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

Finished my build a few weeks ago and am really impressed at how nice the phono pre sounds. :beerchug: I'm using it with various LOMC cartridges and SUT's.

I assembled it with all std parts, pretty much as per the Mouser BoM except:

-I used one of those filtered IEC input sockets
-I'm going to try 2.0uF 200v KBG output caps.
-I'm going to use a mix of SGM/SSG/KSG RIAA caps in lieu of the 'stock' caps in there right now. It'll help me sleep at night.

Once I get all those somewhat large Russian kaps sorted out I'll know what size case to use. Right now it's all on a pc of plywood.

For a power transformer I used a PCB mount Stancor TG2H-24 (24vct @ 100mA or 12v @ 200 mA). Is anyone aware of a PCB that may be available to mount the transformer? There are mounting holes on the PT and I can solder directly to the pins, but a ready made PCB would be neater and easier.
 
Glad you like it!

Most everyone has been pleased with their work and enjoyed putting the CNC together. Most have put personal touches into whatever enclosure they have chosen, or designed, so there are rarely any two that look alike. Sounds like yours might need an onion dome to hold all those Russian caps.
 
new build and no sound. Are there some tests I can perform to find out where the problem lies?
 
Double check that all your connections are good and tight, no shorts or soldier bridges, coninuity between the board and jacks is good with no shorts between signal lead and ground, basically make sure that the work you did was completed correctly without shorts or opens. Maker sure that the orientation of the op amps is correct, not just to the socket but to the circuit as well. Check to see that the power supply is getting the right voltages to the board.

that is the starting point.
 
Thanks . Been messing with this most of the day. Everything looks good to the eye. Is there something I can check with voltmeter? This is my 4th one. The other 3 run fine.
 
Check that you have the incoming DC voltage on the power pins on each chip. Then, as Shelly suggested, check from the RCA jacks to the circuit board for continuity. You should read less than an Ohm.

If this is Ok, check from the RCA jacks to the chip. When doing this check to the leg of the chip on top of the PCB.

You didn't mention if you checked the orientation of the chips. Maybe post a picture of the top and bottom of your boards.
 
.3 ohm measured from RCA to boards. Over 14v to the power pins. RCA to chip measurement? When I make this measurement voltage starts out good then falls. Measurement taken on the same pins, the 4 corners.Help appreciatedDSC_0323.JPG
 
Why the resistors next to the large caps (r30) are mixed? Error on the PCB or mixed resistors? (150 ohm and 3k32?)
 
Don't know if it's an optical illusion of the photo, but r30 in the lower right looks kablooey. And the 3k32 above looks like a 150r as compared to the same resistors on the other channel.

elnado you're just too quick of me...
 
A couple of checks for shorts:

At each RCA jack, measure resistance between center connector and shield, Input should measure your input load, probably 18K if I read the switches right. Soes you cartridge call for 18K? Most carts like 47K. Output should be very high or open. Low readings indicate a short to ground which would need to be traced and fixed.
 
All:

Given the changes that the forum has undergone and the policy shift that Photo Bucket did a while back, this thread no longer seems to include the final schematic of the circuit. If someone has that, would they please be kind enough to post it.

Many Thanks.

Shelly_D
 
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Thanks. It's up and running. I'm using 18k on a Grado Z2+/8mz. Haven't got a clue why it started working. Took a nap Sunday and when I awoke, it was working.:dunno:
 
Thanks. It's up and running. I'm using 18k on a Grado Z2+/8mz. Haven't got a clue why it started working. Took a nap Sunday and when I awoke, it was working.:dunno:
I've heard of sleep walking, but sleep repairing?????:beerchug:

Glad its working.
 
Hello to everyone in this thread. I just completed my CNC build, this weekend and wanted to share my thoughts. I got my board from Sachin, and ordered all my parts from Mouser. I used an aluminum card case I bought on eBay to house it. I built the CNC just as the bill of materials outlined, with the exception of using 1uF Russian PIO caps in place of the Wima caps. It went together smooth, and once I hade it built and tested it and it worked fine. I pulled it back out of my system, and hooked it to my FryBaby to burn in on the moving magnet setting for 36 hours. After the 36b hour burn in, I reinstalled it and began doing some critical listening. I routinely listen to Fleetwood Mac’s dreams when evaluating component changes. The CNC sounded good, and I proceeded to listen to 3 or 4 more records, then went to bed. The next morning I remembered I had some .1uF teflon Russian caps I had burned in for 225 hours previously on a capacitor burn in rig I have. I added some short leads with alligator clips, ands clipped them onto the 1uF PIO caps, as a bypass cap. This took the CNC up another notch in separation of performers, and added a realism to the voices of Stevie Nick’s and Christine McVie. The stage was deeper, and I could hear Christine’s wonderful fills as a back ground vocalist. This is a pretty special piece of gear. If you haven’t tried bypassing, I would recommend it. I’d also love to hear what caps you have experimented with. For me, it’s easy to hear the difference in caps, it has more impact in my system than cables (but I don’t from big money on cabling, it’s all DIY stuff). Here are some pictures with the hood up. I need to figure out how to secure those Teflon’s and solder them in permantly. Thanks for looking, and thanks to Sachine and Hypnotoad for a wonderful phono stage. Up next is the AD797 for my Denon 103.

Onebean18FBF981-6005-4A70-AFF5-EE60C28C8F77.jpegE74D14A7-D2B1-490D-9B2C-280201C5D9A6.jpeg
 
Amazing to me how many blow this pre off. I've tried many times trying to get peeps to give this a try. There loss.
 
I think the best part of any DIY gear is the ability to tweak it to what fits your system best. Cap rolling, tube rolling, dialing in the load for your cartridge, cables building, all this makes a system what you want. It’s a blessing and a curse all at the same time. I can’t seem to leave nothing alone. :D

Onebean
 
My beautiful old Technics SU v9 is acting up again, I think I will take it out of the main system and thus will need another amp. I want to partner my CNC to something modern. Anything out there that comes to mind for a couple of hundred bucks or is that just dreaming.

Edit, maybe I should move this to the solid state forum.
 
I was checking out a CNC at a friend's house today. I have it in a wooden box. He was incised! ! I told him, repeatedly, that it doesn't hum. There was nothing wrong with it. There wasn't a hint of hum in the output.

He didn't know what to say.
 
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