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Roender'S FC-100 - Group Buy

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Rudi_Ratlos

Rudi_Ratlos

Member
Joined 2009
pinnocchio,

the backend-PSU that you are using does not differ much (does it at all?) from the "PSU" that I have done a layout for on the FC-100 PCB.

Keep in mind: you do not need a regulated power-supply, nor does the PSU need to be "silent" and accurate!
What you need is: current, immediately, when it is and how much is demanded.
The demand for current shall not be delayed by filters or whatsoever.

The frontend power-supply should be very stable, accurate and silent though.

Best regards - Rudi
 
L

lordoff

Member
Joined 2006
Yes! Rudi, you are a absolutely right!
I don't even think that your design are not the best decision for FC-100.
Main reason that I liked separated PCB from Project16, are possibility to use big
4pole capacitors and eventualy CRC...
This give me a idea to use in CRC filter KMH (or even SMH) Nichicon series for primary capacitors and Mundorf M-lityc (for example) after resistors...
But in your design Rudi, I like excellent ground topology, directly straight to the Output stage and speed...
Will try both to experiment.

@Telstar:
read all pages :) This power amp. design deserve this! :)
 
L

lordoff

Member
Joined 2006
Telstar said:
OK, it’s only 30 pages after all :)
Click to expand...
Hm :) I'm afrad it is not only to read.

This is mandatory if you want to understand amplifier:
RMI-FC100, a single stage audio power amplifier by author Roender! 133pages only, but precious...

and Rudi's "Roender's FC-100 prototype and builder's thread" not more than 101p. :) and essential!

and even small "GB For RMI-FC100 Parts"

and interesting for your fun: "RMI-FC100 MKII, single ended folded cascode VAS"

So you have a lot for serious reading :)
 
pinnocchio

pinnocchio

Member
Joined 2010
quebecdiy.forumactif.com/
lordoff said:
Anyway, for possibly balanced input to FC-100:
Input transformer? Or other solution? Anyone with that experience?
Because for preamp I'm planing to orient to some good balanced tube design.
In my preliminary research and emotional predilection are for Allen Wright's RTP (FTP5 are good contender to)
or some transformer coupled... parafeed may be.
Do not thinking for preamp with essential gain stage. 6dB is enough may be for FC-100.
Just trying to have best from "two worlds" :) if this is possible ever...
Click to expand...

Thanks for the compliments! :D

For balanced input, you can use transformers from Lundahl, Jensen, etc...
There's also the electronic way using something like this :
THAT Receiver: Differential line receiver / preamp

The α24 fully-differential line amplifier

Hope this helps!

Do
 
T

Telstar

Member
Joined 2007
lordoff said:
Hm :) I'm afrad it is not only to read.

This is mandatory if you want to understand amplifier:
RMI-FC100, a single stage audio power amplifier by author Roender! 133pages only, but precious...

and Rudi's "Roender's FC-100 prototype and builder's thread" not more than 101p. :) and essential!

and even small "GB For RMI-FC100 Parts"

and interesting for your fun: "RMI-FC100 MKII, single ended folded cascode VAS"

So you have a lot for serious reading :)
Click to expand...
It seemed too easy ;)
Now I know what to do during Easter holidays, while listening to music.
 
L

lordoff

Member
Joined 2006
pinnocchio said:
Thanks for the compliments! :D

For balanced input, you can use transformers from Lundahl, Jensen, etc...
Click to expand...
Thanks Do,
I know well Lundahl's, even now I have in "closet" LL1674A and LL1544A lying around.
I just asked if someone have real trials with FC-100 and transformer coupling...
And yes, it's very dependable from preamp output impedance, reflected Z and etc. Not so easy "universe"...

By now I will reject semiconductor way :)
 
pinnocchio

pinnocchio

Member
Joined 2010
quebecdiy.forumactif.com/
lordoff said:
Did you change anything from original?
Excluding some different from BOM parts (Takman resistors and GPD series capacitor in shunt regulator) and back-end PSU arangement?
Click to expand...

In the shunt PCB, I believe there was an error on the traces for one of the MKP capacitors that was not connecting anywhere for one of the pads. I'm not too sure if it was on this shunt but it rings a bell. Please double check this.

I kept all the same values for everything but partly used some of the parts I like to use in most of my builds. You noticed the more important ones. I'm thinking of changing the input cap (which is a Panasonic) to a Jantzen Supreme or Jantzen Silver. I have them in stock so I will try. The only thing to watch with these is the possible pickup of RFI due to them being much larger and away from the PCB ground plane. I usually put some copper tape around them and solder a cable on the tape and link it to a star ground on the amp PCB.

All the best!
Do
 
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