I work with a lot of audio. The unfortunate answer is, it really depends on your own voice. Those of us here with our own studios and dedicated mics, have really specifically tuned equalization settings. The good news is, we have station and news studios that are used by many people, and have to have more of a general setup. Just working with bass, treble, and reverb or echo; shouldn't be too hard. I'd start from bass and treble each in the middle, or at neutral. Just in general, people need a slight to moderate amount of bass added (something like a third of the way between neutral and max,) unless you already sound like Sam Elliott. Without being able to adjust a mid-range it would probably help to boost treble just slightly more than bass. I've found that helps, it gives a voice a brighter tone... but in a subtle way. Like a brass instrument with a sharp edge on its bell rather than a rounded edge. As for reverb, that is really subtle. You want some, it creates a more "solid" tone. But you don't want it to be particularly noticeable. A good test of that, turn it up about a quarter of the way (way too much) and contrast that with it at 0. You will be able to hear the difference. Keep adjusting it down and contrasting that with 0 until you get something that you cant tell much difference between it and 0. Then turn it down a little more and that's what you are probably looking for. Oh and a tip, echo or reverb doesn't generally have negative settings. So its neutral is 0, off, all the way down. Neutral for bass and treble should be halfway (giving you the ability for negative adjustment.) But I have seen equipment that only allows boost, with neutral at 0. So if the way I had you set it up sounds particularly odd, its possible that neutral position is 0 instead of 5 out of 10 or whatever halfway would be labeled.