Sorry that should say XLR - RCA adapters. Thanks.
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Although a lot of equipment having balanced outputs can tolerate having the inverted signal (pin 3 per the convention used in the USA and many other countries) grounded, some can't (see this thread for example, although it involved a solid state component), and personally it strikes me as being being poor practice at best. Also, the output impedances of the Einstein preamps are very low (especially for tube designs), which everything else being equal increases the likelihood of there being a problem.
There are three approaches that occur to me:
1)Cardas can supply adapters which leave pin 3 unconnected, although they are significantly more costly than standard adapters.
2)You could have a cable supplier custom make an adapter cable which leaves pin 3 unconnected.
3)You could purchase a Jensen transformer, such as their model PI2-XR (which is the same as the illustrated model PI2-XX except with RCA output connectors), and an additional set of cables if necessary. It would connect to the amp input with a very short length of RCA cable, and to the preamp with whatever length of XLR cable is necessary.
A transformer such as that one would in effect convert the unbalanced input of the amp to a balanced input, with the advantages that can potentially provide. Those would include reduced susceptibility to ground loop issues; reduced sensitivity to cable differences, especially in combination with the low output impedance and excellent drive capability of your preamp; perhaps lower noise levels, etc. A number of users here whom I consider to be highly credible and have very high quality systems have reported excellent results using Jensen transformers to adapt balanced to unbalanced connections, or vice versa, although there are also one or more highly credible members who assert that they introduce subtle sonic compromises.
Good luck. Regards,
P.S: A fourth option, which I suspect would be an excellent choice although at a considerably higher price point, would be Steve McCormack's transformer-based SMc Audio Flex Connect. Note though that it provides a gain reduction of 12 db, which should be considered in the context of the gains, sensitivities, and source levels of your particular system.
A fifth option is to have the amplifier updated with a balanced input. Its not that hard (finding a place to put the connector is the hardest part), its cheap to do, does not change the character of the amp, does not use transformers, and does process both the inverted and non-inverted phases of the signal correctly.
We have been doing this update for years. But its not hard and any technician qualified to work on audio electronics could do it.
How it works: all tubes have two inputs, the grid and the cathode. Normally the cathode is ignored as an input. In this case we put it to work. While the result is differential, it is not truly balanced, but it does work quite well. The RCA input becomes pin 2 (signal) and pin 1 ground), pin 3 is the cathode input; a coupling cap is installed for this purpose. The input impedance is low but if the output impedance of the preamp is as low as touted, this is not and issue.
The problem you are up against is that normally balanced and single-ended connections really are not that compatible (one result of that is hum and buzz if there it trouble). But there are ways to make things work- we've been doing this longer than anyone else so we've learned a few tricks along the way.
I love this forum... so many experienced people who are happy to help.....
So not as simple as I first thought.
Al...I like the sound of the flex connect it looks... flexible and it can stay with me agnostic of amp.
Atmas how about having my local technician install a pair of single ended outputs on the Einstein... I think Einstein offer this as an option in its pre-amps now so it is do-able, but I'm not sure how complicated it is. My pre-amp is cosmetically second rate so I'd rather work there...I'll investigate.
I don't know what SET I'll end up with yet but installing a balanced input would be something to keep in mind too.
Thanks Both, much appreciated.
The advantage of balanced operation is that your cables will impose less artifact on the system if the balanced line standard is observed. If you go single-ended you loose that advantage.
This is why its to your advantage to receive the balanced signal at the amplifier even if it is single-ended. A transformer input is an excellent solution as most line transformers will have wider bandwidth than most SETs, and if I am not mistaken, you are looking for an SET with a little more power to go with those Devores as I saw on another thread. So a line transformer will not impose any coloration (Jensen makes excellent transformers for this purpose). Devores, like Tannoys, like a bit of power.
It is cheaper though and just as effective to have the amp set up to process the signal directly as I posted above. If the SET designer does not acknowledge how that is possible, have them contact me and I can walk them through it.
Atmas.. As usual you make a lot of sense. I really hadn't thought about maintaining the advantage of The balanced cables.
Thanks for your kind offer of technical know how. When I decide on my amp I'll talk to my designer and see if he is confident in doing this and if he has questions I'll point him in your direction. Again thanks very much for your generosity. :-).
I am late here, just discovered this thread, so it may be irrelevant. My Einstein The tube mk2 has two RCA out, but they are line out, not fit for an amp. Why not get a balanced SET amp? Hearing how the Einstein integrates with balanced amps (Atma-sphere MA-1) using balanced cable, I would not want to go back to SE/RCA.
Thanks holter. I am looking at ways of using the balanced out. It is, after all , what the tube was designed for . My current thinking is to pair it with the pass labs xa30.8. But my planets have to align before I make that purchase. It's a very different route to the SET. But a change is as good as a rest . Thanks again.
My experience with two very different, and both excellent, amps - Krell FPB600 and Atma-Sphere MA-1 - tells me that balanced is generally the way to go. Not in all cases, perhaps, since tastes, experiences and systems differ. But like you say, Einstein The tube is designed for balanced output, although it also has two single ended line outputs. I have listened to both, and prefer the balanced outputs.