# Question about Noise Floor **URL:** \ **Category:** Tractor\ **Created:** [May 19, 2023, 1:05am UTC](https://forum.quantasylum.com/t/question-about-noise-floor/896 "2023-05-19T01:05:27Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Vinylitic](https://avatars.discourse-cdn.com/v4/letter/v/f6c823/32.png) [@Vinylitic](https://forum.quantasylum.com/u/Vinylitic)\ **Post date:** [May 19, 2023, 1:05am UTC](https://forum.quantasylum.com/t/question-about-noise-floor/896/1 "2023-05-19T01:05:27Z")
Hello… I have a question that is not specially hardware related, but more so about amplifier measurement… Please forgive if the question is inappropriate. The question is about “Noise Floor”… Is a pre-amp noise floor of -140db to -150db theoretically and practically attainable.? Would it be measurable with any of the QA-40x analyzers…? Thank You in advance ---
**Author:** ![Claudio](https://avatars.discourse-cdn.com/v4/letter/c/7cd45c/32.png) [@Claudio](https://forum.quantasylum.com/u/Claudio)\ **Post date:** [May 19, 2023, 5:56am UTC](https://forum.quantasylum.com/t/question-about-noise-floor/896/2 "2023-05-19T05:56:43Z")
Hi @Vinylitic. Try reading this post, I think it will be helpful. > [@Measuring Amp Noise with the QA451 and QA401](https://forum.quantasylum.com/t/measuring-amp-noise-with-the-qa451-and-qa401/142): > > This post explains how to measure amplifier output noise using the QA401 Audio Analyzer and the QA451 Programmable Load. Amplifier output noise is generally expressed as an RMS voltage reading in a given bandwidth. Since most finished amp makers are pretty loose with their specs, let’s turn to the silicon vendors as a first point of reference. Below is the spec for the TI TPA3255: Notice they have specified 85 uV, A weighted, with an AES17 filter and the amplifier input grounded. We … ---
**Author:** ![Vinylitic](https://avatars.discourse-cdn.com/v4/letter/v/f6c823/32.png) [@Vinylitic](https://forum.quantasylum.com/u/Vinylitic)\ **Post date:** [May 20, 2023, 12:37am UTC](https://forum.quantasylum.com/t/question-about-noise-floor/896/3 "2023-05-20T00:37:12Z")
Hello Claudio… Thank you for your response and the lead to the post… I will review, and hope I will have a better understanding…