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Electrovoice dx38: Modification


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Hey Guys,

There had been post about a modification to the Electrovoice dx38. This mod was designed to reduce the noise floor (or hum) and may have been based on advice or schematic from Chief Bonehead / Bodcaw Boy. 

 

Have searched but I am unable to find it. Can anyone point the way? Was this a general solution or was it just for unbalanced / balanced mis-matches?

 

Thanks,

-Tom

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For the record, I've found that both of my Dx38s are very quiet, even compared to the Yamaha SP2060. Adjusting the preamp--Yamaha crossover--amplifier gain structuring has helped in the latter case.

 

Chris

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As I recall, there were two items on the list.

 

one was to tie the ground.  The other was to replace some resistors with higher (lower?) value to attenuate the signal a bit.  (vague memory)

 

Here is a picture of DocWho doing mine.  You can see the resistor he's working on (there are like eight in a row) and, you can see them on their own.

 

I might caution....  later in life, I've obtained a second Dx38 and now, they are not 100% matched.  Not a huge deal...  just saying beware of growing needs!

 

 

post-12967-0-60980000-1469228550_thumb.j

post-12967-0-30980000-1469228601_thumb.j

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For anyone interested here is a good paper by Jensen and especially note page 4 (sections 4 and 5 )which might explain why EV doesn't ground it's input circuits XLR's Pin1 of the EV DX38. Basically in some situations ungrounded can be superior for Balanced Hookup of componets but in the case of some unbalanced componets using 2 prong AC corded equipment especially(ie: equipment without a 3rd prong for earth ground) who's chassis are allowed to float the ungrounded Pin1 of a balanced XLR input circuit can lead to hum/noise problems.

Even though I also use unbalanced equipment(all my equipment does use 3 prong grounded AC cords) I have no hum/noise problems in my system whether I ground pin1 or not of the EV but some users with unbalanced equipment should try this modification for optimum hum/noise rejection.

 

 

miketn

 

 

 

Jensen-InterconnectionofBalAndUnbalEquip.pdf

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