I recently put together a nice phono stage pre-amp board. It is a VSPS. Anyway, I stuffed it into my source selector and wasn't happy with the crowding, and how I had to arrange the power (dual rail for the VSPS, single for the relays and dac board). So, now I have decided to put the VSPS board in it's own chassis, and I am going to include the power supply.
My question is, how much shielding or distance between the transformer and the pre-amp board is needed to be more or less hum free? The chassis is 10x6x2 inches. I will have the IEC power and transformer (50VA +- 12VDC) on the left, and the board on the right. About 4-5 inches separation. The chassis is steel. What additional shielding if any should I expect to need to keep hum to a minimum?
Thanks in advance,
Roger
My question is, how much shielding or distance between the transformer and the pre-amp board is needed to be more or less hum free? The chassis is 10x6x2 inches. I will have the IEC power and transformer (50VA +- 12VDC) on the left, and the board on the right. About 4-5 inches separation. The chassis is steel. What additional shielding if any should I expect to need to keep hum to a minimum?
Thanks in advance,
Roger
At this point I've built more than 10 phonostages. Experience says the power transformer needs to be at least 3ft/1m from the RIAA circuits to be genuinely quiet. The only quiet solution is an off-board PSU, particualy if you're wanting MC noise performance.
Could you shield things enough to work? Perhaps, however with what’s required it would likely be cheaper and easier to just get the 2nd chassis.
Don't know what is common, but useful and best price are liion batteries for power tools, 18V and min 2,5 Ah capacity. Each model has bit different battery management That can be used or simply removed) . I use from brand Einhell, batteries are directly connected to power pins (no electronics on the way), it has charge indicator and usually comes with charger.
With some work the can be inside chassis, but you need acessable charge indicator as minimum, than you can switch on a charger on demand
With some work the can be inside chassis, but you need acessable charge indicator as minimum, than you can switch on a charger on demand
Roger, do you mean what is ground? The same thing that is ground in any series-stacked ("Bipolar" or "+/-" ) PSU... the middle of the two supplies.
Thought that might be it, but wasn't sure it was wise to connect pos to neg poles. While interesting, it will not be my first choice, but certainly an option.
Roger
Roger
Well..... sold my X-Ono clone a couple of days ago, and just neede something to play vinyl....
This is what I got... A couple of hours...... Just grabbed whatever I could find, res. and caps form the waste bin.
Riaa is placed 20cm beneath a 55" plasma screen, which is "ON".
No hum, no hiss, no nothing besides music 😛
From an AT-33PTG/II into a diy stepup (Silk audio transformers) to the riaa..... sometimes it´s about construction more than
screening the sxxt.......
This is what I got... A couple of hours...... Just grabbed whatever I could find, res. and caps form the waste bin.
Riaa is placed 20cm beneath a 55" plasma screen, which is "ON".
No hum, no hiss, no nothing besides music 😛
From an AT-33PTG/II into a diy stepup (Silk audio transformers) to the riaa..... sometimes it´s about construction more than
screening the sxxt.......
Attachments
Two opamps...... OPA 2604 for input and an old JRC/NJM2114 for riaa/output.... sound fabulous 👍