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Old 30th October 2011, 10:08 PM   #2971
Joachim Gerhard is offline Joachim Gerhard  Germany
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No, output impedance is over 700kOhm so the 1Mohm resistor is not right. Sorry, that the schematic appears on page two. It has reasons that are hard to explain.My drawing program tries to put known component names to the semiconductors. Because it uses only weak artificial intelligence it has no idea about what i use. Removing the not used names shifts the component names up and down, creating 3 pages. I do not think that you need spoon feeding, just read EVERYTHING i post here and you will be able to make the best phono stage in the word in a minute. The Opamp has gain. I try to help sampler to get enough gain with his DL103 into my transimpedance input. "I am not perfect, but i am perfect for you "
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Last edited by Joachim Gerhard; 30th October 2011 at 10:35 PM.
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Old 30th October 2011, 10:37 PM   #2972
RCruz is offline RCruz  Switzerland
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I am reading... carefully

I really like your design.... Would it work with a benz ACE M (0.8mV output) ?

So IOP2 is the servo and compares DC offset with GND, feeding the difference to the other opamp. That 1u (C1) must have a big impact in the final voicing... what type do you use ?
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Last edited by RCruz; 30th October 2011 at 10:43 PM.
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Old 30th October 2011, 11:02 PM   #2973
Joachim Gerhard is offline Joachim Gerhard  Germany
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What impedance does the ACE M have ? What schematic are you referring too ? Using a servo is a two side sword. It will not have much impact on the treble response so some authorities like Malkolm Hawksford ( my "father" ) uses a simple TL071. By 1kHz the gain has rolled off. Others claim that they can even hear the opamp used. For the cap i usually use Wima MKT. I f i want to scare the demons away i use EVOX-RIFA PPS:
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Old 30th October 2011, 11:07 PM   #2974
Joachim Gerhard is offline Joachim Gerhard  Germany
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That is my preference :
https://www.distrelec.de/folienkonde...c31tr24/820150
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Old 31st October 2011, 09:08 AM   #2975
RCruz is offline RCruz  Switzerland
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Thank you.

This is the schematic I am refering to: MPP

The benz ACE M has 24ohm output imp. and 0.8mV out
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Last edited by RCruz; 31st October 2011 at 09:10 AM.
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Old 31st October 2011, 11:56 AM   #2976
Joachim Gerhard is offline Joachim Gerhard  Germany
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When it is the schematic with the helper transistors you will get 64dB of gain with your Ace M. That should be more then enough. Gain can be changed by changing the components in the RIAA. For example if you half the values of the resistors and double the caps you get 6dB less gain. It also works the other way around.
I like the parameters of your cartridge. That gives a good combination of low distortion and decent noise performance into my circuit.
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Old 31st October 2011, 01:46 PM   #2977
RCruz is offline RCruz  Switzerland
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That is new concept for me. I mean modifying the Riaa values to set gain. I will do that because I only need 48 ~50dB gain.

Acording to my calculations, using C7 = 20n I need R16 = 15k9; C8 = 6.86n; R15 = 1M and output impedance of the first stage (the one with the wilson mirrors) should be 122k8.

Can you verify my calculations ? What about R17... can it stay as 1k ?
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Old 31st October 2011, 01:51 PM   #2978
Joachim Gerhard is offline Joachim Gerhard  Germany
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Now i need the exact schematic. Your link did not send me there but in principle your calculations are right. Less gain buys you less distortion so if you do not need more, that is good.
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Old 31st October 2011, 01:59 PM   #2979
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by Joachim Gerhard View Post
Now i need the exact schematic. Your link did not send me there but in principle your calculations are right. Less gain buys you less distortion so if you do not need more, that is good.
Here it is:
Attached Files
File Type: pdf Starless Transconductance Floating.TSC - TINA[1].pdf (14.6 KB, 75 views)
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Old 31st October 2011, 02:30 PM   #2980
Joachim Gerhard is offline Joachim Gerhard  Germany
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Ok, that one has over 700kOhm output impedance. The floating input has never being tried. Who has the guts to build it ?
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