Hello Mr.apexaudio
i did build your AX-14 ... it's working just have two problems :
1- i cant measure the 30mv bias on both of the emitter resistors ... however the 2SC5200/2SA1943 affected by the bias trimer and get very hot and very cool but no change in the sound.
2- the output by anyway not more that 40w/8ohm i'm applying +ve and -ve 40VDC supply.
and suggestions??!!
i did build your AX-14 ... it's working just have two problems :
1- i cant measure the 30mv bias on both of the emitter resistors ... however the 2SC5200/2SA1943 affected by the bias trimer and get very hot and very cool but no change in the sound.
2- the output by anyway not more that 40w/8ohm i'm applying +ve and -ve 40VDC supply.
and suggestions??!!
Yeah, I know the voltages are all wrong. I'm attaching an updated file. It doesn't work either. I changed the OP and added a model for the 2SK117.
Anyone?
Yes I checked the data sheet and saw that I had the wrong part. For the updated file I changed it to LT1022 which should be closer to the TL071. THe polarity is correct too. It still doesn't run right.
Hi Mile,
Did you try the revised asc file?
Thanks, Terry
Hi Olaf,
I went over your layout with a highlighter and found no errors. I still can't get the spice file to work. Mile says it works in Multisim but I don't have that program so I can't test it there. I do think the input needs the resistor that AndrewT suggested. All the amps I have built have that resistor. Most have an input cap as well that this one doesn't have. I'm glad we started with this one before jumping into the tube version. If this won't work, the tube probably won't either. I'm sure we'll get it working and probably learn something along the way.
Blessings, Terry
I went over your layout with a highlighter and found no errors. I still can't get the spice file to work. Mile says it works in Multisim but I don't have that program so I can't test it there. I do think the input needs the resistor that AndrewT suggested. All the amps I have built have that resistor. Most have an input cap as well that this one doesn't have. I'm glad we started with this one before jumping into the tube version. If this won't work, the tube probably won't either. I'm sure we'll get it working and probably learn something along the way.
Blessings, Terry
This picture coming from the revised schematic. C2 is wrong for sure. I had no time to play with the schematic yet...
Sajti
Attachments
That is true, but the inverting, and non-inverting input of the opamp is opposite.
I just played a bit, and You can see my revision attached.
Sajti
Attachments
I think you are referring to a resistor between Signal Ground and Power Ground?
If so, then it is only necessary when you have a multi-channel power amplifier.
If you are testing a Mono-Block, then that loop current reducing resistance has no purpose. There is no loop that needs the current to be attenuated.
The basic sch is correct for a mono-block.
The Signal Ground to Power Ground link is shown just below V3 at the input.
It is this link that would need a resistance value when building a two channel, or multi-channel, power amplifier. And for a faulty source, this resistance needs a pair of safety inverse parallel diodes to take Fault Current to Chassis and thence to PE.
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No, I'm talking about the 1k resistor ahead of the 330p cap. It's not there in Mile's schematic. I added it to the spice file. It's the one that Olaf added with an SMD. The ground lift resistor you refer to is missing but you still need to run an extra wire from input ground to star. Kind of a hassle when you use a pin header plug like I did.
Did the file run properly after the changes? I am not at my computer so I can't test it right now.
Blessings, Terry
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Yes, it was OK then. I have to change some part number too, as I had no modell for them in my office computer. But the main thing to change is the connection of the DC servo.
Sajti