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Cable required for HP60 External input from Balanced TRS source?

Posted: Sun Nov 22, 2015 1:21 am
by patrickjackman
I am researching Headphone Amplifiers and your HP60 looks very nice but I have a question.

I would be driving the (more me) External Inputs from an RME ADI-8 (link below), which supplies a mono balanced signal on a 1/4" TRS connector. What kind of cable would I need to get audio into both the left and right headphones from this source without using the mono button?

Whoa, I think I have found the answer in your owner's manual. Can you please confirm that the Mono button affects only the Ext In source and not the A/B Mix as well?

Thanks!

http://www.rme-audio.de/en/products/adi_8_ds.php

Re: Cable required for HP60 External input from Balanced TRS source?

Posted: Sat Dec 05, 2015 12:10 pm
by patrickjackman
Disappointed there is no reply yet from Presonus.

So I purchased an HP60 and it's obvious that not every cable will work. For example, with a DB25 connected to my ADI-8 when I plug one of the 8 TRS ends into one of the HP60s External Inputs and click the Mono button it cancels out most of the External Input signal.

Re: Cable required for HP60 External input from Balanced TRS source?

Posted: Mon Dec 07, 2015 7:21 am
by Karyn
patrickjackman wroteSo I purchased an HP60 and it's obvious that not every cable will work. For example, with a DB25 connected to my ADI-8 when I plug one of the 8 TRS ends into one of the HP60s External Inputs and click the Mono button it cancels out most of the External Input signal.

That's not a fault with the cable, but a misunderstanding of what it is providing and what the HP60 is expecting.

The individual inputs on each HP60 channel are stereo, where the TRS connections are expecting Left/Right/Ground. The Mono button simply sums the Left and Right.

The DB25 output on your ADI-8 provides 8 balanced mono signals, where the TRS on each plug gives Hot/Return/Ground.

If you use this un-altered you should get the signal in the LEFT channel of the HP60. Pressing the mono button will sum the Hot and Return, leaving you nothing....

To make it work as required you need to lift (cut) the wire on the RING of the plug and connect it to ground in the plug. This unbalances the signal so when you press the mono button you get it in both ears.

Re: Cable required for HP60 External input from Balanced TRS source?

Posted: Thu Dec 10, 2015 1:15 am
by patrickjackman
Thanks for explaining that Karyn. The ADI-8 also provides 8 balanced line level outputs on 1/4" TRS connectors. What would you recommend as the simplest solution for getting audio from those into the HP60's individual inputs?

BTW, I'm very happy with the flexibility and sound of your HP60 and look forward to using it with the ADI-8.

Re: Cable required for HP60 External input from Balanced TRS source?

Posted: Thu Dec 10, 2015 6:03 am
by Karyn
Whether you're using the DB25 with a breakout cable or the individual outputs your issue is the same.
You have a series of mono balanced outputs that you need to connect to an un-balanced, stereo input.

What you have to do is make (modify) a cable that has 2 TRS (or DB25) on one end and a TRS on the other, wired as my post above. We have exactly the same issue connecting the aux outputs on the RM mixers to an HP60.

I have made a couple of short patch leads for my rack to do exactly this, you have to do the same.
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Re: Cable required for HP60 External input from Balanced TRS source?

Posted: Thu Dec 10, 2015 6:34 am
by Karyn
If you only want mono input to each headphone amp you can simply use a standard 1/4" jack patch cable from the ADI-8 1/4" outputs to the HP60 ext input and press the mono button. Do not use a cable with TRS plugs on each end, just standard TS plugs.



Yes, I know the picture shows a Behringer headphone amp... I have an HP60 in a different rack ;)

Re: Cable required for HP60 External input from Balanced TRS source?

Posted: Mon Dec 14, 2015 12:36 am
by patrickjackman
Again, thank you Karyn. Great photos and a very clear explanation. Regular 1/4" plugs it will be.

Patrick.

Re: Cable required for HP60 External input from Balanced TRS source?

Posted: Sat Oct 22, 2016 10:04 am
by Scoox
I was considering the HP60 for my headphone distribution needs. The routing capabilities are very attractive, but I have some reservations about some of the design choices made by Presonus, some of which like putting the power switch on the back are ridiculous. So I'm just going to make my own amp and probably start selling it since nobody is making a decent headphone distribution amp. :reading:

Re: Cable required for HP60 External input from Balanced TRS source?

Posted: Sat May 20, 2017 8:47 pm
by alexstewart1
I know, 1st time poster on a Zombie Thread!!!!

Thank you Karyn for explaining TRS vs TS wiring.

I found this thread because I was having the same problem with my Foucrite Clarett 8pre; TRS mono outs going into the Presonus HP60 TRS Stereo External Input. What I found though, is that the signal in the 'More Me' gets substantially louder using the TRS cable (no Mono) vs the TS cable in Mono mode.

What is even weirder is that as I turn up the 'More Me' volume with the TRS cable, it starts off mono/left (as Karyn described) but the more I turn it up, the more I hear it in both sides.

The HP60's Stereo External Input's output sounds much better (louder) using the TRS cable, imo.

Thanks for the good information-Alex