Sending balanced signal to unbalanced subwoofer

[starfly]

I ordered a Minidsp Flex, the balanced version (found it for less than the unbalanced version because of all the tariffs), to be used in a 2.2 setup.

My main speakers are driven by a purifi amp with balanced inputs, so those will be fine. But my 2 subs only have unbalanced inputs. Will the 4vrms output of the Flex cause issues for the subs? Will be using TRS > RCA cables.

 

[NTK]

This from the miniDSP support portal should answer your question. Since the recommended cable is using only one of the 2 branches of the balanced output, the voltage as received by the RCA input will be reduced by half to 2 V.

Flex Balanced connectivity: Which TRS to RCA cable should I use?

The Flex balanced is balanced in/out. If you'd like to use an unbalanced amplifier (e.g. Powered subwoofer) downstream of the Flex series, here is the recommended TRS to RCA cable to minimize detrimental effect on the audio quality. Note how...

support.minidsp.com

 

[starfly]

This from the miniDSP support portal should answer your question. Since the recommended cable is using only one of the 2 branches of the balanced output, the voltage as received by the RCA input will be reduced by half to 2 V.

Flex Balanced connectivity: Which TRS to RCA cable should I use?

The Flex balanced is balanced in/out. If you'd like to use an unbalanced amplifier (e.g. Powered subwoofer) downstream of the Flex series, here is the recommended TRS to RCA cable to minimize detrimental effect on the audio quality. Note how...

support.minidsp.com

Now if I could only find such a cable somewhere. The article only references the type of cable to be used. Will look into it.

 

[rcstevensonaz]

Now if I could only find such a cable somewhere. The article only references the type of cable to be used. Will look into it.

You can order custom cables in USA from Performance Audio (and several others places). I started down the path of doing my own wiring, and then realized I would have been far ahead just ordering custom from them instead.

If looking for pre-made cables, be sure they use 2-wire STP (single twisted pair) rather than coax cable. And that the wring exactly matches this diagram.

 

[starfly]

You can order custom cables in USA from Performance Audio (and several others places). I started down the path of doing my own wiring, and then realized I would have been far ahead just ordering custom from them instead.

If looking for pre-made cables, be sure they use 2-wire STP (single twisted pair) rather than coax cable. And that the wring exactly matches this diagram.

Good call. I also made my own cables in the past, and overall it's just way cheaper (and probably better soldering lol) to have a company like this do it. But perhaps less fun

 

[rcstevensonaz]

Good call. I also made my own cables in the past, and overall it's just way cheaper (and probably better soldering lol) to have a company like this do it. But perhaps less fun

Yep. The markup by Performance Audio is way below the value of my time spent making cables. That might be different from someone who makes cables all the time; but I only do it on a few occasions.

I was also impressed with the range of connector and wire options they provide, including all of the components I decided were the ones I wanted to use on my interconnects.

 

[Panelhead]

I have made my own. Used one leg and ground and also both legs and no ground. Gain was high with both legs and no ground.
Since your dac has 1/4” connections just use a TR plug and a RCA. TR plug into a TRS jack is single ended. Buy one TR to RCA if you do not want to make one.

 

[rcstevensonaz]

Since your dac has 1/4” connections just use a TR plug and a RCA. TR plug into a TRS jack is single ended. Buy one TR to RCA if you do not want to make one.

Which is different from the specific cabling guidance from the manufacturer, which shows leaving Ring unconnected.

 

[KSTR]

This from the miniDSP support portal should answer your question. Since the recommended cable is using only one of the 2 branches of the balanced output, the voltage as received by the RCA input will be reduced by half to 2 V.

Flex Balanced connectivity: Which TRS to RCA cable should I use?

The Flex balanced is balanced in/out. If you'd like to use an unbalanced amplifier (e.g. Powered subwoofer) downstream of the Flex series, here is the recommended TRS to RCA cable to minimize detrimental effect on the audio quality. Note how...

support.minidsp.com

Their recommendation is highly questionable. While it is really important to leave the R contact of the TRS unconnected it is also important to make the ground connection as low impedance as possible and for that you have to connect the shield on both ends, notably if the cable is long. Otherwise increased hum levels may result.

 

[KSTR]

Since your dac has 1/4” connections just use a TR plug and a RCA. TR plug into a TRS jack is single ended.

... but shorts out half of the driving circuit which has to be avoided as degradation and even damage may result.

Gain was high with both legs and no ground.

Using T and R but no GND may work but is not best practice. Depending on the grounding scheme of the devices, this can still short out the Ring signal or even destroy the driver circuit.

 

[MCH]

What I did (for two subs) is to buy a long trs to trs cable from amazon, cut it in the middle and solder RCA connectors leaving ring floating. It was the most cost effective solution I could think of. It works fine, but there are pops if I switch off the DAC (Motu interface) before the subs. Asked Motu about this and they rightly pointed out to the trs > RCA solution was not ideal. But other than transforming the amp inputs to balanced, I don't know anything better.

 

[starfly]

... but shorts out half of the driving circuit which has to be avoided as degradation and even damage may result.

Using T and R but no GND may work but is not best practice. Depending on the grounding scheme of the devices, this can still short out the Ring signal or even destroy the driver circuit.

So what would be best in your opinion?

 

[KSTR]

So what would be best in your opinion?

TRS-Plug with R not connected, then going to a good (low shield resistance) standard coaxial interconnect with RCA on the other end.

 

[starfly]

TRS-Plug with R not connected, then going to a good (low shield resistance) standard coaxial interconnect with RCA on the other end.

Alright, I'm gonna build my own cable I guess, just ordered all the parts. So how should I be soldering this exactly on the TRS side? Do you happen to have a resource with a diagram?

 

[KSTR]

https://www.ranecommercial.com/legacy/note110.html, Figure 9, just that the right side is an RCA instead of TS.

Simplest way to do this -- as others have mentioned -- is to buy a longer RCA--RCA cable, cut it in the middle and solder TRS plugs to the open ends,, leaving R unconnected.