Are the (DIP) pinouts the same as CS4398 pinouts?Sheet for CS 4398 shows VD and DGND as pinout 7and 8 ,Just checking Thanks
He probably made an error when writing his message. Pins 7 and 8 are the correct ones.
did you upgrade the psu regulator to something better or still using stock 3 pin regulator on the DAc board after this mod?
Hey folks,
A couple things I'd really appreciate help with after reading through a zillion pages. So I got one of these things, ran it stock for awhile (all was fine), and just did an output transformer upgrade last night. Edcor XSM600/600s. Broke off the 4 little caps near the DAC chip and took the output signal's from there to the Edcors and then the RCAs. Did it according to this guide: DIY DAC Kits and Easy Mods
Now I have serious hum / buzz after this mod (sound is there too though). Tried moving the power and output transformer around and it made no difference. I hear talk of grounding the neg of the output transformers. I've got everything in a wood case -- so how would I do this? Could I just take a nail to the case and make a star ground from that? Would anything besides the OTs need to be connected to it?
Also: I (perhaps foolishly) wired the 1K, 1nf RC Filter at the transformer secondary, but I see in most photos people place this at the RCA jack -- would that be a cause of this hum?
Any help is appreciated -- thanks!
A couple things I'd really appreciate help with after reading through a zillion pages. So I got one of these things, ran it stock for awhile (all was fine), and just did an output transformer upgrade last night. Edcor XSM600/600s. Broke off the 4 little caps near the DAC chip and took the output signal's from there to the Edcors and then the RCAs. Did it according to this guide: DIY DAC Kits and Easy Mods
Now I have serious hum / buzz after this mod (sound is there too though). Tried moving the power and output transformer around and it made no difference. I hear talk of grounding the neg of the output transformers. I've got everything in a wood case -- so how would I do this? Could I just take a nail to the case and make a star ground from that? Would anything besides the OTs need to be connected to it?
Also: I (perhaps foolishly) wired the 1K, 1nf RC Filter at the transformer secondary, but I see in most photos people place this at the RCA jack -- would that be a cause of this hum?
Any help is appreciated -- thanks!
I have mine in a 12x12x3" chassis with the IEC earth ground connected directly to the case. I have tried 7 or 8 different trafos on the output and only once had ANY hum, and that disappeared when I turned the trafos 90*. I've used mine both balanced and single ended. I have to believe that the hum people are complaining about from time to time is either from their construction methods or from a fault or questionable circuitry in their preamps. A ground loop is not a possibility because the trafos provide complete isolation so grounding one side of the trafo is somehow affecting the preamp input circuitry.
Where you have the secondary RC filter has no effect.
I'm not sure you can call the Edcors an upgrade, but I have never heard them.
As usual, I'm probably being too blunt. Sorry.
Where you have the secondary RC filter has no effect.
I'm not sure you can call the Edcors an upgrade, but I have never heard them.
As usual, I'm probably being too blunt. Sorry.
Thanks Bill. Hmmm. I guess I'll have to look at the wiring -- this was definitely dead silent before the "upgrade" (which I guess is more of a mod 
) and a few people have mentioned that grounding the OTs eliminated their hum.
There is no grounding on this system by the way -- DAC is two pronged plugged into a switched outlet on my preamp: I've ran all my other DACs like this no problem and have never had hum.
Any suggesting as to where I should start, divide and conquer wise?
And just to rule out wiring issues, this is how I interpreted the above diagram.
- C1 to both primary taps on the trans. R1 to each Pri tap. Wires from board output to each R1.
- C2 to neg. trans secondary. R2 to C2 and + secondary. Wires from + Sec to + RCA, - Sec to - RCA.
) and a few people have mentioned that grounding the OTs eliminated their hum. There is no grounding on this system by the way -- DAC is two pronged plugged into a switched outlet on my preamp: I've ran all my other DACs like this no problem and have never had hum.
Any suggesting as to where I should start, divide and conquer wise?
And just to rule out wiring issues, this is how I interpreted the above diagram.
- C1 to both primary taps on the trans. R1 to each Pri tap. Wires from board output to each R1.
- C2 to neg. trans secondary. R2 to C2 and + secondary. Wires from + Sec to + RCA, - Sec to - RCA.
Last edited:
I have some Bursons on hand but never tried them because I abandonned this project. I'll perhaps try them soon but i'm still amazed by the sound improvement I had with the added caps on the CS4398 little board.
In the past, I also tried to use one power supply transformer for the digital and another one for analog on CS4398. The result was more sound definition which gaves a harsher sound than using only one transformer.
Now with the added caps mod, it could be great to use 2 transformers as harsh mids is gone with the cap mod.
Thanks Bill. Hmmm. I guess I'll have to look at the wiring -- this was definitely dead silent before the "upgrade" (which I guess is more of a mod
There is no grounding on this system by the way -- DAC is two pronged plugged into a switched outlet on my preamp: I've ran all my other DACs like this no problem and have never had hum.
Any suggesting as to where I should start, divide and conquer wise?
And just to rule out wiring issues, this is how I interpreted the above diagram.
- C1 to both primary taps on the trans. R1 to each Pri tap. Wires from board output to each R1.
- C2 to neg. trans secondary. R2 to C2 and + secondary. Wires from + Sec to + RCA, - Sec to - RCA.
Well, look at it this way. You have isolated the dac from ground except through the power trafo, and whether your preamp is isolated I don't know. You'll have to look inside or use an ohmeter to see if there is continuity between signal ground, neutral, and chassis. If it's isolated the trafo is acting as an antenna, picking up any stray fields that exist, and not just from the dac's power trafo. It could be coming from a whole host of things. My son was having trouble with a field coming from the breaker for his water heater directly below his room. You are isolated but not shielded so just providing a metal case should help, and grounding the secondary could alleviate the problem also. I would do it if nothing else worked.
Thanks Bill: this is really helpful. If I kept the wood case, would 'grounding' the secondary simply be wiring it to a nail or screw? Or to the PCB somewhere? Also: because the ground wire isn't going anywhere on the power transformer (I'm using a 2 prong plug) I believe the PT is isolated from ground as well.
Thanks again.
With the Jensen transformers replica (RE 11DM) I don't use any R C filter and the secondary is loaded at 270K with 50K by the preamp potentiometer.
These Jensen Replica transformers are simply the cream of the best. They're above ALL I tried by a long margin.
About hum
Everytime i didn't ground the secondary corresponding to the - of the transformers I had hum.
These Jensen Replica transformers are simply the cream of the best. They're above ALL I tried by a long margin.
About hum
Everytime i didn't ground the secondary corresponding to the - of the transformers I had hum.
Thanks I'm going to try this. Do you know how I should ground it if there's no real connection to earth on the DAC? To the PCB? Star point?
I think I used the ground hole left when I took out the plastic output jack from the board.
Woot! Ran two wires from neg secondary of each OT to the ground hole from the original RCA output jacks and hum is instantly gone! Dead silent. Thanks everyone, and I hope this ends up being useful to someone else.
Oh one small thing: when I power down (it's in a switched preamp power input in a tube system) with the volume up I get some serious spacey / theramin sounds as the amp dies. Doesn't affect listening just wondering why that would be?
Thanks again!
So what do you think of the Edcors? I also have the Jensen 11DMs, they are the best I have heard. I also have some Tamura 87xxxx, can't remember the entire number, that are a reasonably close second. They are also high nickel cores.
Can't comment on your space sound effects, you have defeated the isolation so the trash on the dac ground is getting to your preamp.
Can't comment on your space sound effects, you have defeated the isolation so the trash on the dac ground is getting to your preamp.
Last edited:
I also have a tube preamp
Don't turn off the dac. Leave it on all the time. It will play better when warm and this will not break it.
Normally, there's a relay to shut off these noises when turning the dac off, With the transformers, you don't use this relay so it's normal to have strange noises like it is now.
I suspect that you have a locking problem with your transport or computer.
Does your dac have CS8416 upgraded PLL values ?
A definite improvement over stock -- bigger soundstage, more detail -- but I haven't heard any other OTs so I can't compare. For $12 per though, they are a great way to dip your toe in, and from what I've read the impression I get is they'll get you 90% of the way there.
Thanks -- never occurred to me to leave it in will give that a try.