Its not crucial. Q7 is a local CCS for the LEDS reference shunt stabilizer that biases the cascode transistor. So you need same IDSS at say +/-0.5mA tolerance for same total Vf quartet of LEDS. 5mA is good enough for the Q7s both for biasing the LEDS well and for not getting too hot themselves.
Last couple of things (whilst I'm on the internet ordering stuff), "lift diodes" what are they? A specific type of diode? Can't find out anything, could someone link to the relevant product please.
Star quad cable, is this decent 4 core cable for internal wiring in the psu?
Star quad cable, is this decent 4 core cable for internal wiring in the psu?
Star Quad cable comes from the sound reinforcement professional world. It is microphone low noise cable. Check brands like Canare Mogami Gotham etc. I use it and its OK
The ground lift diodes here are normal robust diodes connected in anti-parallel between signal ground and mains ground. So when the potential difference goes >0.6V either way positive or negative between grounds due to a fault they channel the fault current to the mains ground. Otherwise they keep the two grounds electrically apart. Its all sorted out in the RAW-PSU PCB anyway. Also pictured in the guide's generic PSU schematic. Listed for type in the guide's BOM.
The ground lift diodes here are normal robust diodes connected in anti-parallel between signal ground and mains ground. So when the potential difference goes >0.6V either way positive or negative between grounds due to a fault they channel the fault current to the mains ground. Otherwise they keep the two grounds electrically apart. Its all sorted out in the RAW-PSU PCB anyway. Also pictured in the guide's generic PSU schematic. Listed for type in the guide's BOM.
Anyone who recently purchased the Folded Minikit may want to check the set of four resistors to make sure they are 120R, and not 100R. It appears I may have made a mistake in putting those kits together. Although the circuit will likely work fine with them, it's not Salas original design intent. Let me know via PM if you need them and I will get them sent out to you.
Tea
Tea
Thanks Marra, I see the common value is 20 Ohm and 5W, it'll vary with transformer output I assume and can be calculated fairly easily.
I'm aiming for between 33V and 37V, is the value dependant on gain required (my cartridge is 0.35mV so I'm using the 63db option)?
I'm aiming for between 33V and 37V, is the value dependant on gain required (my cartridge is 0.35mV so I'm using the 63db option)?
No, its more or less random due to active parts tolerances regarding DC bias. Its only relative to achieving the right test points voltage. Many times its 32-35V given the LEDS are usually lower VF than my prototype's LEDS VF was.
What should I expect straight out of the raw psu, my meter is showing 58.7v using a 18-0-18 30va toroidal transformer with a 22 Ohm 5W resistor in the rd/link position.
I have a 470 Ohm 10W resistor, do I attach it across +ve and ground or just to +ve and measure the detached end and ground? wWhichever way what reading should I expect? All of the trimmers are set mid position.
I have a 470 Ohm 10W resistor, do I attach it across +ve and ground or just to +ve and measure the detached end and ground? wWhichever way what reading should I expect? All of the trimmers are set mid position.
Ok, with the 22 Ohm resistor in place and the dummy load acroos +ve and ground I have 48.5v so my reading on here suggests I'm good to go to the next step?
Yes you are good. But continue the technical questions regarding the build steps in the njfet simplistic riaa thread so we don't congest the GB thread too much with the technicals
The minikit parts are likely still all available, the boards however are not.
You can sign up for any or all parts using the spreadsheet in signature for "Salas boards". 🙂
Let me know if there are any questions.
IF you get no replies, I am doing another GB for these. You will need to sign up using the "Salas Boards" sign up sheet in my signature.
The GB for the Salas boards is open for payment up until 11:59PM EST 06/26/2016.
Payment is via PayPal invoice only in US dollars. You will need to send me your paypal email via private message for me to start this process. Then I will invoice the parts you requested from the spreadsheet. If you reply to this email - cut out some of the existing text, otherwise the message is too big.😉
Customs forms
DO NOT ask for me to fudge up a customs form with really low amount. These are based on a reasonable wholesale price.
Shipping
In general boards are a set costs, and mini kits are built into the shipping costs and larger full kits are 10.00-12 to ship. Starting price for shipping is 8.00 for just a small board and can rise from there.
The boards will ship around 2-3 weeks after the GB closes typically. The boards need to be ordered, I don't have them on hand.
Here is more details on the boards
Folded Simple Phono Preamp
Per board cost is 52.00
RAW Power supply board is 15.00 - Other parts available, see post below and Mini-Bom Section
Link for first post and to build guide
http://www.diyaudio.com/forums/grou...-folded-simplistic-phono-pcb.html#post3615620
Payment is via PayPal invoice only in US dollars. You will need to send me your paypal email via private message for me to start this process. Then I will invoice the parts you requested from the spreadsheet. If you reply to this email - cut out some of the existing text, otherwise the message is too big.😉
Customs forms
DO NOT ask for me to fudge up a customs form with really low amount. These are based on a reasonable wholesale price.
Shipping
In general boards are a set costs, and mini kits are built into the shipping costs and larger full kits are 10.00-12 to ship. Starting price for shipping is 8.00 for just a small board and can rise from there.
The boards will ship around 2-3 weeks after the GB closes typically. The boards need to be ordered, I don't have them on hand.
Here is more details on the boards
Folded Simple Phono Preamp
Per board cost is 52.00
RAW Power supply board is 15.00 - Other parts available, see post below and Mini-Bom Section
Link for first post and to build guide
http://www.diyaudio.com/forums/grou...-folded-simplistic-phono-pcb.html#post3615620