[LAU] JACK (or LADSPA or LV2) spectrum analyzer?

I'm mixing away, and at times I want to LOOK at the spectrum of a sound-- my ears are not yet well-developed enough for me to say "oh, that lump is at about 420Hz, and there's another at 3172Hz...", and sitting here sweeping with a parametric EQ seems prone to inaccuracy. I really like the spectrum analyzer built into JAMIN. At times I've been hooking up the output of a track to JAMIN, just to see what its spectrum looks like and where the peaks and/or resonances are. Is there a LADSPA or LV2 spectrum analyzer, similar to the one that's in JAMIN? And/or, is there a standalone JACK spectrum analyzer-- less heavyweight than JAMIN-- that I could use as a client, and just patch it in and out of tracks to view them? -ken