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

[Andy_H]

I have not included the 10pf input caps as they are not necessary IMO, if you need to have a higher shunt capacitance that whats in the tonearm and turntable cables then you can add the difference here. Most carts do not need more than 200pf which is already in the cables and tonearm. If you do want to put them in anyway you can use in order of preference Polystyrene if you can find them, Micas (2 X P/N 338-1061-ND / CAP 10PF 500V MICA RADIAL), or Ceramics (only if all else fails).

I have a question about the 10pf caps. I did not order any as they were not in the BOM, and as I stuffed the board I got to wondering what I was missing. But now I see they are not necessary. So my question is: do I need to put jumper wires in those holes or do I just leave them empty? I'm thinking I just leave them empty but I wanted to check.

Also, another battery heads up. I was at Lowe's yesterday and saw they had 6v lantern batteries (Energizer IIRC) for $3.97 ea. Not as cheap as the others mentioned, but it's option for those of us who don't shop at Walmart. I'm going to run mine on 9v batteries for now, but maybe I'll try the 6v batteries somewhere down the line.

 

[bsabel]

For those who with MyDigi-Key accounts, I have saved the exact BOM HypnoToad posted at #193. Here is the data:

BOM ID: 39226
BOM Name: CNC MM PHONO STAGE

 

[HypnoToad]

I have a question about the 10pf caps. I did not order any as they were not in the BOM, and as I stuffed the board I got to wondering what I was missing. But now I see they are not necessary. So my question is: do I need to put jumper wires in those holes or do I just leave them empty? I'm thinking I just leave them empty but I wanted to check.

Also, another battery heads up. I was at Lowe's yesterday and saw they had 6v lantern batteries (Energizer IIRC) for $3.97 ea. Not as cheap as the others mentioned, but it's option for those of us who don't shop at Walmart. I'm going to run mine on 9v batteries for now, but maybe I'll try the 6v batteries somewhere down the line.

Just leave the empty slots, if you ever get a cart that needs over 200pf of capacitance you can use them then.

The Energizers would be fine, I plan to put four in a separate box and just run a 3 conductor wire to the CNC, in fact I could use it to power different phono stages.

 

[Andy_H]

The more I thought about it I figured I should just leave it empty.

I got all the components on the board, hooked up the jacks, switch and batteries, and as per usual with my projects it only kinda works. :scratch2: I am pretty much baffled as to what the issue might be.

First, I only got sound on the left channel - nothing at all on the right. I figured it might not be anything serious, probably a bad solder joint or broken wire on the inputs or outputs. So I swapped the output interconnects left to right expecting the dead channel to switch as well. Instead, I got full signal on the right and partial (I don't have a way of measuring, but I'll say 50%) output on the left. Switched them back around - full signal on the left, absolutely nothing on the right. Right now I am at a loss to understand how this would be happening, but I'm getting tired and will think on it more tomorrow.

 

[HypnoToad]

The more I thought about it I figured I should just leave it empty.

I got all the components on the board, hooked up the jacks, switch and batteries, and as per usual with my projects it only kinda works. :scratch2: I am pretty much baffled as to what the issue might be.

First, I only got sound on the left channel - nothing at all on the right. I figured it might not be anything serious, probably a bad solder joint or broken wire on the inputs or outputs. So I swapped the output interconnects left to right expecting the dead channel to switch as well. Instead, I got full signal on the right and partial (I don't have a way of measuring, but I'll say 50%) output on the left. Switched them back around - full signal on the left, absolutely nothing on the right. Right now I am at a loss to understand how this would be happening, but I'm getting tired and will think on it more tomorrow.

Can you post a close up pic?

 

[Andy_H]

Can you post a close up pic?

Sure. I'm at work right now but when I get home this evening I'll post pictures. It just seems really odd to me that the one side works only intermittently depending on how the output cables are connected. I would expect the bad channel to stay completely quiet and just swap sides along with the cables.

 

[HypnoToad]

Sure. I'm at work right now but when I get home this evening I'll post pictures. It just seems really odd to me that the one side works only intermittently depending on how the output cables are connected. I would expect the bad channel to stay completely quiet and just swap sides along with the cables.

When you solder the RCA jacks sometimes a strand of wire can touch the end of the RCA plug and short it out, I have had this happen and it causes intermittent loss of sound. It will be something simple like that I am sure.

 

[dodog]

I was creating a BOM at Digikey and a few (actually a lot) of the resistors came back with ominous warnings about the parts being obsolete/not recommended. For example, for the part P8.20KCACT-ND (RES METAL FILM 8.2K OHM 1/4W 1% (LED Loading Resistor)), I get two messages:

14733 STK/BAL OBSOLETE BY MFG
Part is obsolete, not recommended for new design

Should I be looking for different parts? Will I be able to order these? Or, is this just Digikey telling me what's left in stock, that it's an old part that will no longer be carried, etc.?

 

[HypnoToad]

I was creating a BOM at Digikey and a few (actually a lot) of the resistors came back with ominous warnings about the parts being obsolete/not recommended. For example, for the part P8.20KCACT-ND (RES METAL FILM 8.2K OHM 1/4W 1% (LED Loading Resistor)), I get two messages:

14733 STK/BAL OBSOLETE BY MFG
Part is obsolete, not recommended for new design

Should I be looking for different parts? Will I be able to order these? Or, is this just Digikey telling me what's left in stock, that it's an old part that will no longer be carried, etc.?

They have 14,732 of these in stock. Just look at the quantity available box.

Just warning you that this is all they have in stock and new ones will either be a different part number or not made by this manufacturer in the future.

As long as they can supply what you want just ignore the messages.

 

[ghazzer]

I just completed my CNC order, plus the transistors and diodes for the bias diode retrofit of my Sansui 5000 and never saw a single warning like that.

The only anomaly was that the minimum order for the 3.83KXBK-ND was 5, so I'll have an extra one.

I guess that you really need to watch which of the jillion options that you finally select.

.

 

[Andy_H]

Well, I took pictures and was in the process of uploading them when, as usual, the simple and obvious problem that was right under my nose the whole time finally became apparent to me. I had the signal and ground wires for the right channel output reversed at the board. Got those put right and now there is nice balanced sound on both channels. :thmbsp:

I'm going to spend some time listening now and report some impressions later. Sometime in the next few days I'll have to get the assembly and the enclosure cleaned up and finalized as it's still in more of a 'test fit' state right now. I'm just glad it's working now. Thanks for the cool project and 'tech support' Hypno! :thmbsp:

 

[Andy_H]

I've been listening for the past couple hours and I'm very happy with the sound thus far. It's clean, clear and quiet. The sound is quick, detailed and precise. I like it!

 

[FrankPA]

I'll take one (to start), if there are any left.

 

[sachu888]

I've been listening for the past couple hours and I'm very happy with the sound thus far. It's clean, clear and quiet. The sound is quick, detailed and precise. I like it!

Very nice looking enclosure.I am waiting for my PCB and parts from Digikey.Thanks HT for inspiration.

Regards,

Sachin

 

[HypnoToad]

I've been listening for the past couple hours and I'm very happy with the sound thus far. It's clean, clear and quiet. The sound is quick, detailed and precise. I like it!

After it has about 30 hours plus break-in, it really opens up.:yes:

Neat case, can you post details for others?

 

[dodog]

I just completed my CNC order, plus the transistors and diodes for the bias diode retrofit of my Sansui 5000 and never saw a single warning like that.

The only anomaly was that the minimum order for the 3.83KXBK-ND was 5, so I'll have an extra one.

I guess that you really need to watch which of the jillion options that you finally select.

.

I just copy/pasted the BOM that HT listed into the excel file that Digikey provides as a template, then uploaded. Not sure what option I selected to give the warnings.

 

[bsabel]

I got the warnings, too. They list the part as "obsolete" but they actually mean "discontinued." I checked the data sheet and everything checks out. I originally had some concern about them but after a little investigation I was pretty comfortable with it.

 

[sachu888]

I got the warnings, too. They list the part as "obsolete" but they actually mean "discontinued." I checked the data sheet and everything checks out. I originally had some concern about them but after a little investigation I was pretty comfortable with it.

I didn't get any warning when I ordered parts on Digikey.

Regards,

Sachin

 

[Andy_H]

After it has about 30 hours plus break-in, it really opens up.:yes:

Neat case, can you post details for others?

The case is by Velleman. I bought it at a local electronics shop. I'm not sure of the exact model but I think it is this one. It works well and I like the overall appearance but note that everything just barely fits in it. I still need to get some standoffs for the board and secure the batteries as right now everything is just sitting loose inside the box.

 

[HypnoToad]

I got the warnings, too. They list the part as "obsolete" but they actually mean "discontinued." I checked the data sheet and everything checks out. I originally had some concern about them but after a little investigation I was pretty comfortable with it.

If you put in P8.20KCACT-ND for example you will see a notice at the top of where you put in the quantity to be ordered:

"Limited quantity available, not recommended for new design."

There is nothing wrong with these parts, it's a warning they will either be discontinued or will have a new part number in future. If you were a company and going to build thousands and thousands of CNC's using this part they are warning you there won't be an endless supply.

You will also see this message to the right:

Possible Substitute
* S8.2KCACT-ND

Which gives you an alternative part to order.

So in future we may have different part numbers or be using parts from different manufacturers.