IceFyre13th wrote:Shannon,
What are the dimensions of the PCB? I am going to build in a larger sized chassis so I can add a Phono stage in it later on........that leads to another idea, 24 volt phono preamp to match the power supply requirements of this build.
tomlang wrote:What is the overall gain of this?
What is the gain of the bass-boost and at what frequency?
Looks awesome!
EWBrown wrote:What is the optimum 12B4A plate current for 24VDC operation, and what would be the SWAG setting for the cathode trimpots?
EWBrown wrote:I'm thinking of trying a bare-bones basic version, without the micro-controller, with just the active tube section. 24V power supply would consist of eight series-connected 5000 mA/H Li-Ion 18650 size rechargeables. I've found some of the rather "elusive" battery holders, and I have a couple of small "smart" chargers which can charge four cells at a time. All found on e-bay, US sellers, quick & "free" shipping.
IceFyre13th wrote:I did take your advice on the phono stage, I found a kit that runs on the same 24 volts DC and has been highly recommend by other DIYer's. Not JFET, but the "circuit topology that uses low noise audio opamps implementing passive split equalization filters and to provide a low output impedance". In quotes cut and past from the manual of the kit, not sure if I should post the brand or link here as this is your site.
IceFyre13th wrote:Need your opinion on a power supply, I have a few Astrodyne OFM60-240 ( http://ecatalog.astrodyne.com/usa/open- ... /OFM60-240 ) I could use. Do you think this will be ok? Yes I would shield it inside the chassis to help prevent noise, in its own Faraday shield so to speak.
IceFyre13th wrote:The Phono amp I will be using is the Bugle 2 ( http://www.hagtech.com/bugle2.html )
Hammond Chassis is 17" X 10 "
IceFyre13th wrote:I see there are unused digital pins on the Nano (D0, D1, D2), my thought would be to use one pin to drive a transistor (2n2222 NPN) that would drive the relay coil with a delay. This would allow the preamp to be fully on before turning on the amp (eliminate thumps).
//set up the LCD, splash screens and tube delay
Setup_LCD();
//set up the LCD, splash screens and tube delay
Setup_LCD();
//Energize 120VAC Relay added by IceFyre13th 1-23-2014
pinMode(transistorBasePin, OUTPUT);
digitalWrite(transistorBasePin, HIGH);
// Digital pin assignment notes
// Analog pins used as digital are considered D14 thru D18 (e.g. A0 is D14)
//
// D0 and D1 are reserved for serial bus (TX & RX)
// D13 can only used as an output as there's a status LED is on that port
// SPI bus is not used other than for digital pins (no MOSI, MISO or SCK)
// D2 is the only spare pin, but it supports hardware interrupts and PWM
const byte transistorBasePin = 2; //added by IceFyre13th 1-23-2014
const byte CLK_595 = 3;
const byte LATCH_595 = 4;
const byte ENABLE_595 = 5;
const byte POWER_LED = 6;
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