Tír Na HiFi

I made this pic based on xrk's output stage to show how AC paralleling is done. In my amp the resistor becomes a CCS and its place with the FET is swapped over, turning the FET into a PMOS.

If you're needing more power than for headphones you could look at TK9A20DA which has similar curves to the 2SK1530 but lower capacitance so you can parallel them without much penalty. I've not looked if there's a P-channel complement but for classA SE you only need one kind.

nige2000 wrote: ↑Thu Jun 22, 2017 9:27 pm ill be bringing a class a mosfet prototype version for comparison that i think sounds sweet too
should be fun

You should think strongly about letting this amp near your place Fran!! Have heard it. It might upset people who have invested in the alternative. Of course alternatively Nigel could supply two amps per person as part of the group buy :)

tony wrote: ↑Fri Jun 23, 2017 5:02 pm

nige2000 wrote: ↑Thu Jun 22, 2017 9:27 pm ill be bringing a class a mosfet prototype version for comparison that i think sounds sweet too
should be fun

You should think strongly about letting this amp near your place Fran!! Have heard it. It might upset people who have invested in the alternative. Of course alternatively Nigel could supply two amps per person as part of the group buy :)

this prototype class a amp was only a mad theory made possible because i had psu parts for the GB here,
im really kinda mesmerized how it didnt explode

its a real testament to the components and design we have in the GB amp that can deal with the amount of current demanded by this stereo version
and its working like clockwork since i got it set right

i feel a more reliable/stress free and better sounding way to do it is mono and that almost doubles the cost
so the cost difference and space they'd take up will likely prevent anyone from being upset
anyway i think its good company for the GB amp
from what i think and Frans been saying off and on this last wk or so there's not many amps out there in the same league as the GB amp
its good to push the envelope thats how to get progression

i think you listened to my revision 2, this is like a revision 4

abraxalito wrote: ↑Fri Jun 23, 2017 3:29 pm I made this pic based on xrk's output stage to show how AC paralleling is done.paralleledFETs.png

In my amp the resistor becomes a CCS and its place with the FET is swapped over, turning the FET into a PMOS.

If you're needing more power than for headphones you could look at TK9A20DA which has similar curves to the 2SK1530 but lower capacitance so you can parallel them without much penalty. I've not looked if there's a P-channel complement but for classA SE you only need one kind.

i think i got the idea,
you use four of them circuits above to replace the 8 paralleled fets?
So each of these fet output is ac coupled onto headphone out?

No doubt the amp from the get go was special. Kinda scared on how it is going to sound against the Jadis. It will be interesting to see what people think of the Class A in comparison.

tony wrote: ↑Fri Jun 23, 2017 11:38 pm No doubt the amp from the get go was special. Kinda scared on how it is going to sound against the Jadis. It will be interesting to see what people think of the Class A in comparison.

hmm.......
i bet the GB amp won't be as different to the class a amp as u think, i know last time i compared it wasnt for me

vs the jadis id guess it would sound more dynamic/lively, higher resolution/quieter
will have to try it and see
Anyway i was aiming to get the GB amp sitting were the Jadis is :)

nige2000 wrote: ↑Fri Jun 23, 2017 11:36 pm you use four of them circuits above to replace the 8 paralleled fets?

Now its me that's gotten lost. Where were there 8 paralleled FETs?

So each of these fet output is ac coupled onto headphone out?

Ya and you can add as many as you like, input drive permitting.

Was nice to see all of yous, which manage to come. :)

Was nice to hear Nigel's amps, like them, specialy class A one, nice. :)

I hope we can do something similar soon.
Thanks to Fran for the hospitality and the home brew beer, was nice alright. ;)

Glad to have you Georgi!!

We got on pretty well today, most of the regulator/charger boards are done now. Some pics below!

It has taught us how grateful we are to Nigel for doing the SMD parts!