Yes, I know, that is why it seems strange.... anyway I found that bypassing the two 4,7u with a smaller (100n) cap, reduced the noise dramatically and it is very stable now.
The strange noise at full volume comes from the bad magnetic isolation of the enclosure I used for this build... moving the case slightly was enough to eliminate the issue
The strange noise at full volume comes from the bad magnetic isolation of the enclosure I used for this build... moving the case slightly was enough to eliminate the issue
Today I have really good news
I removed C103 (47u EL) and placed 1 ohm on R107 and a 4,7u MKP as C104.
With 10k dummy load, I could not reach more than 31v even with the trimmer fully turned. Touching the dummy load made the DMM jump. Placing a 330uCap over the dummy restored normality so I thought that it would work with the folded that has two big caps on the power line... but no, I could not get it to go higher than 28v....
This touch thing made me oscilation suspicious so I placed a smaller EL (47u) on the output of the shunt across the sense lines and bingo... everything came into place.
Sound is more lively with more attack but it is soon to tell.... but now comes the good part..... with the volume full on, I can barely hear a very faint hiss with my ear 5cm from the tweeter.... outstanding.... a real winner. And I am experimenting with the 3 x k170 build (63dB).
I removed C103 (47u EL) and placed 1 ohm on R107 and a 4,7u MKP as C104.
With 10k dummy load, I could not reach more than 31v even with the trimmer fully turned. Touching the dummy load made the DMM jump. Placing a 330uCap over the dummy restored normality so I thought that it would work with the folded that has two big caps on the power line... but no, I could not get it to go higher than 28v....
This touch thing made me oscilation suspicious so I placed a smaller EL (47u) on the output of the shunt across the sense lines and bingo... everything came into place.
Sound is more lively with more attack but it is soon to tell.... but now comes the good part..... with the volume full on, I can barely hear a very faint hiss with my ear 5cm from the tweeter.... outstanding.... a real winner. And I am experimenting with the 3 x k170 build (63dB).
Some pics
Now sound is really good, almost on par with my best builds using V12r.... Not so refined but really good.
What amazes me is the silence...
I can only guess what it would sound like if built with higher q vref and output caps.
Next I will try with two shunts
Fun
Now sound is really good, almost on par with my best builds using V12r.... Not so refined but really good.
What amazes me is the silence...
I can only guess what it would sound like if built with higher q vref and output caps.
Next I will try with two shunts
Fun
Attachments
One more thing.... I am begining to believe the folded works well with everything we throw at it... no need for fancy caps in the riaa.... I am using only ussr caps and it does rival my best builds that use "special" tin foils.
Dynamics are really outstanding.... micro detail is always aparent and that really delineates the bass.
I am getting experienced.
Dynamics are really outstanding.... micro detail is always aparent and that really delineates the bass.
I am getting experienced.
Looks very good Salas!
Maybe you already seen that, but I would put one more hole for the trimmers, a la BIB, in order to accommodate the various pinouts. I like the switchable
input resistors and the tight layout.
Also nice that inputs and outputs are on the back of the board, so to be close on the connectors on the back of the chassis.
Maybe you already seen that, but I would put one more hole for the trimmers, a la BIB, in order to accommodate the various pinouts. I like the switchable
input resistors and the tight layout.
Also nice that inputs and outputs are on the back of the board, so to be close on the connectors on the back of the chassis.