Congratulations for the new LCR, could you post a picture? How much cost it?Now I will ask you to measure mine caps🙂
Thks for advice not overshoot RIAA caps.
Here you have.... quite inexpensive but correct reading 🙂
TENMA|72-8150|MULTIMETER, CR | Farnell Portugal
TENMA|72-8150|MULTIMETER, CR | Farnell Portugal
Now the 48dB is sounding right !
Must do the same procedure in the 57dB machine..... It is a pity I must disassemble everything again.
Must do the same procedure in the 57dB machine..... It is a pity I must disassemble everything again.
Today I dismantled the 57dB machine, desoldered one leg of the 47n cap, measured 46.5 and replaced the // 680p by a //560p.
This happened in both chanels..... The difference is amazing.... Now it really sings (and it uses only one shunt) ... maybe a second shunt is redundant but I will try it anyway 🙂
This happened in both chanels..... The difference is amazing.... Now it really sings (and it uses only one shunt) ... maybe a second shunt is redundant but I will try it anyway 🙂
Now I completely removed hum !!!
It is incredible.... using an inboard r core and beeing carefull about GND I got even lower noise with the 57dB than on the 48dB I built before with external double psu´s.
After studying the schematic for a while, I decided to lift the psu GND and now there is no hum.
Maybe I will need to rethink this when I add the second shunt but for now I have a "floating GND" psu.
😎
It is incredible.... using an inboard r core and beeing carefull about GND I got even lower noise with the 57dB than on the 48dB I built before with external double psu´s.
After studying the schematic for a while, I decided to lift the psu GND and now there is no hum.
Maybe I will need to rethink this when I add the second shunt but for now I have a "floating GND" psu.
😎
I am really happy because with an r core we can have even better results than with toroids in an external box.
Ricardo, in mine tests the external EI-cores give better results than external R-cores or Toroids, if you can not do it external the best are R-Cores. Could you try external EI-cores?
As I always needed small low radiation TX, my experience is based only in toroids.
I will keep it in mind for future projects 🙂
I will keep it in mind for future projects 🙂
Two shunts are definitively worth.
Even with only one tx and one rectifying bridge followed by two smoothers the difference for 1 shunt is producing much better separation between channels... The image grows laterally and the instruments are better focused.
Care must be taken with GND. To avoid hum at maximum, star earth linked to mains earth and case is connected to both shunts (-).
Do not connect the rectifier bridge directly to GND as this intruduces more hum.
Ricardo
Even with only one tx and one rectifying bridge followed by two smoothers the difference for 1 shunt is producing much better separation between channels... The image grows laterally and the instruments are better focused.
Care must be taken with GND. To avoid hum at maximum, star earth linked to mains earth and case is connected to both shunts (-).
Do not connect the rectifier bridge directly to GND as this intruduces more hum.
Ricardo
Ricardo
I'd recommend a shunt for each stage... and for grounding, use star ground to the negative rail of each shunt.
Um bom fim-de-semana
Joao
I'd recommend a shunt for each stage... and for grounding, use star ground to the negative rail of each shunt.
Um bom fim-de-semana
Joao
Hi João
You are correct... I had trouble earthing the (-) of the rectifier bridge and opted to use floating earth... (it works in this case) but after some studying I decided to ground the (-) of both shunts and that produced the best results.
Did you build one of these ?
Ricardo
No I didn`t build one yet. My expericence is from my tube amps and as well what my old professors - one of them was a designer of high frequency amps & tuners - told me from the experience of her works.
I've got my transistors and will nuild a version from Salas phono amp with a 600 ohm LCR-RIAA. It will be interesting because I'm building up my new tube phono stage with LCR-RIAA as well!