You are here

Advice solving ART DTI grounding issue

All about the tools and techniques involved in capturing sound, in the studio or on location.

Moderator: Moderators

Advice solving ART DTI grounding issue

Postby jessemcgoldrick » Wed Apr 07, 2021 10:20 pm

Hi all, thanks in advance for any help or advice.

I’m trying to connect a pair of balanced XLR outputs to a pair of unbalanced RCA inputs using the ART DTI but I get a really loud humming...

Sound source is mains powered with earth (3 pin)
XLR cables go from source XLR outputs into DTI XLR inputs.
RCA cables go from DTI RCA outputs to destination RCA inputs.
Destination is mains powered without earth (2 pin)

The issue seems to be with connecting the DTI’s unbalanced RCA outputs to a destination which doesn’t have a mains earth connection, as if I keep everything else the same but connect to a destination which uses a 3 pin earthed power supply the humming is gone...

Any ideas how I can solve this?

Thanks in advance for any help or suggestions!
jessemcgoldrick
Posts: 2
Joined: Wed Apr 07, 2021 9:09 pm

Re: Advice solving ART DTI grounding issue

Postby Hugh Robjohns » Wed Apr 07, 2021 11:34 pm

Is the DTI box near something with a mains transformer?

Or it could be that the class-2 destination device doesn't like a floating input...in which case, try running a wire from the earth terminal on the input side to the sleeve/barrel of one of the RCA output connectors.
User avatar
Hugh Robjohns
Moderator
Posts: 30718
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound
In my world, things get less strange when I read the manual... 

Re: Advice solving ART DTI grounding issue

Postby shufflebeat » Thu Apr 08, 2021 9:47 am

Hugh Robjohns wrote:Is the DTI box near something with a mains transformer?

Or it could be that the class-2 destination device doesn't like a floating input...in which case, try running a wire from the earth terminal on the input side to the sleeve/barrel of one of the RCA output connectors.

Not in a position to check at the minute but if memory serves the earth terminal isn't on later versions, or possibly earlier versions depending on which order mine were constructed.
shufflebeat
Jedi Poster
Posts: 6160
Joined: Sun Dec 09, 2007 1:00 am
Location: Manchester, UK
"Dance, dance. wherever you may be, for I am the Lord of the damp settee..."

Do yourself a favour, wear earplugs at gigs.

Re: Advice solving ART DTI grounding issue

Postby Hugh Robjohns » Thu Apr 08, 2021 10:27 am

Odd... it's been on all the ones I've used over the years.

An alternative test arrangement would be to plug a TRS-TRS cable into the input side, and then touch the sleeve of the other end against the outer collar of the RCA on the output side.
User avatar
Hugh Robjohns
Moderator
Posts: 30718
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound
In my world, things get less strange when I read the manual... 

Re: Advice solving ART DTI grounding issue

Postby shufflebeat » Thu Apr 08, 2021 7:44 pm

Hugh Robjohns wrote:Odd... it's been on all the ones I've used over the years.

Image

vs

Image
shufflebeat
Jedi Poster
Posts: 6160
Joined: Sun Dec 09, 2007 1:00 am
Location: Manchester, UK
"Dance, dance. wherever you may be, for I am the Lord of the damp settee..."

Do yourself a favour, wear earplugs at gigs.

Re: Advice solving ART DTI grounding issue

Postby Martin Walker » Fri Apr 09, 2021 12:48 am

Good evidence shufflebeat- odd to see ART abandon an earthing point for the sake of a single knurled screw connector in a hole that still exists in the chassis!


Martin
User avatar
Martin Walker
Moderator
Posts: 17401
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: Advice solving ART DTI grounding issue

Postby Hugh Robjohns » Fri Apr 09, 2021 11:01 am

Wow. Fancy that! I've checked and all the ones I have here have the earthing screw, so it must be a relatively recent change...

But not one for the good, because there are situations where that lug is essential to the correct functioning and application of the unit, and I can't imagine its removal would save any significant component costs or production time.
User avatar
Hugh Robjohns
Moderator
Posts: 30718
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound
In my world, things get less strange when I read the manual... 

Re: Advice solving ART DTI grounding issue

Postby Tomás Mulcahy » Fri Apr 09, 2021 12:08 pm

Something is amiss here.

My older one had no earthing screw, my newer one does. Unfortunately I sold the older one. The new one has a sticker saying it was manufactured 11/2010. It does not have the legs that Shufflebeat's one has either.
User avatar
Tomás Mulcahy
Frequent Poster
Posts: 1984
Joined: Wed Apr 25, 2001 12:00 am
Location: Cork, Ireland.

Re: Advice solving ART DTI grounding issue

Postby jessemcgoldrick » Fri Apr 09, 2021 3:29 pm

Hugh you’re a lifesaver. Connecting TS at input and linking sleeve to RCA output sleeve did the trick. I’ll come up with something more elegant now. Thanks so much!

Edit: My unit does have a chassis ground pin luckily, linking this to the RCA output ground did the trick and only required a few cm loop of wire. Brilliant.
jessemcgoldrick
Posts: 2
Joined: Wed Apr 07, 2021 9:09 pm

Re: Advice solving ART DTI grounding issue

Postby Hugh Robjohns » Fri Apr 09, 2021 4:32 pm

jessemcgoldrick wrote:Hugh you’re a lifesaver.

It has been known... ;) ...but in this case it was simply the appliance of science! :ugeek:

Connecting TS at input and linking sleeve to RCA output sleeve did the trick. I’ll come up with something more elegant now. Thanks so much!

No problem, glad it solved your problem.

Edit: My unit does have a chassis ground pin luckily, linking this to the RCA output ground did the trick and only required a few cm loop of wire. Brilliant.

Quite -- it was provided for exactly this kind of scenario and that's why its apparent omission in (some) current units is rather disturbing!
User avatar
Hugh Robjohns
Moderator
Posts: 30718
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound
In my world, things get less strange when I read the manual... 

Re: Advice solving ART DTI grounding issue

Postby shufflebeat » Sat Apr 10, 2021 12:07 am

Tomás Mulcahy wrote:My older one had no earthing screw, my newer one does.

I wonder if that's the development timeline, "hey, we have the wherewithal to add a chassis earthing point for the price of a short threaded shaft and a nut, I wish we'd thought of this before we'd sold all those others".

I'd like to think it was that way round anyway.
shufflebeat
Jedi Poster
Posts: 6160
Joined: Sun Dec 09, 2007 1:00 am
Location: Manchester, UK
"Dance, dance. wherever you may be, for I am the Lord of the damp settee..."

Do yourself a favour, wear earplugs at gigs.

Re: Advice solving ART DTI grounding issue

Postby Wonks » Sat Apr 10, 2021 10:50 am

No, the current ART page for the DTI has no feet or ground knob. SO taht wil be the latest incarnation, although the ART manual still indicated a ground connection. The Thomann page for the DTI shows the grounded version, but without feet, but I'd expect that you'd get a non-ground knob version.
User avatar
Wonks
Jedi Poster
Posts: 11270
Joined: Thu May 29, 2003 12:00 am
Location: Reading, UK
Correcting mistakes on the internet since 1853

Re: Advice solving ART DTI grounding issue

Postby merlyn » Sat Apr 10, 2021 11:26 am

It's not as neat or user friendly but if the internal connections are still the same (i.e. that screw is still earthed) it would be possible to loosen the screw, wrap a bit of wire around it, then tighten the screw.

Just in case anyone with the new model needs an earth.
merlyn
Regular
Posts: 242
Joined: Thu Nov 07, 2019 3:15 am

Re: Advice solving ART DTI grounding issue

Postby Sam Spoons » Sat Apr 10, 2021 11:32 am

I'd have thought it easy enough to replace the screw with a longer one with two nuts and a couple of washers between them. Use on nut to secure the panel and the other to sandwich a wire between the washers. Worth checking but it'll almost certainly be earthed via the internal thread in the chassis, if not then clean the paint off the panel around the hole.
User avatar
Sam Spoons
Jedi Poster
Posts: 15643
Joined: Thu Jan 23, 2003 1:00 am
Location: Manchester UK
Still taking this recording lark seriously (and trying to record my Gypsy Jazz CD)........