Ferrofish A32 AD/DA - do I need DB25->TS?

[Facetigris]

Hi,
I'm on the fence to get a Ferrofish A32 AD/DA-interface for connecting synths to my RME UFX+ via MADI.

I'm wondering about the cables needed. Most of my synths are unbalanced. Will ordinary DB25->TRS looms be fine to use in this scenario. Or is it worth the extra cost and hassle to order custom made looms (DB25->TS) from for example proaudiola.com? I think no cables would exceed 2,5 meters (8 feet).

Or would it be a better alternative to use a balanced patchbay (I have 2 or 3 Neutriks hanging around unused) and use TS or TRS cable to it, depending on the source (Balanced or unbalanced)?

[porthoss78]

Hi there,

I can't answer your question about the Ferrofish, but another option you might want to consider is the RME ADI-648 MADI to ADAT convertor. You can usually pick them up second hand for less than £500 and would enable you to add an additional 8 ADAT interfaces to the UFX+. You could then have these ADAT convertors much closer to your equipment, requiring shorter cabling so you could use unbalanced cables without any issues. Not sure this would work out any cheaper from getting the Ferrofish and DB25s etc. though but thought I would mention it in case you didn't know about the ADI-648.

Good luck with it though, I'd love to have a UFX+ one day...

Thanks
J

[Hugh Robjohns]

Most of my synths are unbalanced. Will ordinary DB25->TRS looms be fine to use in this scenario.

I'm afraid the answer is... it depends!

As a general rule, you can plug unbalanced sources, like your synths directly into balanced inputs.

However, there are two potential issues to consider.

The first is that there is a risk of creating ground-loops between the synths and interface, resulting in unwanted hums and buzzes. This will normally only apply to those synths which have three-pin mains supplies (class-1) rather than those which have two-pin (class-2 or double insulated).

And the second is that the quarter-inch sockets of some synths are only built to accept TS plugs. In these cases, the ring contact of a TRS plug is left isolated and 'floating' instead of being grounded, and that might cause more unwanted noise problems.

The short cable distance (under 10 feet) won't cause problems with interference, if that's what you were worried about, since you're handling reasonably strong line-level signals anyway.

Or would it be a better alternative to use a balanced patchbay (I have 2 or 3 Neutriks hanging around unused) and use TS or TRS cable to it, depending on the source (Balanced or unbalanced)?

Personally, I'd go down this route. Not only will it allow you to patch in other equipment, effects processors etc when needed, but it also overcomes any potential TS/TRS connection issues if you run TS-TS instrument cables from the synths into the rear of the TRS patchbay.

If you subsequently find you have ground-loop noises on any particular channels, there are various ways of resolving that on a case by case basis which I'm happy to discuss if necessary.

[Facetigris]

Thank you Hugh, much appreciated.

I was a bit unspecific. I'm thinking of getting an A32, which uses DB25-connections or two Ferrofish 16 MX (also via MADI), which uses TRS-connections. I already have an A16 which also has TRS-connections. I use TS->TS cables to connect my synths to that, without any known hassle. The A16 is connected via optical MADI.

I have many synths and would like to get them hooked up permanently, hence the original question. The A32 solution is tidy, both at the synth end and also the connection to the i/f. I could use optical MADI to one of the units and BNC MADI to the other. As the AD/DA converters are placed at opposite sides of the room I can omit some cables by doing so, instead of daisy chaining (which is the case with the option of two 16MXs). Also some additional latemcy could be avoided, not daisy-chaining them.

The patchbay solution I asked about was actually to connect the A32 to a patchbay and then the synths to that same patchbay. But that might not change anything about the problems specific due to TS-TRS mismatch? I'm going use a patchbay anyway, for some of the channels, for the specific reasons you mention.

All my synths are modern, from 1990 and onwards, if that info says something regarding the possibilty of omitted ring contacts.

I also have an ART T8 8-channel isolation transformer to bring into the picture if that's helpful here.

/Roger

[James Perrett]

I think I'd go the DB25 to TRS route with a patchbay. It makes the system so much more versatile and the cables are very cheap if you go to CPC (though I'm not sure how good they are at supplying to EU countries at the moment).

[Facetigris]

Many thanks. I think I will go that way. Thank you all for sharing your knowledge and taking your time doing so.