Just placed my Digi-Key order for the power supplies, LT4320/MosFET rectification and 47000uF > 0R2 > 47000uF times four. I should be able to start assembling the PCBs soon, once the metalwork is sent off to be tarted up.
I'm still mulling over adding a volume control. I was going to use a spare Muses module but it seems to be dead so I may put together a shunt switched attenuator.
I'm still mulling over adding a volume control. I was going to use a spare Muses module but it seems to be dead so I may put together a shunt switched attenuator.
do not - volume
even if Rin of SissySIT is highish, so not burdening preceding stage at all (and you can up input shunt resistor up to 330K without engaging brain at all) , you'll clearly hear anything detrimental in signal chain in front of Sissy
it deserves best you can give it, and passive connected attenuator in front of it - simply isn't that
why removing it from box later, and dealing with hole patching
even Muse, if not buffered properly, is Kiddie thing
even if Rin of SissySIT is highish, so not burdening preceding stage at all (and you can up input shunt resistor up to 330K without engaging brain at all) , you'll clearly hear anything detrimental in signal chain in front of Sissy
it deserves best you can give it, and passive connected attenuator in front of it - simply isn't that
why removing it from box later, and dealing with hole patching
even Muse, if not buffered properly, is Kiddie thing
OK ZM, not having a volume control makes the build simpler but what is your thinking for "it deserves best you can give it"?
The conventional options I'll have to hand will be a 2P29L tube preamp (about 20dB gain) or a buffered passive preamp (vintage BUF-03 buffer) - both have Muses volume controls.
Alternatively...
I only use a digital source, DSD based with HQ Player, which has a properly implemented software volume control. I have DSC2 and ValveDAC decoders (both of which have Lundahl LL1684 transformers on their outputs) though their output levels are lower than most digital sources at around 0.6V RMS (IIRC).
The conventional options I'll have to hand will be a 2P29L tube preamp (about 20dB gain) or a buffered passive preamp (vintage BUF-03 buffer) - both have Muses volume controls.
Alternatively...
I only use a digital source, DSD based with HQ Player, which has a properly implemented software volume control. I have DSC2 and ValveDAC decoders (both of which have Lundahl LL1684 transformers on their outputs) though their output levels are lower than most digital sources at around 0.6V RMS (IIRC).
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best you can give it
and that is not non- buffered attenuator, in same case with amp
you'll manage, I'm sure
and that is not non- buffered attenuator, in same case with amp
you'll manage, I'm sure
Am I missing something? SissySIT has a buffer stage in front of the transformers so wouldn't something like a switched attenuator be buffered by it?
Sorry if this is obvious to many others but I've still a lot to learn, in fact I'm still learning just how much I have to learn!
Sorry if this is obvious to many others but I've still a lot to learn, in fact I'm still learning just how much I have to learn!
well, that will work (you wrote exact reasons)
fact is that I'm used on standalone line stage and sometimes I'm simply forgetting that some other ppl are completely happy using just one source
in that case, go for it, you're buffered
fact is that I'm used on standalone line stage and sometimes I'm simply forgetting that some other ppl are completely happy using just one source
in that case, go for it, you're buffered
Some more porn for your edification...
To answer the question about the PS arrangements, here are some pictures withthe toroid temporarily in place. The 'Cap Bank' PCBs will be mounted on the opposite side of the channel section, you can see some of the holes for the stand-off bolts and the wiring feed through.
To answer the question about the PS arrangements, here are some pictures withthe toroid temporarily in place. The 'Cap Bank' PCBs will be mounted on the opposite side of the channel section, you can see some of the holes for the stand-off bolts and the wiring feed through.
Thanks Ray,
Looking very nice! I think the layout is fantastic. Where are you mounting the input and output terminals?
Jon
Looking very nice! I think the layout is fantastic. Where are you mounting the input and output terminals?
Jon
Agreed! SissySIT is an 'end game' amp contender.
I do park the Class A Papa-amps in the hotter months though and have been looking for cooler alternatives but I'm mostly headphones this summer.
I do park the Class A Papa-amps in the hotter months though and have been looking for cooler alternatives but I'm mostly headphones this summer.
My chassis metalwork is all but done so I'll be taking it off to be anodised on Tuesday. I've now started to assemble the electronics, today I started on the power supplies, four of Prasi's LT4320 rectifier boards assembled and tested and some big caps going onto the cap bank PCBs..
With a bit of reshaping of some header pins the LT4320 active rectifiers sit nicely on the Cap Bank PCBs.
DC supply noise spec
I am looking at my power supply and testing out a few options. First up is a cheapo SMPS driving a DIYAUDIO CRC board with 88mF per rail.
I am seeing around 10mV of 50Hz noise bleeding through from the SMPS. What is the supply noise spec for the SissySIT? Should I keep looking to reduce/ change to iron or is this low enough?
Top trace is output from CRC filter, 5mV/div.
I am looking at my power supply and testing out a few options. First up is a cheapo SMPS driving a DIYAUDIO CRC board with 88mF per rail.
I am seeing around 10mV of 50Hz noise bleeding through from the SMPS. What is the supply noise spec for the SissySIT? Should I keep looking to reduce/ change to iron or is this low enough?
Top trace is output from CRC filter, 5mV/div.
Attachments
never bothered even to look with scope
33m-0R1-33m being my standard for long time
it works, so I'm not thinking
33m-0R1-33m being my standard for long time
it works, so I'm not thinking
Wanted to poke my head in here 
and mention that my current configuration is sounding REALLY nice. Sissy seems to have enough guilty pleasure on it's own, so I wanted to try something really clean in front of it. Wayne's LS has just the right amount of gain in stock form, super low distortion, and direct coupled..... I'm thinking of rebuilding it and going full dual mono with Jung/Didden regs to see if it can be taken even further (maybe even going with completely separate power company substations... well maybe not...)
and mention that my current configuration is sounding REALLY nice. Sissy seems to have enough guilty pleasure on it's own, so I wanted to try something really clean in front of it. Wayne's LS has just the right amount of gain in stock form, super low distortion, and direct coupled..... I'm thinking of rebuilding it and going full dual mono with Jung/Didden regs to see if it can be taken even further (maybe even going with completely separate power company substations... well maybe not...)