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Title: Need help with KT DN410 eq
Post by: Matt Sum on April 19, 2011, 07:48:18 am
Hi guys,

I finally managed to get a couple of Klark Technik DN410 parametric eq's from eBay (thanks to Dick Rees and Marlow Wilson for the offers to help with getting stuff shipped to me!).

However, one of the DN410s hasn't been working.  I've been trying to use it as an unbalanced insert on channels of a Mackie Onyx 24:4 (using an insert cable that is 1/4" TRS to 1x M-XLR and 1x F-XLR).  It will pass audio without problems (and each of the filters will work without any obviously audible problems) and then it will suddenly stop passing any audio at all.  This can happen in the middle of programme material going through or when there is a break in programme material (in which case, when the programme material resumes, no audio will pass through).  If I then really crank the gain on the Onyx mic preamp, it will suddenly start passing audio again (although it may stop doing so within five minutes).  In that regard it seems to be behaving like a "dry" solder joint.

The issue is on both channels "A" and "B" of the DN410.

I believe I have excluded a problem with the Onyx channel strip because I've had the problem on two different channel strips which have otherwise been working.  Furthermore, things start working immediately after I pull out the insert cable.

I also believe that I have excluded a problem with the insert cable because I have tried two different insert cables and encountered the same problem.

I should note that the DN410 has output balancing transformers.  However, my other DN410 appears to work when inserted unbalanced, so I don't think that it's the fact that I'm inserting unbalanced although the unit has balanced inputs and outputs.  Having said that, I have not tried using the DN410 with balanced connections.

Ordinarily, at this point, I would simply take it to a repair technician.  However, I have tried to replicate the fault at home (the Mackie mixer is at church) on an A&H Zed10fx and have been completely unable to.  The A&H doesn't have inserts on each channel, but does have inserts on the left and right main outs.  When the faulty DN410 is inserted on these left and right main outs, it always seems to pass audio.  So I'm not sure I'll even be able to demonstrate a fault to a repair technician.

Does anybody have any suggestions as to what might be going on with my misbehaving eq and what I should do about it?

Any advice would be much appreciated.


Title: Re: Need help with KT DN410 eq
Post by: g'bye, Dick Rees on April 19, 2011, 01:10:13 pm

Take a look in here:

Go to the page which describes the balanced/unbalanced input and output configuration.  It will tell you which type of insert cable you need regarding the pin2/3 hot variations and how to reconfigure the unit as needed by changing the internal jumpers to get it to use the same type of insert cable as the rest of your gear.  I had to order a special insert cable for all my KT stuff as I didn't want to change the jumpers.  That said, I have no explanation for why it would work with one console and not the other.  There should be no (global) phantom issues as there should be no phantom applied to the insert jacks.
Title: Re: Need help with KT DN410 eq
Post by: Chris Hindle on April 19, 2011, 03:18:37 pm
Sounds to me like a dirty insert jack on the Mackie.
If you have never used the inserts before, there is likely a bit of corrosion built up. Time for some DeoxIt, and work the plug in and out 20-30 times.
Open up the board to see if you can get to the fingers that do the switching. That's what needs cleaning, not so much the parts the 1/4" plug rides across.

Title: Re: Need help with KT DN410 eq
Post by: Marsellus Fariss on April 19, 2011, 08:47:18 pm
I bet it's either a cracked soldier joint of the insert jack of the mackie or a bad insert cable. Is your insert cable of the molded end variety or does it have ends that can be screwed off and checked for broken/frayed connections?
Title: Re: Need help with KT DN410 eq
Post by: Matt Sum on April 23, 2011, 07:45:56 am
Hi all,

Thanks very much for the replies.

Sorry for the delay on my part.  I've been away.

I shall try to check the insert jack on the Mackie as well as the insert cable. 

However, I'd kind of be surprised if it was either, because I've tried two different insert jacks on the Mackie (of course, it's not impossible that two insert jacks are dirty) and I'm reasonably sure I've tried two different insert cables (of course, it's not impossible that there are intermittent faults in the insert cables).  Furthermore, the other DN410 has worked with these insert jacks on the Mackie as well as with both insert cables (although, gain, an intermittent fault somewhere is possible).

Any other suggestions from anyone?  If there is something wrong with the KT DN410, what might it be that would explain the possible "intermittency" of the problem?