I'm not sure if this is true or not but even though the attack times are short, if you follow the instructions that come with the MXR you'll find they recommend running a constant gain reduction as many bass players do already. What I mean is during regular play the gain reduction is always going on and only stops when there is a break in the music. How long of a break depends on the release time setting but in general a quarter note pause in playing won't completely dissengage a compressor. So, in reality, many bass players wouldn't hear the attack time take place except for the first note of a song. After that first note, the threshold has been crossed and it's all ratio until the player stops and then it's release time. Is this not the case?
I don't know what kind of release times are set with the TLC as there is only an attack setting. I'm guessing the release times are variable relative to the attack setting?? My guess is if one had the threshold turned down enough on the TLC they wouldn't hear any difference in the attack setting anyway. Without any indication of when the threshold is crossed makes setting the threshold on the TLC tricky. I use my ears but for many who are not familiar with what compression, ratio, attack and release differences sound like it might be hard to decern what a proper setting is for them.
I think the MXR is still great for regular compression. It would make an excellent limiter no doubt but I wanted to convey that most people wouldn't notice the somewhat short attack time range of the M87.
Attack, release, ratio and threshold all have a large impact on the compression characteristics. Depending on the range of each of these controls, you may be able to set the comp for a lively sound (somewhat transparent), a constant volume (lacking dynamics = high ratio + fast attack) or an effect-y sound (exaggerated dips and swells = low threshold + high ratio + extended release times). So, all of these controls play an important roll and interact with each other to produce the overall response.
In general terms, the attack is the time it takes for the increased signal over the threshold to be fully brought under control. This happens with every increase in signal level (hitting a note) whether or not the compression is currently active. In some scenarios the musician may not hear the punch (attack time) of each note played if the attack time is really fast or the release time is long with lower thresholds and higher ratios. This is similar to what you have described with the longer release times, where the successive notes are already compressed enough to the point where the initial note dynamic wont jump out as much. But that is only one way that the compressor can be used.
It is true that not knowing exactly what release times or method (fixed release time, adaptive release time or variable times associated with the attack setting) that the TLC uses makes it a bit more difficult to call. But, I think it is safe to assume that since I have not seen anyone say that the TLC has an effect-y sound, that the release time(s) are closely following the signal envelope. If this is the case, then the attack times that the TLC has should allow you to set it up to get the punch from each note played. The MXR with its fast attack can not be set up in such a manner, although the lower ratios will allow for more signal dynamics.
I am sure the MXR is an excellent compressor and its design allows it to be a fantastic limiter. All we are pointing out is that its really fast and people need to understand that significant difference when compared against the TLC. It all boils down to what works best for you
if you like fast compression or a limiter then lean towards the MXR if you like a slower attack then the TLC wins. If you are not sure, as in the case for the OP (with what he stated his goals are), I suggested to audition both to see what works best for him, because either one can work for his gentle compression needs. Sometimes what you think you may want may be totally different after actually trying them.
Another thing that has not been mentioned is that a comp or limiter set with a low threshold, short release time, high ratio with a fast attack will sometimes cause unwanted distortions. What is happening here is that the comp or limiter is acting upon the low frequency waves more than the signal envelope (behaving more like a signal clipper). I only mention this because someone in another thread was describing this type of distortion with the MXR. This is usually can be somewhat remedied with a longer release time and/or a slower attack to better follow the envelope.
I agree that without a compression indicator on the TLC it may be harder to adjust until you are familiar with it. But once you have a feel for it, the lack of an indicator will only be a minor inconvenience for most people. IMO, I dont think the lack of an indicator should be a deal breaker when looking for a compressor.
-Frank
BTW, I just read some posts by chessrocks in the Dr. Strangecomp thread where he uses some humorous analogies to explain compression. Its a good non-technical explanation of compression that anyone new to compression should read.
I mean, there's really nothing left there to compress, so let's at least get that straight. There is nothing left to compress, period and end of story.
