Comparing battery-powered phono pre-amps, from RS ($$) to ASR ($$$$) ... and beyond!

Thank you Sir, what are the quality of the capacitors like?
 
With my limited knowledge, I don't fully understand what he has done with all the component changes, but there has to be a reason for them.

screenshot_817.png
 
I’m pretty sure you can too. Wyn indicated his preamp could be run off a pair of 9V batteries and it uses a +/- power supply.
 
That would be handy, after about 15 hours of solid use on a stock unit. the battery went from 9.5v to 9.2v. Im curious as to what the battery life is on a standard duracell alkaline battery.
 
I got four nice rechargeable D cells from China a while back.

The Sony D5M uses two, and regular cells don’t last too long. These last at least as long; probably longer, and have a mini YSB plug in them with an LED, so no fancy charger needed. Not expensive. eBay of course.

It started with D adapters that take three AA batteries each, since I’m already using those everywhere. But the single D has higher mwH than any three rechargeable AAs combined.

The D5 steps up from 3V to 6V so voltage isn’t an issue.
 
Ultimate bang for buck situation.

But we can load it up with overpriced boutique caps and get it from $20 to $2000 in no time!

We can design larger boards to fit the bloated caps.
 
I’d take that theory to the next level-

Run balanced from the cartridge: hot to left; cold to right, on each preamp. You’ll increase gain without increasing distortion. Plus benefit from balanced line noise rejection. Very handy with milivolt signals.

I’m making my Rega output this way, using Mogami Neglex Quad mic cable. I’m terminating the cable with an RCA (because I have a single ended phono pre) but all I’d need to do is change the RCAs to XLRs and plug ‘er in.

I’m using mini XLRs at the table to reduce bulk. These are used on headphones these days so more popular than the 3-pin Lemo connectors I was planning to use (also less expensive).

I have been thinking about new cables system-wide, and I will probably make up the new ones with this recipe. (Amphenol Audio has some nice RCA connectors for reasonable money)

Edit- this might give you enough gain to run MC…
 
We're reading off the same sheet of music.

Placing the preamps inside the turntable is a fine idea, actually. Just need to mind shielding from motor and airborne noise.

The trick is getting a "battery-quality" power supply to keep it fed, and then run line level out of the turntable. That's probably the best scenario.

And I keep falling back to my rechargeables that decouple from the A/C charging circuit when you turn the power "on". But since there's 110 inside the turntable anyway (usually, and if it's 24 VDC, filter and hyper-regulate that to the required DC voltage), might as well use it.

Finding the balance between interconnect length and quality and power supply quality of external noise shielding need to be considered.

In my case, it's a matter of chicken and egg- the preamp is (nearly) done, so adapt the table to it. Meanwhile, do it in such a way so as to keep things more-or-less universal, in case something changes later.

As an aside, when I was designing my turntable (now lost), I was considering the motor's physical placement in the plinth, from an electrical interference standpoint as well as a vibrational transfer standpoint. MANY changes but we'll never know now...
 
You must log in or register to reply here.
Back
Top