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Audio Research Amplifier Balanced Input Question

Hello, I am thinking about upgrading my Audio Research VS55i amplifier to one of the higher Audio Research amplifiers which use balanced connections only... specifically a Reference 110 power amplifier.

Would I be able to run a regular (single ended) linestage such as a Manley or a Herron that uses standard RCA inputs/outputs only into the balanced connection of the Audio Research amplifier and have the amp still operate and amplify correctly given its internally balanced configuration? (They do sell high quality handy RCA to XLR connectors/adapters, so making the jacks compatible is no problem, but I am unsure and not knowledgeable about if the two types of circuits are fundamentally incompatible.)

Or does a balanced amplifier require a balanced input signal to run correctly? What happens when a balanced amp sees a single ended signal (only two of three pins of the balanced connector carries signal)?

Any useful input would be welcome.
troidelover1499
atmasphere's avatar
atmasphere
11,815 posts
 
The Reference 110 is very unhappy with a single-ended source! Essentially its input circuit has a very poor Common Mode Rejection Ratio (CMRR); another way of putting that is that it will have high distortion and low gain if operated by a single-ended signal. The distortion goes to about 10% and the output power to about 1/5th of what it should be. So you need a balanced source!

But you can use your single-ended preamp- you just have to drive a line transformer (Jensen makes some that are excellent) to do the conversion for you.
jjss49's avatar
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jjss49
6,612 posts
 
interesting ralph

iirc correctly back 20-25 years ago ARC made some small boxes called Balanced Line Drive (1 2 and 3) or something like that .... could just be for this purpose.

of course there must be active components inside to produce a ’mirror’ image signal to get the full balanced voltage swing from the middle ground neutral level... op amps or transistors or transformers... ralph can this be done just with passive components? there must be a small sonic penalty to adding this in the chain... prob best to just buy a balanced pre

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hey i found 'em! woohoo!!!!

https://www.arcdb.ws/model/BL1

https://www.audiocircle.com/index.php?topic=166675.0
atmasphere's avatar
atmasphere
11,815 posts
 
ralph can this be done just with passive components?
Yes- the Jensen transformers I mentioned. This is the part needed:
https://www.jensen-transformers.com/product/pi-2xx/
There are several versions- the one needed has XLR and RCA connections.
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