Its done! I have now +/-28.5 VDC on the rails. The transformer secondary covers only a bit less than half the core but the sound is now much better than with the other small EI tx.
The problem now is that the tx hums and the speakers go along too
. Man, it took me two years to teach my kid how to speak .
I have to reinforce the expanded plastic/rubber sheet under that transformer to get more damping. Maybe the unbalanced covering of the secondary has something to do with it. And then I have to convince my speakers that the star ground I made is awesome.
Just one thing that worries me is that the volume pot is around 3 cm away from the tx.
Miguel
The problem now is that the tx hums and the speakers go along too
. Man, it took me two years to teach my kid how to speak . I have to reinforce the expanded plastic/rubber sheet under that transformer to get more damping. Maybe the unbalanced covering of the secondary has something to do with it. And then I have to convince my speakers that the star ground I made is awesome.
Just one thing that worries me is that the volume pot is around 3 cm away from the tx.
Miguel
Miguel,
Before you go after the transformer for your speaker hum, make sure you didn't induce a ground loop somehow. Is the new TX connected to the bridges the same way as the EI or did you do some rerouting. If the pot is Al bodied, is it grounded? Peter had an original problem with hum (especially when he touched the pot) until he grounded the case of his pot with a small wire. If the pot is wirewound the close proximity to the Tx could be inducing the hum. If all the above is good, how tightly did you tape up the remaining secondaries? I have reduced transformers a couple of times and have used clear packing tape with good success.
Philip
Before you go after the transformer for your speaker hum, make sure you didn't induce a ground loop somehow. Is the new TX connected to the bridges the same way as the EI or did you do some rerouting. If the pot is Al bodied, is it grounded? Peter had an original problem with hum (especially when he touched the pot) until he grounded the case of his pot with a small wire. If the pot is wirewound the close proximity to the Tx could be inducing the hum. If all the above is good, how tightly did you tape up the remaining secondaries? I have reduced transformers a couple of times and have used clear packing tape with good success.
Philip
I use shielded cable (microphone) for the inputs but the outputs of the pot are cat-5. The pot is an Alps blue, which is made of metal, and is connected to chassis, being the chassis connected to the star ground via 100R/.22uF.
The EI tx was center tapped with only one wire (the secondaries were connected) while this new one has two independent secondaries. The difference in cabling is that I route the two secondaries to the star ground separately, while in the other I had only one wire.
I finish wraping of the secondaries with some strenght, using cloth adhesive tape and the plastic tape that came with the tx. So I guess that the secondary wires are not vibrating. Maybe it is from some unbalance between the two halves of the core.
Carlos, I though of wraping with Al but I am thinking of making another set of secondaries for the sub amp. I have half of the tx for that. Oh, and my thrusty conventional Canon still has around 20 photos to go...
I am going to try a piece of metal between the pot and the tx. And use shielded cable on the pot instead of cat5. BTW, the shield of the cables is connected to chassis or to the star ground? As I don't have a ground connection in the plug (just hot and neutral) I dont know if this even makes sense.
Miguel
The EI tx was center tapped with only one wire (the secondaries were connected) while this new one has two independent secondaries. The difference in cabling is that I route the two secondaries to the star ground separately, while in the other I had only one wire.
I finish wraping of the secondaries with some strenght, using cloth adhesive tape and the plastic tape that came with the tx. So I guess that the secondary wires are not vibrating. Maybe it is from some unbalance between the two halves of the core.
Carlos, I though of wraping with Al but I am thinking of making another set of secondaries for the sub amp. I have half of the tx for that. Oh, and my thrusty conventional Canon still has around 20 photos to go...
I am going to try a piece of metal between the pot and the tx. And use shielded cable on the pot instead of cat5. BTW, the shield of the cables is connected to chassis or to the star ground? As I don't have a ground connection in the plug (just hot and neutral) I dont know if this even makes sense.
Miguel
Hi,
In the unwinding process I just took off the sleeves from the secondaries. So after this step I just saw with DMM which were the wires from each secondary and plug them into the bridges. But now I understand that there is only one way to connect them, and the center tap must be well chosen. As I do have the right voltages, is there any chances I had swap the secondary wires?
I still have hum that I cant get rid off, so I am checking all possibilities.
Miguel
In the unwinding process I just took off the sleeves from the secondaries. So after this step I just saw with DMM which were the wires from each secondary and plug them into the bridges. But now I understand that there is only one way to connect them, and the center tap must be well chosen. As I do have the right voltages, is there any chances I had swap the secondary wires?
I still have hum that I cant get rid off, so I am checking all possibilities.
Miguel
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