help: Aleph x temperature sensitive - Page 2

wuffwaff · 10th October 2005, 10:11 AM

Hi,

1.try to set the bias (start with both (V1/V3) pots at 0 Ohm) . Both sides should have the same bias, you´ll have to adjust them a bit as the bias changes during warmup.

2.Then set the absolute dc-offset to zero with V2 that set´s the bias through the diff pair. This should be done with the lid on the amp cause this is quite temperature sensitive. Adjust when warm (1-1.5 hours)

William

Berry · 10th October 2005, 05:47 PM

Thanx all, it looks like the problem is fixed. The output to te speaker terminals has now 9mv dc. From the -+ output to the ground 20 mv. There were some problems:
1 unbalanced - terminal connected to the groud without a cap.
2 the two resistors 2.2k changed to 4.7k
3 start point off v1/v2/v3 0 ohm, not in the center.
4 changed the irf9610 no heatsink, but mounted together(with an insulator).
5 changed the resistor of the irf9610 (not the differential pair) to lower the bias.

After building 2 stereo aleph 5 without any problems, this mono aleph x amp is finished(i hope). Maybe i will change the aleph 5 to aleph x high voltage

.

10th October 2005, 10:11 AM	#11
wuffwaff diyAudio Member Join Date: Aug 2001 Location: Ingolstadt Germany	Hi, 1.try to set the bias (start with both (V1/V3) pots at 0 Ohm) . Both sides should have the same bias, you´ll have to adjust them a bit as the bias changes during warmup. 2.Then set the absolute dc-offset to zero with V2 that set´s the bias through the diff pair. This should be done with the lid on the amp cause this is quite temperature sensitive. Adjust when warm (1-1.5 hours) William __________________ een ooievaar is geen konijn want zijn oren zijn te klein!

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10th October 2005, 05:47 PM	#12
Berry diyAudio Member Join Date: Apr 2004 Location: Netherlands	Thanx all, it looks like the problem is fixed. The output to te speaker terminals has now 9mv dc. From the -+ output to the ground 20 mv. There were some problems: 1 unbalanced - terminal connected to the groud without a cap. 2 the two resistors 2.2k changed to 4.7k 3 start point off v1/v2/v3 0 ohm, not in the center. 4 changed the irf9610 no heatsink, but mounted together(with an insulator). 5 changed the resistor of the irf9610 (not the differential pair) to lower the bias. After building 2 stereo aleph 5 without any problems, this mono aleph x amp is finished(i hope). Maybe i will change the aleph 5 to aleph x high voltage .