Vintage Mixer Setup (Unbalanced Outputs Question)

[Aimes]

Hi all, I have an old SpeckMix 16 MK2 that I use for various studio inputs, mostly synths. It sounds great but the outputs are unbalanced so I def get some buzz.

Would a stereo DI box help reduce noise and should I be going into preamps into my soundcard or basic line-level?

Much appreciated for any advice!

[Tomás Mulcahy]

This is more appropriate than a DI box. On sale here for example. If your soundcard has balanced line inputs that is useful, but not necessary once the ART DTI is in the signal path. But check first if the buzz is present on mixer headphone outputs, for example. Because it might not be a ground loop.

[Hugh Robjohns]

Depends on the cause of the buzz...

If it's ground-loop noise then a (stereo) DI box should help. A passive box would be fine.

DI boxes output a balanced mic-level signal, so need to be connected to a mic preamp.

Alternatively, you could use a line isolation transformer box which will also mitigate a ground loop problem, but output a line level signal.

And finally, if your mixer is connected to a balanced line input you could avoid transformers altogether and use pseudo-balanced cables... although you'll probably have to make them yourself as they are very rarely available commercially.

[Wonks]

Here's the mixer details (for the benefit of others).

http://www.speck.com/pdf/misc/Speckmix_16_Brochure.pdf

[Aimes]

This is more appropriate than a DI box. On sale here for example. If your soundcard has balanced line inputs that is useful, but not necessary once the ART DTI is in the signal path. But check first if the buzz is present on mixer headphone outputs, for example. Because it might not be a ground loop.

Thanks, how does this ART box sound? I always thought they were more on the budget side.

[Tomás Mulcahy]

This is more appropriate than a DI box. On sale here for example. If your soundcard has balanced line inputs that is useful, but not necessary once the ART DTI is in the signal path. But check first if the buzz is present on mixer headphone outputs, for example. Because it might not be a ground loop.

Thanks, how does this ART box sound? I always thought they were more on the budget side.

You're welcome. Read the review, first link

[Aimes]

This is more appropriate than a DI box. On sale here for example. If your soundcard has balanced line inputs that is useful, but not necessary once the ART DTI is in the signal path. But check first if the buzz is present on mixer headphone outputs, for example. Because it might not be a ground loop.

Thanks, how does this ART box sound? I always thought they were more on the budget side.

You're welcome. Read the review, first link

So what exactly is the difference between this and a passive DI?

[James Perrett]

So what exactly is the difference between this and a passive DI?

The transformer ratio.

A DI box will have a transformer with something like 10 times the number of turns on the primary compared to the secondary. The DTI has a transformer with the same number of turns on the primary and secondary.

[Sam Spoons]

A DI attenuates an instrument/line level signal to mic level, a line isolator is the same level out as in.

[Aimes]

A DI attenuates an instrument/line level signal to mic level, a line isolator is the same level out as in.

Ok so stupid question and excuse my ignorance, do I want to keep my mixer out at line level or would i want to bump it up mic level for any reason?

[Tomás Mulcahy]

A DI attenuates an instrument/line level signal to mic level, a line isolator is the same level out as in.

Ok so stupid question and excuse my ignorance, do I want to keep my mixer out at line level or would i want to bump it up mic level for any reason?

Mic level is lower than line level*. You might want to avail of mic pre-amp voodoo. But in your case you already have voodoo with the Speck, so more of it seems unecessary? Plus you will get ever so slightly more noise* (hiss).

*the actual levels could be ascertained from reading the Speck, destination soundcard and ART DTI specs.

[Aimes]

A DI attenuates an instrument/line level signal to mic level, a line isolator is the same level out as in.

Ok so stupid question and excuse my ignorance, do I want to keep my mixer out at line level or would i want to bump it up mic level for any reason?

Mic level is lower than line level*. You might want to avail of mic pre-amp voodoo. But in your case you already have voodoo with the Speck, so more of it seems unecessary? Plus you will get ever so slightly more noise* (hiss).

*the actual levels could be ascertained from reading the Speck, destination soundcard and ART DTI specs.

Got it, thanks again!

[Sam Spoons]

A DI attenuates an instrument/line level signal to mic level, a line isolator is the same level out as in.

Ok so stupid question and excuse my ignorance, do I want to keep my mixer out at line level or would i want to bump it up mic level for any reason?

As Tomás says mic level is lower than line level (by about 30dB). You would use a DI box in a live situation to connect an unbalanced instrument to the stagebox as typically the stagebox/multicore only connects to mic inputs on the desk (the same may apply to the tie lines in a studio's live room) so you need to attenuate (reduce) the signal from line/instrument source down to mic level and change it to balanced before sending it to the desk input.

[Aimes]

A DI attenuates an instrument/line level signal to mic level, a line isolator is the same level out as in.

Ok so stupid question and excuse my ignorance, do I want to keep my mixer out at line level or would i want to bump it up mic level for any reason?

As Tomás says mic level is lower than line level (by about 30dB). You would use a DI box in a live situation to connect an unbalanced instrument to the stagebox as typically the stagebox/multicore only connects to mic inputs on the desk (the same may apply to the tie lines in a studio's live room) so you need to attenuate (reduce) the signal from line/instrument source down to mic level and change it to balanced before sending it to the desk input.

Thank you, thank you, thank you.

So should I be using unbalanced cables still when running this?

[Sam Spoons]

The Art DTI linked has various connectors but I'd use TS (unbalanced) cables between the mixer outputs (if the outputs are unbalanced on TS jacks which I think is the case) and the DTI. The inputs on your audio interface (sound card) will determine what connectors you need at that end of the output cable from the DTI but you can use either XLR or TRS at the DTI end.

This all assumes you have an audio interface with line level inputs capable of handling the +4dBu the main outputs from your desk (though you have outputs on the desk which also output -10 dBv) so tell us what you 'sound card' is.

[Aimes]

The Art DTI linked has various connectors but I'd use TS (unbalanced) cables between the mixer outputs (if the outputs are unbalanced on TS jacks which I think is the case) and the DTI. The inputs on your audio interface (sound card) will determine what connectors you need at that end of the output cable from the DTI but you can use either XLR or TRS at the DTI end.

This all assumes you have an audio interface with line level inputs capable of handling the +4dBu the main outputs from your desk (though you have outputs on the desk which also output -10 dBv) so tell us what you 'sound card' is.

I have an Apollo x6. It has balanced inputs but Unbalanced ¼ TS cables can also be used. They can be set to –10 dBV or +4 dBu.

So I want to set them to +4dBu?

Then have TS (unbalanced 1/4in) to from mixer to ART DTI, and then the art has XLR balanced out or TS unbalanced out. So should I do two XLR to TRS cables balanced or unbalanced into my interface?

The ART DTI also has balanced or unbalanced outs.

https://media.uaudio.com/support/manual ... Manual.pdf

[Arpangel]

This is more appropriate than a DI box. On sale here for example. If your soundcard has balanced line inputs that is useful, but not necessary once the ART DTI is in the signal path. But check first if the buzz is present on mixer headphone outputs, for example. Because it might not be a ground loop.

Thanks, how does this ART box sound? I always thought they were more on the budget side.

Don’t worry about the sound, I've got a couple of ART boxes and they’ve never drawn attention to themselves in a bad way, they sound good and just do the job.
Nice mixer, Speck make good stuff.

[Tomás Mulcahy]

The ART has balanced TRS outputs as well.

Unbalanced TS jack from the ART would probably be fine, unless the buzz is not a ground loop. Could be EMI in the room. So TRS jack to Apollo line inputs would be better. Put ART as close as possible with short cables out of the mixer. I think it only has line out on RCA phono sockets, is that correct?

Pretty cool it has transformers on the mic inputs. I have an ancient Shure 4 channel mic pre that is really terrible, but the transformers in it are high grade.

[Sam Spoons]

The Art DTI linked has various connectors but I'd use TS (unbalanced) cables between the mixer outputs (if the outputs are unbalanced on TS jacks which I think is the case) and the DTI. The inputs on your audio interface (sound card) will determine what connectors you need at that end of the output cable from the DTI but you can use either XLR or TRS at the DTI end.

This all assumes you have an audio interface with line level inputs capable of handling the +4dBu the main outputs from your desk (though you have outputs on the desk which also output -10 dBv) so tell us what you 'sound card' is.

I have an Apollo x6. It has balanced inputs but Unbalanced ¼ TS cables can also be used. They can be set to –10 dBV or +4 dBu.

So I want to set them to +4dBu?

Then have TS (unbalanced 1/4in) to from mixer to ART DTI, and then the art has XLR balanced out or TS unbalanced out. So should I do two XLR to TRS cables balanced or unbalanced into my interface?

The ART DTI also has balanced or unbalanced outs.

https://media.uaudio.com/support/manual ... Manual.pdf

In theory the optimum would be TS from the mixer to the DTI (looking at the images in the brochure it has ¼" TS outputs) at +4dBu and either TRS-TRS XLR-XLR or a combination (XLR-TRS in either direction) between the DTI and the Apollo*. set the Apollo to +4dBu and use appropriate outputs from the desk (which has most outputs at +4 but a couple at -10dBv, these latter would usually be on phono/RCA jacks). That way signal levels in the cables are highest so the ratio of wanted signal to EMI is greatest and you have broken the earth loop, if that is what is causing the hum issue.

The DTI (as Tomás says) ¼" outputs are balanced TRS and there is no point in using unbalanced anywhere between the DTI and the Apollo. The actual connectors don't matter as long as both can carry a balanced connection (i.e. TRS or XLR not Phono or TS) so use what you have.

[ken long]

Another vote for ART DTI box. Very useful bit of kit and built like a tank. For passive, I've been using Orchid electronics transformers. They do the job! https://orchid-electronics.co.uk/Single_Isolator.htm

[The Elf]

So should I do two XLR to TRS cables balanced or unbalanced into my interface?

Whenever you can use balanced cables, use them. Your audio will thank you for it.

[Martin Walker]

So should I do two XLR to TRS cables balanced or unbalanced into my interface?

Whenever you can use balanced cables, use them. Your audio will thank you for it.

Indeed it will - when using unbalanced audio cables you can minimise the amount of external interference getting in by carefully routing them well away from mains cables and any RF rubbish from other gear, but going balanced means that you shouldn't have any interference at all at the destination end of the cable.

[Hugh Robjohns]

Just for info, the transformers in the ART DTI box are wired in such a way that they can accept balanced or unbalanced in, and provide balanced or unbalanced out., both cases depending only on what cables you plug in on either side.

So, as others have said, ideally I would use short TS-TS instrument cable between the mixer's unbalanced +4dBu line level output and the DTI in.

And then use TRS-TRS or XLRf -TRS to carry a balanced +4dBu line level signal to the interface.

Remember to keep the DTI box away from anything with a mains transformer in it, as the radiated magnetic field can induce hum directly into the DTI's transformers.

[Aimes]

The ART has balanced TRS outputs as well.

Unbalanced TS jack from the ART would probably be fine, unless the buzz is not a ground loop. Could be EMI in the room. So TRS jack to Apollo line inputs would be better. Put ART as close as possible with short cables out of the mixer. I think it only has line out on RCA phono sockets, is that correct?

Pretty cool it has transformers on the mic inputs. I have an ancient Shure 4 channel mic pre that is really terrible, but the transformers in it are high grade.

This mixer is actually the SpeckMix 2 so it has TS outputs

https://reverb.com/item/89553300-speck- ... -1985-1987

[Aimes]

Just for info, the transformers in the ART DTI box are wired in such a way that they can accept balanced or unbalanced in, and provide balanced or unbalanced out., both cases depending only on what cables you plug in on either side.

So, as others have said, ideally I would use short TS-TS instrument cable between the mixer's unbalanced +4dBu line level output and the DTI in.

And then use TRS-TRS or XLRf -TRS to carry a balanced +4dBu line level signal to the interface.

Remember to keep the DTI box away from anything with a mains transformer in it, as the radiated magnetic field can induce hum directly into the DTI's transformers.

Thank you! Would the mixer itself and power supply have the mains transformers?