Well, it's pretty much done. I can't explain how many things went wrong, actually things are still going wrong. But it's working despite me manhandling it repeatedly (bent capacitors about a thousand times). Got boards all soldered up then realized I wanted wires routed underneath instead (think a speaker out pad is now threatening to lift). The Nutube is wildly microphonic... behaving worse with top case on chassis. Just problems galore. I still have to 3D print a battery tray and might need to add voltage divider.
Certainly not an original idea. Dodd made a battery powered preamp. Altman had a battery powered amp and dac. Red Wine Audio made battery powered tubed HiFi. Mine is a battery powered hybrid amplifier via Korg Nutube B1 and Bottlehead Quicksand.
Not ready to report impressions yet. Waiting for battery to get closer to 24V to tune my tubiness. Not to mention my current source and speakers aren't ideal for critical listening. I'm hoping the charge circuit works, haven't tried that yet. The charge circuit and voltage display are separate from amp circuit. One switch position is amplifier on, one off, and one for voltage check or charging (assuming a charger is connected).
Certainly not an original idea. Dodd made a battery powered preamp. Altman had a battery powered amp and dac. Red Wine Audio made battery powered tubed HiFi. Mine is a battery powered hybrid amplifier via Korg Nutube B1 and Bottlehead Quicksand.
Not ready to report impressions yet. Waiting for battery to get closer to 24V to tune my tubiness. Not to mention my current source and speakers aren't ideal for critical listening. I'm hoping the charge circuit works, haven't tried that yet. The charge circuit and voltage display are separate from amp circuit. One switch position is amplifier on, one off, and one for voltage check or charging (assuming a charger is connected).
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Wow! Are you driving speakers directly from the preamp output? They must be very sensitive, what are they? What are you feeding the preamp with and how do you control volume?
Lovely job on the casework!
It's a new Dalaudio clone that I modified. The amp would have been done months ago if powder coaters weren't so uncooperative.
I built two chassis. I wasn't crazy about the powder job on first build, so I bought a second and powder coated it too. I kept the second chassis and now I am selling the first chassis, which is closer to chrome in color (on eBay and diyaudio marketplace).
Wiser folks suggested that I shouldn't regulate (Thanks for the help, btw). It's a Nihm battery, so it should stay in the sweet spot (24V) longer than alkaline, I believe. Other than a whistling Nutube, it hasn't been misbehaving so far. Though it's been close to the target range, things could change around 29V or 20V.
My are the same ~ 1% tolerance. So maybe solder joints of the capacitors or jfets ?
Normally a solder suction pump can do the job. I like those with a soft tip of silicone (most has a hard teflon tip).
Litz wire can also be used to remove solder but can be more tricky with double layer PCB. I prefer a pump.
I notice you have the revision 0 board. Did you remember to add the little solder bridge to the back of the board?
