# Speaker Impedance with QA403 + QA461

**URL:** <https://forum.quantasylum.com/t/speaker-impedance-with-qa403-qa461/873>\
**Category:** Uncategorized\
**Created:** [April 29, 2023, 5:18pm UTC](https://forum.quantasylum.com/t/speaker-impedance-with-qa403-qa461/873 "2023-04-29T17:18:31Z")\
**Posts on this page:** 1\
**Showing post:** 158

<div class="post-metadata">

**Author:** ![Frunse](https://avatars.discourse-cdn.com/v4/letter/f/5daacb/32.png) [@Frunse](https://forum.quantasylum.com/u/Frunse)\
**Post date:** [June 25, 2024, 5:29pm UTC](https://forum.quantasylum.com/t/speaker-impedance-with-qa403-qa461/873/158 "2024-06-25T17:29:55Z")

</div>

Ok Guys like i told now the last Test with this little Amp 😉  
Removed the AC from PCB and Connected directly to an Lab Powersupply.

 ![IMG_20240625_190339_6](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/2/2984d21b25a2d1d979f9150b13e0f427d6a487ce.jpeg)  
 ![Powersupply](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/b/b3adb9de51ce44676bcccdc3263336c03c2568b6.jpeg)  
±25V (Measured befor on that Amp, AC Transformer 2x 19V 2A)

Frequenzy Response: (No little Peak @ 100Hz anymore!)

 ![AKB-60 Moded wit Lab Powersupply 1 Watt](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/3/38ee38613b5f22f9f4cac6398c3148ba9cf845eb.jpeg)

THD and THD+N Differential now so much better:

 ![XLR 1Watt 8.35Ohm Lab Powersupply no AC](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/5/5752a726a43b1e368fb3c5e746c049e28e4a7195.jpeg)  
before:  
 ![XLR 1Watt 8.35Ohm Moded cap changed from 22uF to 100uF witout Enclousure](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/e/e3abc69348d8fe85565e1a0b148d459ff77f86e4.jpeg)

 ![THD+N vs Power 8,35Ohm Powersupply no AC](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/2/228ed39b7486d4e652d37238ee03834a38744792.jpeg)

before:

 ![THD+N vs Power External Resistor_XLR vs Single Ended](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/c/c28a038d0f5823742a49c964e821b38683859228.jpeg)

So now i go for this Linear Regulated Powersupply for this Amp:  
[https://www.audiophonics.fr/en/linear-regulated-psu/lv1084-20v-5a-dual-controlled-linear-power-supply-module-p-8426.html](https://www.audiophonics.fr/en/linear-regulated-psu/lv1084-20v-5a-dual-controlled-linear-power-supply-module-p-8426.html)  
2x LT1083 up to 7,5A Regulator 😉

Any Suggestion what i could do better here??? Adding Mains Filter Probably?

For the INUC and USB Hub and all QA USB devices i will use this PSU for Mains and also an big switch with 2 4mm Connector for 12V Battery Supply for in Car Measuring.  
[https://www.audiophonics.fr/en/diy-kits-and-boards/audiophonics-psu-s4-hp-linear-power-supply-module-dc-micrel29752-p-10435.html](https://www.audiophonics.fr/en/diy-kits-and-boards/audiophonics-psu-s4-hp-linear-power-supply-module-dc-micrel29752-p-10435.html)

Robert

---

_[View the full topic](https://forum.quantasylum.com/t/speaker-impedance-with-qa403-qa461/873)._