PrestonTom Posted July 22, 2016 Share Posted July 22, 2016 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 Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted July 22, 2016 Share Posted July 22, 2016 I bumped this thread Tom. https://community.klipsch.com/index.php?/topic/109276-humbuzz-ev-dx38-xlr-rca-adapters/page-2#entry2041493 I do remember DrWho doing some mods to one but the above is what Roy suggested if Hum is a problem. miketn Quote Link to comment Share on other sites More sharing options...
Chris A Posted July 22, 2016 Share Posted July 22, 2016 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 Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted July 22, 2016 Share Posted July 22, 2016 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 +1 on my use of the DX38 also...... miketn Quote Link to comment Share on other sites More sharing options...
babadono Posted July 22, 2016 Share Posted July 22, 2016 Wow really in this day and age a PROFESSIONAL piece of balanced audio equipment in which pin 1 of XLR connectors is not tied to the chassis? Really? Quote Link to comment Share on other sites More sharing options...
mark1101 Posted July 22, 2016 Share Posted July 22, 2016 The DX38 is not from this day and age. Quote Link to comment Share on other sites More sharing options...
Coytee Posted July 22, 2016 Share Posted July 22, 2016 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! Quote Link to comment Share on other sites More sharing options...
Coytee Posted July 22, 2016 Share Posted July 22, 2016 I can't say I ever heard any real change in any noise. Seems most of my issues were caused by mismatched cables.... the one I had wired backward didn't help! Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted July 23, 2016 Share Posted July 23, 2016 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 Quote Link to comment Share on other sites More sharing options...
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