C-Audio-BHOA

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Balanced Headphone Operational Amplifier

A high powered differential headphone amp with a focus on modularity and prototyping. Inspired by the Schiit Audio Magni Heresy.

Features

All sections of the amp should be modular (Filter, VA, CA, Output protection)
All sections should be accessable via pin headers
Output power >1W per channel

Schematic

The Amp consists of a simple differential input filter for very high frequency noise, an instrumential amplifier input stage for differential voltage amplification and 8 paralelled opamp sections in buffer topology per channel (of which there are 4 for differential amplification for a total of 16 opamps(!!!). Mental, I know).

The instrumental amplifier in the prestage was chosen, because it is really easy and straight forward to set the gain with just a a single resistor per channel.

Furthermore the output is protected via muting relays driven by a mosfet and a turn on timer for a startup delay.

The power supply is off board to stay in the limits of JLCPCBs cheap 100x100mm PCB service. It can range from +-5V to +-18V (or how much the Opamps will take). The output relays are 5V, a simple 78l05 so8 IC is supplying them with 5V.

TODO

Improve stability of current amplification. Maybe high value resistors to ground to give a reference for the inputs. Also cascaded topology might be a better CA stage as per SBOA553A
Improve output protection. Firstly ADD some DC protection and improve the circuit for setting delay time.

Comments

Balanced Headphone Operational Amplifier

A high powered differential headphone amp with a focus on modularity and prototyping. Inspired by the Schiit Audio Magni Heresy.

Features

All sections of the amp should be modular (Filter, VA, CA, Output protection)

All sections should be accessable via pin headers

Output power >1W per channel

Schematic

The instrumental amplifier in the prestage was chosen, because it is really easy and straight forward to set the gain with just a a single resistor per channel.

Furthermore the output is protected via muting relays driven by a mosfet and a turn on timer for a startup delay.

TODO

Improve stability of current amplification. Maybe high value resistors to ground to give a reference for the inputs. Also cascaded topology might be a better CA stage as per SBOA553A

Improve output protection. Firstly ADD some DC protection and improve the circuit for setting delay time.

C-Audio-BHOA

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Balanced Headphone Operational Amplifier

Features

Schematic

TODO

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Balanced Headphone Operational Amplifier

Features

Schematic

TODO