OPENAMP1 - MM phono preamp open project

Turn on the SL-1200mk2, set it rotating, cued-up and place the cartridge over the platter...

Then bring the headshell nearer the centre of the record. Real world S/N before even hitting the record.

Hi John, by your command, Sir. I did that many times and now again for you. Headshell is near the record centre, motor is running. As you know, the result depends on proper TT-pre shielding and grounding point. This is where beginners make most mistakes. There is no worsening of parameters, if system is set properly.

openamp_5534_2mblue_10mcable_TTrot.png
 
  • Like
Reactions: mlloyd1
Many thanks @PMA

Only this week I have read more and more in my internet research that my SL-1210MK2 as a DD representative (with the ancient development status of the very early 1970s or late 1960s) is supposed to be really bad. I immediately panicked and wanted to get an even older but proper friction wheel drive, as recommended in the relevant expert forums.
In the past forty years, I have had absolutely no problems with this beautiful Technics turntable.

How old I've gotten!


greetings,
HBt.


Psst
The Internet is a real blessing, finally one have problems and feel cheated and lied to ... 🙄
 
  • Like
Reactions: PMA
How old I've gotten!
😊. I am 70. Still young guy, right? 😉

BTW, the measurement in my previous post is taken from left channel from the Openamp preamp connected with SL-1200MK2 (motor running, headshell near record centre). The right channel from that phono preamp is connected to my main system - linear preamp + power amplifier. The linear preamp has multiple inputs and the DAC and also 10m cable from the other room are connected to preamp inputs. So these are "real" listening conditions (with real possible EMI or cable ground currents), not a clinic laboratory ones.
 
Quite remarkable SNR result of Openamp (with NE5534 op-amp) under real world system consisting of:

Technics SL-1200MK2 turntable ==> Ortofon 2Mblue cartridge ==> Openamp with NE5534 ==> 10m single ended Tasker C121 shielded cable between 2 rooms ==> measuring place in my home lab

SNR is 77.24dBA referred to 5mV/1kHz input:

I think this might be interesting as well - I have simulated the A-weighted noise of the Openamp (with NE5534) and Ortofon 2m blue cartridge. This is the result:

openamp_5534_2mblue_noisesim.png


Simulated (MC11) A-weighted noise at the output is 68.344uVA. Measured result was 68.72uVA. This equivalence is really not bad.