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Class AB Audio Amplifiers

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#23
Cristi,

I've just looked at large image of 4702 SAP15 module - it looks like it doesn't need separate drive voltage (only + and - VCC) ? What voltage is needed for this board (for 100W/8ohm) ?
This would simplify things even further, as pretty much any SMPS would work with it ...

Thanks,
Bratislav
 
#27
The actual version of the SAP15 LM4702 amplifiers can work well with SMPS350. Note that this smps doesn't have the aux. voltage which is required for the other versions of the LM4702 amplifiers.

Andrew,
acctually to get 100W at 8R there is enough 1.25*(1.41*sqrt(100W*8R)) for each rail, which is 50V as you mention. but because the maximum performance from this amplifier is the main goal and not the efficiency, i prefer to increase the voltage with few volts, and i also consider that the smps being unregulated the voltage may drop in case of high load current demand.
 
#30
Hello Cristi,
I consider LM4702, hesitate MOS-FET or SAP15.

1.I see you work on a new SAP15 with dual voltage. I will use linear power supply. Given the additional cost involved for dual power and larger space required, what is according to you the benefit of sap15 dual voltage ?

2. what is the size of the heatsink you provide with mosfet version ? it seems bigger than the pcb on the pictures

3. I guess pcb size of sap15 and mosfet versions are the same. can you provide the heatsink with the sap15 module ?

thanks,
 
#31
The dual, actually four voltage rails topology offer a better utilisation of the supply voltage, less heat dissipated in the output transistors, and better linearity due to the lower temperature span.
the heatsink for the LM4702 amplifiers is 170x70x45 mm. it is bigger than the pcb, to provide larger area for heat dissipation. and to be easy to install in the case.
the SAP15 modules are smaller than MOS or BPL ones. just 112x50mm. i have available heatsink for this modules as well. the new version of the SAP15 amplifier board will be a little bigger that the actual one and will be mounted on the heatsink directly, similar to the BPL or MOS versions.
 
#32
Cristi said:
The dual, actually four voltage rails topology offer a better utilisation of the supply voltage, less heat dissipated in the output transistors, and better linearity due to the lower temperature span.
the heatsink for the LM4702 amplifiers is 170x70x45 mm. it is bigger than the pcb, to provide larger area for heat dissipation. and to be easy to install in the case.
the SAP15 modules are smaller than MOS or BPL ones. just 112x50mm. i have available heatsink for this modules as well. the new version of the SAP15 amplifier board will be a little bigger that the actual one and will be mounted on the heatsink directly, similar to the BPL or MOS versions.
Click to expand...
Thanks. A promise for an even better sound 🙂.
Let us know when you are ready to ship the new LM4702/SAP15, the recomended voltages and the size of pcb/heatsink (mandatory to plan case layout 😉)
 
#35
Cristi said:
the SAP15 v1 modules are smaller than MOS or BPL ones. just 112x50mm. i have available heatsink for this modules as well.
The heatsink for the amplifier should be at least 150mm wide, 30-40m fins lenght and 50-70mm tall depending on the airflow and position, to achieve <1.2*/W.
Click to expand...

Thanks. I actually meant : what is the size of the heasink you have available for this module ? Same as for the other LM4702 modules (170x70x45) or other size ?

If you can provide any size, my perfect size would be 140x70x45. This would fit the housing i have in mind (yes, size matters ;-). About half of the heatsink will be out of the case, which helps.

What is the voltage required to reach 2x100W max at 8ohms ?
 
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#37
I have been unable to access the 'product's webpage' from any of the Class AB module pages. I would like to know information for the LM4702 modules such as voltage gain, input impedance, how the four voltage rails are derived, and max and min supply voltages.
Is the new version of the SAP15 module still planned to appear?
Thanks,
- John
 
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