F5 Turbo Builders Thread

put fat and short(est you can manage) wire between two central grounds of two main pcbs

that will look as bridge between them

Humming problem solved.

I think there are some conditionalities in the schematic of dear NP. He forgive me if I'm saying something stupid, but after several tests is my interpretation

One is the choice of transformer, I have a 2x24VAC, has no center tap, so I only have 24V on each winding, they are completely independent, can unite in series but I'm not 48V.

And it was here that I received what seemed like half-wave rectified.

I used the layout of the original full F5TV2 only takes a bridge when I joined two exits to the GND got a common point, and the other two will bridge that connected, but in this case 0 Volts enters and exits the bridge 0 Volts.

Only when I connect GND will get that PSU is 24V to 24V and over one side to the other side, but there is failure in the rectification of the union that always behind AC.

disassembled the entire PSU, soldered everything again, and used a bridge to each side, all was well, I notice less 2V on each rail, with only one bridge there is less voltage drop and would be faster.

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

I'm using two KBPC35404W, but I need faster, someone gives you a hint ...
 

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Blink

I really struggled to understood what you are trying to say, but I think I get some of what you are saying and that tells me that you have an inbalance between your 2 transformer secondaries, which is exactly why NP uses 2 bridges when having 2 separate secondaries.

I think you had DC going back into your transformer which caused it to hum. Am I making sense here?
 
Blink

I really struggled to understood what you are trying to say, but I think I get some of what you are saying and that tells me that you have an inbalance between your 2 transformer secondaries, which is exactly why NP uses 2 bridges when having 2 separate secondaries.

I think you had DC going back into your transformer which caused it to hum. Am I making sense here?

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.
 
Blink, just exchange one of the blue or red coloured wire from your diagram with its another counterpart of same color. It seems you haven't done series of secondaries correctly.


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?
 
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.
 

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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 !
 
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.
 
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 ...
 
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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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?
 
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?
 
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.