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Another Super High End Phono Stage! No expense spared...

Onebean said:
Very nice @Dux !

Sachin offers a power supply board that works great with CNC.

Where did you purchase your opamps?
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Yes, I have bought from Sachin that psuboard also.
Opamps where purchased from Farnel before they become obsolete. The main reason to build this phonostage is that I already have opamps.
 
You may try swapping Opamps. I would suggest in same types of pairs. There are some members posted their experience about mix n match opamps, but they always returned to having same opamps in both stages.
For start, you can try NE5532 in both the stages as you already have them.

Regards
Sachin
 
rothwellaudio said:
What makes you believe that?
A higher psu voltage will increase the maximum output before clipping, but "more dynamic"? If the circuit isn't clipping at present, how would it become more dynamic?
Click to expand...

Yes, you are right. I had headroom in mind when I wrote this.
 
Onebean said:
I originally operated my CNC on batteries. When I switched to Sachin's PS board (called OPS I think), the only difference I noticed was the convenience of not having to swap batteries. I don't claim to have a golden ear, but I don't remember there being any real difference.
Click to expand...

I have a Allo streamer based on Pi3 which is powered by battery. When switch on Allo shanti progres was hearable.
That's the reason why I'm also expecting progres with dedicated psu on phonostage.
...maybe I'm wrong.
 
Good day, folks.
I'm wondering if someone could advise me whether I can mount the DC jack and the DPST switch directly on chassis? The original CNC manual say that both must be fully isolated from chassis/enclosure, however the ones I bought are "panel mount". I would assume that they can go on the panel and they are somehow insulated but correct me if I'm wrong.
They look like this and below are the links to their description.
Thanks in advance!




Swicth jack.jpg
 
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ZeRask said:
Good day, folks.
I'm wondering if someone could advise me whether I can mount the DC jack and the DPST switch directly on chassis? The original CNC manual say that both must be fully isolated from chassis/enclosure, however the ones I bought are "panel mount". I would assume that they can go on the panel and they are somehow insulated but correct me if I'm wrong.
They look like this and below are the links to their description.
Thanks in advance!




View attachment 2927928
Click to expand...
You can mount them on panel.

Regards
Sachin
 
Dear AK,

I have read through all 159 pages, honestly I am a bit confused about it, but is the gist :
1. Print circuit board by skrodahl - https://audiokarma.org/forums/index...o-expense-spared.371889/page-119#post-9300015
2. Buy materials and just populate (1) - https://www.audiokarma.org/forums/i...no-expense-spared.371889/page-10#post-4858571

I am just aiming to have a simple DIY phono with batteries.

I apologize if this is obvious from the pages, just want to make sure. Thank you very much!
 
ngdilin said:
Dear AK,

I have read through all 159 pages, honestly I am a bit confused about it, but is the gist :
1. Print circuit board by skrodahl - https://audiokarma.org/forums/index...o-expense-spared.371889/page-119#post-9300015
2. Buy materials and just populate (1) - https://www.audiokarma.org/forums/i...no-expense-spared.371889/page-10#post-4858571

I am just aiming to have a simple DIY phono with batteries.

I apologize if this is obvious from the pages, just want to make sure. Thank you very much!
Click to expand...
Well, there are several circuit board options. I don't think it makes much difference other than which components will fit well.
If you're in the US, my bill of materials is probably a bit more up to date. Although, I may have some parts that aren't necessary for other boards.
Check out my BOM and RIAA spreadsheets https://www.thingiverse.com/thing:5347188/files

My suggestion is maybe use Sachin's boards if you're using larger components. If you want a physically smaller build, my layout is worth trying.
 
Another one built
xymdKLo.jpg

VJRDzoC.jpg

p80vSSJ.jpg


Regards
Sachin
 
Hey, can anyone post the dimensions of the CNC phono boards that Sachin sells?

I think I might have the perfect donor chassis with nice regulated 15-0-15vdc power supply already in it. Just need to make sure the CNC pcb will fit into the existing space.

Thx.
 
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dogwan said:
Hey, can anyone post the dimensions of the CNC phono boards that Sachin sells on Etsy?

I think I might have the perfect donor chassis with nice regulated 15-0-15vdc power supply already in it. Just need to make sure the CNC pcb will fit into the existing space.

Thx.
Click to expand...
Hi
CNC phonostage PCB dimensions 107 mm* 76 mm
Power supply 100 mm* 63 mm

Regards
Sachin
 
Here's mine. For a chassis I re-purposed a dead Keces USB dac. The PS section was still good and puts out a nicely regulated 15-0-15 DC supply. I figured if it was good enough for digital it would be good enough for a phono sections. So I cut off the PS end of the PCB board. That also left an unused 9v single ended supply voltage so I reconfigured the pads for an LED with a current limiting resistor. Then just needed to add a 2nd set of RCA's, a ground post, and stand-offs to hold the CNC board.

Just had time to test if for a few minutes tonight and it works. At first I had some nasty 60hz hum and I knew I was taking a chance on that transformer being so close to the phono stage. But then I tried a cheater plug and most of the hum disappeared. When it was a DAC the chassis was floating not connected to the mains earth. So I had added a connection between the chassis and earth, but now I realize that was a mistake.

I'm still planning on adding a shield partition between the transformer and the PCB's. But it's totally listenable as is. Plus my living room deck is running a MC. I tried moving the Denon SUT around and it was definitely picking up some interference. I bet if I move some components around and run a straight MM it will get even quieter.

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Today I removed the earth to chassis connection and added a copper partition. Much quieter. Any 60hz hum is pretty much gone. There is some hiss at full volume, but at listening levels it's virtually silent.

Also, I had the TT ground post isolated from the chassis and only connected to the ground plane of the CNC PCB. I played around and found connecting ground post electrically to the now floating chassis as well as the PCB further dropped the noise floor. It was negligible, but every little bit helps.

I think I'm going to order from Permalloy stick on sheets and make that partition a Mu-Copper-Mu sandwich. Right now the partition is just wedged in so I need to figure out how to make it more permanent at some point.

Now I'm just need to get it hooked up and play for a while before I try upgrading the OpAmps. I also have some nice film caps for the output coupling cap positions, and some Silmic II's for the 6x 10uf electrolytic caps.

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I am running a college project (building a phono pre-amp) and am basing it of this CNC circuit, any cheap op-amps that can drop in for NE5532? It is sadly out of stock locally. TL072? LME49720 is a bit too high as it may blow the project budget.

Good thing I bought them couple of months ago for my personal CNC.
 
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