Studio Reference Amplifier

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cook77

Member
Joined 2013
44250 said:
my SR150 works with 2x35Vac transformer,and that is a voltage that you connect to AC/AC on left/bottom side of pcb. AC/AC are connectors to supply protection circuite. you have a schematics of protection circuite in a post where i posted that pcb,instead 2N5401 better use BC516 (reversed pinout!!!),there is also an explanation how to chose resistor 560r,depending on your relay coil resistance.

protection circuite is based on APEX simple protection,only i changed voltage direction and with it polarity of diodes and capacitors and type of transistors (npn to pnp).

there is also clip-indication on this pcb.

here are all those schematics used on pcb again:
Click to expand...
Can you help me with pcb for apex pro stereo? First one of the 3 picture you add . Or maybe let me know the address where can I find it. For 24V relay if it's posible :eek::confused:
 
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44250

44250

Member
Joined 2011
forum.yu3ma.net
rohin:
i have output simetry of 5mV and 23mV on my SR150 left/right channel without any matching hfe. bias is 50mA per pair (100mA total for one channel).

cook77:
that protection circuite is on APEX SR150 pcb that i have done and shared here - rohin is doing his SR150 by those files and my SR150 is working nicely for almost a month now. it goes very very well with reggae www.youtube.com/watch?v=QnhsDl5gymo :)
 
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cook77

Member
Joined 2013
Thanks @44250!
I made the simple stereo protect, from APEX, and I intend to use it with A33 apex. Just said that this one is more complete, has curent detection in final output transistors.
Separate pcb I have needed.
BTW, I have done 2 modules of sr150, simple, but didn't tested yet.
 

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rohin

Member
Joined 2012
hi ,i check everything before start my sr 150 on 44250 pcb.sr 150 working good but there is some little mistakes on protection layout in first version with 2n 5401 not working good and you made another layout with change of some resistance and bc 546 but connection is wrong because it is cbe and it is npn but 5401 is pnp.i fix it and use bc 557 and it didn't give any headache to me.i like protection circuit it is very fast and i like mini relay i also got 15 vdc on relay then i add a 12v zinor diode on relay. thanks to apex audio and 44250 for giving us beautiful amp.
 
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rohin

Member
Joined 2012
hi sir ,today i test my amp for 2 hour and find that one mje 340 and mje350 are hot other all transistor are normal.even mje are in series with 10 r and 220 r from +-55 v.they need heat sink but not small.other mje pair is cool.is it normal?i need your suggest.
 

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44250

44250

Member
Joined 2011
forum.yu3ma.net
rohin said:
hi ,i check everything before start my sr 150 on 44250 pcb.sr 150 working good but there is some little mistakes on protection layout in first version with 2n 5401 not working good and you made another layout with change of some resistance and bc 546 but connection is wrong because it is cbe and it is npn but 5401 is pnp.i fix it and use bc 557 and it didn't give any headache to me.i like protection circuit it is very fast and i like mini relay i also got 15 vdc on relay then i add a 12v zinor diode on relay. thanks to apex audio and 44250 for giving us beautiful amp.
Click to expand...

no need for zener diode on relay, it will work well with that voltage on it. thank you for pointing me to a mistake i did with labeling BC transistors, i will correct it on lay document.
.
you have a great amplifier that i like the most of all APEX amplifiers i did so far,it sounds just great and gives me more and more pleasure each day i listen it. my kind of amplifier sound...
 
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