As you do not say what mic you have or how it is connected, there is a lot of guesswork involved...
A TLM103, like any true condenser studio mic, must be used with an elastic cradle mount and a breath shield, so you cannot get too close to it.
If your mic is distorting "sometimes", either you are too close, you are not using an appropriate breath shield / pop shield, or the input level is too high on whatever you have it connected to.
If it's a large diaphragm true condenser type it also needs an elastic cradle shock mount. (If the mic "thumps" when you move it suddenly, it's one that needs a proper mount).
Breathing on a condenser mic, or even a sudden draught, can make the diaphragm move too far and rattle against the backlate, causing thumps or distortion.
If you want to be able to get really close to a mic and not need any extra mount or breath shield, you want a dynamic stage mic such as a Shure SM58.
With those, the closer the better - if you see performers using them in stage shows, it often looks as if they are almost chewing on the mic.
Or, for an exceptionally good studio condenser mic at a reasonable price, try an MXL V87; about $250 or so last time I looked and on a par with some costing ten times as much.. They come in a kit with an appropriate mount and breath screen.
The MXL V67g is somewhat similar but not quite as good noise levels, at around $100. Or an MXL990 is OK for general vocal use & you can sometimes find them for $50 to $70..
ps. For any genuinely good quality mic, you need a separate audio interface that accepts an XLR type mic cable - something like a Focusrite Scarlett or similar.
"Sound card" type inputs or interfaces are not suitable.
Answers & Comments
a wind screen over the mic might be all that you need. prevents your breath from causing 'popping'
As you do not say what mic you have or how it is connected, there is a lot of guesswork involved...
A TLM103, like any true condenser studio mic, must be used with an elastic cradle mount and a breath shield, so you cannot get too close to it.
If your mic is distorting "sometimes", either you are too close, you are not using an appropriate breath shield / pop shield, or the input level is too high on whatever you have it connected to.
If it's a large diaphragm true condenser type it also needs an elastic cradle shock mount. (If the mic "thumps" when you move it suddenly, it's one that needs a proper mount).
Breathing on a condenser mic, or even a sudden draught, can make the diaphragm move too far and rattle against the backlate, causing thumps or distortion.
If you want to be able to get really close to a mic and not need any extra mount or breath shield, you want a dynamic stage mic such as a Shure SM58.
With those, the closer the better - if you see performers using them in stage shows, it often looks as if they are almost chewing on the mic.
Or, for an exceptionally good studio condenser mic at a reasonable price, try an MXL V87; about $250 or so last time I looked and on a par with some costing ten times as much.. They come in a kit with an appropriate mount and breath screen.
The MXL V67g is somewhat similar but not quite as good noise levels, at around $100. Or an MXL990 is OK for general vocal use & you can sometimes find them for $50 to $70..
ps. For any genuinely good quality mic, you need a separate audio interface that accepts an XLR type mic cable - something like a Focusrite Scarlett or similar.
"Sound card" type inputs or interfaces are not suitable.