Training an LLM from Scratch, Locally — Angelos Perivolaropoulos, ElevenLabs
- Source
- youtube.com
- Author
- AI Engineer
- Date

Context
Training a small makes the difference between learning and memorization easier to inspect. A researcher at ElevenLabs uses this workshop to build a model from random starting weights and train it to predict the next character in Shakespeare text.
The training process adjusts the model using one portion of the text and checks its predictions on a separate, held-out portion. A falling training error shows improvement on the material used for those adjustments. If held-out performance stops improving while training performance continues to improve, that can expose overfitting: increasingly fitting the training examples without a corresponding gain on unseen material. The exercise makes this distinction concrete without requiring a frontier-scale model.
- LLM — A large language model — the neural network behind tools like Claude and ChatGPT, trained on huge amounts of text to predict what comes next.
“Okay, we need to train this new TTS model and we're going to spend maybe 6 months thinking about the tokenizer, and then we're going to spend 2 months on the architecture.”
Angelos Perivolaropoulos
“you don't necessarily need to know in a very deep level how transformers work to to be able to train something like this”
Angelos Perivolaropoulos
“I remember when OpenAI was about to release uh GPT-2 and they were saying we're not going to release it because it's too dangerous for for humanity”
Angelos Perivolaropoulos
“if this data set has like even some small issues it can literally make or break your model”
Angelos Perivolaropoulos
“you can't just go on like Reddit and just get random posts. You're not going to learn how to think this way for sure.”
Angelos Perivolaropoulos
- 0:00Introduction and background of the speaker
- 1:21Overview of the workshop objectives
- 3:12Inspiration from Andre Karpathy's NanoGPT
- 4:37The four fundamental building blocks of an LLM
- 7:08Prerequisites and setup tools (UV, Python, hardware)
- 9:06Part 1: The Tokenizer (character-level tokenization)
- 24:29Model architecture and parameters
- 30:13The GPT class structure and transformer blocks
- 37:52Parameter count and model sizing
- 40:54The training loop: next-token prediction
- 44:44Optimization and learning rate strategies
- 47:56Validation and monitoring loss
- 53:07Part 3: Text generation and inference strategies
- 56:30Putting it all together (project file structure)
- 58:46Monitoring training and debugging common issues
- 1:00:27Workshop challenge and competition details
- 1:05:24Q&A: Base models vs reasoning models
- 1:11:31Q&A: Applying concepts to audio and multimodal models
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