Its true that most later Leds measure lower than those I used in the FSP prototype and noted their forward voltage drop in its pdf guide. Its also true that such differences never created a practical problem with correct stage biasing or adjusting T.P.
Little lower VDS created across the 2SK369s by the four Leds Vref vs the prototype is also safer for not promoting Igsx (gate leakage current).
Little lower VDS created across the 2SK369s by the four Leds Vref vs the prototype is also safer for not promoting Igsx (gate leakage current).
This looks good. (As good UFSPs use to look) 
Just a cautionary nag: I would improve the shield between the raw PSU and the UFSP. Mine, built in a separate box, needed quite some distance from any transformers—like 50 cm and 2 metal shelves—to not pick up annoyingly much hum. It’s still picking up a little bit, but not disturbing anymore…
Just a cautionary nag: I would improve the shield between the raw PSU and the UFSP. Mine, built in a separate box, needed quite some distance from any transformers—like 50 cm and 2 metal shelves—to not pick up annoyingly much hum. It’s still picking up a little bit, but not disturbing anymore…
Yeah i was doubting about the supreme audio transformer from toroidy, but it was almost twice the price of the normal audio, and only adding the stainless cap and some resin. The rest of the construction is the same.
I have been thinking about adding a stainless steel cup over it, or putting the transformer in one of those small aluminium boxes separatly and then add it to the chassis. Also have been thinking about adding a second strip close to the shunt boards, leaving an airspace in between.
Any other suggestions that may improve the shielding?
Btw i see you have a lowMC as well (0,25mV). My current cartridge is a 2M bronze (5mV) so i guess this will help with reducing the hum as well for now. Allthough maybe i will some day switch to an MC, so if there are things i can improve, i will try.
I have been thinking about adding a stainless steel cup over it, or putting the transformer in one of those small aluminium boxes separatly and then add it to the chassis. Also have been thinking about adding a second strip close to the shunt boards, leaving an airspace in between.
Any other suggestions that may improve the shielding?
Btw i see you have a lowMC as well (0,25mV). My current cartridge is a 2M bronze (5mV) so i guess this will help with reducing the hum as well for now. Allthough maybe i will some day switch to an MC, so if there are things i can improve, i will try.
I somewhere read about tin cans being very effective….
ZM once mentioned it here, thought that was a joke, but on another just as serious forum somebody said that too, but I can’t find it anymore …
(Citing from groupdiy.com: „mu metal if your pockets are deep, but i think regular old hot rolled 20 ga would be fine.“ )
ZM once mentioned it here, thought that was a joke, but on another just as serious forum somebody said that too, but I can’t find it anymore …
(Citing from groupdiy.com: „mu metal if your pockets are deep, but i think regular old hot rolled 20 ga would be fine.“ )
Hi Salas and all,
Apologies for not being around lately.
Due to illness my pre amp has had to take a back seat for now.
I'm presently recovering from 'by-pass' surgery, so wont be back in action until around the new year . In the mean time could anyone recommend a decent enclosure please, I'm struggling to find one.
Seasonal Greetings to all
Roy
P.S. @Thiez - may I ask where you sourced your enclosure and phono plugs etc from ?
Apologies for not being around lately.
Due to illness my pre amp has had to take a back seat for now.
I'm presently recovering from 'by-pass' surgery, so wont be back in action until around the new year . In the mean time could anyone recommend a decent enclosure please, I'm struggling to find one.
Seasonal Greetings to all
Roy
P.S. @Thiez - may I ask where you sourced your enclosure and phono plugs etc from ?
My enclosure is a hammond chassis, nice chassis for a good price. I ordered it from www.tubetown.de i think they also have RCA phono conmections.
The phono plugs are from a dutch electronics store (www.eoo-bv.nl)
The phono plugs are from a dutch electronics store (www.eoo-bv.nl)
I used the „galaxy“ cases from modushop,
2U 124 x 170 for the raw PSU (this makes for a really crammed box!)
2U 330 x 170 iirc for the RIAA board, which gave me options of board-arrangement, although when orientated with in/out on the back, there’s no space left…
(Couldn‘t find a pic of the boards in the enclosure, but… you get the picture pun pun)
https://modushop.biz/site/index.php?route=product/category&path=25_291_293
2U 124 x 170 for the raw PSU (this makes for a really crammed box!)
2U 330 x 170 iirc for the RIAA board, which gave me options of board-arrangement, although when orientated with in/out on the back, there’s no space left…
(Couldn‘t find a pic of the boards in the enclosure, but… you get the picture pun pun)
https://modushop.biz/site/index.php?route=product/category&path=25_291_293
Attachments
Last edited:
What will be the best approach for grounding in a single chassis?
Im thinking a chassis ground at the AC power inlet, also add the RAW ground and the transformer ground to this.
Isolate the inputs, outputs and phono ground from the chassis, only connecting it to the preamp boards in, out and ground?
Or is it better to have the inputs, outputs and phono ground connected to the chassis?
Im thinking a chassis ground at the AC power inlet, also add the RAW ground and the transformer ground to this.
Isolate the inputs, outputs and phono ground from the chassis, only connecting it to the preamp boards in, out and ground?
Or is it better to have the inputs, outputs and phono ground connected to the chassis?
Hi Salas, I'm collecting the components for a future FSP Ultra build.
I've no problem to find the 2SK170BL in the desired Idss (around 8- 8,5mA), but I only have 2SK369 in V grade, and well matched pair around 19,5mA Idss. Are they usable? If so, do I need to change some resistor values (I imagine R2, R3)?
Conversely, I have a nice quad of 2SK170BL at Idss 11,15mA
Thank you for your advice
G.
I've no problem to find the 2SK170BL in the desired Idss (around 8- 8,5mA), but I only have 2SK369 in V grade, and well matched pair around 19,5mA Idss. Are they usable? If so, do I need to change some resistor values (I imagine R2, R3)?
Conversely, I have a nice quad of 2SK170BL at Idss 11,15mA
Thank you for your advice
G.