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Old 9th October 2008, 09:12 PM   #161
RCruz is offline RCruz  Switzerland
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So, for 0.8mv cart I could use 20v psu right ?
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Old 9th October 2008, 09:23 PM   #162
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yes you can try ,only few resistor to change at last for 36v
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Old 9th October 2008, 09:25 PM   #163
RCruz is offline RCruz  Switzerland
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Quote:
Originally posted by nicoch46
yes you can try ,only few resistor to change at last for 36v
I am puzzled... should I use 36v instead ?

I am seraching for the best sound possible.
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Old 9th October 2008, 09:27 PM   #164
Salas is offline Salas  Greece
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Rcruz, what kind of input impedance does your line stage have?
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Old 9th October 2008, 09:43 PM   #165
RCruz is offline RCruz  Switzerland
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Quote:
Originally posted by salas
Rcruz, what kind of input impedance does your line stage have?
It is difficult for me to say....

I am using a meridian 101 pre with a MM phono stage built in.

It also has a buffered radio input.

The other input is tape with a 10kohm before the 10k volume pot. (Itīs here I want to plug your RIAA)

Can not post the schematic but will send it to your e-mail if you care to analyse it for me.

Ricardo
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Old 9th October 2008, 09:57 PM   #166
Salas is offline Salas  Greece
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Don't bother, I just read its schematic. We will avoid its complex enough & dated radio buffer. We will feed through tape 10k in.
For 0.8mV you better make what I attach. Has the best gain for that.
4.1k resistors are made by 8k2//8k2. 45k from 100k//82k. The Rx is what you will find as best damping for input load for your cart in your system. Start with 1k, and see for lower. Choose by ear. This circuit has a simple Jfet buffer and will drive the 101 happily.
Use a 22V 50VA toroid, that will rectify to around 30V. Regulate for 25V. When you will make it we will be happy to see some photos here and your review. Thanks.
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Old 9th October 2008, 10:15 PM   #167
Salas is offline Salas  Greece
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Quote:
Originally posted by RCruz

The other input is tape with a 10kohm before the 10k volume pot. (Itīs here I want to plug your RIAA)

Can not post the schematic but will send it to your e-mail if you care to analyse it for me.

Ricardo
That input adds to 20k load. The 10k that I show in the schematic's output above is a virtual load. Just use 22k for that. The Meridian will shunt it down to nominal.
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Old 9th October 2008, 10:30 PM   #168
RCruz is offline RCruz  Switzerland
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Quote:
Originally posted by salas


That input adds to 20k load. The 10k that I show in the schematic's output above is a virtual load. Just use 22k for that. The Meridian will shunt it down to nominal.
Perfect

Thank you very much for your help.

I will be posting the evolutions and ask for advice.

Ricardo
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Old 13th October 2008, 10:06 PM   #169
Salas is offline Salas  Greece
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Quote:
Originally posted by anatech
Hi Salas,
The Ortofon drives a MM input just fine, but this opens a possibility to use a preamp with no phono input.

Thank you very much Salas.

-Chris
Hi Anatech,

Here is a refined MM cascoded & buffered version. Make this one.
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Old 16th October 2008, 12:59 PM   #170
Salas is offline Salas  Greece
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Default Some measurements

So to conclude the presentation, I guess that some measurements are in order. First is the FFT spectra and THD.
It does 0.091% THD for 2.2mV input, 220mV output on 100k load. The hiss is 80dB down. The 50 Hz hum in the particular built is 70dB down, and no 100Hz can be seen from the PSU at all. Remember that is for the 40dB 20V version for high MC. Pretty good for a non feedback SE circuit I would say. Hence the distortion is 99% 2nd harmonic.
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