-10dbu to +4 dbu converter

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Kir_For_Pleasure

Well-known member
Joined
Jun 25, 2005
Messages
207
Location
Hallstahammar Sweden
Must be a few threads about convert consumer levels to pro levels, maybe someone can fill in with a nice project to built.
I want to go from my mixers direct out -10dbu to a SSL Alphalink converter +4dbu

cant find something when i use the search function
 
have looked at your balancing boards many times...what i dont get is the -10 +4 thing with signal/impedance matching..must read more..

also found this
DIY-Fig.-1_lg.gif
 
Surely this has been discussed here multiple times.

A couple quick observations in passing;

R6 could be connected directly to U1A pin 1 for a cleaner feed.
R3 and R4 both seem a little high impedance for much practical benefit (if any).

For layout R12 needs a clean shot to output RCA gnd to provide a good reference to the output, not input caps and pin 1 common which is a shield ground.

JR
 
Yes... While technically they are all connected together we need to think of current flowing in those individual PCB runs.

Pin 1 from the XLR is shield and chassis ground so there could be all kinds of garbage noise current flowing in that path.  The ground on the RCA jack is the clean -10dBV signal ground. So while they both ultimately connect back to the PS ground, you don't want shield noise corrupting the signal ground by flowing in a shared PCB trace.

JR
 
Kir_For_Pleasure said:
ahh transformers are fun !!! but that would be from +4 to -10...step down ??
Sowter makes it a bit confusing- you don't want to decrease a -10 level by 12-14 dB but the opposite.  That could be achieved by reversing the transformer and doing a little Zobel work.  I love iron, but for this application use the balancing circuit posted or check the THAT Corp. balancing datasheets.  Do a search here for "That Corp balancing" and you will get sumpin'.

If you were in the states, I would say get this.  Uses 5532, and you can get picky if you want and change caps, set fixed gain, etc.  Can't beat the price.
Mike
PS: and in your case you need not concern yourself with impedance matching.  The SSL is not 600 load impedance.
 
Kir_For_Pleasure said:
Thanks for replys and suggestions should etch a card as soon as possible.

In case you don't want to design your own layout but use something existing instead...

http://www.groupdiy.com/index.php?topic=29333.0
 
I don't get the thought behind R4 (100k). I suppose this could/should be 0 ohm, because U2A acts as a unity gain buffer.
IMHO you could even omit R3, R4 and U2A completely!
 

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