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Comments
Has anyone here ever used anything with a phase invert switch? Wondering if I should put that in while I'm at it.
Really? Yeah I have plywood.... I'll give it a try!
Here's a layout that might work.. haven't thought about switch locations yet
The layout should work. Bear in mind that if you are using plywood as a base...you might want to consider a 'star earth' to control any hum issues.
I thought phase invert was only useful if you were too senile/too drunk to make sure your wiring was in phase?
Hah hah, both channels. Maybe I'll put it in, it's only another switch. I have a bag of 4-pole switches somewhere. I think...
Yep, the PCB has a star ground on it so I'll wire all the connection to that. Having a transformer in the middle helps too.
Oh hang on. The chassis is aluminium. So... mount the power supply to plywood to kill the vibration? I don't remember having this issue before.
Today was coupling capacitor day. Here's the BCF cirquit:
With a transformer now between the DAC and the BCF, the lower input coupling capacitator is no longer needed. Also, the input impedance of the top input is quite high, so that cap only needs to be small ish. I ended up with a 0.1 uF Auricap there.
On the output side, mercy me if it didn't sound better with a 1 uF PIO cap in parallel with the big Dayton film cap. Wish it hadn't... anyway, could be fooling myself, wonder if I should rig up a switch and blind test it.
One thing I hadn't quite realized fully until now is that the circuit has a gain of -6dB.
Output impedance measures around 116 ohms. Still to try cathode bypass caps, which will reduce it to ~60.
With cathode bypass caps, measuring around 52 ohms output impedance. So that's all right. Sounds fine, no bad capacitor effects that I notice... however it's become a bit hummy and buzzy all of a sudden. Could just be I moved something in this rats nest of wiring.
Well... you know, the basic circuit of the BCF is so simple that I can't stop wondering about doing a point-to-point version. Over half the board is space for coupling caps, which are easily accommodated on terminal blocks in a PtP build...
And then I thought, well, I'm only likely to do this once, so why don't I use the chassis I was going to use for the original Aikido build... with the solid state power supply, looks something like this:
A bit tight but doable? The DAC will have to go into its own box. That's OK, because it will no doubt be upgraded anyway.
But... I also have an overkill chassis-mount toroid with all the windings needed to do a Janus shunt regulator, which could also be point to point.... so lots of stuff on the top of the chassis, more like a "classic" build.
I think I like that one...
Schematic of the no-DAC version:
The reason for the 4-pin XLR input is that I want to put a flying lead out of the DAC (in a separate box). Since this has DC on it I want to use a less common connector.
Better/safer:
Yes on my old AN dac & my pre . I think I used it once or twice .
I decided to finish the original Aikido board I had. I found a pair of Magnequest line out transformers I've had for ages and connected my headphones using those.