Explendid amplifier designed by Michael Bittner, our MikeB

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#583
the 2sc3281, have you bought it long time ago ?
Click to expand...

2SC3281 were bought this summer from Donberg Electronics. Should be fake, probably, but I can't tell from appearance. I will probably get 2SC5200 for final version, which is the complementary for 2SA1943.
My 330 pF capacitors also look like LEDS! I have not the slightest idea what kind of capacitors they are.
 
#586
Pingrs said:
"the RL circut in the output need to be after the Zobel-circut!"

That usually seems to be the norm, but not for the Leach,why?


Is the diode connected transistor in the bias generator to modify the multiplication factor for an EF output, as per Doug Self's idea?

Brian.
Click to expand...


It gives better thermal compensation, and less internal impedance for the Vbe multiplier.

sajti
 
#593
Hello,

This has been one of the best threads in diyaudio.com for a long time along with GEM thread.

I´ve been following this thread from the beginning and now I decided to build this amp for two reasons.

First : I think that PMA likes the design so it cant be bad since I build his audio buffer as a preamp and it is excellent.

Second: I have been previosly playing around with chipamps related stuff and I would like to try my wings in building a solid state amplifier.

Now my motives has been introduced I would like to know if MJE4302/4281 pair can be used as output devices and mje15034/15035 pair as drivers?

I will probably need a lot of help with the tuning because I have no electronics education, but I will it a give try.

Regards:

Jarno
 
#594
jarkaa said:
Hello,

This has been one of the best threads in diyaudio.com for a long time along with GEM thread.
I´ve been following this thread from the beginning and now I decided to build this amp for two reasons.
First : I think that PMA likes the design so it cant be bad since I build his audio buffer as a preamp and it is excellent.
Second: I have been previosly playing around with chipamps related stuff and I would like to try my wings in building a solid state amplifier.
Now my motives has been introduced I would like to know if MJE4302/4281 pair can be used as output devices and mje15034/15035 pair as drivers?
I will probably need a lot of help with the tuning because I have no electronics education, but I will it a give try.

Regards:

Jarno
Click to expand...

Hi Jarno !
Until now, all having built this amp were impressed, so i am sure you won't regret it !
PMA has not heard it yet, but i am very anxious about his evaluation.

About the MJL4302/4281, i took a look to specsheets and compared
it to the older one. It seems that the MJL1302/3281 is the better
choice here, it shows better currenthandling and 200v rating is enough.
In an amplifier like the symasym with a single pair i would recommend
the older one.
The mje15030/31 also seem better than the mje15034/35,
maybe the mje15032/33 is interesting ?
I've read that the mje15034/35 sounds harsher ?

If you don't have already the 4302, i would recommend the 1302...
Maybe someone has already directly compared them ?

Mike
 
#595
Hello Mike

Thanks for the quick answer.

It seems that I was unfortunate to buy 10 pcs. of all the transistor types I posted on my previous message. Since my initial plan about year ago was to build four channels of Rod Elliots P3a amps.

I think I will try what I have. If I am not satisfied I´ll have to try others...

I´ll have the boards ready in next weekend.

Jarno
 
#600
Hello folks

I´ve been busy, but I made some progress

Here are the board after heat transfer
 

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