Another Sum Box - My first DIY project

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AUDIO-ON

Member
Joined
Feb 15, 2010
Messages
16
Location
Switzerland
Hi there to everybody!
This is my first post since I've started reading your posts here a few weeks ago. Finally I decided to start my first DIY Summer.
Basically, a passive 16ch summer (inspired on NYDave's schematic - a copy). I will implement a basic dual mic pre to gain the output, an auxiliary bus to monitor, a bypass for the active output (to load it into different preamps) and a stereo VUMeter.
I've seen this schematic for the pre http://sound.westhost.com/project66.htm but I can't see that the output is balanced. Is there any way to transform this into a balanced output? Using a transformer? I don't know too much about electronic, but I'm working hard on it.
I will publish a schematic for the summer as soon as it is ready.

Thanks for the interest and sorry for my english.
Regards
 
welcome to hell  ;D
while you still have time; leave... dont  look back...
or you will invest every single penny in your pocket to DIY, its endless...
i have at least 5K of components in my stock, plus measuring equipment... more on the way....

anyway, its really great here, the very best forum ever.

there are some real cool mic pres here... check white & black market...
A*I. ne*e, SS* , tube... you name it... its all here... most with high quality PCB and great support....
 
kambo said:
i have at least 5K of components in my stock, plus measuring equipment... more on the way....

It's a black hole...tried several times to de-stock but somehow ending up with different (and in the end more) stuff.
 
Patience Grasshopper.

You could use transformer or IC balancing. You would need two of whatever you choose as you're talking a stereo signal. Gustav sells balancing pcbs designed to go with the 9k pre in his white market thread. (http://www.groupdiy.com/index.php?topic=10776.0)

::edit::

Upon further inspection it appears to me like that circuit has a TL071 in it to specifically unbalance the output signal. I'll have to leave it up to those more knowledgeable than myself, but I think you could get a balanced signal from that board by leaving off the differential gain stage. You would lose some gain though... (6 or 15 db it says?)
 
Thanks for the quick reply. A loss of 12 -15 db would be probably no problem 'cause the passive summing has a loss of 40 db and mic pre a gain of 60db. 45 db still enough to raise the output level from the summing bus to nominal.
 
Hi there!
Finally I found a Mic pre kit at jlm audio. Bic Ban Kit.
Anyone know something about them? I think they're quality kits but if anyone assembled and test them, reviews would be fine...
 
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