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PostPosted: 30 Nov 2010, 02:43 
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Joined: 24 Jun 2010, 00:48
Posts: 788
Location: Christchurch, NZ
Hi guys,

My obsession for SS amps must end someday, but for now I cannot resist the temptation! :cold:
This amp has a slight modification from the original Symasym 5 designed by Micheal Bittner.
I've ordered and received the German boards for the modified version on diyaudio.
The PCB contains both the PS section as well as amplifier module. The pic below shows the modified Symasym PCB with jfet input stage. Very compact in size.

It all started when I asked a friend from Germany (Rudi), "Rudi, can you recommend an amp with crazy dynamics and bass "? He said " Ahh , then you must try the Symasym amp! " :mrgreen:

I have yet to order the remainder of parts, but for now I already have the crucial OnSemi power transistors : MJW3281A and MJW1302A. See how small they are when compared to a 2SC5200 in the middle.

This amp has a very high feedback and thus has sufficient gain so a preamp is not required - which is what the designer planned originally. I expect a hyper lively, speedy sound at the expense of some warmth and musicality.

Some specs :
THD: ~0.005% (measured) sim'd: 0.002%
Power into 8ohm: 60 watts
Power into 4ohm: 100 watts
Gain: 32dB (~1:40) full output at 0.7v input (0.5v rms)
Feedback: 57dB
GainBandWidth: ~400Mhz
Slewrate: ~20v/us (symetrical)
Supply voltage: +/- 36v
Biasing: 55ma, ~12mv across a single 0.22 ohm
Frequency response: 3.2hz to 145khz (-1db) using 4.7uf input cap
Phaseshift at 10khz: <3°
SymAsym T-Network Schaltplan neu.pdf

More to come!! :up:

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Kind Regards,

Some of my diy audio projects:

PostPosted: 30 Nov 2010, 19:20 
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Joined: 28 May 2008, 21:53
Posts: 4592
Location: Winnipeg, CANADA
Cool. Can't wait for your report.


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