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First One - mosFET amplifier module

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#2,203
First One M module's sum bias current range is from 80-360 mA, 280 mA recommended. At this point output mosfets (two pairs) have 220 mA bias current, that sets them to thermal equilibrium - neutral thermal coeficient. Idle power dissipation is therefore 35 W at +/-60 V power supply. Of course module's bias current can be lower to get less idle power dissipation (smaler heatsink) but not below 100 mA if sonics is to be preserved.
C1 chassis uses SK157 heatsink, 0,4 K/W.
 
#2,205
Lazy Cat said:
First One M module's sum bias current range is from 80-360 mA, 280 mA recommended. At this point output mosfets (two pairs) have 220 mA bias current, that sets them to thermal equilibrium - neutral thermal coeficient. Idle power dissipation is therefore 35 W at +/-60 V power supply. Of course module's bias current can be lower to get less idle power dissipation (smaler heatsink) but not below 100 mA if sonics is to be preserved.
C1 chassis uses SK157 heatsink, 0,4 K/W.
Click to expand...


Up to how many watts are these modules running in Class A with the 280mA bias?
 
#2,209
Four First One M v1.4 prepared to send to US, calibrated and tested as OEM parts for professional studio monitors.
 

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#2,211
These are the last four modules from test series prepared to be send out.

Almost there to accept the orders, if everything as planned, this week we'll start the production, last reels expected to be received shortly and then automated assembly line will be ready to start the step motors.

Please give me few more days as I don't want to get payments before material is ready.
 
#2,215
NicoB said:
Hi LC,

I would like to know how many 1.4 S or M we can put in this aluminium box, at maximum

Thanks
Click to expand...
Concerning idle power dissipation:

- normal bias setting - easily 4 x First One M or 8 x First One S.

- 50% reduced bias setting - up to 8 x First One M or 12 x First One S

I wonder what happened with Pass amp's original electronics you wish to replace or it will be just a copy of Pass chassis?
 
#2,216
#2,217
mbrennwa said:
I read about different power supply options here: https://hifiduino.wordpress.com/2014/10/31/first-one-power-supply-selection/

Why there is so much focus on SMPS? What about good old linear PSUs (possibly with ample CRC or CLC filtering)?
Click to expand...
That much focus on SMPS is because once you hear it, you won't go back, ever. Its input energy storage is easily 50-100 J (310 V on input elco bank) which is served to output capacitors/load at enormous rate, so there is power on demand always present at its output, resulting in better and faster bass response, etc. Also on such small footprint as compact module design and its light-weight you cannot form classic linear power supply, no way. I find unregulated SMPS like SMPS1200 much better since its output duty cycle is fixed 50% at 500 kHz, no matter the Z load present.
You have to try it once.
 
#2,220
Lazy Cat said:
Concerning idle power dissipation:

- normal bias setting - easily 4 x First One M or 8 x First One S.

- 50% reduced bias setting - up to 8 x First One M or 12 x First One S

I wonder what happened with Pass amp's original electronics you wish to replace or it will be just a copy of Pass chassis?
Click to expand...

Thanks, yes it's hightly inspired from Pass ^^.

I can add two radiator in more inside, 300×160×40. Idea is to put 12 channels, 8 in S and 4 in M. M is for woofers.
With one smps 1200A180 or may be two of them.

What is the reduced bias setting and the consequence?
 
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