Current sensing phono stages w/Rega?

This morning I reviewed this thread for some reason. To sum it up, the OP reports that his Rega TT works fine with the Konus phono stage. He posted here because he is contemplating the purchase of either the Channel D Lino C or the Sutherland Little Loco phono stage, and he is aware that the Rega TTs cannot do balanced connection to a phono stage. Both the Lino C and the LL are balanced, for sure. But the point is that the OP is currently using the Konus and a Rega TT with no issues. I then looked for specs on the Konus. So far as i can tell it is single-ended, much to my surprise. However, neither the description on the Konus website nor any of the reviews is really very good at describing the technology. Photos of the rear of the Konus show only RCA inputs and outputs, further leading me to believe it is SE by nature. This explains why Hleeid has no issues. He WILL have an issue if he elects to purchase a Lino C or the original LL. (I gather the LL2 is now capable of accepting SE inputs via RCAs.) But we know there is an easy fix.

Then along comes jc51373 who is having loud hum with his combo of Konus and Rega. I and several others heretofore assumed this was due to the incompatibility of the Rega TT with balanced operation, owing to the way the Rega is grounded. (I confess that due to my thick skull and careless reading, I hadn't previously noticed that the OP has no problem with his Rega/Konus set up.) And we suggested there is a simple fix for that. JC himself seems to have assumed that his hum is the fault of the Rega. But since the Konus appears to be SE, JC’s problem cannot be that simple. JC needs to look elsewhere for the cause of his hum, maybe a broken ground connection somewhere. Funnily, if the internal connection between the tonearm body and the L channel audio ground (described by Dover)  has been disrupted, that would cause loud hum in SE operation. Just saying.

If what you say is true, it's possibly because the necessary modification to the wiring (not to the arm) is so simple there would be no need to get the factory involved.

Regardless of your definition of “it”, read Dover’s post again. All you have to do is disconnect tonearm ground from left channel ground, and then you’re free to use a balanced connection. The tonearm itself can then be grounded separately.

What is the “it” in your last post?

Since hum by conventional definition is usually 60Hz or 120Hz, you really cannot filter it out without destroying bass response.  I don't understand "floating ground" with a single-ended connection. (You say Rega does not use a balanced connection; SE is the only other alternative.)  In an SE circuit, the signal MUST see ground or maybe that is why you have hum. (One normally gets a very loud hum if audio ground is disconnected.) In a balanced phono circuit, the signal is divided into pos and neg phases and audio ground is left to "float", which is to say there is no ground reference.

Sorry for perhaps being overly bossy.  But again, you would be doing no harm to Roy Gandy's design.  Wires is wires.  If it's beyond your skill set or your desire to do the work, I am sure you can find a local person competent to do it.  I have never owned a Rega anything, so I don't know how ground is wired, but I am sure there are other Rega-philes here who could guide you.  It has to be a very simple thing to do.  And there I go being bossy again.  The good thing is, you can totally ignore me.

You’d be “modifying” the wiring, not the tonearm, in such a way as to make it suit your needs and which could always be put back to original. It’s just a thing you bought with your money to suit your needs. It’s not a holy object.

It should be possible to rewire the Rega to make it compatible with balanced, floating ground operation. All you’d need is a soldering iron, a pair of XLR plugs or RCAs where you’d solder the negative phase output to the outer barrel while also disconnecting ground, and knowledge of the OEM Rega wiring scheme.

Mijostyn, you are extrapolating from “your own experience “ to a general principle. The results will vary according not only to internal R but also voltage output of the cartridge and input Z of the phono and intrinsic gain of the current driven input stage. Your report is valid for your Lino and your cartridge. I’m saying the BMC works fine with the 12-ohm ART7 that puts out only 0.12mV in terms of voltage. Thus you can discern it doesn’t make much current. Yet the +7db setting on the BMC will blow you out of the room with the linestage attenuator at 9 o’clock.

Those are all very expensive cartridges, and the fact remains that most current driven phono stages work well with cartridges that have internal R in the range 2 to even 20 ohms, though I would be leery of going that high myself.

I am curious to know what cartridges have an internal impedance of 2 ohms or less.  My own MC2000 fits the criterion, and I know there are others such as the Haniwa that present an even lower internal R, but I would think the list is very short after that.  Also, maybe we should make a distinction between "works" and "works best" into a current mode phono stage. Hdm is quite right to point out that "works best" also depends upon the actual input Z of the phono stage.  With the 12-ohm AT ART7, which puts out only 0.12mV, you have a cartridge that is on the fence for either current- or voltage- mode.  I find that it works great with my BMC (2-4 ohms input Z), usually in the +7db gain mode.  It's a little more robust sounding into that device than it is into my high gain SS voltage-mode phono stage, but either works fine.  Don't you think it's a little severe to say that 2 ohms is the upper limit for internal R???  If that were the case, the market for current-mode phono stages would be very tiny. (Perhaps it is only a little better than "tiny" in reality.)  On the other hand, why would you want to use current mode with a 40-ohm cartridge that has 0.4mV output?  One reason would be if you don't own a high gain voltage-mode phono stage and mating such a cartridge with a SUT would be problematic (although could work with a 1:10 SUT, but preferably no higher ratio). Anyway, lots of folks seem to be using current mode with cartridges, even up to 20 ohms internal R.

I think 10 ohms would work fine, for one thing because 12 ohms works fine with my AT ART7, but you really do have to be sure about balanced wiring. In most cases the tonearm wiring easily adapts to balanced mode, but with Rega being British, all bets are off. The reason for extreme caution is that with no or very low load resistance on the phono end you run the risk of damage to your cartridge due to a jolt of current.