly acquired records during the last few weeks or very old ones that I hadn't heard for years. But now, the familiar records surprised me with a lack of "something" (there was actually one recent change of IC)

The chain of the signal is Transfiguration Spirit III cart -> Well Tempered Reference arm with original wiring sitting on Well Tempered Reference table -> Synergistic Research Tricon analog IC -> Tidal Preos pre-amp.

Possible culprits I can think of:
1 (the one I hope it to be) The SR Tricon is only a few weeks old; before that the dealer had lent me a broken-in demo cable that I was allowed to keep several weeks until my newly ordered one arrived. So could this be a questin of break-in?
2 Could the arm somehow have "deregulated" itself, e.g. in respect of VTA?
3 Resistive load is fixed at 120 Ohm; could I just be growing aware that is the wrong value? Does anyone know the preferred value for the Spirit III ? (I can't experiment changing it myself, but the Tidal guys could fix another value if can tell them which one)

Does someone know of other possible causes that are perhaps subtle first and then just "snap"? It can't be my hearing since I don't notice any change in the digital department.

Thanks for your insight.
So, are you saying, other than the IC change, nothing's changed recently? Can we assume that the bass is fine with SACD, DVD-A and CD? Has any furniture or the speakers been moved within the room recently? When you listen on your headphones is the bass still lacking?

No change with CD or DVD noticeable. Very minor furniture moves in the past weeks (no change in listening position or overall geometry), but if that were the cause, I would have expected a change with the other sources as well. I never had headphones in this system, so I can't be completely sure about what is "normal" bass there but thanks for mentioning it, I'll try to test that as well.

I'll throw in another unlikely suggestion (one never knows ...) Could my Well Tempered be telling me I need to check/change bearing fluid or arm damping fluid or something of that kind?
Do you have the old IC? if so hook it back up and see if the bass comes back. I had the same experience once but it had to do with the overall sound when I changed IC. I put it back and moved on after returning the IC's. If you bought the IC from a dealer and he tells you to wait until they are broken in tell him no problem but if after break in it still is bass shy tell them you want a refund. Tell them NOW not later when it is too late.
Valuable suggestion, thanks. I haven't got the previous Tricon anymore, I gave that back when the new IC arrived; I have no other dedicated phono IC anymore, but I will experiment a bit with one or the other IC
Have you checked the TT set-up? Too little weight? Or it it no longer level? It very easily could have been bumped. Any tubes in the chain? It could be a weak tube?
Burning in anything in the phono stage is tough. I bought this inverse RIAA circuit http://www.hagtech.com/iriaa.html from Hagerman Technology which really speeded up the process. It's really hard to know what's going on 'til you've gotten everything burned in and it's easy to put on a couple of hundred hours in just over a week with the Hagerman.

You do need to be certain that your arm damping fluid is at the correct level. Either too little or too much can impact bass response.

If you bought them from a dealer ask them if they would burn them in for you free of charge of course. Also when you took the old ones out and put the new ones in did you bump the table? maybe it isn't level anymore.
Dear Karel: Other than IC and tonearm damping fluid level I think that could be worth to re-install ( like a new cartridge ) your cartridge just from the begin: clean the cartridge connectors pins, be sure that the tonearm to cartridge connectors make good connection, overhang, Azymuth, VTF, VTA, stylus deep clean, check that the cartridge cantilever is right on " target ", etc, etc.

It seems to me that the load impedance is not the problem. You could try with a different cartridge and see what happen.

If nothing works and I mean that you don't recovery that " bass " then you have to thing that maybe there is a trouble on the cartridge it self or on the phono stage.

Regards and enjoy the music.
Thanks to everyone. I actually bought ithe new IC directly from the SR distributor for the Benelux - in Germany it is not even distributed - who is an extremely helpful guy, but since the Tricon is so novel, I'll talk to SR first, see what they think about the Tricon's burn-in period.

If that is not the cause, looks like I'm going to have to roll up my sleeves (sigh, probably started this thread, to have all you good people encourage me)
obtain a Frequency test LP if you do not have one. Play the frequencies at 1Khz first. measure the voltage output from your phono stage or pre amp tape outputs.

Then start playing lower frequency tones and measure the voltage for each. If you are hearing a true drop off in freaq. response, and can confirm it with the voltage meas. then you either have a cart, that is not broken in yet, has a poor low freq. response, or need to tweek the RIAA circuit, to increase the gain where the drop off happens.

Make sure you keep the same time contant by changing out equiv. cap and resistor values.

To elaborate on Dcstep's comments, changing damping (either by using a different viscosity or by reducing the contact with the fluid) will have the effect of altering the effective mass of the arm, and hence the bass response.

I would absolutely revisit every setup parameter on your rig. Something has changed (perhaps only the cable), but you won't know if your setup is correct until you re-verify it. Bond with your turntable ;-)

Thom @ Galibier