AB100 Class AB Power Amplifier

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#185
vdi_nenna said:
Thanks 2pico, but that's a bit above of my paygrade.
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Output stage with lateral mosfets is absolutely dead set easy no complex regulation required. Can be done even simpler than F4.
We just need a pcb for Sony part 2 front end.

If you are not in a rush to finish the project there will probably be pcb for the front end available before july (touch wood). If not I could possibly get off my lazy **** and do something.
 
#187
If I understand correctly, low biased F5 would be a nice class AB amp, no? F5 is like as simple as a good amplifier circuit can be. Lower the bias current from 1.3A to somewhere acceptable, it would get a little more THD and lower(higher?) output power, but still must sound good.
 
#189
I said - switching mosfets ..... so IRFP ones (aren't good for small Iq)

then I said - use laterals , and you're good to go

whatever , simpler than F5 with laterals you can't .....then you don't need :

- NTC's ,
-mosfet source resistors

however - if you want two pair of outputs ...... you can put source resistors , but no need for more than 0R1
 
#191
I have not built an F5, so I am relying on previous posts and my little knowledge of laterals and how they behave.

I agree that an F5 biased low and using Lateral mosFETs in the output stage would likely be a good and easy to build candidate.
So little in the amp side that it can be wired up point to point (P2P) with some careful planning.
I'd use around 75mA to 100mA of output bias and select a pair of 9 to 11mA jFETs to drive them.

A low bias F5 could easily put out 40W of ClassAB power and double that if you go for a 2pair output stage. But, the 80W version would require a cascoded input stage. More complexity.
 
#194
vdi_nenna said:
I have an old version set of F5 boards with Hitachi mosfets.
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Just my opinion here, but for a class AB amp, you would be much better served with a source follower (common drain) output eg BA3 or Sony Vfet 2 style of amp rather than common source output in F5.

Also Hitachi mosfets aren't a show stopper if you can't get them. ALFET or Exicon laterals are perfectly fine for the task
 
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#195
Hitachi laterals are obsolete.
There is a flourishing vastly overpriced market for new old stock (NOS) Hitachi devices.

As a result of the devastating earthquake a decade or so back, it appears that the ONE factory fabricating the Lateral mosFET wafers was the sole source of all high power Lateral mosFETs. They became unavailable world wide.

It appears that the modern Laterals are all made in the new factory built after the quake.
There is near identical specifications and parameters for all the modern Laterals.
Small variations in maximum current and maximum power are the only differences available in the different versions.
Double die versions obviously increase current and power capability.

Just choose versions available to your locality at sensible prices.
 
#198
Two things before I go...

@ 2 pico- I could not find your version of the F5 lateral by searching for your moniker or "F5 lateral". I saw where you posted in other's F5 posts. Can you post here where your thread is?

Second, I didn't realize the Hitachi 2SK1058 and 2SJ162 were lateral mosfets.
The datasheet I found didn't mention that. Only reason I know is someone on diyaudio.com posted it is a lateral mosfets set. 🙂

At any rate, if I can use these and save $40, that would be a nice start. 🙂
Which brings me to something unrelated. I was selling this kit for $35, boards, all parts, IRFP and Hitachi mosfets. No one wanted it. Good for me. 😉

Thanks guys!

Vince
 
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