Help me understand compliance!


Hello all,
I have a Rega Planar 25 with an RB-600 tonearm. I am at a loss with words like compliance. What weight/ compliance combination is correct for a cartridge for this tonearm? I’m looking for the correct weight and compliance so I can go shopping. Also, any recommendations/ experience with cartridges on this rig would be appreciated. The rest of the system is a Conrad Johnson premier 11a power amp, sonic frontiers sfl-1 preamp, B&W 804s speakers and a MF lx-lps phono preamp. Cables are Musica Bella emberglow speakef and ic
thanks in advance!
skipper320
skipper320
compliance relates to the stiffness of the cantilever and suspension.  
a higher compliance is more flexible.  lower compliance is stiffer. 
if you have a heavy truck you would want a stiffer suspension for more stability.  if the suspension was too flexible the truck would lean and sway on the road.  
an overly stiff suspension on a light car would also be unstable because the tires could lose contact with the road if it was bumpy. 
a low mass tonearm would be a bad match with a stiff, low compliance cartridge because trackability could suffer.  
a high mass tonearm would be a bad match with a flexible high compliance cartridge because the position of the stylus would be fighting against the higher inertia of the heavier tonearm, e.g. the suspension could be over stressed trying to track a warped record.  
soundsmith has a very good chart that matches cartridges of diffrrent compliances to a range of tonearm masses.  
Words of wisdom, short and sweet:
Rega table.

Get a Rega cartridge that's in your budget-simple. Enjoy records.
The more you find out, the more unnecessary audio neurosis you'll develop.

Perhaps you will indulge me a little poetic license.  I assure you this is pertinent, not crazy stuff.  A person says something that is totally outrageous.  A listener accepts the message at face value without reservation.  That is compliance.  Second scenario:  A person says something that is factual and provable.  A listener rejects the message resolutely and without qualification.  That is non-compliance.  As applied to phono playback, any given cartridge/arm combination traces a record groove.  Does it comply?  How well?  What do you hear?  Clues that the combination is not fully complying with the requirements would be sibilance and similar forms of unnatural sound.  The violin, human voice, and piano are three extraordinarily difficult instruments to accurately record and reproduce.
Actually bill, non compliance manifests itself as feedback, poor tracking and the stylus hopping right out of the groove.

Skip, lewm and chakster have it right. Chakster's suggestion about the HI FI News Analog Test LP is very important. You have a light medium arm.
It will match up well with the more compliant moving magnet cartridges like anything from Audio Technica, Clear Audio or Goldring. The Goldring 1042 is a favorite of mine. 

Compliance is a measure of the stiffness of the cantilever's suspension. It is analogous to an automotive suspension. Lets use a pickup truck as an example. Empty pickups (no load) have a choppy ride but if you load one up with a ton of brick the truck now wallows and bounces at a low frequency. That is it's resonance frequency. Add weight the resonance frequency drops, take off weight and the resonance frequency rises. The test record will tell you where your resonance frequency is. If it is too high you add a little weight to the head shell. If the cartridge is too heavy or the compliance to high the resonance frequency will be too low and you would have to remove weight (mass) which can be hard to do. So, it is better to start with a cartridge that might be on the stiff side as you can always add weight. But, any of the above moving magnet cartridges will be just fine. If you tell me how much you want to spend and I'll tell you which models to look at.
As one engineer to another we can communicate with each other in technical terms and understand each other.  The great beauty of science. In layman's terms my explanation of the matter has left you with an inability to track my thought process.  We need to increase your compliance to see this philosophically.  :-)  Not everybody as the scientific method at their fingertips.