As this is single ended class A amplifier, it draws constant current from power supply all the time. You need well filtered PSU, so that ripple is minimal.
I would recommend using switch-mode PSU for this amplifier.
I would recommend using switch-mode PSU for this amplifier.
i do not see the need for a regulated power supply or a supply with very low ripple.
The constant current source shall shield from the ripple.
As soon as the CCS is allowed to give the design current through the lower mosfet to ground, the B+ shall stabilize regardless how conductive we make the lower mosfet.
I'm going off Papa's recommendation to get the ripple down below 5mV.
Many of Papa's single gain stage circuits use some sought of regulation/capacitance multiplier circuit.
A modulated regulated supply is often a favourite.
Edit: Sony V2 is also using a similar regulated circuit, I don't think Papa would use it, if it significantly affected dynamics.
To do it passively you will need need huge caps and a huge inductor with low series resistance.
Last edited:
I was just think about this method. I will go this route. Less parts to break, even though it might be more expensive.
I'm building a linear power supply for a friend and used a 2.0 mH Jentzen inductor. Was $23 on sale, but it's a nice specimen. 15ga, 400w and .5 ohm.
Anyone built the amp yet?
Has anyone built SE BAF2015 amplifier yet? Which devices and transformer did you use? Have you compared it soundwise to another FirstWatt amp?
Has anyone built SE BAF2015 amplifier yet? Which devices and transformer did you use? Have you compared it soundwise to another FirstWatt amp?
No choice there. The low Drain resistance of the VFETs lets any supply
variation right through to the output.
😎
You have more choices, but still needs some attention.
Pentode device is much better than triode device at rejecting power supply ripple.
Is this the correct input transformer: http://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-112p-2hpc.pdf
Yes important if pcb used with hockey pucks thx Pico 🙂
SLPC are winner on distortion & give + gain , co$t are higher
Attachments
Somewhere in my pile o' stuff I have some huge "ashtray style" IGBTs from Fuji or the like, purchased in a spirit of speculation from an Ebay retailer that parts out monster motor drives - their huge, reasonably priced heat sinks have featured prominently in various of my class A projects. So, IGBTs are not great on linearity by themselves, but in a "buffered Schade" implementation with a P-channel mosfet to provide some drive, maybe we can break the 50W barrier for a simple Class A single ended amp, with some decent sound along the way. One man's trash is another man's treasure...
Here is a version I would like to try:
I am listening to something very similar at the moment but with IXYS mosfets (IXTH140P05T and IXTK100N25P) and a MU follower current source.
The Schade feedback IXYS IXTK100N25P has the same powerful and effortless vivid "alive" character as a good triode amp or the IRFP7430 in a simple NFB Zen amp. It sounds much larger and captivating, - much less held back then normal pentodish mosfet amps. Most addictive!!!
Cheers,
Johannes
You'll have to explain how that circuit works for my dumb brain, all I see is source follower with cascode.
I can't see how you'll get gain out of that.