Explendid amplifier designed by Michael Bittner, our MikeB

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#3,862
#3,865
Porfido said:
Quite interesting post here about Symasym without coupling caps:..............Did somebody else try? 🙂
Click to expand...
probably lot's of people have tried.
Take any AC coupled Power Amplifier and connect it to an AC coupled output stage of the source equipment.

You now have doubled the DC blocking capability of the Source to Amplifier connection.

There is absolutely no benefit in double blocking the connection.
The solution is easy.
Go into both pieces of equipment and determine which blocking capacitor is doing most harm to the resulting sound quality. Short out that "not so good" blocking capacitor.

That solution is quite different from "Symasym without coupling caps".
 
#3,866
formula 22 said:
Hello!
I want reduce the AC-gain of about 27dB what changes should I do with amplifiers (symasym 5_3), understand the characteristics remain almost the same?!
Thanks and cheers :cheers:
Click to expand...

Mike B describes this in the Symasym webpage at:
http://http://www.lf-pro.net/mbittner/Sym5_Webpage/symasym5_3.html
He writes: If the gain is too high because symasym is driven from preamp, R30 can be increased from 499ohms to 1k, but in this case R16/19 (22 or 33 ohms, not on schematic, REs to Q1/2) are required to keep feedback at same level and symasym stable.
 
#3,867
Nicke said:
Mike B describes this in the Symasym webpage at:
http://http://www.lf-pro.net/mbittner/Sym5_Webpage/symasym5_3.html
He writes: If the gain is too high because symasym is driven from preamp, R30 can be increased from 499ohms to 1k, but in this case R16/19 (22 or 33 ohms, not on schematic, REs to Q1/2) are required to keep feedback at same level and symasym stable.
Click to expand...
All that said low-understand?!
I ask for a little explanation of the changes of the schematic.
Where are the resistors R16/R19 and etc.,....?
thanks and regards
 
Last edited:
#3,868
formula 22 said:
All that said low-understand?!
I ask for a little explanation of the changes of the schematic.
Where are the resistors R16/R19 and etc.,....?
thanks and regards
Click to expand...

These resistors are not on schematics, but there are premade connections for them only on the PCB board version 5.3.
 

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#3,870
AndrewT said:
probably lot's of people have tried.
Take any AC coupled Power Amplifier and connect it to an AC coupled output stage of the source equipment.

You now have doubled the DC blocking capability of the Source to Amplifier connection.

There is absolutely no benefit in double blocking the connection.
The solution is easy.
Go into both pieces of equipment and determine which blocking capacitor is doing most harm to the resulting sound quality. Short out that "not so good" blocking capacitor.

That solution is quite different from "Symasym without coupling caps".
Click to expand...

Thank you very much Andrew! Wise advice!
In my case, having a B1 with double output (main amp and subwoofers amp connected to it) I will short the cheap mks2 wima in symasym...
Thank you again!
Regards!
Andrea
 
#3,871
The DCB1 is a DC coupled source.
You should not bypass the only DC blocking capacitor.

If you have the experience to recognise the pitfalls of converting an AC coupled system into a mixed AC and DC coupled system then go ahead and make that informed decision.

The B1 is an AC coupled source and with that you can safely bypass the DC blocking cap in the Symasym.
 
#3,872
AndrewT said:
probably lot's of people have tried.
Take any AC coupled Power Amplifier and connect it to an AC coupled output stage of the source equipment.

You now have doubled the DC blocking capability of the Source to Amplifier connection.

There is absolutely no benefit in double blocking the connection.
The solution is easy.
Go into both pieces of equipment and determine which blocking capacitor is doing most harm to the resulting sound quality. Short out that "not so good" blocking capacitor.

That solution is quite different from "Symasym without coupling caps".
Click to expand...

Andrew is right (as usual) this is a very nice idea and often can be a huge improvment where ever is possible to do so .
 
#3,873
sakis said:
Andrew is right (as usual) this is a very nice idea and often can be a huge improvement where ever is possible to do so .
Click to expand...
and why I have been advocating dual inputs to Power amps and dual outputs from Sources.
Going back to Jens' Leach clone where he had installed 3pin input (0.1" sil) for the PCB.
The 3 pins offered AC coupled, or "test position", or DC blocker bypass, by just moving a 0.1" shorting plug. Takes near zero PCB space and near zero cost, for great flexibility in operation.
 
#3,879
he he 🙂

drowranger said:
may be my eyes are just tired😀

regards,
joel
Click to expand...

It could be an optical illusion,the way that they are spreaded on a pcb. I thougt the same thing before i counted them one by one. I have done SymAsym 5.3 and first thing i have noticed that is different on your pcb than on my is two diodes between E and C of output transistors. MURS120 exists on your pcb and on my they are not provided. It works anyway! 🙂
 
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