Simple Symetrical Amplifier

[guitar89]

LC,
The order of my VAS transistor has arrived, 2SA1707/2SC.
http://docs-asia.electrocomponents.c...6b810021b5.pdf
having 150Mhz response, high Hfe, seems suitable to as VAS.
What should I improve in my circuit other than having a driver and better VAS ?
(which transistor should i use as driver ? is MJE13032/33/34/35 enough or use MJL3201 better ? or other recommendation ?)
Given that have sufficient improvement, what value should i put on feedback resistor ?

[Lazy Cat]

Originally Posted by Sheldon

Question: Any benefit from paralleling a few BC550/60 devices for the driver, as opposed to a single lower gain device?

Sheldon

Hi Sheldon

Quite possible but the more devices in parallel the less performance you get according to single one. Problem is very low Uce for BC550/560, gain matching selection, degeneration emitter resistors, TO-92 case not really suitable for thermall dissipation even if there are few in parallel, etc.

Better to use one of TO-126/TO-220 Sanyo/Toshiba high performace transistors.

[Lazy Cat]

Originally Posted by Jay

I'm looking forward to LC's answer to this question. Also answer from anybody else. Imo, there are those who really are experts in this field, and there are those who really can hear. They are not always the same person.

Hi Esperado & Jay

First I have to say it's topology that matters to define the "sound" of an amplifier, than it's about the ingredients, spices used. To my opinion it is very important for an active device, to find out the most important role it's playing in certain position and than to search the most suitable device for the job. Of course this decision is of very subjective nature but nevertheless it is always worth to try different type of devices for the best end-result.

My suggestion for a power amplifier configuration would be high biased j-fet devices for the input zero voltage-gain buffer, BJT-s for the input differential gain stage and VAS, mos-fet-s for the ouput drivers and again BJT-s for the outputs.

For the future task I intent to try modern power SiC-fet devices, since I don't prefer output mos-fet-s.

[Lazy Cat]

Originally Posted by maxente

LC, what is the maximum rail voltage for this version?
In the schematic is +/-31v, can i use something like +/-55 - 60v for higher power ?

Up to +/- 60 V as also specified with 63 V ELCO's voltage. But than do not use less than 4 ohm nominal speaker impedance per channel.

[Lazy Cat]

Originally Posted by shaan

It is.

Even my awfully inefficient speakers came alive when I played SSA through them. Beforehand, only my JLH could do this, but it had a volume limit for clean listening. SSA, on the other hand, sounded more and more cleaner and ALIVE as I turned the knob clockwise. I am building it again!

Hi Shaan

It is indeed an excelent amplifier as recognized by many. Have fun with new SSA project.

Regards Andrej

[Lazy Cat]

Originally Posted by PauloPT

Sorry for the intromission. I was wondering if it will be a group buy for pcbs of this amp?

Thanks

Maybe, it depends how many members would express sympathy for the group buy. It is matter of future discussion and the course of events in this thread.

[AKSA]

Homemodder,

Regardless of what you think of the design, your inputs are judgmental and often offensive. You seem to subscribe to the belief that putting clever people down makes you look even smarter.

I think Andrej's work is excellent. Along with the outstanding pcbs from Alexx MM, Andrej has made the SSA very buildable and easy for DIYers. You too have contributed meaningfully before, lighten up and play the game. I find Andrej's view on devices and their relative positions very interesting, and I've been designing amps for many years and have seen most schematics. The quest for originality is mostly fatuous; nothing is new under the sun, but that is no reason to condemn golden oldies.

I know you have a good mind, you don't need to prove it, some of your comments in other threads are very constructive.

Andrej,

Swordfishy, Mikelm, Lineup and I ran a Group Buy for the FetZilla, and we have sold about 160 pcbs. There is no reason your SSA would not sell twice that, so I would encourage you to go for it....

Cheers,

Hugh

[a.wayne]

Originally Posted by Lazy Cat

Maybe, it depends how many members would express sympathy for the group buy. It is matter of future discussion and the course of events in this thread.

LC,

How many would you like we are all waiting with baited breath and the SSA tree is getting very dangerously crowded...

[Smiley 09]

Originally Posted by Lazy Cat

Very efficiently spent time recently, regarding business and hobby

Some jerks will never learn their lesson, morons up to their ends.

Dear Andrej,

I Just Wonder To Speak Here For All The Good Will, Good Diy Spiritual Members,
Who Simply Admire Yours Great Heart - Soul - Unselfish Will . . . and Give . . .
To All Of Us Positive Sound Lovers . . . .
I truly Wish You A lot of Good Business Spirit
and Even More Nice & JoyFul Hobby Time
and Most of All,
I wish You As Much As Possible Tastefully Sound Listening Moments,
With Yours Soul & Spirit Inspired Designs, For Which Most Of Us We Are
Truly Thankful To Yours Genius Gifts Giving to the All
Audio Community World-Wide





A. G.

[fredlock]

Andrej,

Release the Kraken!!!



Fredlock