I find that transformers tend to obscure detail and they limit bandwidth. So if you have enough gain, an MC high gain phono section might be better if properly designed.
The loading of the transformer is critical, else it can ring (distort), making things brighter and obscuring detail. All the following is assuming that the transformer is properly loaded:
If you do not have enough output from your cartridge, most phono sections will loose some bass impact. Where a transformer will normally do that too, in this case they will win you some back.
If you have too much noise, the noise will obscure low level detail. Where transformer will also loose detail, it also gets you gain without noise, and so wins you back some of that low level detail.
So- its not something that you can always state what will work in all cases. Usually the manufacturer of the phono section will know if the cartridge you have will need a transformer or not.
If there was a panacea, I would state it but as a manufacturer myself that is well-known for not liking transformers, I'll be the first to admit that they can be very beneficial in a variety of situations! |
Yes, SUTs are susceptible to hum. If running direct- there are big differences in high gain phono sections too, so comparison is anything but a level playing field! |
We've specifically avoided using SS input in our tube phono section. Instead, we created the first fully-differential phono stage (1989) as a means to keep noise down. I've tried a variety of SUTs (and never had a hum problem, FWIW).
SUTs do offer a great noise floor, but at a slight loss of detail and musicality. We did everything we could to make sure they were loaded correctly- BTW if not properly loaded the SUT will express the inter-winding capacitance rather than the turns ratio- IOW loading is **essential**. I am sure that with some preamps, the SUT is an important part of getting a LOMC to work, but with our preamps as longs as the cartridge is over 0.2mV going direct sounds better. |
Dertonarm, IME LOMCs have a lot of current. So much that if you short them out completely, the sound from the phono section will only be a few db down (and rolled off on top). Most audiophiles don't seem to realize that in exchange for low output voltage you get high current.
If there is any advantage to using an SUT, it is this fact, although a direct-coupled input stage can take advantage of this as well. I suspect that 20 years from now this will still be a debate, and still largely be dependent on the topology of the phono section. |
Emorrisiv, sounds like you have a grounding problem. Make sure the arm ground, transformer ground and cable shields are all good. You can tie the arm ground to the SUT ground at the SUT's input and that should be consistent with the ground at the output of the SUT.
There could be a loading issue, but I would not mess with it until you have the hum problem fixed! If the ground is not right there could be ringing in the cable (anyone how has worked with oscilloscope probes knows what I am talking about); IOW the hum and the sibilance could be related. |
If you are getting sibilance you need to look at why. I guarantee its not on the records. You could be having RF problems- that is in keeping with sibilance and hum BTW.
We always solder the DIN connections when we build a phono cable. My advice: be very careful!
The ground scenario I outlined previously will be fairly resistant to RF BTW. |
If you have a low output cartridge, the phono cable will need a good 200 hours. Its best if you don't disturb it! |
Yes- don't move the wire. It only breaks in with a signal though it. There are break-in boxes made for that that can speed things up. We have a number of customers using Acoustats. I've heard a few of them with our amps over the years. They are not hard to drive but some of them have very low impedance, so depending on the model, you may need to use a set of ZEROs http://www.zeroimpedance.comIn one system that I was very familiar with, the Acoustats were so low impedance that the ZEROs were needed for the Audio Research that the guy owned, IOW the ARC would not drive the speaker right even on the 4-ohm tap. The ZEROs can be a real problem solver! |
Emorrisiv, one thing you will find in working with cartridges in general is it is best to keep your connections between the cartridge and the preamp to a minimum.
In the case of an SUT, I think you will also find the cable **after** the SUT to more critical than the one before, as the impedances involved are much higher at the output of the SUT and so more susceptible to cable issues. By comparison, the cable from the cartridge (if the cartridge is properly loaded) is relatively non-critical, especially if you run it balanced, which is possible if you have an SUT. |
Brent, All transformers have a primary and secondary winding (if they only have a primary then they are called autoformers). The windings do not care if one side is at ground or not. So at the input to the SUT, you could lift the winding connection that is at ground, and use an XLR connector, set up with pin 1 (ground) being the arm ground and transformer shield, pin 2 being the + output of the cartridge and the 'normal' input wire to the SUT, and pin 3 being the minus output of the cartridge and the wire that was lifted from ground.
This effects a balanced input, and the output can then be single-ended or balanced, again using the same technique. |
Emorrisiv, have you been playing with loading? |
IME you can get excellent results with an SUT but the cartridge and the SUT must be matched for best results, including all the loading issues, as cartridges have loading issues and SUTs have loading issues of their own and neither can be ignored. That is why they have to matched, so that when the SUT is properly loaded, so is the cartridge.
However I have found the transformers anywhere in the audio chain represent a loss of bandwidth and detail with added distortion. It is in the phono section that they potentially represent the least effect, but as they are located at the very first place the signal will pass through, any issues they have are compounded by the gain and distortion of everything downstream. Now that might not be so bad if an active stepup (that is also being considered) is poorly designed, but it is obvious that a properly designed phono section that has enough gain will give any SUT a run for the money.
Sometimes though you do find certain people who cannot tolerate any noise (and therefore may prefer digital on this account, despite analog being better in every other way). For anyone who has noise issues SUTs represent an excellent compromise. IOW it is possible, using and SUT, to get signal to noise ratios in the -90 db range.
In a nutshell: for maximum transparency and bandwidth go direct if you can. For minimum noise go with an SUT.
With less than state of the art equipment IMMV! |
