symasym 5.3 parts

406vette

Member
2008-01-11 7:14 pm
I plan to build a symasym 5 but am having a hard time finding all the components, some of the resistors specificly. If anyone out there has built one please let me know where you found everything. Is there a consensus on the best supplier to order from? I've tried Allied, B&D, Newark.
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
If it is this one:

SymAsym5 - Project

then you need to check that the voltage across the 100nF cap that is connected to the vbe multiplier increases as you turn the bias preset. You need at least somewhere in the region of 2.5 volts before the output stage will conduct.

Is the amplifier otherwise OK, having no DC offset and playing music OK ?
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
2.5 volts reading across the cap, not to ground. That's an approximate figure, if the voltage is significantly below that with the bias preset turned up then you have some construction or component problem.

You should also have around 0.34 volts across R10 which is a 68 ohm.
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
I doubt that it is anything to do with the PCB material.

Are the boards ones that you have designed and made yourself ? In other words is there any possibility of a layout error.

To get to the bottom of this is going to need careful voltage measurements... all the evidence will be there, its a matter of piecing it together.

Would you like these posts moving to the main thread for this amp ?
http://www.diyaudio.com/forums/soli...ifier-designed-michael-bittner-our-mikeb.html