Ulti Amp problems
hi Jack,
Missed your last posting during the august holidays, sorry.
Did you resolve the problems by now?
Piersma
hi Jack,
Missed your last posting during the august holidays, sorry.
Did you resolve the problems by now?
Piersma
Measurement Ultiamp
Hi Piersma,
No problem, I hope you had a good holiday. I haven't had much time in the meantime also.
Regarding the Ultiamp project:
I've purchased some poti's to replace R13, R14, R15 and R27. In this way I hope to get the DC-settings in the correct range.
I've noticed that sometimes one channel doesn't produce any audio although the security PCB indicates everything is switched on and OK.
Do you have any suggestions? Do you have some detailed pictures of your modifications?
Thanx!
JackV
Hi Piersma,
No problem, I hope you had a good holiday. I haven't had much time in the meantime also.
Regarding the Ultiamp project:
I've purchased some poti's to replace R13, R14, R15 and R27. In this way I hope to get the DC-settings in the correct range.
I've noticed that sometimes one channel doesn't produce any audio although the security PCB indicates everything is switched on and OK.
Do you have any suggestions? Do you have some detailed pictures of your modifications?
Thanx!
JackV
Problems
hi Jack,
Check the idle current stability over at least one hour and see what happens, it might be the cause of the problem you mention. I would strongly suggest, as mentioned earlier in this threat, to use 0,1% resistors in the front end stage to resolve the DC offset.
regards,
Piersma
Jack V please sent me a private message
hi Jack,
Check the idle current stability over at least one hour and see what happens, it might be the cause of the problem you mention. I would strongly suggest, as mentioned earlier in this threat, to use 0,1% resistors in the front end stage to resolve the DC offset.
regards,
Piersma
Jack V please sent me a private message
check out this thread:
http://www.diyaudio.com/forums/soli...s-paralleled-place-one-output-transistor.html
http://www.diyaudio.com/forums/soli...s-paralleled-place-one-output-transistor.html
The only one I could find on that list that's sold by a respectable supplier is 2N3810. Only difference I spot that ICmax on the BFX36 is 100 mA and it's 50 mA on the 2N3810. I don't know if that's a problem.
If you check the LTP current sourrce, you will come to the conclusion that the Ic max of 50mA is no issue in this particular (differential) setup.
Thanks for th response. I haven't been able to find an available replacement for the 2N2914 so I asked voor a quote from 'Electronicpool.de'.
Ebay offers some nice original (old stock) matched transistors.
I have used and experimented with different duals in the Ulti Amp.
The 2N2920 works fine, just as others..
I have used and experimented with different duals in the Ulti Amp.
The 2N2920 works fine, just as others..
Thanks for the tip, that will settle it as a replacement for the 2N2914.
What would be your favorite replacement for the BFX36 (preferably NOS).
I have had a look at the component layout (p.74 -elektuur 12/92) and it looks to me that diode D8 has the wrong orientation. On the layout there is a trace that runs from the anode of D8 to pin 2 of IC3. I think the trace should run from the cathode of D8 to pin 2 of IC3 according to the schematic.
Swapped
Part numbers of D7 and D8 are swapped on the silkscreen printed in Elektor february 1994.
Part numbers of D7 and D8 are swapped on the silkscreen printed in Elektor february 1994.
Are there other mishaps in the final PCB/schematic. I tried to look up a 'lek van elektuur' voor this amplifier but I came out empty handed.
Could you send a large image of this photo?
What kind of fuses did you use. The 6.3 amp car fuses are unobtainable.
Ulti Amp Elektor 1994 document can be downloaded: https://worldradiohistory.com/UK/Elektor/90s/Elektor-1994-03.pdf
