That was the point of my CMR statement. See my preamp article.
Let's run the numbers for noise of an SUT. In my aticle, I used a Sowter 8055, a moderately priced unit. Primary resistance is 0R72. Secondary resistance is 100R, with 1:10 stepup. So the input-referred ENR is somewhat over an ohm. Not noiseless, but well below the ENR of most MC cartridges.
At audio frequencies, the ENR of even the exotic tubes is 100R or more- usually a LOT more.
Let's run the numbers for noise of an SUT. In my aticle, I used a Sowter 8055, a moderately priced unit. Primary resistance is 0R72. Secondary resistance is 100R, with 1:10 stepup. So the input-referred ENR is somewhat over an ohm. Not noiseless, but well below the ENR of most MC cartridges.
At audio frequencies, the ENR of even the exotic tubes is 100R or more- usually a LOT more.
BIC MC amplifiers are about 0.3 nV rt/Hz - pretty good.
But, they can't compete, without a lot of added complexity and noise degradation, with a transformer when it comes to CMR.
I'd give on balance to the transformer - but you need to spend a bit of money for a decent product.
IIRC the Jensens are about $300 each
But, they can't compete, without a lot of added complexity and noise degradation, with a transformer when it comes to CMR.
I'd give on balance to the transformer - but you need to spend a bit of money for a decent product.
IIRC the Jensens are about $300 each
The tube input ENR issue is further compounded by the fact that it is usually calculated based on measurements at frequencies tens to hundreds of MHz removed from the audio band. Tubes are usually significantly noisier than the ENR would seem to imply, particularly at the low end of spectrum where flicker (1/F) noise is usually the dominant noise source.
Generally by the time you are done with the cartridge resistance, primary and secondary resistances of the SUT will generally be significantly worse than the ENR of most good high transconductance triodes and perhaps on par with a quiet 12AX7A. Note that the ENR on the primary is multiplied by the square of the turns ratio and you have to add the secondary resistance as well. (As an approximation)
The quietest tubes I have used so far are the D3A, 5842/417A, and 6S3P-EV. There are others out there, particularly of Russian and European Post Office/Telecomm origins.
Generally by the time you are done with the cartridge resistance, primary and secondary resistances of the SUT will generally be significantly worse than the ENR of most good high transconductance triodes and perhaps on par with a quiet 12AX7A. Note that the ENR on the primary is multiplied by the square of the turns ratio and you have to add the secondary resistance as well. (As an approximation)
The quietest tubes I have used so far are the D3A, 5842/417A, and 6S3P-EV. There are others out there, particularly of Russian and European Post Office/Telecomm origins.
ooopppss, sorry i asked 
from what i can see the SUT will only sound as good as the MM stage it's going into. ok so the SUT might be silent but the MM stage might be noisy so the end result will be a noisy stage.
on the other hand if you have a dead silent MM stage then i can see that a SUT would be good.
so if you have a noisy MM stage and want an MC cart then from what i can see you would be better off building a nice silent MC phono stage as the SUT will make no difference to the sound of a noisy MM stage.
from what i can see the SUT will only sound as good as the MM stage it's going into. ok so the SUT might be silent but the MM stage might be noisy so the end result will be a noisy stage.
on the other hand if you have a dead silent MM stage then i can see that a SUT would be good.
so if you have a noisy MM stage and want an MC cart then from what i can see you would be better off building a nice silent MC phono stage as the SUT will make no difference to the sound of a noisy MM stage.
I have both, and prefer the transformers, however the solid state unit (based on an AD multi-tan amplifier IC and not of my design) is much more versatile and more than quiet enough, it also manages to sound pretty good.
Bibio I did not mean to discourage you, in most cases the noise floor with any decent tube MM phono stage and SUT is still going to be lower than the noise floor of the actual recording.
Bibio I did not mean to discourage you, in most cases the noise floor with any decent tube MM phono stage and SUT is still going to be lower than the noise floor of the actual recording.
Hi,
There are a few more out there that could be considered for MC headamp use.
What matters most to me is the linearity and noise figure in the region close to Vg0.
There's no point of building a tubed MC stage if you need a huge input cap to begin with.
When valves are carefully selected and controlled by CCS there is no good reason not to // them and take advantage of the lowered noise figures and reduced Rp.
I've build several valve based MC stages (one of them was publicized on this forum which is really cheap to build) that are absolutely dead quiet, have no cap input and would take all but the obscenely low output MC.
Valve noise is rarely a problem, RF often is and so is PS induced noise. Other than that it is fairly straightforward to build either a SE or a fully balanced MC stage.
The reason why it never got anywhere I suspect is that it's so much easier to use either a solid state input or a SUT.
I'd like to avoid SUTs as whatever they're qualities or shortcomings, you're just stuck with what you've got and that will determine everything that is attached to it.
IOW, I'm a bit of a control freak.
Ciao,
There are a few more out there that could be considered for MC headamp use.
What matters most to me is the linearity and noise figure in the region close to Vg0.
There's no point of building a tubed MC stage if you need a huge input cap to begin with.
When valves are carefully selected and controlled by CCS there is no good reason not to // them and take advantage of the lowered noise figures and reduced Rp.
I've build several valve based MC stages (one of them was publicized on this forum which is really cheap to build) that are absolutely dead quiet, have no cap input and would take all but the obscenely low output MC.
Valve noise is rarely a problem, RF often is and so is PS induced noise. Other than that it is fairly straightforward to build either a SE or a fully balanced MC stage.
The reason why it never got anywhere I suspect is that it's so much easier to use either a solid state input or a SUT.
I'd like to avoid SUTs as whatever they're qualities or shortcomings, you're just stuck with what you've got and that will determine everything that is attached to it.
IOW, I'm a bit of a control freak.
Ciao,
Why bother - you will never get it as noiseless as a ss head amp.
An Aussie guy named Trevor Lees came out with a tube-based head amp, phono stage and line stage in the 80s. I owned his head amp (which had been upgraded/recapped by someone who knew what he was doing) but, once I heard my current ss head amp - which just amplifies, without adding any noise - I got rid of it, as there was no contest.By all means have tubes in your phono stage ... but use an ss device for head amp duties, IMO.
Regards,
Andy
Why bother - you will never get it as noiseless as a ss head amp.
All you have to do is get it as quiet or quieter than the MC's intrinsic noise. Past that, which is quieter is academic.
Hi,
There are two types of noises that bother me no end, one is tape hiss the other being SS noise.
For some reason tube noise does not seem to interfere all that much with the music IME. I just don't hear it in a properly executed design.
You'll need to think frame grid construction, TFK, late Seventies.
A trioded D3A is certainly a good candidate for this service as it is one of the lowest noise ever tubes, so is a EC8010.
Then, you need to look at the curves: you want a valve which is linear at Vg0, this is extremely important.
Even more important is to look at what happens when the grid goes slightly positive. Does the grid start to draw current?
You won't find these data in a regular data book, it takes one the size of the yellow pages to retrieve such information.
Philips and Telefunken are great sources of such info but these books are extremely rare.
Think of this stage in terms of I/V conversion instead of a mere voltage amplification stage. Once you understand that you know you need an end of era kind of valve, one that is almost transistor like (I apologize for the unintended blasphemy), has high transconductance and high perveance too and you'll have your cake.
If such valve does not exist, a clever designer (not me) can create it.
Think about it.
Kevin, if you don't mind, I'd rather discuss this further with you via PM.
Ciao,
There are two types of noises that bother me no end, one is tape hiss the other being SS noise.
For some reason tube noise does not seem to interfere all that much with the music IME. I just don't hear it in a properly executed design.
You'll need to think frame grid construction, TFK, late Seventies.
A trioded D3A is certainly a good candidate for this service as it is one of the lowest noise ever tubes, so is a EC8010.
Then, you need to look at the curves: you want a valve which is linear at Vg0, this is extremely important.
Even more important is to look at what happens when the grid goes slightly positive. Does the grid start to draw current?
You won't find these data in a regular data book, it takes one the size of the yellow pages to retrieve such information.
Philips and Telefunken are great sources of such info but these books are extremely rare.
Think of this stage in terms of I/V conversion instead of a mere voltage amplification stage. Once you understand that you know you need an end of era kind of valve, one that is almost transistor like (I apologize for the unintended blasphemy), has high transconductance and high perveance too and you'll have your cake.
If such valve does not exist, a clever designer (not me) can create it.
Think about it.
Kevin, if you don't mind, I'd rather discuss this further with you via PM.
Ciao,
Hi,
Besides that you'll need to take into account that any cartridge riding a groove is putting out much more noise than the intrinsic noise of a MC.
Which is why it is so important to reduce this noise by choosing the best stylus tip and make sure the record is as clean as the proverbial whistle.
Ciao,
Besides that you'll need to take into account that any cartridge riding a groove is putting out much more noise than the intrinsic noise of a MC.
Which is why it is so important to reduce this noise by choosing the best stylus tip and make sure the record is as clean as the proverbial whistle.
Ciao,
Hi,
Besides that you'll need to take into account that any cartridge riding a groove is putting out much more noise than the intrinsic noise of a MC.
Which is why it is so important to reduce this noise by choosing the best stylus tip and make sure the record is as clean as the proverbial whistle.
Ciao,
I have replicant, line contact and various ellipticals in my collection of MC carts, mostly various incarnations of the SPU, and a Benz Ebony H that I find myself liking a lot. (Relatively low hours and new to me.) I also have a VPI record cleaner, and try to keep things clean. Some of my LPs are extremely quiet, most not so much..
How did this thread go from a simple question regarding voltage ratios using a SUT to a debate about tube vs SS? Surely there are other threads where this can (and has been) openly debated...
I think the OP had a valid question and I don't know that it has been answered.
I also posted a question and I have yet to see it addressed:
How is the output voltage of a cartridge characterized (open circuit or loaded)?
I think the OP had a valid question and I don't know that it has been answered.
I also posted a question and I have yet to see it addressed:
How is the output voltage of a cartridge characterized (open circuit or loaded)?
1. It has been.
2. Depends on what the spec sheet shows. Usually, it's with the recommended load, but the difference between unloaded and loaded is generally less than 1dB.
Cartridge termination
1. My mistake. I interpreted the OP's last contribution as still not receiving a clear answer. I stand corrected.
2. Not sure I follow the math on this one: 1dB difference between open circuit and terminated by internal impedance? By definition, there should be a 6dB difference, correct?
On the spec sheet for my Benz Glider 2 cartridge, it lists the internal impedance as 95 Ohms, but recommended loading is 1K-47K. That would certainly show a -0.8dB difference (@1K termination) . So maybe the question should be:
Do you terminate the cartridge with a value equal to the internal impedance or with the mfr's recommended value. If the latter, how is that value determined. Inquiring minds want to know.....
1. My mistake. I interpreted the OP's last contribution as still not receiving a clear answer. I stand corrected.
2. Not sure I follow the math on this one: 1dB difference between open circuit and terminated by internal impedance? By definition, there should be a 6dB difference, correct?
On the spec sheet for my Benz Glider 2 cartridge, it lists the internal impedance as 95 Ohms, but recommended loading is 1K-47K. That would certainly show a -0.8dB difference (@1K termination) . So maybe the question should be:
Do you terminate the cartridge with a value equal to the internal impedance or with the mfr's recommended value. If the latter, how is that value determined. Inquiring minds want to know.....
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