I build the latest RC/AC booster PCB from AION again and socketed the different components.
Started with the AC and noticed there was a very prominent hiss coming from the build. All controls were working with their normal range, volume can go well above unity etc. I built it before and had the original pedals so I have an idea how they’re supposed to work.
I tried various opamps (5448P, 5448DD, OPA2134, TL072) and all were generating hiss, so its likely not the opamp causing issues.
I decided to swap the components to try out the RC. Again the same issue with hiss.
I mean with hiss a constant noise that changes prominently with increasing the bass or treble and volume/drive of course. The Lone King I finished yesterday also has noise which most boost or drive pedals do, but when turning off the guitar volume it normally goes away. The hiss from this circuit is constant.
I tried using an audio probe and I noticed that in the circuit the hiss starts to build up, in the clipping section of the opamp and on its output it’s increasing a lot, but maybe the noise starts earlier in the transistor etc? My specific questions are:
- Is it possible to measure the transistors (2n5088) and how would that work? What voltage to expect? Since replacing the opamps didn’t change the amount of hiss I’m concluding it’s not opamp related.
- Which components are most likely to influence/cause hiss? Is there an order or specific way of probing or measuring?
- Can clipping diodes increase hiss for instance?
Circuit doc is here: https://aionfx.com/app/files/docs/malacandra_documentation.pdf
i will post a pic later today.
Thanks for your help!
Started with the AC and noticed there was a very prominent hiss coming from the build. All controls were working with their normal range, volume can go well above unity etc. I built it before and had the original pedals so I have an idea how they’re supposed to work.
I tried various opamps (5448P, 5448DD, OPA2134, TL072) and all were generating hiss, so its likely not the opamp causing issues.
I decided to swap the components to try out the RC. Again the same issue with hiss.
I mean with hiss a constant noise that changes prominently with increasing the bass or treble and volume/drive of course. The Lone King I finished yesterday also has noise which most boost or drive pedals do, but when turning off the guitar volume it normally goes away. The hiss from this circuit is constant.
I tried using an audio probe and I noticed that in the circuit the hiss starts to build up, in the clipping section of the opamp and on its output it’s increasing a lot, but maybe the noise starts earlier in the transistor etc? My specific questions are:
- Is it possible to measure the transistors (2n5088) and how would that work? What voltage to expect? Since replacing the opamps didn’t change the amount of hiss I’m concluding it’s not opamp related.
- Which components are most likely to influence/cause hiss? Is there an order or specific way of probing or measuring?
- Can clipping diodes increase hiss for instance?
Circuit doc is here: https://aionfx.com/app/files/docs/malacandra_documentation.pdf
i will post a pic later today.
Thanks for your help!
![FE267DCD-E029-4835-BC9A-7B53707EE445.jpeg FE267DCD-E029-4835-BC9A-7B53707EE445.jpeg](https://forum.pedalpcb.com/data/attachments/24/24009-7b72e028f23980275a5f521dfbe4e557.jpg)
![D9131837-BC78-4A65-9AC5-C00198C73F96.jpeg D9131837-BC78-4A65-9AC5-C00198C73F96.jpeg](https://forum.pedalpcb.com/data/attachments/24/24010-56050386904a3c9568d700babc64294f.jpg)
![8171D2B6-7BFF-48B4-A905-076F5E1850C8.jpeg 8171D2B6-7BFF-48B4-A905-076F5E1850C8.jpeg](https://forum.pedalpcb.com/data/attachments/24/24011-7dbdf73b65f88f40ca49a5d97ea14a86.jpg)
![B608F49C-9811-4CF8-8139-6CFB5E9B6E41.jpeg B608F49C-9811-4CF8-8139-6CFB5E9B6E41.jpeg](https://forum.pedalpcb.com/data/attachments/24/24012-a1141f6a82a2ca9b5fd35b627c78da0e.jpg)
![D7CD00C5-0F1C-4258-AB02-3F4664516971.jpeg D7CD00C5-0F1C-4258-AB02-3F4664516971.jpeg](https://forum.pedalpcb.com/data/attachments/24/24013-c8d112b38f34c4b3380ee9eb5c8a37a0.jpg)
![0BC491F8-9801-4A52-9904-75ED3C7D6440.jpeg 0BC491F8-9801-4A52-9904-75ED3C7D6440.jpeg](https://forum.pedalpcb.com/data/attachments/24/24014-515caa009b6ece4b4209f84b1dfa93b1.jpg)
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