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post #46 of 50

Something like this:



post #47 of 50
Thread Starter 
Double post...again
Edited by UnknownAX - 5/20/13 at 5:26am
post #48 of 50
Thread Starter 
Thanks a lot! Exactly what I wanted to know.
I'll order a 230-18v 250mA transformer, 2x 1500uF 35V Panasonic FR caps, a few 1n4001 diodes and the resistor. The power supply will be a great addition to the amp because I won't have to charge the batteries anymore. 2x njm4556 Isn't the most energy saving setup... smily_headphones1.gif
post #49 of 50
Thread Starter 
Until yesterday I used the PSU posted by Avro_Arrow a few posts above. The transformer had 16V 2.5A.
Now I switched to a 18V 155mA transformer + a lm317 circuit that converts the 39VDC to 20.6VDC. I use 2x 1500uF , 1x 150nF on the input of the lm317. The output side has 1x 150nF , 1x 100uF. The amp draws 85mA.
My problem is, that the amp doesn't sound alright, anymore. The sound lacks body and it is "thumpy". It sound really boring...
Do I have a problem with current? Maybe I should add a big cap after the lm317? I hope someone can help me...
post #50 of 50

I'm not an expert, but you could compare your implementation to the σ25 (which uses the similar LM78xx parts). In that design, there is a smoothing cap before the rectifier (0.1 uF), a bulk cap (1000 uF electrolytic) and a bypass cap (0.1 uF) at the input of the reg, and another decoupling cap after the rectifier (10 uF dipped tantalum, which are pricey so presumably chosen specifically).


Overall pretty similar to yours but maybe something is making the difference.

Edited by joeyjojo - 8/21/13 at 5:22am
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