100W Ultimate Fidelity Amplifier

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#11,462

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#11,463
prasi said:
Hello mprivitera1,
Yes, you may use BC547B/BC557B.
Also there was no requirement of Jumpers as you have the manufactured double sided PCBs. The jumpers were provided for single sided home etching, though it doesnt hurt.

regards
Prasi
P.S. the power resistors are meant to be something like this, though whatever suits one/ available in parts bin is ok to use... 5pcs 5W 0.1 0.15 0.22 0.25 0.33 0.5 ohm Non inductive Cement Resistor 5% 0.1R 0.15R 0.22R 0.25R 0.33R 0.5R-in Resistors from Electronic Components & Supplies on Aliexpress.com | Alibaba Group

P.S. 2: Mount Q10 on one of the output transistors

P.S. 3: Q1 Q2 can be thermally coupled for better offset behavior.
Click to expand...


thanks Prasi,

you think to use these resistances KNP05SJ033KA10 ROYAL OHM - Resistore: a filo KNP05WS-0R33 | TME - Componenti elettronici
I have problems ?
In relation to the Q10 do you mean to mount it on the heatsink of the power transistors?

Thanks
 
#11,465
mprivitera1 said:
thanks Prasi,

you think to use these resistances KNP05SJ033KA10 ROYAL OHM - Resistore: a filo KNP05WS-0R33 | TME - Componenti elettronici
I have problems ?
In relation to the Q10 do you mean to mount it on the heatsink of the power transistors?

Thanks
Click to expand...

No, no mprivitera1,
I was merely meaning to convey the PCB foot print is suitable for the BPR56 type of resistors. The one you used, are perfect , no problems there.
For Q10, yes, mounting it on any output transistor with a single bolt would be better. It should have thermal paste on between output transistor top and Q10 back side. So it senses the temperature rise / fall quickly.

One can also mount it on main heatsink, but I feel above option is better as it would not require drilling and tapping of hole for Q10.

regards
Prasi
 
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#11,467
AX14 offset

prasi said:
mistake with orientation of input coupling cap... even bigger one with NFB cap orientation.

Also while asking for debugging, best to upload some close up pics ..
Click to expand...

Thanks Mr Prasi for pointing out the errors. I have corrected the errors, still the offset voltage is there, i have a feeling that the 2SA1943 is slightly warmer than its counterpart, any way the current drawn is equal in both sides, appx 105 mA.
Thanks and regards.
 
#11,476
Those are the ones I have in my cart now.

Thank you for going to all the work to put together the full BOM as well as the PCB. It really makes this so much more accessible to the hobbyist like myself. Not having to guess at which parts will fit and work properly makes it much easier.
 
#11,479
anoopkrajan said:
Hi all,
As suggested by Mr Terry and Prasi, connected PS ground to the input ground, the problem vanished away. An offset voltage of 11v to 65mv. Is 65mv acceptable ?
Thanks to all who spent their valuable time for me.
Click to expand...

Great to hear that sorted it out for you. Perhaps one day Mile will add that info to the first post so that folks don't continue to have this problem.

65mV won't hurt anything but you can probably get that a little lower by matching Q1 and Q2 a little more closely. Enjoy your amp.

Blessings, Terry
 
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