Phono preamp. Dealing with ground

[nonost]

Ey guys. I'm gonna build this phono preamp:

http://phonoclone.com/diy-pho5.html

This is the VERIFIED vero I did:



I'm not sure how to do regarding ground stuff. That's a stereo circuit, one input and output per channel. Should I make a cut in the bottom row so each channel has its own ground? And then run wires for each ground. Should I ground the enclosure? The rca connectors are isolated.

BTW, I'm going to use the Bipolar voltage converter (https://tagboardeffects.blogspot.com/2014/01/bipolar-voltage-converter.html) with one 9v battery.

Without the cut both grounds are together...ground issues drive crazy.

Any help is welcome!

[Highsmith]

        I wish I could help, nut I don't know.

I am very interested in this project though, I think I waver built about every pedal I am interested in, time to move on to phono preamps!

[mug]

I'm absolutely no expert here, but my guess is that ground = ground, so no cut required. I'd even speculate that "split ground" would induce problems.

[Travis]

These things usually have a single external ground connection. I would guess that the RCA jacks are not grounded but there should be a single point to connect ground

[nonost]

Ey guys, I've updated the layout.

What I know for sure is that the input rca should use shielded cable. And yeah, no cut at ground row. For the output rca grounds,I will run a wire from the ground row and take it to the rca's ground pin.

I will let you know how it's going.

BTW, should I ground the enclosure?

[Travis]

Yes always ground the chassis/enclosure

[nonost]

It's working :)

I've tweaked the Bipolar Doubler Voltage daughterboard to fit the needs. Just added a couple 12v regulators with two caps to ground (10uf and 100nf ceramic) at the output. This:



What I've done:

1) Input RCAs isolated with shielded cable. Both ends go to the veroboard (input and ground last row).
2) Output RCAs with standard stranded wire. One of them isolated, the other one not.
3) Run a wire from ground row to the isolated RCA output.
4) Join the two RCAs output ground lugs.
5) At the non-isolated RCA output ground lug met the Bipolar 12v Regulated Voltage ground and the battery ground.

I don't know if there is a better way to do it but it's working fine. I have to finish the enclosure and the box it properly.

Cheers!

[Highsmith]

Hi, did you ever get this boxed?

I would love to see some gut shots!

[nonost]

Ey. I'm varnishing the enclosure so it won't take long. But I can tell you it's been a bit of a nightmare. There's not a lot of room for this project in a 1590B enclosure. I can post some veroboard pictures though.

[nonost]

Done it!





Works great!

The big 100uf electro caps are Panasonic FC rated up to 63v, they are big. I wish I had the 35v version.

If you have any doubt do not hesitate.

Cheers!

[Highsmith]

Nice!

I'm going to attempt my own this weekend...

[nonost]

Cool. Let me know how it goes.

I'm quite surprised with this thing, I thought it would be noiser because all the voltage x 4 and then the regulators and all those caps charging and discharging. Not to talk about ground...I can't believe it's working that good.

Now, I've been thinking about a better ground path:

1) Both outputs isolated and their ground lugs connected with the circuit ground only
2) Put a screw in the enclosure (outside) so you can use a terminal ground, and run a wire from it to the amp's ground. Inside of the enclosure you run the:

    -voltage doubler circuit
    -battery ground
    -led -

    all these three to the screw. You can use a nut and nut washer in the inside.

That way you have your audio ground separated from the rest. I think it should work even better.

I'm not using this idea because I want it to work with amps without any ground posts at the outside.

Good luck!

[Highsmith]

OK,  I made it, it fucking rules.

 no noise,  even without using the king-size ground bolt I put on there.

Do you think you could do the other RJM circuits on Vero?

That would be so rad.

[nonost]

Glad it's working!

Which one?

[Highsmith]

If you could Vero the phonoclone without the power supply stuff, ala this:

https://audiokarma.org/forums/index.php?threads/build-a-phonoclone-3-on-a-pcb-powered-by-batteries.395898/

(See pcb pic in middle of page)


That would be super cool...

I would buy you a pair of the boards in thanks!

Cheers,

C

[nonost]

I've been taken a brief look at it and I can't start without knowing first what all those "PADxx" are...

For example: PAD18, PAD19, PAD21 and PAD22. I don't get it, what is that mierda? They are all over the place.

[Travis]

Lol nonost do you happen to live in SoCal? Just noticed your español there. I’m in Anaheim.

[Highsmith]

Thanks, idk either--I should have gone electrical school instead of law school. I suspect it's due to power supply stuff which I plan to avoid by using your 12V Vero unit. Wall power frightens me.

So here is the link for the project: http://phonoclone.com/diy-pho4.html

This is a dual mono project...How does this schematic look?

[nonost]

I encourage you to try it the next time. Start with something easy like a SHO or something. It's actually easier than it looks. I did my first one just months ago.

I've used 5mm spaced caps for the 3nf value. There are some WIMA within 2.5% tolerance with that spacing so it's great for this purpose.

Note that the south opamp is flipped 180º.

I'm not going to build this since I don't have any moving coil cartridge...Do you have any?



Ey Travis! I'm actually a bit far away in Cáceres, Spain. It would be great to go there though!

Cheers.

[Highsmith]

Holy cow, you are the man.

I suppose you don't need any phono clone boards, as you don't have a MC cart, and the clone is Vero'd.

I have a spare Denon DL103r I can send you, it's got some hours on it, but a lot of life left.

Let me know your address, and I'll get it posted next week.