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Improved Regen sound




I was asked for details of an easy & reversible modification to the Regen that greatly improves its sound quality.

This is not another PS to plug into the DC input of the Regen - it's a bypass of the 3.3V on-board regulator with a 3.3V LiFePo4 battery supply. I know the regulators are said to be state of the art but a LiFePO4 battery smashes this out of the park.

Obviously you need to open up the Regen to connect a battery to the output from the 3.3V regulator & ground, thus bypassing the regulator. There is a ceramic capacitor C3 right at the output of that regulator - the reg at the top of the pic - REG33.

There's a copper via with a 5 beside it at top of that C3 capacitor - this is the GROUND point for connection of the negative battery pole. The other side of the capacitor is the connection to 3.3V positive (the one with two vias side-by-side). You need to attach the battery + pole to this point - soldering to one of these vias is best. It's very easy to reverse this if desired.

This powers the USB hub chip & the clock which is all that's needed for audio devices that don't need USB Vbus 5V power for signalling or for powering the audio device. If your need 5V supply you can still do this tweak but you need to supply the 5V separately

BTW, I forgot to include this: this provides a far superior sound than using 2 of the same batteries to power the Regen through its DC input so it's not just the batteries that make the difference but bypassing the REG33 also.

This signifies, to me, that the regulator is a limiting factor. The likely reason for this improvement might be that the clock is getting a cleaner PS particularly at low frequencies where Fmak reported issues with these regs? It is a disputed but widely held belief that reduced close in phase noise is one of the most critical factors for sound quality - LF noise on the clocks PS is one source of this close-in phase noise, the other being inside the oscillator itself (the crystal cut & it's surrounding circuitry).

I don't exactly know how a better PS on the Regen's clock & USB hub chip translates into a better sound downstream at the audio device - I don't believe any measurements have yet revealed this?

Try it & post your reports

Edit: I am reminded by some of the posts on this thread to warn people that they do this at their own risk & that they should be somewhat competent in DIY to do this. These batteries can put out a lot of power - treat them with respect - as you would a car battery - they are that powerful


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Topic - Improved Regen sound - jkeny 13:43:48 11/22/15 (165)

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