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Mine are all long. Got to be ready to step in for Keef at short notice, and have to bring my own stadium lead. Those guys!
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11-27-2021 12:34 PM
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If there is no audible hum, short unbalanced cable might be even better than balanced as it skips some active circuits that exist only to make signals balanced.
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Good to know!
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I didn’t have any short leads either, so I just bought a pack of 3 patch leads online (forget where now). Useful anyway for messing about with pedals etc.
Originally Posted by Rob MacKillop
Mine are all long. Got to be ready to step in for Keef at short notice, and have to bring my own stadium lead. Those guys!
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I agree - I hear no difference when recording an instrument either mic’ed or direct. But I’ve had some hum and even RFI from a few devices over the years when using unbalanced connections. So my studio is entirely balanced except for the unbalanced instrument input into which I plug the guitar, keyboard etc. Originally Posted by grahambop
I do hear more detail in my audio systems when using balanced lines, if all the electronics have true balanced differential I/O. I have balanced DACs and powered monitors with balanced input stages. My default studio monitoring system (an Emotiva Stealth DC-1 DAC driving JBL powered monitors) seems a bit more transparent with balanced interconnects. As an example, this is audible in the separation among individual notes from multiple instruments (like piano and guitar) playing different inversions of the same chord.
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And here’s me thinking my question was naive, risible, but it’s triggering some interesting points.
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That’s not entirely correct. A true balanced audio device is actually a pair of parallel circuits that process the signal with opposite polarity and drive the + and - output terminals separately. There are 2 for each processing channel, so a stereo device has 4. This is also called a differential amplifier, and it provides direct connection to source and destination. Originally Posted by msankowski
For true balanced devices (DAC, preamp, amp, processor etc), the only way to add an unbalanced input and output is to add a stage that converts each. And unbalanced circuits can accept balanced inputs only by adding a stage to convert. In either case, the added stage can affect sound quality.
So it’s important to know if the device in question is truly a balanced circuit from in to out or if those XLRs just feed an input stage that converts a 3 conductor balanced source to an unbalanced signal. If it is, the only advantage to using 3 conductor cable and connectors is a bit better shielding against external noise and (if the input impedance is truly low) the ability to use longer cables without signal degradation.
Also note that true balanced outputs will almost always deliver 6 dB more signal than unbalanced outputs added onto a true balanced device.
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You are right, I also use balanced connections in my studio where it is possible. If units support balanced connections one should use balanced and can not go wrong.
However, inexpensive devices like Art tube or TubePRE are unbalanced designs and they are adapted to provide balanced and unbalanced outputs. The TubePRE I was using some time ago has unbalanced output that goes directly from the preamp and additional opamp stage to provide balanced output. Opamps add noise, more or less.
When we talk about connecting two units (some may also call it studio): preamp and audio interface, the risk of making a ground loop is low.
If there is no hum (no ground loop) in practice one can use balanced or unbalanced.
But generally speaking: yes, balanced means better.
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I haven't encountered any unwanted noise with the V3 yet. What noise is there is simply low voltage 'tube glow' for lack of a better word. Good noise.
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I can’t find my schematic right now, but as I recall my Art MP has a pair of differential op amps in each channel and is a true balanced device. The mic input is balanced and it’s the unbalanced instrument input that’s added on. I think the 12AX7 (a dual triode) is used single ended in a balanced output. This was a common design in ‘60s and earlier tube preamp circuits in recording consoles. Originally Posted by msankowski
The Art is inexpensive but it’s definitely not cheap!
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If you intend to buy new this one would be a good one: Originally Posted by Rob MacKillop
https://www.amazon.co.uk/Female-Anca...-16&th=1&psc=1
If you wish to look in other shops look for balanced
XLR female (ART tube) into TRS (Scarlett).
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That’ll work. But I’d go balanced with the 1 meter Stagg SMC RD 1 , the kenable, or similar - there are many equal alternatives available from Amazon UK. Originally Posted by Rob MacKillop
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I’m curious as to why you recommend an XLR to TRS cable when both devices accept XLR. Is there an advantage I don’t recognize? Originally Posted by msankowski
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That (cable on A'zon) is probably good enough, and may even be cheaper than the cost of the parts. If you want to minimise the amount of noise it picks up, get one with all-metal plugs (I didn't check if this one has those).
I have the same ART Tube pre-amp as shown here. It's my understanding that you can get the same control over voicing with the output gain as you can with the presets dial. Except you need to compensate with the input gain yourself if you want the output to remain constant. I just marked a number of combinations on mine, with an engraving pen.
FWIW, these use a 9V AC PSU. Not a common thing that's easy to replace AFAIK, so keep that in mind. I've been down a rabbit hole earlier this year because my preamp had a very weird noise that kept me from opening the output gain for more than about 25% of its course. I made myself a shielded mains cable with a passive noise filter in it, and put a ferrite ring around the 9V lead that goes into the preamp. Replaced the stock, Chinese tube with a TungSol equivalent. All to no avail, and at the time I needed thing for my online classes.
I ordered a second hand older version (with the nice analog VU meter) from eBay so I could send the other unit in for warranty repairs ... and got a lemon that only produced noise. Seller reimbursed me but on a hunch I hooked my own unit onto the PSU that came with the lemon (which does look like an aftermarket replacement) ... problem solved! I did keep the TungSol installed, btw
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Before recommending it I lookked into Scarlett manual. Jack part of the combo accepts (switchable) instrument or line / balanced or unbalanced. Originally Posted by nevershouldhavesoldit
XLR was not as clearly described, I suppose it accepts mic only.
Anyway, XLR to TRS will work correctly witch switch in the LINE position.
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Here is the schematic. Balanced input signal goes through balanced circuits until first opamp O1. Then it is unbalanced until last stage that converts to balanced output. Originally Posted by nevershouldhavesoldit
In fact the output circuit, unlike the TubePRE, is the same for balanced and unbalanced input. Hence no advantage of using unbalanced cable with ART Tube.
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I knew you guys would soon baffle me with science
I bought the Stagg.
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I know it looks like too much science
In the discussion linked below people confirm XLR input in Scarlett is for mic only. This Stagg XLR to XLR migh not be the best choice.
Preamp to USB Interface - XLR or TRS? - Gearspace.com
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Rob, you should have checked the Stagg cable schematic before buying. Originally Posted by Rob MacKillop
I knew you guys would soon baffle me with science
I bought the Stagg.
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Definitely!
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Seriously Rob, for the purposes of trying out how the ART gadget sounds via the Scarlett, just use the shortest guitar cable you’ve got, for now. I doubt it’ll make that much difference for just playing around with it.
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Aggree. Switch to LINE position. Originally Posted by grahambop
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I am soooo sorry, Rob!!! I only remembered that there was an instrument/line input switch on the Focusrite and did not recall that the XLR input will only accept a microphone. Msankowski is correct in the recommendation of the XLR-to-TRS cable and I was wrong in my recommendation. As my M-Audio and TASCAM DAIs all have the same combination jacks as your Scarlett and accept either source in either configuration, I relied on memory alone.....and it failed me (and, unfortunately, you). As one who keeps advocating a fact based approach to decisions, I obviously failed to take my own advice. Originally Posted by nevershouldhavesoldit
From the schematic of the V3 version, it appears that the input is a direct balanced connection but the output is derived. This seems to be a change from the early versions but I still can't find my manual or an online schematic for the original MP.
Again, my profound apologies - I was simply wrong and I should have known better.
David
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Don’t worry, David, I managed to cancel the order in time.
If a regular guitar cable works (it does for Graham) then that’s the simplest solution. But I’ll also look for an XLR-TRS cable too.
Thanks, everyone. You are all being very helpful. I do appreciate it.
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