Finished this a few weeks ago and finally got around to taking photos. I went with SLA batteries. MC only, wiring the Cinemag step up transformers directly to the jacks and board. Really enjoying the sound of it! Very quiet. The batteries last way longer than I can listen, even giving it a couple hours to warm up, and they charge quickly. Now that I’m confident in the battery solution, I’ll probably swap the power supply wiring with something better than lamp cord. A rotary switch or pins for R1 & R2 to vary the loading would also be a good addition. Very happy with it for now!
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The charger is external. This one https://www.amazon.com/gp/product/B07W46BX31/ I just unscrewed the clamps. The 4PDT switch on the back switches the batteries between the charger and the phono pre so the charger is disconnected when the pre is powered on. The charger charges the batteries when the pre is switched off and keeps them trickle charged.
I went with SLA for simplicity, cost and familiarity.
I went with SLA for simplicity, cost and familiarity.
But not weight? Worth considering LiFePO4 batteries as these have allegedly 2000+ charge cycles so should endure a long time, and are less heavy(!)
My experience with LA is I always trash them through neglect unless used in a vehicle. My experience with LiFePO4 is they just work (always use a BMS).
In this case there is no power transformer!
But often times capacitors are labelled as bad actors and have undesirable sonic properties when in the signal path.
There appear to be no capacitors at all in the signal path of the Millett preamp.
It's just another way to accomplish the same goal. And a rather interesting one, at that.
But often times capacitors are labelled as bad actors and have undesirable sonic properties when in the signal path.
There appear to be no capacitors at all in the signal path of the Millett preamp.
It's just another way to accomplish the same goal. And a rather interesting one, at that.
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I did some tests with LR and LCR networks. For this purpose I made a phono preamp where the riaa filter was pluggable, in order to switch between RC, RCL or LR.
LR and LCR always sounded better and had less noise than RC. However, they also had a (much) lower impedance than the RC networks tested