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Pearl phono PCBs Group Buy

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That sounds absolutely nice, Promitheus - I'll take three sets in pre order - no matter the look ! I use small standoffs with 3mm internal threading, so I am playing with the idea of using those to stack on top of each other, so I can mount the MC input board directly on top of the MM input stage.

Cant wait to se your outcome !!


Keep it up...
Cheers !
Hans
 
Hi,

I am working on the board and almost have the Layout done.
I am still trying to find a solution on how to mount the MC Stage ontop of the Pearl.

What did you have in mind?

It wil also be alsmot as tall as the Pearl itself because it has 3 same 3300uF capacitors like on the Pearl.
I used the circuit from the Aleph Ono with Gain selection and buffer at the output.

See attachment below.
 

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Here is the bottom layer
 

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Hello Ilias - I think it looks good, although I dont have very much experience in judging PCB layout - nice with groundplane covering everything... Also nice with the "mouse piano" for adjusting input impedance....

About the stand off problem, I have assembled a small mock up showing the idea I had using PCB standoffs stacked on top of each other. You will need about 34mm to get clear of the 3300uF caps, that seems to be the tallest part around the input stage - each standoff I use on the picture is 12mm high, thus three should do th trick - this is only to show my idea.


Cheers !
Hans
 

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My Pearl box is pretty big: 8 x 12 x 3 inches, but I don't think there will be room for these boards. All the floorspace in the box is taken up with the Pearl PCBs, so my only choice would be to stack the MC boards. But if they have more of the 33000 caps standing vertically, It will be very tricky to fit it in the 3 inches of height.

Is it possible to make the caps lie flat, instead of standing up?

Hans, are you thinking of having the caps between the two PCBs?
 
I was thinking that it could stack above the input stage of the Pearl. The Pearl components there are not very tall.

The MC inputs and outputs would be above the MM input pads on the Pearl. The power connection would be at the other end. Perhaps there's a spot on the Pearl PCB where a second mounting hole could be drilled, that would align with one on the MC board.
 
If it can be got down to about 100mm x 60 mm, it would fit above the input area of the MM board, and would be much more convenient.

Here's an edit of your component layout to show what I mean. Put all the power components at the right end of the board. Put both the input and output at the bottom left, near the input pads of the Pearl MM board.

I currently can't attempt to lay this out, so of course it may be impossible. But it's worth a try.

Also, is all that extra regulation needed? Isn't the regulated supply from the MM board enough, perhaps with just a small RC filter on the MC board? If so, you could eliminate c4, c5, r19, r18, q6, and c13.

An externally hosted image should be here but it was not working when we last tested it.


What do you think?
 
Well theoreticaly it could be done but practicely its almost impossible.
One more reason that the board is so big is because I made space on the board for a 10uF MKP at the output instead of the 220uF in parallel with the 47nF ( thats C11 and C12). This 10uF cap is soldered to Pads Cap1 and Cap2.
If this isnt needed then the board can become smaller.
The regulation must stay because its needed for low noise levels of the MC preamp.
What do you guys think?
 
If there's a switch on board, then perhaps it would be best to connect both MM and MC inputs to the MC board, and use the switch to route either the MM input, or the output of the MC, to the MM input of the Pearl.

But folks might prefer to have a switch on the back panel of their Pearl box. The wiring for that would be much more ugly. In this case, the MC input would run from the RCA connector, to the MC board, then back to the switch. The MM input would run from the RCA connector to the switch.

Do you have a copy (or link) of the Ono schematic? I've been looking, but can't find it. I thought I had it at one time.
 
It's OK. I finally found it. It was on my work computer, but not my home one.

I think the dip switch (like the Ono) to bypass the MC stage would be a good idea.

I was thinking of a design for 2 turntables connected at once, one MM and the other MC, and a switch to select between them. But that's probably way to complicated for most folks.

I will have to mount the MC boards in a separate box, as they won't fit in my Pearl box. Maybe I could run an extra cable from my Pearl unregulated supply.
 
So I made a new version of the board.
It can be mounted on top of the Pearl board.
You can use the same screw in the below right corner of the Pearl board.
Then you need a hole on the Pearl board between C5 and C9.
In the other corners you cant make holes but you can use Pcbs mounts which are glued.
 

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