# QA403 attenuation not working? **URL:** \ **Category:** Uncategorized\ **Created:** [September 6, 2024, 9:38pm UTC](https://forum.quantasylum.com/t/qa403-attenuation-not-working/1545 "2024-09-06T21:38:06Z")\ **Posts on this page:** 1\ **Showing post:** 6
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://forum.quantasylum.com/u/matt)\ **Post date:** [September 8, 2024, 12:07am UTC](https://forum.quantasylum.com/t/qa403-attenuation-not-working/1545/6 "2024-09-08T00:07:39Z")
> Mod, feel free to delete the thread. Hi @RAW-CAt, I’ll leave in place if you don’t mind. this is a fairly common problem and bit me the first time measuring class single-supply D push pull. I just posted some spice simulations at the link below to help illustrate this. In short, when measuring a push-pull amp, you probably want a 3-resistor attenuator. But when measuring a single-ended amp, you probably want a 2-resistor attenuator. > [@QA402 Input Range Violations using Differential Inputs](https://forum.quantasylum.com/t/qa402-input-range-violations-using-differential-inputs/1486/31): > > Hi @cfortner, overall this looks like a solid setup. But there is a bit of a wrench lurking inside the setup that isn’t surmountable, but needs to be understood since you are working towards a universal setup for all topologies. Let’s start with SPICE to understand the external divider. In the picture below, I’m using a voltage controlled current source to generate a balanced signal. This is TI’s preferred way of nudging SPICE to do what is needed. I wish I could find the TI engineer’s name tha… --- _[View the full topic](https://forum.quantasylum.com/t/qa403-attenuation-not-working/1545)._