I think per tombo suggestion using 12VAC with an active rectifier I get around +/-17.65vdc unloaded. Active rectification usually gives around 1-1.5vdc more than conventional bridge rectifier as the losses are less and hence went with this rather than 15vac secondary toroidal.
If mentioned additional 56 mF capacitors are meant to be after the regulated PS, then they are with no function other than increasing weight.
Voltage regulators keep output flat under any load change. Several mF at output is fine. I have 10 mF Kemet ALC10S at PS output.
With regulated PS first reservoir capacitor should be big as it gets. With unregulated PS, I would use big capacitors for booth positions or bigger one at the output.
I am thinking about using this amp for my super low-efficient headphones. They are 60 Ohm impedance (flat across the audio spectrum). Efficiency is only 83 dB-SPL @ 1 Vrms. The target for the output voltage and current (peak values) would be +/- 23 V and +/- 0.4 A. Yes, that's a lot for headphones, but that's what I'd want and need. So, I am wondering if / how this could be achieved with this amp design. My guesstimate for the biasing of the output stage would need about +/- 25 VDC rails, with a bias current of 0.4 A. I guess that would be relatively straight forward to implement, except...
...what would be the best way out? Would I need a different opamp that can swing more voltage?
...what would be the best way out? Would I need a different opamp that can swing more voltage?
For such high swing, only solution would be a different opamp as is OPA551/552 but performance would be nowhere near in all departments. Opamp supply can be +/- 18 V and amplifier supply +/- 20 V. That would provide max. +/- 17 V peak output. Unfortunately, this amplifier is not a swiss knife.
However, clean 10 V rms, which this amplifer can provide, is 103 dB at your eardrums.
Bias would be enough at 0.2 A for remaining in class A up to 0.4 A peak.
Have you considered this amplifier: https://www.diyaudio.com/community/threads/small-class-a-amplifier-with-thd-below-0-0001.385676/
Made some progress on Bliss this relaxing first day of the new year.
Worked on the PSU mechanicals and fitment today. She’s a double decker!
I like to use WAGO connectors in order to made changes/modification easier.
Rear panel layout and machining is next up….
Happy New Year!
Worked on the PSU mechanicals and fitment today. She’s a double decker!
I like to use WAGO connectors in order to made changes/modification easier.
Rear panel layout and machining is next up….
Happy New Year!
Attachments
The plan for this chassis is to share time between two amplifiers. (F6 Diamond and Bliss)
Swapping heatsinks and power transformer then adjusting R21 modules for proper output voltage is all that's needed to pull this off. The WAGO 221 connectors will make swapping the Toroidy's super easy and convenient.
Swapping heatsinks and power transformer then adjusting R21 modules for proper output voltage is all that's needed to pull this off. The WAGO 221 connectors will make swapping the Toroidy's super easy and convenient.
