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In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage
Post Subject: MiscelaneaPosted by N-set on: 9/1/2011
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 Romy the Cat wrote:
1)      Be very careful with use Halco resistors. They were very good 15 years back but they turned south very aggressively. I bought a party of Halco in 2005 and I forced myself to trashed them as they were very noisy. You do not use then in critical location, still I would be very watchful with them.


Ok, thank you. Actualy I have one of them at the critical location: the temporary cart load resistor, but will remove it
(perhaps there will be no load resistor even, we'll see). The grid bias resistor is also quite critical, but getting a 2M
resistor is not that easy to get.

 Romy the Cat wrote:
2)      I do not know about the SS stabilizers in filament supply. Why do you need them? Chokes stabilize current well and if you have some voltage jump then .1-.-2V on filament would not do any deferments.  None of the stabilizers that I heard sound as good as no stabilizers. I have made a very good tube and ultra fast stabilizers on tube but it was not as good as no stabilizers. I truly do not see use of them if they are not necessary.


It was more of a capriccio. I've read good things about constant current heating from people like Loesch ect.
Their role is rather to precisely stabilize heater conditions and filter some HF (as well as the audio signal) trash.
Something big mega uF caps and big iron chokes would have problems in doing.
 My I ask if the stabilizers you've made and tried
were constant current or more common constant voltage. There seem to be a critical difference between them,
with the former beeing supposedly far superior--like AC heating but without hum and line trash issues.
But I agree, at this moment I cannot defend the choice more than that.

 Romy the Cat wrote:
3)      The common mode filter you have at the PS’s input- why do you use them? They do eat some dynamics. As many time I removed them from all imaginary components as many time I witnessed better sound.


Ok, got it. Do you also  suggest getting rid of the chokes at the power entry?

 Romy the Cat wrote:
4)      The values of the air caps. Stick to 330p and 110pF BUT it would be depends from your mounting of the caps, the assembly techniques and so on. Do not be afraid if you need to change the values for +/- 5%-10% in YOUR case. What you need to do. After you will be done, take YOUR cartridge with your typical load for that cartridge and play frequency sweep record into a RTA with resolution of .25dB. Then adjust the value of your caps. You might use a tested inverted RIAA filter and run the sweep from CD player. I still fill that you will end up with 330/110pF but it might be 335pF and 105pF as well.


I've just put the nominal values of the parts. All the tuning is still in front of me.

Thank you for the comments, Romy.

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