LCR Phono the EZ Way - Vinyl Song

[bcherry]

We are spinning vinyl again. Didn't have time to really do the setup since we moved in April but its needed for the work we are doing with the UTS phono system. Also we have a sample of our turntable bearing and the setup gives us a chance to test it.

The Cinemag step up transformers have gotten good comments wherever they turn up. They are the real deal: Mumetal, Faraday Shield, 18 or 36:1 and measured bandwidth up there with the exotics. They are compact and easy to mount. Their small size means means smaller core and more winding thus copper losses. But they are well-engineered and must be the best value step-up transformers around.

We've connected them close to the input jacks and HiLo silver contact switches make for less stray wiring and thus avoid antenna effect. They add no noise to the MM side of the circuit despite the extra +20db gain. I'd read about some noise problems so was worried we would have a challenge taming the noise. But no problem and result is the quietest phono stage we've ever had in-house.

So on the back panel we have from (background to foreground):
RCA outputs
MM input
MM/MC switch (made-in-Japan silver contact toggle)
Hi/Lo switch (also silver contact) to control gain and loading (36ohm/56db; 145ohm/63db)
MC RCA input
Chassis ground

MM gives 36db of gain and MC switchable 56/63db

Then you see the Cinemag transformers
Next the RIAA network (polysytrene and tantalum or Takman)
In the middle are the UTS boards with Tinfoil caps for coupling.
The rectangular box provides shielding and an enclosure for the transformers.

Been playing using a Shelter 501 Mk2/Bluenote arm (the best one they made at the time). Sound is full range, dynamic and throws a big soundstage. The Cinemag really surprises considering the cost. Next I need to dig out my Denon 103r and a Shelter MM I have around here somewhere.

So all in all a reasonably priced fully MC capable phono stage that's EZ to build and maintain.
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EZ is as EZ does..

The ultimate RIAA EQ solution is an 'LCR'. Unlike cap/resistor networks, it puts nothing in the signal path except high quality chokes. The caps and resistors are to ground so they are mostly out the way. The result is a bigger soundfield, and more dynamic contrast and transparency.

BUT, not so easy to implement as stages around the LCR need to be impedance friendly and layout is critical, noise becomes the problem. An LCR phono stage is one of the more difficult DIY projects.

As explained in a previous blog, two UTS modules set for high gain, in series, with an RIAA network in between makes a dead quiet 36db gain phono stage. (UTS >> RC RIAA >> UTS = 36db phono stage).
Now just remove the RC RIAA and replace with 10k LCR: UTS >> 10k LCR >> UTS = 36+ db phono stage. Everything needed is already there - only a 10k loading resistor needs to be added across the LCR out and ground. = 36+ db because there is an increase in volume level of about 1 or 2 db compared to the RC RIAA.

This recipe is playing now.
There is one more possibility: 600 ohm LCR. The UTS has low enough output impedance to drive it and offers the possibility to direct couple to the driving stage. Over the next few days we will be exploring that possibility as well.

Whichever turns out best will be our UTSphono-Max.

BTW: the picture shows LCR with different labels but they are both 10k.

[bcherry]

10k LCR - that was fun.

Today we installed the 600ohm LCR modules. Just remove the RC RIAA and drop in the modules. This takes advantage of the very low output impedance of the Universal Tube Stage (UTS) (50-100ohms). Adding a series resistor to the input side to bring the load that the first stage sees up to 600ohms allows us to direct couple. So...exchange one 2.2uf capacitor for one series resistor. Make it a good one.

On the output side we need a decoupling capacitor - ~0.47uf in value. Again quality matters in this position so best use the best - teflon, polystyrene, silver - because you can hear the quality in this position. It won't be wasted. We used polystyrene.

Done. Playing now. First few minutes were a bit splashy sounding but settling in nicely. From 20hz-25khz we're at -0.5db which is as good as it gets with LCR.

LCR's impress with their open sound and huge dynamic swings.

This will be our new UTS Phono Max. It is EZ enough and we will release it as a kit. Instruction manual to be written.

[bcherry]

The LCR600/UTS sandwich sounds great.

It took a bit of time but we've landed on this as the final layout for lowest noise:
LCR modules need to standup and are wrapped in MUmetal. So we cut some holes into the base plate so the modules would have clearance to stand up.
All wiring kept to the right away from the power transformer box. Tube shields used.

This gives us very low noise (scope jumps between 0.1mv and 0.3mv).
We will soon do a listening session with the original Cole LCR600 compared to this one as there are significant differences.
This is also the most RIAA compliant EQ we ever seen among LCR phono stages.

Got me reaching for vinyl again.

[bcherry]

Projekt box 70 x 300 x320
2 x UTS + 2 Tx
2 x Tesla ECC88
4 x feet
6 x silver RCA
steel box transformer shield
power switch japanese
teflon connection wire
MUMetal Cinemag Stepup Transformer
Silk LCR600
MC/MM switch 12 terminal Japanese
2 x 0.68uf polystyrene
2 x 680r 1w tantalum
30um MuMetal Shielding for LCR
2 copper tube shields

The above (minus the Cinemag)is what will go into The Vinyl Song LCR phono. Not to mention the labour to prepare the parts

We will offer this for the stupefyingly low price of $999USD for the kit. This DOES NOT INCLUDE the highly recommended Cinemag stepups. Add $150USD for the stepups.
+ shipping of your choice.

We are writing the manual now and should be ready to ship in 2 weeks. Unlike the original Cole LCR this one is simple enough for the average DIYr to put together. The CCS on the gain stages self regulate. Most of the parts will be installed so that the DIYr only need make the connections.

This crazy low price is only temporary until we get a few out there. After that it will go up at least $250USD

This may be the cheapest price ever for a complete LCR phono stage. It is definitely and without a doubt the world's best value phono stage

[bcherry]

AS I'm getting a lot of requests for information about the differences between the Cole LCR and the Vinyl Song: