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#101 |
diyAudio Member
Join Date: Sep 2013
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Very nice.
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"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass |
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#102 | |
Official Court Jester
diyAudio Member
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Quote:
also , it helps if you have mosfets mounted on heatsink ![]()
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my Papa is smarter than your Nelson ! clean ![]() ![]() ![]() |
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#103 |
diyAudio Member
Join Date: Dec 2002
Location: Denmark, Fredericia
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![]() ![]() I powered up our little AlephJ (Renamed to Alepj_Mimi!) Accecdentily i renamed some pictures to _Mimi!, so hereby a new name... tadaa : AlephJ_Mimi! ... Cool yes ? ![]() Some of the parts are slightly different from schematic, but not much; i will ofcause post that later on, when prober testing is done. Bias is easily adjusted, up/down around 0.6V (1,27A Bias)... I figured out that voltage divided by sourceresistor (eg. 0.6/0.47 = 1.2A)... Silly me i should have know that before i asked that yesterday Sry... After a short while, without prober heatsinking devices are heating up. DC-offset was a little jumpy for a start, but after 30sec. it was also good enough to adjust... So i guess circuit is working. Next week i will try mounting heatsinks, and ofcause adjust the thing for good. Thanks everybody for helping me, get this far by now. Good sunday! Jesper.
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DCG3 Dual DCSTB, AK4490 Dual SuperDAC ![]() AlephJ Mimi! http://www.diyaudio.com/forums/pass-...mimi-mini.html |
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#104 |
diyAudio Member
Join Date: Sep 2013
|
Congrats mate
__________________
"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass |
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#105 |
diyAudio Member
Join Date: Dec 2002
Location: Denmark, Fredericia
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Morning.
I have mounted some heatsinks, which size should match the dissipation (i hope), for our MiniAmp. here. Rail is with this PSU ~ -19 "0" +19 vdc. I tried setting bias at 0.61 (~1.3A), but source resistors/mosfets are getting hot to the touch. Setting Bias around 0.51 (~1A) is much better. I just remember, that i read somewhere Bias should be set to no less than 1.2A ? -Can't remember where i read this? -And why? Can someone comment on this ? - I mean, what is pros and cons ? - Later today i will try listning to some recordings, to hear if Amp. is swinging enough watts for my setup! Really exciting ![]() Jesper.
__________________
DCG3 Dual DCSTB, AK4490 Dual SuperDAC ![]() AlephJ Mimi! http://www.diyaudio.com/forums/pass-...mimi-mini.html |
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#106 |
diyAudio Member
Join Date: Sep 2013
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At 1.3 A, 0.47Ohm resistor is only dissipating 1.3 x 1.3 x 0.47 = 0.8Watts
Set at 1.3A and stop worrying about it. This is a single ended amp (not push pull), you want as much bias current as the mosfets, and your heatsinks allow, so set at 1.3A and stop worrying about it.
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"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass |
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#107 |
Official Court Jester
diyAudio Member
|
all Danes are having same heatsinks
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my Papa is smarter than your Nelson ! clean ![]() ![]() ![]() |
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#108 |
diyAudio Member
Join Date: Dec 2002
Location: Denmark, Fredericia
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You allready know that ZM
![]() I am lucky, that mine is partly, so i can use lower half, for making a lower chassis. Jesper.
__________________
DCG3 Dual DCSTB, AK4490 Dual SuperDAC ![]() AlephJ Mimi! http://www.diyaudio.com/forums/pass-...mimi-mini.html |
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#109 |
Official Court Jester
diyAudio Member
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aha
in spirit of the day , you can name it Aleph SissyJ ![]()
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my Papa is smarter than your Nelson ! clean ![]() ![]() ![]() |
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#110 | |
diyAudio Member
Join Date: Dec 2002
Location: Denmark, Fredericia
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Quote:
I see the point here. Running at 1.3A will give near 25w pro mosfet, and 100w for stereo, which is i think perfect. I will start it up again and cranck bias to 0.6 now... Too be continuied ![]() Jesper.
__________________
DCG3 Dual DCSTB, AK4490 Dual SuperDAC ![]() AlephJ Mimi! http://www.diyaudio.com/forums/pass-...mimi-mini.html |
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