Agus Widarto said:
I have not built an amp before and i only know how to read a schematic. I have no idea how to calculate SOA resistor. I think MJ15003/04 are much cheaper transistors i could use. May i know what changes i need to make to the original Lynx in order to use MJ15003/04 ? and how to calculate the resistor values ? i dunno which other SOA resistors too.
Ragnwald,
I do plan to use a CL60 thermister...at least. The size of the capacitor bank and all the copper in the large transformer combine to "suck" up quite an in-rush of current. I'll start with small fuses and work my way up to a point of confidence.
Speaker protection may be a prudent thing with an amp of this size.
I do plan to use a CL60 thermister...at least. The size of the capacitor bank and all the copper in the large transformer combine to "suck" up quite an in-rush of current. I'll start with small fuses and work my way up to a point of confidence.
Speaker protection may be a prudent thing with an amp of this size.
Hi,
I think you must be refering to this setup where the soldering lug is connected to the power ground (0V), right?
The R113 and R115 are connect to the pot where the R115 is connected to the flipper. I guess it won't matter if I flip this over (as long as the R113 is connected to Q105). Just trying to eliminate any 'cross-overs' for easy with the eye while 'proofing'.
Tks for your time and help.
I think you must be refering to this setup where the soldering lug is connected to the power ground (0V), right?
The R113 and R115 are connect to the pot where the R115 is connected to the flipper. I guess it won't matter if I flip this over (as long as the R113 is connected to Q105). Just trying to eliminate any 'cross-overs' for easy with the eye while 'proofing'.
Tks for your time and help.
Hi ACD,
As I was checking other post on lynx, I saw there has been some issue on the caps in the circuit about the representation of the poles. According to the convention you use for the psu, the solid line for a polar cap is +ve whiel the unfilled rectangle is -ve. For C105,C106 the way showing the polarity in the schematic doesn't care too much for they are bipolar anyway. But for C110, the schematic shows that the +ve is connected to R121 but for the pcb, it is the other way round. (Hope I had it right : the square pad of a polar cap. on the pcb is a +ve) Which one is right then?
Tks for clearing this out.
As I was checking other post on lynx, I saw there has been some issue on the caps in the circuit about the representation of the poles. According to the convention you use for the psu, the solid line for a polar cap is +ve whiel the unfilled rectangle is -ve. For C105,C106 the way showing the polarity in the schematic doesn't care too much for they are bipolar anyway. But for C110, the schematic shows that the +ve is connected to R121 but for the pcb, it is the other way round. (Hope I had it right : the square pad of a polar cap. on the pcb is a +ve) Which one is right then?
Tks for clearing this out.
Class A ?
I was describing the Lynx amp to a friend and what plans I had for its construction when he asked whether the amp could be modified to run in class A. I said that I had no idea and that it would serve no real purpose as I already have central heating!!?and you would probably not hear any difference anyway. In theory however, would it be possible, and if so, how? I do not mean class A for the whole power output, just a proportion of it.
I was describing the Lynx amp to a friend and what plans I had for its construction when he asked whether the amp could be modified to run in class A. I said that I had no idea and that it would serve no real purpose as I already have central heating!!?and you would probably not hear any difference anyway. In theory however, would it be possible, and if so, how? I do not mean class A for the whole power output, just a proportion of it.
That gives me some thoughts on moving in that direction as the heatsinks that I have are quite big and would probably take some degree of Class A operation. How high could the bias be set without causing any problems? I am still collecting the components so have plenty of time to consider all the options. Thanks Jan.
it's quite simple...
The Bias Current (Bias Volt over emitter resistor devided by the emittor resistor) = Bias V/Re makes your Class A rating.
Example:
Bias over emitter resistor = 1 Volt
Emitter resistor = 0.22R
= 1 Volt/0.22R = 4.5A
If you are using 8 Ohms speakers the Class A will run up to:
4.5A*8R = 36 Watts
For 4 Ohms speakers it's doubble up = 72 Watts
Please note that this Class A requires very large heatsinking !!!!
The Bias Current (Bias Volt over emitter resistor devided by the emittor resistor) = Bias V/Re makes your Class A rating.
Example:
Bias over emitter resistor = 1 Volt
Emitter resistor = 0.22R
= 1 Volt/0.22R = 4.5A
If you are using 8 Ohms speakers the Class A will run up to:
4.5A*8R = 36 Watts
For 4 Ohms speakers it's doubble up = 72 Watts
Please note that this Class A requires very large heatsinking !!!!
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