Not sure if the question is addressed to me... or even what FS stands for
My line stage has a 20k attenuator at input. No idea why. Should probably change this to at least 47k.
It is 6H30 running at nearly μ.
Yes it was to you. FS=folded simplistic.
You would prefer 4u7 output cap on 20K. Also try load your cart at 20x its internal resistance or straight to 47K to see about more bass "slam". This phono does not seem to turn harsh enough at higher than usual loading while the MC carts pick up output and bass meantime.
Maybe i did not update on this, but since i got the chokes in the PS, the bass slam has been great. The phono stage is now boxed with sufficient room for more regulators, yes, i still intend to try this out 
Will post some pics once the PS gets also boxed. The tube rectifier fantasy delayed this a bit...
Will post some pics once the PS gets also boxed. The tube rectifier fantasy delayed this a bit...My guess that would make a very slow (high Z) psu. You'd need to shunt it. LC to start with.
Maybe i did not update on this, but since i got the chokes in the PS, the bass slam has been great. The phono stage is now boxed with sufficient room for more regulators, yes, i still intend to try this out
OK then. We will marvel on the pics in due time.
P.S. I had a Balanced Audio Technology Rex preamp for a week to service once in my system, was full of those 6H30s both in signal path and as CCSs or shunt regs. Hi res but rather lean especially in the bass. Maybe its a preamp thing you got to have particularly good bass at the source else it highlights small omissions there?
That's the idea behind the FS release. To offer a simple but competent enough "musical" circuit that works straight away and then have fun shooting for details and customization. You are on the right path.It is probably appropriate to make something clear: i don't do any of this because i feel the FS has any deficiencies or needs improvement; messing around with good stuff is what i enjoy doing
About the 6H30: it can do excellent bass if a cathode follower is included. Not sure if the BAT has a follower, but mine doesn't as i don't like the way it sounds above the bass region.
Anyway, i have had this preamp for much too long, it's days are numbered
Can't remember if it had a follower, probably not. It was years ago. But from a tear down picture I did back then and I dug up now, I can see the 6C45/6H30 shunt options in the center and 6C19 Mosfet CCS loaded blocks daughter boards only.
P.S. That was the PSU, the signal box was surely unistage now I read. So no follower.
Attachments
With a bit of luck I'll have the PSU done tomorrow before the Patriots-Broncos kickoff
View attachment 394694
View attachment 394696
Here's detail of my dropping resistor lash-up. Hitting exactly 50V at about 100mA, but I'm planning another R and C in the other chassis:
View attachment 394695
So tomorrow I'll drill and install a chassis ground screw, and work on the back panel. Fitting the power entry module is the hardest part, especially in a steel chassis. All the rest are round holes, which are easy
Do you use 20 Ohm for RC? Is it not too high? How much is your V drop there?
Salas advised to go for 1 Ohm.
My transformers are rated 36VAC but actually produce over 43VAC, so I need a hefty voltage drop to get the raw supply output down to 50V. Yes, it's about 20 Ohms (12R + 8R2). I will add another small-value resistor in the second chassis to get the voltage down to about 47V. I'm not happy about dumping all this power as heat just because the transformers are 20% out of spec.
My transformers are rated 36VAC but actually produce over 43VAC, so I need a hefty voltage drop to get the raw supply output down to 50V. Yes, it's about 20 Ohms (12R + 8R2). I will add another small-value resistor in the second chassis to get the voltage down to about 47V. I'm not happy about dumping all this power as heat just because the transformers are 20% out of spec.
Mine as well above 50V. It is actually 52.4V/52.6V, but it is not because of my transformer (115V primery, 2x 36v secondary, 100VA). It is because of my AC line. It is 119-121V in stead of 115V. Should I drop it too with RC for about 47V?
No, I do not have such chokes and unfortunately, I have no space in my PSU box for such big chokes. So, I guess I should go for RC. The big question is what value of resistor should I use there?
In addition, resistor before diodes - can you guys explain more what and how.
47R 2W to yet another same type 4700uF/63V cap. So you form CRC. About 100mA X 47R=4.7V loss per channel raw DC line. Put 10K 2W bleeder across that last cap too.
If it is for R input filter, I.e. in line directly after the bridges feeding the existing filter capacitor only forming RC, use 15R 2W since there will be no cap directly to the bridge to hold the full peak voltage of the rectification cycle. Thus, its less efficient. Smooths for EMI in that position too. It rounds off the sawtooth looking charge edges.
If it is for R input filter, I.e. in line directly after the bridges feeding the existing filter capacitor only forming RC, use 15R 2W since there will be no cap directly to the bridge to hold the full peak voltage of the rectification cycle. Thus, its less efficient. Smooths for EMI in that position too. It rounds off the sawtooth looking charge edges.
Nez, stating that your transformers are "20% out of spec" shows you do not understand what you are attempting to build.My transformers are rated 36VAC........ just because the transformers are 20% out of spec.
The Output voltage of a transformer is given by
Vout = Vinput / Rated Vinput * Rated Voutput * [1+transformer regulation] +- manufacturer's tolerance
for a 115:36Vac 100VA transformer with 12% regulation, fed with 123Vac from the Mains, expect
Voutput = 123/115 * 36 * 1.12 = 43Vac +- manufacturer's tolerance
A small EI will have an even higher transformer regulation.
Expect transformer regulation to be between 3% and 30% depending on design and type and VA rating.