I'm a newbie and would like to try one of those Class-A amps I've been hearing so much about...what kinda PSU are wqe looking at since class A has got low noise rejection?? and why do we use Mosfets instead of Bipolars...is Bipolar usuage possible?? and of course are matched stuff very important?? Sorry for a bit of OT...I understand these amps are at best 45% efficient (if it ever gets there...) so I'll need some BIG heatsinks....
And is building WITHOUT a PCB possible?? I.E I just mount everything on the Heatsinks since the circuit I've seen are pretty easy...and what kinda schematic are we looking at for the Aleph3?? sorry again for the many dumb0 questions...
And is building WITHOUT a PCB possible?? I.E I just mount everything on the Heatsinks since the circuit I've seen are pretty easy...and what kinda schematic are we looking at for the Aleph3?? sorry again for the many dumb0 questions...
Li,li_gangyi said:
The answers to most of your questions can be found at the Pass Labs site here:
http://www.passlabs.com/aleph.htm
There are all the owners and service manuals for all the Aleph series amps. You also want to look at some of the early articles on class A designs. The articles on the Zen amps can be found at the PassDIY site here:
http://passdiy.com/amps.htm
Have fun,
Use differentials in the front end and you'll acheive a certain amount of immunity to PS noise. Current sources can help also. Class A amps need not be sensitive to noise. After all, the front end in class A/B and class B amps run in class A already. After that, it's only a question of how to bias the outputs.
Certainly bipolars are possible. So are tubes, for that matter. Lots of class A amps were build before MOSFETs became practical devices.
Although I don't generally run point-to-point wiring myself, there's no reason a class A amp can't be done that way.
Grey
Certainly bipolars are possible. So are tubes, for that matter. Lots of class A amps were build before MOSFETs became practical devices.
Although I don't generally run point-to-point wiring myself, there's no reason a class A amp can't be done that way.
Grey
I've been looking at the DoZ thingies...seems like they are the easiest to implement...probably gonna use some Bipolars instead of MOSFETs...dun really like them...anyone care to "push" me towards MOSFETs?? Hehe...I did use MOSFETs in a Class A Headphone amp once...sound was very clear but at high volumes it sounded kinda "fake" dunno if it's my PSU sagging therefor inducing some compression though...
i remember Mr. Pass stating the reasons for his choice of the use of mosfets in his amps.
the "arguement" against Bipolars are that they have too low an input impedence.
Am i right Mr. Pass? correct me if i`m wrong.
i am planning on building a Zen Lite myself. mosfets are the top priority after reading the articles posted by Mr. Pass.
the "arguement" against Bipolars are that they have too low an input impedence.
Am i right Mr. Pass? correct me if i`m wrong.
i am planning on building a Zen Lite myself. mosfets are the top priority after reading the articles posted by Mr. Pass.
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