Change the 35C5 tubes to 50C5 tubes and you won't need the 35w4 or a resistor. If I understood correctly that you're using solid state rectifiers.
I am sorry to say that I don't know what you mean. It is my own inexperience showing. Can you explain in more simple terms? Thanks!
I actually like the pilot light, though. And the chassis I put this in does not have space for another tube.
Yes, I am using a solid state bridge rectifier. I do not need the 35W4 for anything other than a ballast to soak up 35 volts. I considered using a pair of 50C5 tubes, but several things kept me from doing that.
First, I have 35C5 tubes and I want to use them.
Second, the chassis I put this in has exactly four tube sockets in it. So the current tube complement works out rather nicely. And it's a tiny chassis made of mild steel; it was a bugger just to cut the hole for the pilot light.
Third, and I may be wrong on this, but I believe the 35C5 is not part of the *C5 family. That is, the 12C5/17C5/25C5/50C5 are all identical except for heater ratings, but the 35C5 is actually a completely different tube. So not only would I be subbing tubes, but creating an entirely new circuit.
He thought you might overcurrent the 12AU7 while tube rolling, and suggested changing the plate load resistor.
wa2ise's is the best idea yet. Should have thought of that. They made tubes like XXC5 and XXL6 with all sorts of filament voltages for series use. There were a lot of 50C5s made for the "All American Five" AM broadcast receivers. NOS GE goes for about $8 on eBay.
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Where I can start?.....You can measure tube current /disconnect cathode from ground and connect in series amper-volt-ohm tester in volt mode/ that must be about 5-8 ma for good sounding. Maybe You can change plate resistor 100 kohm to about 40-70 kohm. This will give you +U plate more 75 v....
How closely did you follow my schematic for the amp? Did you include the 22uf from the 125 volt power supply to pins 2,5 on the 35c5's? On my amp I tried different values for the 22uf starting at 4.7uf and working up. I got the best results with a 22uf. do you have the polarity correct, negative to pins 2,5?
How is your wire management? did you run all audio connections through coax? did you run all the AC lines as far from the audio inputs and the 12ax7 as you could?
Here is the information that helped reduce the hum:
Lowering SE Amplifier Noise (page 4)
double check that the coupling caps on the 12ax7 are not near any AC high voltage lines. I picked up a buzz from that, and had to move them away from the AC supply lines. I ran the 12ax7 side of the caps through coax.
here is the original build log on the antique radio forum:
Antique Radio Forums • View topic - Archer Stereodyne/3 Clone Project
Here is another person trying to build the amp right now.
Antique Radio Forums • View topic - Archer Stereodyne DIY Project
I highly recommend the 12ax7 instead of the 12au7 or at7 as it has higher gain which helps when running battery powered mp3 players to the amp.
My amps is currently at work hooked up to my computer through a ground loop isolation connector driving 2 KLH speaker (very similar to minimus 7's). I love it.
My electronics experience is not much more than beginner so I won't be able to help much with troubleshooting.
How is your wire management? did you run all audio connections through coax? did you run all the AC lines as far from the audio inputs and the 12ax7 as you could?
Here is the information that helped reduce the hum:
Lowering SE Amplifier Noise (page 4)
double check that the coupling caps on the 12ax7 are not near any AC high voltage lines. I picked up a buzz from that, and had to move them away from the AC supply lines. I ran the 12ax7 side of the caps through coax.
here is the original build log on the antique radio forum:
Antique Radio Forums • View topic - Archer Stereodyne/3 Clone Project
Here is another person trying to build the amp right now.
Antique Radio Forums • View topic - Archer Stereodyne DIY Project
I highly recommend the 12ax7 instead of the 12au7 or at7 as it has higher gain which helps when running battery powered mp3 players to the amp.
My amps is currently at work hooked up to my computer through a ground loop isolation connector driving 2 KLH speaker (very similar to minimus 7's). I love it.
My electronics experience is not much more than beginner so I won't be able to help much with troubleshooting.
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also here is a better copy of the final schematic:
https://www.dropbox.com/s/uz4159als8k08a9/little12a Finala.jpg?dl=0
Here is the original Sams:
https://www.dropbox.com/s/vv570k1b1uozzwa/archer 0503-4n.pdf?dl=0
https://www.dropbox.com/s/uz4159als8k08a9/little12a Finala.jpg?dl=0
Here is the original Sams:
https://www.dropbox.com/s/vv570k1b1uozzwa/archer 0503-4n.pdf?dl=0
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