Mober DC Speed Controller for the LP12.

[sq225917]

I think you'll be pleased with it. Good times to be lp12ish.

 

[brendan price]

Thanks for the info and write-ups guys , food for thought......
Brendan

 

[torstoi]

Very nice and informative writeup, Simon,,,the closest to seing it in the flesh due your excellent photos...thank you.

 

[james73]

Sorry for bumping an old thread, but would this control box work on a turntable other than a LP12?

I have a Planar 3 with the less-than-stellar Origin Live DC Motor kit. The motor I'm using is a Premotec 9904 120 18105 12V DC, powered by a Maplin L53BR 9V 3.2A PSU. I also have the Groovetracer delrin platter which has a recess underneath, so could I fit the marker template on that for the tachometer to read?

Or would that not work?

 

[SONDEKNZ]

This follows on from my experience with Edmunds accessory stainless composite sub-pllatter for the LP12. I would have placed it in the diy section but it doesn't really sit there as it's a bona fide commercial product.

Though the humble fruitbox (LP12) has been around for decades it wasn’t until relatively recently that the aftermarket upgrades started coming thick and fast. Linn has always espoused their ‘my way or the highway’ approach to the deck, and modifications simply didn’t sit with the brand’s ethos. Though a staple in the high end firmament since the 70’s it’s only really since the turn of the century that we’ve seen successful upgrades capture real market share with the LP12 faithful.

There has been many attempts at building new PSU’s and speed controllers for the LP12 but the one that really gained any real traction was the Hercules. Basically a Valhalla on steroids the Hercules was a simple plug and play unit, replacing the LP12’s inbuilt motor control pcb and offering 33 and 45 at the flick of a twin Led coloured switch. It was simple to fit, cost effective, didn’t break with LP12 theory and above all it worked. I had a Hercules on my own LP12 before I made the move to SME and then onto Kuzma.

After decades of naysaying the benefits of DC motors Linn finally came out with their own DC motor solution, the Radikal. A high quality DC motor, encased in a pod to dampen any vibrations and linked to optical tacho that provided continuous speed control. It was never going to be a low-cost option, coming from Linn themselves, but it did work. Not only was the speed stability very good but the better balanced DC motor spun the records with lower physical noise. All other things being equal it has been my experience that DC motors are just inherently better balanced and quieter than similarly powered Ac motors.

My own travels have taken me from LP12 with Valhalla to LP12 with Hercules to SME 10 with their own current compensated PWM DC controller and then onto a series of Kuzma Decks and PSU’s that reads like a who’s who of available TT-PSU solutions. If it’s a commercial speed controller or popular DIY options for a Premotec 110v /24v or low voltage DC motor I’ve probably built, measured, lived with and moved on. My experience with DC motors has been that they lack grunt and require effective compensation to deliver decent speed. I’ve spent good money on quite a few of them and even Origin Live’s Advanced controller and DC200 motor was seriously underwhelming. I even moved on my SME10 because the speed stability wasn’t up to snuff. There was nothing ‘wrong’ with it, it was within spec according to a recent service, but to my ears it wasn’t delivering.

After a lot of back and forth I eventually fell into a AC controller for lower voltage motors. A digitally controlled sine-wave regenerator featuring a pair of mono chip amps as the output devices and offering a USB interface to control frequency to 0.01hz and phase to within 0.1 degree. This unit measures very well, it has proven to be rock solid in over 2 years use and I had no interest at all in looking for another solution. I had arrived.

Then a couple of weeks back Ynwoan (Mark) handed me a stainless composite sub-platter he had been lent and said “see what you think of this.” So I did, actually I was very impressed by it. I wasn’t looking for a new sub-platter, there was nothing wrong with the one I had, but this one just sounded better. After a few enquiries back up the supply chain, it turns out that it was designed by Edmund who makes the Hercules PSU board and the Mose (stand alone cased Hercules)- small world! Anyway, cash changed hands and the sub-platter became mine.

In my discussions with Edmund about his sub-platter he asked about my deck. I own a Kuzma Stabi 12” with S unipivot arm, but uniquely I also run it with an LP12 bearing, sub-platter and outer platter. It’s most definitely a hybrid (bastard) but it gels really well and sounds very satisfying. Unlike a full LP12 it never needs servicing, there’s nothing to adjust, no suspension to upset or armboard to detune. It’s just a big black brute hunk of metal with a complicated AC speed controller turning a Rega 24v motor which in turn drives Edmund’s composite stainless sub-platter in a LP12 bearing- but it does so via very viscous oil. In my case 3000cst silicon oil, the same stuff you put in the diffs of remote control cars and suchlike.

Why sticky silicon oil? Simple, it provides a significant amount of drag. It provides this drag without adding noise, like an eddy brake, but it’s much more linear than an eddy brake, utterly. So more drag swamps the tiny variations in needle drag that might occur from differing programme material and stylus drag become a none issue. It also has the effect of compressing the magnetic field in the motor and that helps reduce cogging, very noticeably and easily measured ( see Paul R’s turntable speed thread for pics).

All of which neatly takes us to why the hell would I want to try another DC controller given my past experience with them, my satisfaction with my current set-up and the fact that it wasn’t even designed to work with my deck? Well, my experience with Edmund’s products makes me think he might be the sort of guy who can work out all the bugs with a design and I’d previously been impressed with the difference I’d heard the Radikal make on the two LP12’s I’ve heard it installed on. No pressure then.

A big box duly arrived from Hong Kong. Fancy DC motor, check. Box full of cables and tacho sensors, check. Nicely finished anodized case with central display and simple push button controls, check. The only issue was how the hell am I going to bodge this to my deck? The supplied tacho is fitted to a machined alloy bracket that mounts to the motor mounting screw on the LP12 top-plate, I have no LP12 so no top-plate and no motor mount screws. Trusty old blu-tack was my friend, and with a bit of pressure the tacho pcb is mounted along the chassis of my deck. A little bit of wriggling with the sensors to get them to align to the printed marker ring that has to be fitted beneath your outer platter and we’re good to go.

Initially I started with the DC motor running my bearing as normal, full of honey sticky silicon oil. Though speed stability was impressively good once locked on I couldn’t help but get the feeling that the motor was less than impressed with the stiff bearing and it told me as such via protracted spin up times and significant over and undershoot while getting the deck up to speed. I removed by sub-platter, cleaned the spindle and drained the bearing and refilled it with 50cst silicon fluid that is much closer to Linn Black Oil in viscosity. With the bearing refilled and sub-platter settled we were all ready to go.

The new oil had done the trick, start up time was halved to a few seconds, the deck got to speed more accurately and over and undershoot was significantly reduced on the way to 33.3. Much better. The fresh oil and new DC motor controller combo had also brought about a significant change to the sound of my deck. If you’d asked me if I thought my previous set-up was muddy I would have said not. Detail was always thrust to the fore. Instrumental timbre was accurate and lifelike and my deck achieved a real in-room presence when the mix and mastering allowed for it. However, here I was faced with a dilemma. I was hearing more detail, not more brightness. I was hearing sounds better resolved, instrument placement more clearly defined and an overall reduction in grunge.

So I took everything apart and swapped back to my AC controller. Yes, there it all was exactly as I’m used to. Beautifully rendered and expressed musical intention in all its glory. But now I can hear that muddying of the bass, the lack of resolution of some note shaping and I’m not happy about it. My AC motor is ‘noisier’ plain and simple. It’s darker, muddier, slightly claustrophobic in its staging. However, it’s not any worse in terms of speed stability. Both my controller and The Mober DC controller would appear to be beyond the ability of my ears to pick fault with speed stability. Every cloud, as they say.

Switching back to Edmund’s Mober DC controller once again it was all back as I had previously encountered. There were tricks of set-up, no subtleties that I’d missed that skewed the sound. It’s a cinch to install, even on the wrong deck and what it brings to the sound is utterly consistent. In my case the Mober Dc controller delivers rock solid speed stability, as good as I’ve heard. But what it brings beyond this is a sense of calm, of notes rising up from a deeper floor, painted a darker black. Like a good camera lens it allows you greater focus into the picture, resolving more detail and giving the best of what your system can offer.

So I find myself again looking for a reason not to buy this, and honestly, I can’t think of a single one. I like everything it does which is simply spin records at an accurate speed with as little extraneous noise as possible. It seems so simple when you write it down like that, but when you hear it, it makes perfect sense that Linn should charge you so much for the Radikal. Maybe I should just go the whole hog and add some suspension as well…

@sq225917

I'm seriously thinking of going MOBER DC PSU - so I was very happy to read this write-up of yours. Thank you.

I know this is an old thread, but I just wanted to mention the LINN bearing oil.

I too have experimented with many oils - including silicone oil - in our LINN bearing. Then I was told that silicone oil offers very little in terms of lubrication to the bearing.

Great for dampening, but lousy for protecting the precious bearing surface(s)!

I just wanted to mention it.

Perhaps a silicone oil fortified with MOREY'S or WYNNS anti-friction oil additive might help?

Just a thought.