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Atma-Sphere MP1 with single-ended inputs and outputs? Adapters OK?

I had the opportunity to hear an end-game system (for me) that was fronted by an Atma-Sphere MP1 preamp and their Novacrons.  I was blown away by the overall sound, and am highly considering starting purchases toward that system for myself, but had the following questions I'm hoping someone could answer.

In short, the purchase path for me is likely going to last 18-36 months, given the costs of the various components and speakers, so I'm going to have to be living with "hybrid" systems for that time period while I spread the purchases out.

My current weakest link is my pre-amp (although it's not weak, but...).  If I start with the MP1, both my source material (VPI Classic turntable) and amps (Thoress 845 SET monos) are single-ended.  I'm sure I could get an appropriate balanced output for the VPI (I think?) and my DAC already has balanced out (which is my only other source), but what loss in sound quality will I experience adapting for singled ended RCA connections out from the MP-1 to my SET monos?  My current set-up has short (1.5M) runs, so the length of cable won't be an issue for me in single-ended.  But will using something like adapters or the tape outs on the MP1 negate any sonic benefits of the MP1 I might otherwise be getting for the time period I'll be using single-ended amps?  BTW, I LOVE the Thoress 845 amps, so they will likely be the last part of the chain I will consider replacing, and I may choose to keep them in the end-game system depending on the synergy.

Thoughts or experience with the MP1 and single-ended output?
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atmasphere
11,640 posts
 
The Atma-Sphere MP-1 and MP-3 are both available with optional RCA outputs (in addition to the dual balanced outputs). When this option is added there is also a switch installed to switch between single-ended and balanced operation. This is needed as otherwise you can encounter a buzz. When the switch is in the single-ended position the output of the preamp is then single-ended regardless of the connector used.

You can also use and adapter or cable that does the conversion. If so, it is important that pin 1 and pin 3 of the XLR be somehow connected together. This will not harm the preamp in any way and is needed to prevent buzz.

The reason the buzz can occur is that the output of the preamp (pins 2 and 3 of the XLR) is a true balanced circuit, and therefore is 'floating' with respect to ground. If only one side of the output (for example pin 2 of the XLR connection) is used, it will behave like an open input, because that is exactly what it is. To solve this, one side (usually pin 3) is tied to ground (pin 1). 
parsons's avatar
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parsons OP
149 posts
 
Do the adapters you talk about on the site help alleviate that?
bdp24's avatar
bdp24
9,510 posts
 
The problem with XLR-to-RCA adaptors is that they’re made of brass, including the Cardas. But then so are most RCA jacks. Apparently copper is too soft.
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lowrider57
5,397 posts
 
The Jensen Isomax transformer works very well converting balanced to SE. But, correct me if I’m wrong @atmasphere , doesn’t connecting a stand alone transformer inline w/ an OTL affect the sonics?
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dbphd
1,624 posts
 
clio, almarg, et al.

I'm using Parasound JC 2 BP and JC 1 monoblocks to drive KEF Reference 107/2s.  The amps sit next to the speakers, about 15' from the preamp.  The RCA connections of a KEF KUBE prevent me from using balanced lines between the preamp and amps, but I have Jenson Isomax transformers and wonder if using them on either side of the KUBE would be a good idea.  The Isomax units would be close to the preamp with a long run to the amps.

db
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