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

[NeverSatisfied]

There seems to be a lot of activity in the forum with people building/restoring/optimizing their vintage turntables. It's impressive just how far some have gone in order to bring these electro-mechanical marvels back to Day 1 (or better) operation.

Myself, prior to joining this forum my plan was simply to restore my old audio system & then feed it with a modded CD player supplemented by the occasional DVD and the obscure stuff only found on the internet. In other words, I didn't have plans to play any vinyl...

Of course, hanging out in here & seeing how much fun the vinyl & reel-to-reel crowd are having, it seemed only right to go ahead of see if I could tackle my old Dual 606 and undo the years of neglect. And if I'm going to do that, then I might as well see if I can bring back my first-ever preamp, a PL 2000.

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Once I cleaned up the turntable & it seems to be ready for duty, now I was wondering how was I going to best take full sonic advantage of this analog input? Restoring the old PL 2000 input stage was a given, but then again how would I be able to figure out (quantify) just how far away I was from today's State Of The Art? (As in, how do I ensure that I have the lowest possible background noise level when enjoying vinyl?)

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One thing I've learned over my career is that the single hardest scenario to troubleshoot/fix/characterize/optimize/POOGE/hot rod/comprehend is when you only have ONE item to work with -- that is, no constant unmodified device to compare my progress against in order to keep from lying to yourself. Sure, with high quality test gear you can document the improvements made over time...the problem is, some of what makes us enjoy the listening experience the most seems to be just beyond the reach of what 'mere mortal' test equipment can resolve. (!)

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So, when Gepetto pointed out that I could explore the area of battery-powered phono preamps featuring an affordable price of admission (plus the fact that this same preamp had created quite a stir in the audiophile community back in the day), I was instantly sold:

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As a matter of fact, it was so affordable that I was recently able to further improve my test setup with a 2nd identical (think control) phono preamp -- it arrived early...today! From everything I can tell, it is actually a NOS cream puff:

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To me, this is the best of all worlds, for I now have the opportunity to compare & contrast 3 different phono stages - eventually having the PL 2000 vs. a control unit vs. a unit upgraded by swapping out the old parts with today's low-noise/improved versions of the same. (!)

Done in a disciplined fashion, I can take this just as far as my interest in reproducing high-quality music from vinyl or my system's ability to resolve these differences...

NOTE: To make sure that I'm not just deluding myself with 'expectation bias' my plan is to record the sound of the circuit in question, make the mod, and then record the same test tone or music sample again...and then by using this software be able to clearly define the difference made. (if any!)

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The Perspective:

When you read my subsequent posts, please keep the following hand-drawn graph in mind.

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Once I get the rest of the system restored, my plan is to then take these $20 battery-powered phono stages & see how far I can push them from their 'near zero' starting point towards the knee of the curve on this hand-drawn graph.

Of course, in the unpopulated state the curve above is a pure abstraction that conveys no meaning, so I am going to populate it with a selection of battery-powered phono stages for sale *right now*. Admittedly this is an unscientific sample...but at the same time, my hope is that it provides some food for thought for anyone else tinkering with their vinyl in 2022.

FWIW --

Will be watching with interest.
For most of my audio life, I completely avoided records, fully believing that it was a fool’s errand because digital was superior in every way. Other than my first turntable back when I was a teenager I hadn’t owned one in close to 35 years, until about 2 years ago.
That’s when I got my first PL8000 just because I wanted a complete PL system from turntable to speakers and not because I thought i would use it much. Man was I wrong about vinyl, I FINALLY get it. It not only sounds more alive but the act of getting up out of the chair to change records keeps me more focused on the music. Meaning that often after loading 5 CD’s in the changer or firing up the streamer, it wouldn’t be very long before I was dosing off or not really paying attention to the music.

 

[J!m]

Phono preamps. Yeah.

We have a short list of goals, which conveniently inter relate and conspire against one another.

High gain
Low noise
Accurate RIAA time constant

In general, the answer is: “pick any two”.

Wyn Palmer (Ph.D., but he doesn’t bother with it) used to design IC chips. Op amps we all know and love, among other things. Generally frowned upon by the hi fi community- everything must be “discrete and rare and expensive” or it’s crap. They have a similar opinion of switching power supplies.

So, (just as a kick to the nuts of the industry I suspect) Wyn decided to design a phono preamp with op amps and a switching power supply.

Well, it kicks ass. Noise is very low. RIAA accuracy it within mdBs; not dBs. Plenty of gain available for the lowest output moving coils (no transformers and their distortion), bandwidth is massive.

It uses a cheap MeanWell switching power supply, and a filter board he designed to attenuate every bit of hash that comes out of it.

I built one. It’s scary good. He’s built several for audiophile friends, who went on to sell off their “esoteric” preamps. It easily holds its own in the “over ten grand” phono preamp club

But I like the idea of battery power. I think there was discussion of one Wyn did that ran off a pair of 9V batteries- maybe four of them, because it’s a +15/-15 power supply.

One “trick”Wyn did, that I think it critical, and a deviation from every other preamp (as far as I know), is he divided the RIAA time constant correction into two stages. He has two gain stages and one set of corrections is within the first stage and the others are in the second. I think that was key. Predominately TI chips throughout. They have great specs I’ve seen first hand shopping for replacements for my DAC. plenty of local power conditioning- right at the chips, which are each within a fortress of film caps.

I’ll try to post the specs tomorrow. But listening is something else! Mine is still messed up with the balance pot wiring, but even putting it in mono, it’s just crazy good. Bad in a way because you hear every spec of dust but on a good record it’s scary good.

He also did a headphone amp, using the same power supply and I love it. Wide bandwidth massive headroom and simple. Three chips and the rest is discrete. It doesn’t even use the filter board for the power supply (can’t really, because it ends up limiting current)

The man is a brilliant EE but also an audiophile. No BS just quality designs.

 

[J!m]

I think a line preamp can benefit from pure DC as well.

I envision an outboard power supply (pretty typical) but with a bank of batteries inside. When you turn the power “on”, you are actually disconnecting the charging batteries from the AC line, and connecting that juicy DC to all the goodies in the other box, hungry for electrons.

I guess I’m not the first nut job with this idea, but it just makes sense. At least as much sense as a gross of capacitors to smooth the AC into low ripple DC. I think the cost : performance ratio would favor this contraption.

 

[J!m]

Caviar taste on a cracker budget won’t cut it.

You’ve gotta at least pony up for a burger.

my expectations may be a bit high because for about 45 years I’ve been playing with musicians. (The first few sucked like a black hole) but eventually my skill, and the skill of those around me grew to the point where very few people covered their ears.

Point is: I have a good idea of what instruments sound like. Not just 80’s hum bucket guitars through a rack of processing gear; also strings, horns, reeds and of course percussion of every sort.

To me, if I think it sounds real, it sounds real.

I got a taste of that already, and I think (hope) my updated table and new phono preamp will keep me comfortably in the “HOLY SHIT!!!” zone.

 

[J!m]

$1800 and ya couldn’t do better than the cheapest Amazon batteries?!? WTF?

I wonder if those yellow things are op amp modules, similar to Levinson and old recording consoles (where Mark no doubt got the idea).

I chatted with Wyn about these (formerly discrete) op amp modules, thinking some of his parallel chip op amp trickery could drive noise and distortion way down and he seemed insulted. Discrete was the best they could do at the time. A chip has the advantage of an enclosed thermal envelope so performance is very predictable with change in temperature during use.

Know anyone with an old analogue synth? Like a Moog or Oberheim? Tuning them is an absolute nightmare. You have to throw a blanket on it and get it hot before you even start. Massive tuning drift with temperature. Perfect example of discrete component behavior- parts heat at different rates and their values change.

If you can hear it there, do you think you can hear it in other things?

 

[J!m]

So, it sounds better to have delicate signals from a moving coil going into an unshielded plastic box?

Im an idiot but I’ve gotta call bullshit on that.

I think we’re all foolish to not embrace a balanced line from the table to the phono preamp. Take advantage of the noise rejection of a balanced line! It just makes sense! It’s lower than a microphone output, and those are balanced.

 

[derek92994]

Interesting info there, funny how this thread appeared today. George (Pennysdad) recommended an $18 phono preamp which runs off a 9 volt battery (Thank you George!) I purchased one which arrived a couple of days ago. I didnt think it would be any good, but after hooking it up, wow, for $18 this thing sounds fine. Clean and balanced. Really exceeded my expectations. My usual phono pre is a $500 Project Tubebox DS which Performs very well. Big difference in price there. But for now, I am enjoying the battery powered one, its always good to try new things and they are handy to have as a spare.