I build the second channel and i put the Pre-Pre in the system to listen.
I can not say much about the sound because i still have to fight some hum.
I works though and hiss is low.
Tomorrow i try to erode the hum and i also will publish the actual circuit i build.
I can not say much about the sound because i still have to fight some hum.
I works though and hiss is low.
Tomorrow i try to erode the hum and i also will publish the actual circuit i build.
The circuit in the Curl patent has a rather low input impedance. Some cartridges with a higher inductance do not like this ( the low impedance and the inductance make a treble rolloff that may be audible ) so later Curl made the JC1 - DC that has a more manageable 80 Ohm. As far as i can tell my Titan i sounds fine with the circuit as published but here is an alternative. The transdiodes at the input make a level shift of plus-minus Ube ( ca. 0.65V ) that makes it possible to couple into the bases of the amplifying transistors.
This also has a protection cap at the output and gain can be adjusted.
This also has a protection cap at the output and gain can be adjusted.
Attachments
Here are some pictures of the JC1-DC. It was quite expensive at it´s time and eating batteries like dogs eat chappi. Modern batteries last much longer though.
There was also a JC1-AC version but i do not know what the difference was.
JC-1DC Mark Levinson ¥Þ¡¼¥¯¥ì¥Ó¥ó¥½¥ó ¹â²ÁÇã¼è¡¦ÈÎÇä ¥Ï¥¤¥Õ¥¡¥¤Æ² Ãæ¸Å¥ª¡¼¥Ç¥£¥ª/ Ãæ¸Å¥ì¥³¡¼¥É/Ãæ¸ÅCD/McIntosh/JBL/audio-technica/Jeff Rowland/Accuphase/¿¿¶õ´É¥¢¥ó¥×/¥È¥é¥ó¥¹Â¾¥ª¡¼¥Ç¥£¥ª¤Ê¤ó¤Ç¤âÇ㤤¤Þ¤¹ ²¼¼è¡¦ÄÌÈΡ¦°ÑÂ÷ÈÎÇä¤â¤ä¤ê¤Þ¤¹ 13-74607-88374-0
There was also a JC1-AC version but i do not know what the difference was.
JC-1DC Mark Levinson ¥Þ¡¼¥¯¥ì¥Ó¥ó¥½¥ó ¹â²ÁÇã¼è¡¦ÈÎÇä ¥Ï¥¤¥Õ¥¡¥¤Æ² Ãæ¸Å¥ª¡¼¥Ç¥£¥ª/ Ãæ¸Å¥ì¥³¡¼¥É/Ãæ¸ÅCD/McIntosh/JBL/audio-technica/Jeff Rowland/Accuphase/¿¿¶õ´É¥¢¥ó¥×/¥È¥é¥ó¥¹Â¾¥ª¡¼¥Ç¥£¥ª¤Ê¤ó¤Ç¤âÇ㤤¤Þ¤¹ ²¼¼è¡¦ÄÌÈΡ¦°ÑÂ÷ÈÎÇä¤â¤ä¤ê¤Þ¤¹ 13-74607-88374-0
https://www.google.de/search?q=mark...rCMKs7QaRrIGwCg&ved=0CDQQsAQ&biw=1920&bih=908
Here are some pictures of the AC. It seems to have a PSU instead of the batteries.
If the circuit is different i do not know.
Here are some pictures of the AC. It seems to have a PSU instead of the batteries.
If the circuit is different i do not know.
The circuit from patent seems more interesting than the jc1-dc , the low input impedance is due to the use of feedback, so connecting the 160ohms resistor to ground instead of the input will increase the input impedance, but in this case a low value load resistor should be use at input.
Yes, good idea. The circuit has to drive the 160 Ohm plus the cartridge impedance anyway. So in my system it has to drive 166 Ohm if i am not wrong.
Do you think that this way of connecting makes the distortion higher ?
I will build it and try. The 160 Ohm to ground could be seen as current feedback instead of the original shunt feedback.
Do you think that a loading resistor of 2kOhm at the input is ok ?
Do you think that this way of connecting makes the distortion higher ?
I will build it and try. The 160 Ohm to ground could be seen as current feedback instead of the original shunt feedback.
Do you think that a loading resistor of 2kOhm at the input is ok ?
I have rebuild one channel with the 160 Ohm resistor tied to ground. Distortion is a little bit higher but not much. Maybe i do not measure the same channel and this one was not as good as the other one from the beginning. The 2kOhm resistor seems to be a bit high.
When the cartridge is not connected i get over 10mV offset at the input. That goes down to nearly zero when i connect the cartridge but there could be a short current pulse when the cartridge gets connected. I try now a lower one. My Titan works well at around 300 Ohm so i try that now.
When the cartridge is not connected i get over 10mV offset at the input. That goes down to nearly zero when i connect the cartridge but there could be a short current pulse when the cartridge gets connected. I try now a lower one. My Titan works well at around 300 Ohm so i try that now.
Attachments
The circuit works also floating so the batteries do not have to be tied to ground.
I will now rebuild for floating with only one 9V battery.
The floating circuit gave no improvement in distortioon though.
One advantage of the floating circuit is that the offset trim is obsolete.
Maybe it also picks up less hum.
I will now rebuild for floating with only one 9V battery.
The floating circuit gave no improvement in distortioon though.
One advantage of the floating circuit is that the offset trim is obsolete.
Maybe it also picks up less hum.
I have put a 270 Ohm resistor parallel to the existing 2kOhm. That brings the initial offset without cartridge connected down to less then 2mV. That will not destroy the cartridge, i am sure.
I put the new version in my system. There is still a bit of hum, not better then the version with two batteries, but it is possible to listen.
I like this version better then the first one.
There is an unmistakable transparency and imaging is very good.
Well focussed, wide, deep and high.
Tonally it is a bit light in the bass but i attribute that more to the rather simple MM stage i use. I cranked up my subs a bit ( maybe plus 2dB ).
That restored the tonal balanced more to what i am used to with my more elaborate phonos.
I will work on the hum now and listen more.
I will also publish the circuit how it is now.
I like this version better then the first one.
There is an unmistakable transparency and imaging is very good.
Well focussed, wide, deep and high.
Tonally it is a bit light in the bass but i attribute that more to the rather simple MM stage i use. I cranked up my subs a bit ( maybe plus 2dB ).
That restored the tonal balanced more to what i am used to with my more elaborate phonos.
I will work on the hum now and listen more.
I will also publish the circuit how it is now.
Lyra Titan i. I am really surprised how well this little pre-pre works.
Hiss is really low and the sound is very transparent. This is no toy, it really works.
Hiss is really low and the sound is very transparent. This is no toy, it really works.
Noise is lower then the Quant Asylum shows. I could do a synchronous averaging.
It is possible but i have to check how that works. There is a beta release that allows that.
It is possible but i have to check how that works. There is a beta release that allows that.
