After some trial.. I change 47k resistor on plus side to 10k and negetive side to 12k..Difference resistance to get balance dc offset. If use two 12k bias resistor. I cannot trim dc offset close to zero. Only get 100mv.
Now use 10k and 12k, dc offset can get less than 10mV.
One more issue is,my bridge diode very hot.. I use kpbc2506. Can anyone give suggestion another cold and stable bridge diode model?
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Mount diode to large car amp heatsink.
Use 0.33ohm output resistor. Voltage across this resistor is 0.6v..so bias per bjt is 1.8Amp.
How to measure power output? My power supply is +-16v and speaker 4 ohm
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Flat surface of the bridge must be in close contact with the surface of the heatsink. In the above photo, I can see only a partial contact with the heatsink.
For temporary only. After run 5 hours, temperature maintain 50.5 degree without fan. But my transformer need external fan.
This amp sound very good. Have mid and high. And very deep bass. Bass surprises me. Like hear song using headphone. Very clear even low watt amplifier.
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Thanks Mamak,i wonder,are original 2sc1775a/a872a available these days?
Good question with no answer. I dont remember where i get thit bjt.. Maybe old stock
Hiraga 30W issues
dear all,
i`m just playing around with new build Hiraga 30W.
IMG-6327 — ImgBB
Transistors are the same as DANs.
All old genuine transitors, i had on hand.
PSU is plus/minus 22V
DC offset nearly zero
about 2,2A biased, stays allmost cold, with big heatsinks and additional fan
When switched on and connected to a speaker they are dead quiet.
When using a preamp (gain reduced JFET BOZ) i have small buzz and hum.
Source is a PC with modded STX II.
When i use the same setup with my Hiraga Le Monstre, with same preamp its dead quiet. from where may the buzz come from?
any ideas?
How to troubleshoot that?
best
dear all,
i`m just playing around with new build Hiraga 30W.
IMG-6327 — ImgBB
Transistors are the same as DANs.
All old genuine transitors, i had on hand.
PSU is plus/minus 22V
DC offset nearly zero
about 2,2A biased, stays allmost cold, with big heatsinks and additional fan
When switched on and connected to a speaker they are dead quiet.
When using a preamp (gain reduced JFET BOZ) i have small buzz and hum.
Source is a PC with modded STX II.
When i use the same setup with my Hiraga Le Monstre, with same preamp its dead quiet. from where may the buzz come from?
any ideas?
How to troubleshoot that?
best
Not the layout of the boards is in question, but the layout of the groundings of the inner wirings.
i understand.
but the komplete layout of grounding is the same as in my Le Monstre, except, that in LeMonstre is much more Capacity.
and with LeMonstre there is no noise at all ???
i meanwhile tested with different preamps - always the same
perhaps i should test with a different PSU Layout?
but the komplete layout of grounding is the same as in my Le Monstre, except, that in LeMonstre is much more Capacity.
and with LeMonstre there is no noise at all ???
i meanwhile tested with different preamps - always the same
perhaps i should test with a different PSU Layout?