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Hi Buzz
If you can't get a Gieger to test the 1R's...
...see if they 'fog' normal 35mm film through the can...
...if not...they're 'probably' ... 'fairly safe'.
Si.
No... small coils... I experimented with typical mains socket (filtered) and removed it.
After that I experimented with a bigger filter (Monster mains bar) and the impression was the same.... somehow blacker - darker background but diminished dynamics and muffled highs.
After that I experimented with a "High End" mains filter from Goldenote "Dumbo – AC Power Filter" Dumbo ? AC Power Filter
This time the black background effect was even deeper and the diminished dynamics effect was less pronouced but still there.... So I decided not to use coils.
As a matter of fact, even he small 2r I use in the psu between the caps to drop some voltage is nocive IMO.... but not so nocive as the coils.
After that I experimented with a bigger filter (Monster mains bar) and the impression was the same.... somehow blacker - darker background but diminished dynamics and muffled highs.
After that I experimented with a "High End" mains filter from Goldenote "Dumbo – AC Power Filter" Dumbo ? AC Power Filter
This time the black background effect was even deeper and the diminished dynamics effect was less pronouced but still there.... So I decided not to use coils.
As a matter of fact, even he small 2r I use in the psu between the caps to drop some voltage is nocive IMO.... but not so nocive as the coils.
What about few mH speaker like coil in the rectification & main cap filters side, did you ever try anything like that?
This is all very interesting information.
My mains-filter impressions have not been favourable either.
I hope to experiment more with this, in the coming months.
Looking at other forums, the Pass one for example...
...there's quite a lot of comment on similar issues.
Some want to throw-in every conceivable-concept imagined, to somehow 'conceptualy' improve things like PSU performance of amps.
Same deal here, except this amp is about a zillion times more prone to noticable irregularities, as are all low-level amps & interestingly microphones
( perhaps, worse than power-amps, is what I'm getting at ).
It's quite interesting to check out how the PSU's were done in old-fashioned microphone designs; such as the AKG C12 & Neumann U47 + U67.
Worth a look; schematics easily Google-able.
What we see here for the most, are very simple 'uncluttered' power supplies.
Same as the recent vGeorge report...
...interesting...the plastic amp bypass caps, were, on sonic-grounds, omitted.
'Concepts & theorys' would say, fit them.
OK we've heard it all before...
...but more mains-filters, Tx's, boxes, umbilicals, pre-regs, inductors, resistors & multiple cap-signatures; could possibly be just seen as 'more junk' all connected up, for what reason ?...
...possibly 'conceptual', rather than sonic...
...adding ( certainly not always, subtracting ) it's 'thing' to the mix.
Mmmm...
Cheers.
Si.
KISS ( my amp ! )
My mains-filter impressions have not been favourable either.
I hope to experiment more with this, in the coming months.
Looking at other forums, the Pass one for example...
...there's quite a lot of comment on similar issues.
Some want to throw-in every conceivable-concept imagined, to somehow 'conceptualy' improve things like PSU performance of amps.
Same deal here, except this amp is about a zillion times more prone to noticable irregularities, as are all low-level amps & interestingly microphones
( perhaps, worse than power-amps, is what I'm getting at ).
It's quite interesting to check out how the PSU's were done in old-fashioned microphone designs; such as the AKG C12 & Neumann U47 + U67.
Worth a look; schematics easily Google-able.
What we see here for the most, are very simple 'uncluttered' power supplies.
Same as the recent vGeorge report...
...interesting...the plastic amp bypass caps, were, on sonic-grounds, omitted.
'Concepts & theorys' would say, fit them.
OK we've heard it all before...
...but more mains-filters, Tx's, boxes, umbilicals, pre-regs, inductors, resistors & multiple cap-signatures; could possibly be just seen as 'more junk' all connected up, for what reason ?...
...possibly 'conceptual', rather than sonic...
...adding ( certainly not always, subtracting ) it's 'thing' to the mix.
Mmmm...
Cheers.
Si.
KISS ( my amp ! )
When i switch my source selector to the one where Simplistic is connected i hear and see (on the woofer) a loud pop. I suppose this is happening because of output capacitor remains charged. What should i do ?
See if it has any dcmV when not selected. There is 1meg to ground at cap's out side not to do that. What type of cap?
After moving output cap outside of pcb forget to move also the 1M output resistor. I will do this and check if problems still persist.
I'm using russian K75-10 2.2uf capacitors.
I'm using russian K75-10 2.2uf capacitors.
Salas, referring to the latest RIAA folded cascode sch, what's the purpose of R4 2,2kohm?
It's a load for the f.c. itself or whatever? 😕
Thank you!
It's a load for the f.c. itself or whatever? 😕
Thank you!
to allThank you Ricardo. The low value puzzled me a bit. Thus this R is affecting (lowering I guess) the o/p impedance of the front end and the riaa network as well.
After reinstalling the resistors check DCmV on those NOS hybrid caps (output side to GND) to see if they could be leaky also or not.
OK,
I am winding up things chassis-wise. Here are a couple of teaser photos. I will post some more in a few days.
First learning experience: I had a bolt through the toroid trafo that touched the chassis. (I've never used a toroid before.) Had a 20 volt difference between circuit ground and safety ground. I'll get a nylon bolt.
Dumb question: where can I hook an indicator LED without messing up the circuits? The resistors I have in the raw PS drop less than a volt.
Thanks. More to come.
Doug
I am winding up things chassis-wise. Here are a couple of teaser photos. I will post some more in a few days.
First learning experience: I had a bolt through the toroid trafo that touched the chassis. (I've never used a toroid before.) Had a 20 volt difference between circuit ground and safety ground. I'll get a nylon bolt.
Dumb question: where can I hook an indicator LED without messing up the circuits? The resistors I have in the raw PS drop less than a volt.
Thanks. More to come.
Doug
Attachments
Hi Salas,
I have already built your RIAA Jfet a year ago.
The project has had an update or is it always the same?
Regards
I have already built your RIAA Jfet a year ago.
The project has had an update or is it always the same?
Regards