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Old 22nd February 2013, 05:49 PM   #1431
zoe is offline zoe  United States
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here's one more
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Old 22nd February 2013, 07:01 PM   #1432
WalterW is offline WalterW  Netherlands
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Hi Zoe,

Nice build!
I would change the little blue switch for your mains, is way too small to switch the big transformers. I've used them myself with a 500VA transformer and they are really dangerous. Altough you are using thermistors so the peak surge is dampened...

Happy listening !
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Old 22nd February 2013, 07:10 PM   #1433
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Zoe, are your diodes mounted on main sink? Did you do version with diodes?
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Old 22nd February 2013, 07:48 PM   #1434
zoe is offline zoe  United States
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No diodes yet. For what I have I don't think I need them. This amp with my better preamp sounds better than I thought It could. I've just need to get rid of this hum!! If I short inputs amp is dead quiet. If I short the right input amp is dead quiet If I short the left input right gets louder. Mybe I should cut ground in ps as it forms a loop but I realty don't think that's it? I have four different sets of speakers I have not tried them all but the home built Mark K ER18DXT sounds very good the lack of artifacts is astounding.
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Old 22nd February 2013, 10:37 PM   #1435
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by zoe View Post
Here are some pix of my amp.I was up late last night reworking amp changed resistors in cascaded front end to get 13.3 volts to little fets as they had only 10v before.Also sodered bigger wire for ground bridge and increased resistance to RCA ground wire. I've got the two Anvil Lindberg 625va 25v tranys (parts express) hooked together.I wanted to try one and then two to see the difference. Two is better. Amp still has buzz louder now. Left channel is dead quiet.also changed preamp no difference.
Transformer too close to input ...
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Old 23rd February 2013, 05:02 AM   #1436
coils is offline coils  United States
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Originally Posted by Blink_PT View Post
Humming problem solved.

in short, one can not use only transfores with independent side with a bridge rectifier has to be toroidal with center tap.

...
Blink, your transformer is a good choice, 2x24 v coils is perfect, I wish I had one. You dont need a center tap, although with dual secs, you can always make one. If you want split rails, you should do as NP has drawn in the FirstWatt and Zen articles. Run two rectifiers instead of one and ground the middle of the psu, that will stop iduction on your ground wire.
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Old 23rd February 2013, 05:19 AM   #1437
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Originally Posted by Blink_PT View Post
No, not that. My secundarys has 24V each, are equal.
The problem that can not just use a bridge rectifier with this type of toroidal 0-24, 0-24. They are two independent windings.

I wonder if any member has connected two independent secondary with one bridge.
i have done that many times. never had any problems with it. you just have to connect it right. are you sure that:

Red-Red=24V and
Blue-Blue=24V?

and not:

Red-Blue=24V and
Red-Blue=24V?
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Old 23rd February 2013, 10:51 AM   #1438
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Quote:
Originally Posted by zoe View Post
This amp with my better preamp sounds better than I thought It could. I've just need to get rid of this hum!! If I short inputs amp is dead quiet. If I short the right input amp is dead quiet If I short the left input right gets louder. Mybe I should cut ground in ps as it forms a loop but I realty don't think that's it? I have four different sets of speakers I have not tried them all but the home built Mark K ER18DXT sounds very good the lack of artifacts is astounding.
Zoe, what is the thick green wire in front of the PSU caps?
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Old 23rd February 2013, 12:07 PM   #1439
omishra is offline omishra  India
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Quote:
Originally Posted by Blink_PT View Post
This is not toroidal 24-0-24.

It is 0-24 + 0-24.

Red + Red = 24V
Blue + Blue = 24V

Join any red any blue, never gives 48V, measured in total 0Volts.

Maybe if I had already ordered with center tap work because the winding would be the same, with a connection to medium.

What matters is that now is working very well.

He liked to have the bridges faster, any suggestions?
I agree, still in your diagram you have red wires - one thick and one thin. First choose any blue wire and try connecting with one of the red wire. if it does not work(open ends does not measures 48V) then keep same blue wire (free previous red wire from joint) and try another red wire in joint. In one of the combination you must get correct voltage.
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Old 23rd February 2013, 05:29 PM   #1440
zoe is offline zoe  United States
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Originally Posted by rookakoma View Post
Zoe, what is the thick green wire in front of the PSU caps?
Green wire connects amplifier boards grounds together
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