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Connecting Unbalanced DAC output to Balanced Power Amp

SanjeevM

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#1
How does one connect the unbalanced (2-pin) output from a DAC to a power amp which has a 3-wire balanced input ??
 
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prem

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#2
You can either use a rca to rca cable or a xlr to xlr cable and get the appropriate xlr to rca adapter. Neutrik makes one and is good
 

Kannan

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#3
Sound System Interconnection

Short 1 and 3 on XLR and connect to shield, wire the signal wire to 2 in XLR.
These cables are available off the shelf from MX.

If you can DIY and little better option for better noise rejection is to use a 2-conductor shielded cable.
Short one conductor to shield on RCA end. The other conductor will connect to pin 2 on XLR.
The shield will connect to pin 1 on XLR and the 2nd conductor shorted at RCA end will connect to pin 3 on XLR.

For practical purposes, get the MX RCA male to XLR male cable cable.

quite a few options here

http://www.amazon.in/s/ref=nb_sb_noss_2?url=search-alias%3Delectronics&field-keywords=RCA+male+to+XLR+male
 
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jls001

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#4
@SanjeevM: see the table in the page linked by Kannan. Item#6 is what you need (if going DIY route). Otherwise buy the Neutrik RCA-XLR adapter suggested by Prem.

If you want to go the purist way of using transformer as suggested in the same page, there's a firm in Mumbai that builds such RCA-XLR impedance matched transformers (but very costly).
 

Aniket

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#5
Hi,

I would consider an opamp based balanced line driver/converter, which accepts unbalanced input and puts out balanced output. much better than any simple connector.

Regards,
Aniket
 

sadik

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#6
Hi,

I would consider an opamp based balanced line driver/converter, which accepts unbalanced input and puts out balanced output. much better than any simple connector.

Regards,
Aniket
That's what i was about to say after looking at your latest PCB design for same.

Sadik
 

prem

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#7
Hi Sanjeevm, for home listening, balanced/unbalanced is not really a big thing. Balanced makes sense in a studio where cable lengths can be very long. At home we normally use 1m interconnects. Further, when using an op amp to go balanced, you are adding more circuitry to the signal which may not necessarily be a great thing. And if noise is an issue, I would try shielded unbalanced cables. I would prefer to keep the signal length short.
 
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SanjeevM

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#9
I need a small length only to connect inside the amplifier box, say 8 inches or so.

Can I use a good two core shielded cable?
One core carries signal while other core and shield are grounded. In that sense a single core cable should also do if the third point is grounded at the socket.



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SanjeevM

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#10
(I understand that impedance matching is the proper way of doing it.)

Sent from my ASUS_Z00AD using Tapatalk
 
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Kannan

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#11
I need a small length only to connect inside the amplifier box, say 8 inches or so.

Can I use a good two core shielded cable?
One core carries signal while other core and shield are grounded. In that sense a single core cable should also do if the third point is grounded at the socket.



Sent from my ASUS_Z00AD using Tapatalk
yes. You can do it that way.
 

Aniket

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#13
Further, when using an op amp to go balanced, you are adding more circuitry to the signal which may not necessarily be a great thing.
while most of us dont know this,
the high definition or high end or audiophile music (flac,wav,aiff or a cd and others) we listen at our home has already passed through at least 100 op-amps in the studio mixers and other recording equipment in the studio. and these op-amps are not high end. so adding a few more op-amps in signal path with degrade sound - is completely bogus

a simple unbalanced to balanced converter using a single good op-amp will perform way better than just an adapter.

I need a small length only to connect inside the amplifier box, say 8 inches or so.

Can I use a good two core shielded cable?
One core carries signal while other core and shield are grounded. In that sense a single core cable should also do if the third point is grounded at the socket.
yes of course you can do it this way if the wire run is not that long with little loss in performance.
BTW, which amp are you using which accepts only balanced input.?
 

SanjeevM

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#18
I dont know how to post pictures here, so I have uploaded it's picture in my album. Request you to see it there.
 

Aniket

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#20
Hi Sanjeev,

here's the link : TPA3251D2 2CH Class D Audio Amplifier

now, what i can see on the pcb, it is written: IN A, B, C , D and there's also a jumper to select SE(Single ended) and DIFF(Differential) inputs. so, probably this kit is 4 channel amp in SE mode and 2 channel amp in DIFF mode,

It uses one chip in BTL mode to make a 2 channel amp, and there are op-amps(NJM4580, these are good) on the pcb as buffers for the TPA chips. One op-amp per channel. So, if you wish to use this kit in 2 channel Bridge tied load configuration, then you have to provide differential inputs. It needs an inverted signal to properly work in push-pull configuration.

I couldn't find any documentation for the kit, so my opinion is based on pics of the module.

Regards,
Aniket
 
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