LCR Phono the EZ Way - Vinyl Song
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):
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
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. http://usr.audioasylum.com/images/0/...129_-_Copy.jpg
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.
Vinyl Song - #3
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.
Vinyl Song - Our Solution
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.
Vinyl Song LCR- the cost
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
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
Cole LCR vs Vinyl Song
AS I'm getting a lot of requests for information about the differences between the Cole LCR and the Vinyl Song:
There does not seem to be much love for The Vinyl Song? Or at least it very quite in this thread - let us change that and share experiences with this nice phono stage :)
I have just finished building my LCR Vinyl Song less than an hour ago, it's connected to my system and it's working. Still way to early to comment on the sound, but here are a few pictures of the build.
Please share your experiences with this one. Tube rolling? Different caps? or what ever...!?
Hmm... Seems that it's just me in this thread..! Wonder if I'm the only person who has bought this phonostage? ;)
Here is a bit of an update, and a few questions to you Thorsten if you're reading here also...
The phonostage sounds incredible..! Compared to the Whest Audio I owned before (more than two times as expensive as the Vinyl Song), this phono stage has a sound, that is so much more natural, coherent, dynamic and ''alive''. The Whest Audio sounds sterile and lifeless in comparison. Very nice :)
One small comment on the instruction manual: The wiring of the high/low gain switch for the MC input is wrong. Wiring the switch like described means that the high gain is with the switch in the low position, and the low gain in the high position. Re-wiring the switch is easy to do, and this makes it more intuitive that the switch is up when the gain is up, and the gain is down, when the switch is down. Otherwise the instructions are correct and easy to follow.
My only issue - and the questions to you Thorsten - relates to hum. I'm using my Ortofon MC 70 Anniversary that has quite a low output (0,125 mV) and with this cartridge the gain is on the low side even with the mc step up on high gain, and the hum is a bit much. Well, there is quite a bit of hum actually.
I have tried to work on the hum by doing the following (also see the pics below):
Screening of the input side wires for the mc step up, so that only the last cm or so before the soldering is not screened. The screen is connected to the chassis ground connector as illustrated in the manual.
Wrapping the mc step-ups in Mu-metal.
I have made tube screens of copper and Mu-metal, these are connected to ground.
I have made some Mu-metal shields for the transformers...
These updates has lowered the hum a little bit, but it's still quite loud. Thorsten is there anything else I can do to fight hum? Or should I use a cartridge with higher output that does not challenge the phono stage so much? I have a Sumiko Celebration II Pearwood as well, and it has 0,5mV output.
Such a nice example of a DIY project. Professionally build.
I am using the original LCR Cole for more 7 years now and still very satisfied with the sound. The new Cole max should be better but my current Cole is using the Steve & Billington LCR module and will need some effort to transplant it to the new Cole Max.
@rtsang: Thanks..! I like to build my DIY as nice as I can :)
OK, here are some facts on the hum problem... The test set-up:
The Phono stage sitting on my dining room table, no transformers or anything that can induce noice close by (the soldering station is of course OFF). The inputs are shorted inside RCA plugs on the inputs, outputs are measured on another set of RCA plugs. I tried to move the scope around the table to check if it induces noise, but that does not seem to be the case.
This first measurement is the MM input and the noise is around 2 mV pp on the scope.
The second measurement is the MC LOW gain, there is a slight increase in the noise to around 2,5 - 3,5 mV. As can be seen one channel is a bit worse than the other, that is the channel located closest to the mains transformers in the box.
The final measurement is the MC HIGH gain setting. As can be seen there is again a slight increase in the hum, especially in the channel that's located closest to the transformers inside the box.
IN all these measurements the noise is A LOT higher than the 0,1 - 0,3 mV advertised by DIY HIFI SUPPLY earlier in the thread, so please help with some kind of solutions to bring the noise down to the advertised level? As is there is too much noise for this phono stage to be usefull. It's sounds great, but the noise is very distracting and loud.
Have you got shields (grounded) on the tubes?
Are the wires from the MC Transformer outputs shielded?
Also make sure that any "loose metal" (e.g. transformer cases, shields etc) are properly grounded (low resistance to either chassis or ground.
|All times are GMT. The time now is 05:04 AM.|
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio