Mpp - Page 315 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th November 2011, 10:58 PM   #3141
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Here is a first sketch.....
Attached Files
File Type: pdf Strain Gauge Phono Simple.TSC - TINA.pdf (6.9 KB, 182 views)
  Reply With Quote
Old 21st November 2011, 01:02 AM   #3142
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
R6 has to be reduced to 800 Ohm.
  Reply With Quote
Old 21st November 2011, 01:09 AM   #3143
tabams is offline tabams  Netherlands
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by Joachim Gerhard View Post
First you need a constant current source. That could be a J-Fet with source resistor or a current mirror for example. I assume that the cartridge has then to be AC coupled into the phono amplifier. The most easy way would be to use a good Opamp. If that works we could construct a discrete solution. Concerning the tone controls a strain gauge cartridge does not need much equalization because it has a 6dB/oct falling response by itself. That does not work 100% perfect so you can use your tone controls for fine tuning.
The most easy way would be to use a good Opamp. If that works we could construct a discrete solution. Concerning the tone controls a strain gauge cartridge does not need much equalization because it has a 6dB/oct falling response by itself. That does not work 100% perfect so you can use your tone controls for fine tuning.


+++++++++++++++++++++++++++++++++++++

Sorry the name confusion herr Gerhard,
From the beginning I had in mind to use a coupling cap of > 3.3uf.
Response curve on this link, pg 21
http://www.vinylengine.com/turntable_forum/viewtopic.php?f=19&t=28750&hilit=28750&start=300

Do I need a delicate preamp, because of the relative high impedance 1000 ohm cart? The 3mV output is like a MM. Do you have a "simple amp" for this cart? I cannot make a choice. I like BJT s.
I want to use a good PSU like from LCaudio.
Thanks
  Reply With Quote
Old 21st November 2011, 01:20 AM   #3144
tabams is offline tabams  Netherlands
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by Joachim Gerhard View Post
Here is a first sketch.....
Thanks hr Gerhard, that is a quick reply, I like this circuit from the first moment.
Fantastic, fantastic those BC 550/560 from the seventies, low noise, my REVOX sits full of them.
  Reply With Quote
Old 21st November 2011, 02:06 AM   #3145
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Yes, that should work and do not forget to reduce R6 to 800 Ohm. We need 4 V over the 1kOhm for 4mA. Interesting plot you send me. The cartridge has a presence drop and too much upper frequencies. I have not seen that before. In the deeper ranges that looks fine. The 1kOhm of the cartridge is not that uncommon and close to an MM. I have setup the Opamp stage so that not much noise is added. It has approximately a gain of 70 as you requested. I like to use BC560C in the mirror because they have high Hfe. Noise is more controlled by the emitter resistors but they are high enough so that the mirror does not inject much noise. You can use 3.3uF instead of 1uF. That will extend the bass somewhat but even a 1uF into 47kOhm goes to less then 20Hz.
  Reply With Quote
Old 21st November 2011, 02:12 AM   #3146
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
There is a second error. R3 has to be 1337,5 Ohm. Anything close is fine. Sorry, i am also busy with other things but that should work now.
  Reply With Quote
Old 21st November 2011, 02:33 AM   #3147
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I use the LC Audio PSU sometimes. It has only plus-minus 13V max. so you have to adjust R3, R6 proportionally. In Flavios stage i can not see how he generates the bias and where the cartridge is connected. In all the circuits i have searched on the web this part is left out as if it where a big secret only for the initiated. Maybe i have now broken the law.
Also Flavio generates a difference signal. Are the outputs of the cartridge out of phase or is that for Quadrophonia ?
Attached Images
File Type: png Strain Gauge Preamp First Stage .png (13.7 KB, 307 views)
  Reply With Quote
Old 21st November 2011, 10:52 AM   #3148
tabams is offline tabams  Netherlands
diyAudio Member
 
Join Date: Nov 2011
Default Panasonic strain gauge cartridge

I use the LC Audio PSU sometimes. It has only plus-minus 13V max. so you have to adjust R3, R6 proportionally. In Flavios stage i can not see how he generates the bias and where the cartridge is connected. In all the circuits i have searched on the web this part is left out as if it where a big secret only for the initiated. Maybe i have now broken the law.
Also Flavio generates a difference signal. Are the outputs of the cartridge out of phase or is that for Quadrophonia ?



I want not use Flavios schematic,
In the Panasonic SE-405 preamp each signal is amplified by its own frontend, and only the LEFT channel is reversed by a phase splitter TR401, but furtheron TR509 stage looks as a phase splitter, but between collector and emitter, a signal coming from the subcarrier/demodulator injects a signal there.
Is there a reversal again, I do not know.
Link here:
http://members.cox.net/noffour/quad/cd4_se405_scheme1.bmp
http://members.cox.net/noffour/quad/cd4_se405_scheme2.bmp

Web says, reverse left channel, assume for stereo use, I am not sure now.
I think I can reverse one channel of your SG schematic by changing from non-inv to inverting input, correct? If needed afterwards. Otherwise I should use separated supplies for the SG s, and reverse from there.
  Reply With Quote
Old 21st November 2011, 11:04 AM   #3149
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
My schematic should work. If phase reversal is needed on one channel we can add that later. Does the cartridge have conventional output pins ? 4 of them ?
  Reply With Quote
Old 21st November 2011, 11:15 AM   #3150
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
For Stereo you need of cause two of my amps.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 12:40 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2