title: Poor quality when using multilingual vocoder for persian language with mozilla tts
body: <p>I used tacotron 2 for training persian dataset (around 33 hours). When I use Griffin-Lim, quality of sound is good but when I used other pretrained coqui vocoder such as fullband-melgan and wavegrad, sound quality is poor.
  Here are my config file and two sound file that use two distinct vocoder. Below command is for generating soundfile with fullband melgan vocoder.</p>
  <pre><code>tts --text &quot;سلام حال شما خوب است؟&quot; --model_path &quot;best_model.pth&quot; --config_path &quot;config.json&quot; --vocoder_name &quot;vocoder_models/universal/libri-tts/fullband-melgan&quot; --out_path &quot;example.wav&quot;
  </code></pre>
  <p><a href="https://github.com/coqui-ai/TTS/files/8404687/config.zip" rel="nofollow noreferrer">config.zip</a>
  <a href="https://github.com/coqui-ai/TTS/files/8404689/sound_file_by_full_band_melgan.zip" rel="nofollow noreferrer">sound_file_by_full_band_melgan.zip</a>
  <a href="https://github.com/coqui-ai/TTS/files/8406962/sound_file_by_grffin_lim.zip" rel="nofollow noreferrer">sound_file_by_grffin_lim.zip</a></p>
  <p>I will appreciate in advance if you can help me.</p>