Need help with DIN to RCA phono cable troubleshooting

^^ Actually except for the balanced thing, Dover and I were on the same page. I thought I had made that clear in my last post.

I do feel I should clarify some things in **your** post however :)  (please note that I am not quarreling)

First, if an XLR appears on a preamp the expectation should be that it supports the AES file 48: the balanced line standard. However in practice you are correct in that buyer beware- in high end audio, the XLR connector is often there in appearance only.

I feel the term 'balanced' is the more common word but I like 'symmetrical' as that might be more descriptive when used to describe the preamp.

The reason to go balanced with a phono setup is not simply because the cartridge is a balanced source! There are two advantages- the one most people know about is the possibility of lower noise, particularly if the preamp is fully differential from input to output. Any noise imposed on the cable cannot get amplified. BTW, if a step up transformer is used, all transformers have the ability to operate balanced and even if the output is single-ended, the ability to reject noise in the cable is maintained.

The second benefit of balanced line is less understood by audiophiles, but was actually the intention of balanced line from its inception- and that is to reduce or eliminate any artifacts that come from the interconnect cable itself. For anyone that has been considering a large sum of money to buy an expensive single-ended phono cable this should be welcome news. The fact is that if the interconnect cable is built correctly (twisted pair within a shield, pin 1 of the XLRs being tied to the shield and no need for a separate ground wire) it will not need to be expensive and will compete easily with cables costing thousands of dollars.

IOW it will sound better.

Now you see debate in high end audio all the time about whether balanced is better or not! Some people say its only better if long lengths are employed. While it does excel at long lengths, even if its only 6 inches its still going to work better. But quite often the debate arises simply because the high end audio equipment used didn't support the balanced standard and as a consequently the result are variable!

That standard is there for a reason (which is to eliminate cable artifact).

I know this sounds a bit circular, but frankly I don't understand why a manufacturer would present an expensive product that does not do what it should. This is distressingly common in high end audio!

Here are the elements of balanced operation. If you follow these, the cable will have far less artifact and so will sound better:

1) pin 1 is ground, pins 2 and 3 carry the signal.
2) ground is ignored. It is for shielding only and at no point carries any signal current!
3) the cable will be a twisted pair within a shield.
4) the output of the balanced connection will drive a low impedance if possible, which will appear between pins 2 and 3.

In the case of a LOMC, point 4 is very easy, since many LOMCs are loaded at only 100 ohms. For this reason the interconnect cable should not impose any sonic artifact whatsoever.

FWIW, most high end audio manufacturers get messed up on 2) above. Quite often if they have a balanced product, they design it such that the output of pin 2 is with respect to ground and the output of pin 3 is with respect to ground. This is a mistake- the output of pin 2 should be with respect to pin 3!

@cleeds , Thanks for pointing that out. I have worked on a lot of broadcast gear over the years and have yet to see see any balanced phono sections and so conflated that to thinking that no-one had sorted out that phono cartridges are a balanced source. I do know for a fact though that our MP-1 was the first balanced line preamp ever offered in consumer audio and that its phono section was the first fully differential phono section ever made.

While the above discussions make me to feel like a mental midget, I am happy to report the problem turned out to be a bad rectifier tube in the power supply section of my Modwright SWP 9.0 SE phono stage.

The comments posted above will be great reference material should I ever turn to balanced connections in my analog front end.

Thanks for all the input, regards,
Dan

so you should explain those benefits in the context of  ''full

symmetrical phono-pre'' which is much more expensive to make

because on need twice as many components than by single

ended phono-pre. If this is correct than...[snip]

It isn't. It does not take twice as many components. That is a popular myth.

What one may save on cables one will lose on the amp.

Its hard to put a value on that if performance and the best sound is your goal so I regard  this as a bit of red herring. We simply did the balanced phono section because it sounds better.

I don't think there is room for 'belief' when it comes to the advantages of balanced operation. The benefits have been well-documented and understood for decades. IOW its not a matter of belief. Its a matter of knowledge. If someone tries running balanced and does not get superior results, there are some variables- chief amongst them in high end audio is the simple lack of understanding among many designers that there is actually a balanced standard.

Dover deed not comment on my question about possible benefit of the symmetrical connection.

Correct (I added that part); my intention was in correcting statements which did not seem factual:

Nandric - for all phono both balanced and unbalanced the arm earth ( 5th pin ) should be a separate wire which you connect to preamp chassis.

In this case above, a balanced system does not employ the ground wire as its built-in to the XLR connection. It becomes a separate wire when the cartridge (which is a balanced source) is operated single-ended. You have to do something with the ground (the tone arm itself, which is shielding only) and so it gets connected to the chassis.

-and in the same post, above:

XLR's have a separate -ve signal and earth/ground in a balanced system. Therefore you only need to ensure the shield is connected to the earth/ground pin which is already separated from the -ve signal. The tonearm end is left floating ( not connected ).  

The problem I had here is the tone arm ground should be tied to the shield of the interconnect and then to pin 1 of the XLRs. Its not common practice to leave the arm tube floating as is suggested in this quote.

I suspect that this was not what he mean to say, but that is what was written.