Abomination! or Painting a Mustache on the Mona Lisa meets the Island of Dr. Moreau

[sajti]

And Fairchild have B selected groups...

Sajti

 

[MJL21193]

You can get 2SC5242 from Fairchild as well. The direct order from the manufacturer means no problem with the fake transistors.

Sajti

Digikey has Toshiba's too but I'm going to give the ST's a try.

 

[CECCO]

Hello.

Can I use the a970 c2240 for the input stage and MJ15030,31 for the vas?
I even don't understand the use of LED's. Do they bring any benefit?
For the power I want to use tosh 5200/1943. These cost 1.6euro (10pcs) instead 2.1euro (10pcs) for the ST one's.
Plus, the Toshiba devices are "matched" by suffix ST don't.

Thank You.

 

[sajti]

I have very good experiences with NJW-s. The hfe matching is very close. And the Fairchild FJL4x15 is good too, with quite high hfe (150-200@250mA, O class)

Sajti

 

[AndrewT]

Can I use the a970 c2240 for the input stage and MJ15030,31 for the vas?

the 970 should make a good front end, particularly the BL grade.
The MJE15030/1 are good 8A drivers. They are not suitable for VAS or pre-driver duty.

 

[CECCO]

Is this a Class-A amplifier?

 

[AndrewT]

Is this a Class-A amplifier?

have you looked at the schematic in post1?
ClassAB using the integrated diodes to generate a temperature compensated bias voltage.

 

[CECCO]

Yes, it's true, lots of heat to get rid of. Yet, there are degrees - how much distortion is acceptable? Dropping the idle current down to ~80mA/device has the total dissipation at 50 watts and the distortion at 1k is still less than .01%. Choices...
This raises the question: is it worth this to eliminate global feedback? Will the benefits be heard or are they just assumed? Is global feedback that bad?
Surely, for quiet listening the fact that the amp will be effectively operating class A should be an improvement.

Why should the amp operate in class A?

 

[AndrewT]

it's ClassAB

 

[jacco vermeulen]

2STA1962

Truly remarkable.

(John, if your XX's come close to resembling your avatar maybe we can still work out a deal afterall, whatever their residual mileage)

 

[MJL21193]

Is this a Class-A amplifier?

Hi,
First, which amp are you asking about? The start of this thread has the Abomination amp - the complete schematic for that amp is in post #1. BOM and PCB layout are available.

Further along I have been playing with another design (first named Bain, but changed to Havoc). That amp is the schematics that are in the latest posts. It is not finished, untested and does not have a board layout yet.

Why should the amp operate in class A?

Neither amp runs class A - just the Havoc amp with no global feedback would run a high bias (.2A per device).

 

[MJL21193]

Truly remarkable.

Is that good remarkable or bad remarkable?
Any day now I'll order them...

(John, if your XX's come close to resembling your avatar maybe we can still work out a deal afterall, whatever their residual mileage)

Ah Zooey, just looking at her cheers me up.

Beauty - it truly is skin deep. The exes were pretty on the outside but it's hard for me to see that now, once all of the ugliness oozes to the surface and obscures the features...

Ok, I lower the trade to 1/2 kilo of your best assorted for 1 ex (trial run) complete with electric dog collar (and remote ) and de-clawed for safety.

 

[eyoung]

OK i looked at the first post and was hooked , keep me in the que.


Elwood

 

[rizqi]

hi MJL21193, how is the end result of your work?

 

[jkuetemann]

MJL21193 has stopped participating in this forum, look at his account status and see that is has been disabled.

 

[rizqi]

hi.. @ jkuetemann Ok, thanks 'bout your information,....
then,.. how the next,?..