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Remove riaa stage from cheap phono pre
Remove riaa stage from cheap phono pre
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Old 26th August 2017, 12:14 AM   #1
DIP8 is offline DIP8  Italy
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Default Remove riaa stage from cheap phono pre

Hello guys!
Do not give me crazy please and sorry for my very poor english.
I want to try to remove riaa stage from one of the cheaper phono amp (tc 750 or pyle pp444 etc..)
I would to only use the gain stage and use pc to rip the vinyls using a riaa software.
I read a brief guide here to tweak opamps and discrete phono stage
Stereo Lab - Flat response phono preamplifier
but i can't understand well, how to do in these circuits (i'll buy one of these 3 to do an experiment)

What are the capacitors to be eliminated in these circuits?

1)
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2)
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3)
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Thank you very very much if someone can help me
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Old 26th August 2017, 12:54 AM   #2
rayma is offline rayma  United States
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Quote:
Originally Posted by DIP8 View Post
I would to only use the gain stage and use pc to rip the vinyls using a riaa software.
You'll need the schematics to do a redesign. The article is reasonably correct.

Last edited by rayma; 26th August 2017 at 01:06 AM.
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Old 26th August 2017, 07:58 AM   #3
DIP8 is offline DIP8  Italy
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Thank you Rayma for your reply. There are schrmatics of first board and tc 750. Thank you so muchif you can help me.
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Old 26th August 2017, 08:58 AM   #4
scottjoplin is offline scottjoplin  Wales
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Hi, the equalising network is in the feedback loop of the op amp. Basically the idea is to remove the RC network and adjust the gain as required
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Old 26th August 2017, 09:13 AM   #5
DIP8 is offline DIP8  Italy
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Hi Scottjoplin
thank for reply

In the tc750 that have discrete transistors, I have to remove c4,c5?
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Old 26th August 2017, 11:14 AM   #6
scottjoplin is offline scottjoplin  Wales
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Yes, and you'll need to lower the resistance in the feedback loop or you'll have excessive gain
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Old 26th August 2017, 11:49 AM   #7
DIP8 is offline DIP8  Italy
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Thankyou.
In that circuit, what are the feedback loop resistances?
Sorry... i'm a total newbie..
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Old 26th August 2017, 12:05 PM   #8
scottjoplin is offline scottjoplin  Wales
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R5,6 and 15, in conjunction with R3 and 4. In the article you linked to it suggests shorting the larger capacitor which in your circuit also shorts out R6, this would be a good way to start as it just leaves R5 and 15 in circuit
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Old 26th August 2017, 12:17 PM   #9
DIP8 is offline DIP8  Italy
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I really appreciated scottjoplin
Thankou very very much
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Old 26th August 2017, 12:27 PM   #10
scottjoplin is offline scottjoplin  Wales
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You're welcome. This will help you understand Negative Feedback and Gain
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