Mysterious buzz on laptop output

[sandall]

30 minutes ago, dmxlights said:

........... there is/was a plugin for it to get it to play one track and then stop so you could build the play list.....

It's hard to beat the original MultiPlay for this.  David is working on a new version, but last time I checked it was still at the Beta stage.

[David Duffy]

The v3 releases of MultiPlay are still marked as beta, but they are very good and stable overall.

https://da-share.com/forum/

As for hum / buzz / hiss / hash on a laptop audio out (or even via a USB audio interface), some laptop power supplies are just bad for it.

I've often used a 3.5mm isolation transformer when dealing with laptop audio outputs to fix it.

Edited December 23, 2022 by David Duffy

[sunray]

On 12/23/2022 at 8:34 PM, David Duffy said:

The v3 releases of MultiPlay are still marked as beta, but they are very good and stable overall.

https://da-share.com/forum/

As for hum / buzz / hiss / hash on a laptop audio out (or even via a USB audio interface), some laptop power supplies are just bad for it.

I've often used a 3.5mm isolation transformer when dealing with laptop audio outputs to fix it.

Thank heavens for that, for a while I thought I was the only one doing it the easy way.

[J Pearce]

I'm transitioning our stock of mini-jack to XLRs to this sort of transformer isolated lead. They remove the risk of phantom being applied, they resolve grounding issues, and generally make things more reliable. We also have mini-jack to twin jack if going into a line level input or using a DI box (which probably sounds a bit nicer than the cheap transformers in those leads).

We do have some class compliant USB soundcards in stock, but generally if I'm going to that effort I'll just move the files to one of our mac mini playback machines.

[sunray]

50 minutes ago, J Pearce said:

I'm transitioning our stock of mini-jack to XLRs to this sort of transformer isolated lead. They remove the risk of phantom being applied, they resolve grounding issues, and generally make things more reliable. We also have mini-jack to twin jack if going into a line level input or using a DI box (which probably sounds a bit nicer than the cheap transformers in those leads).

We do have some class compliant USB soundcards in stock, but generally if I'm going to that effort I'll just move the files to one of our mac mini playback machines.

Yep I have some of thos leads however my preference is for this style:  https://cpc.farnell.com/av-link/201-086uk/ground-loop-isolator-rca/dp/AV26879?st=ground loop isolator  In my opinion they are better transformers and less likely to pick up EMR interference. Plus by removing the heatshrink cover the 2 halves of the steel enclosure can be pulled apart to repair or rewire to a preferred format. They were available with different cable ends but CPC now only have the one version.

This is one used to distribute audio around my home, I did exactly the same for studio to many locations using CAT2, 3 and 5 cable and simply parallelled to about 20 locations for local amplification.

I also have these which are parallelled to a single transformer (mono) although very short lead ~6 inches, again they are accessible for repair/customsing which I find to be pretty good too:

I used one at a festival for a bands Ipad and another but with a longer cable and 1/4" jack for their keyboard, they tried to pack both in their kit.

Edited December 27, 2022 by sunray

[Brian]

Laptop headphone outputs are the work of Satan.

I'm sure that I've commented before but I have come across various laptop which helpfully, sometimes, 'blends' the stereo signal to reduce the image width (a bit of L into R and vice-versa). There is no setting in the drivers to disable this and the 'decision' as to whether to do it seems to depend on load impedance and the order that you plus things in and power things up.

Now, for your average dance show/spot playback it doesn't really matter but when your running timecode on one track and a mono mix on the other it can really, really, spoil your day.

A decent USB DI box costs relatively little. Why mess around with half-arsed solutions like 3.5mm to XLR leads/DI boxes/ground loop isolators?

I've got one of these in with each laptop and one in my show bag...

They have a 3-year warranty and just work.

[J Pearce]

They’re good bits of kit for many scenarios, but for me I’ll stick to a 3.5mm cable because I can leave out a 3.5mm adapter in a venue or rehearsal room and know it will service laptop or phone or tablet or iPod or… Because I don’t want to have to stock and hand out (and retrieve) USB-C etc. adaptors for a USB DI, nor deal with the inevitable strange device that won’t work with a standard class compliant device for unfathomable reasons.
And lastly, because often I’m working to a spec from a designer or tour production manager, who has spec’d a 3.5mm and that’s what they expect to see. Adding a USB box would often create confusion/suspicion etc. and it would be my fault if it went wrong because it wasn’t to spec.

However - if I did more corporate and ‘community’ gigs then those boxes would be in the toolbox.

If it’s a proper job to my spec then a soundcard or one of our playback racks will be going in (or a macbook whose headphone outs always seem to be trustworthy), or alternatively one of our bluetooth receivers (which I’d usually avoid for show use due to compression and trusting a wireless connection - but is good for rehearsals and warmup etc.)

 

[sunray]

6 hours ago, Brian said:

Laptop headphone outputs are the work of Satan.

I'm sure that I've commented before but I have come across various laptop which helpfully, sometimes, 'blends' the stereo signal to reduce the image width (a bit of L into R and vice-versa). There is no setting in the drivers to disable this and the 'decision' as to whether to do it seems to depend on load impedance and the order that you plus things in and power things up.

Now, for your average dance show/spot playback it doesn't really matter but when your running timecode on one track and a mono mix on the other it can really, really, spoil your day.

A decent USB DI box costs relatively little. Why mess around with half-arsed solutions like 3.5mm to XLR leads/DI boxes/ground loop isolators?

I've got one of these in with each laptop and one in my show bag...

They have a 3-year warranty and just work.

Our experiences are obviousely very different, for a start most of my work has been small fry: modest sound stages, village fetes, village hall play/pantos, auctions etc and the only time code I've encountered has been firework displays for which the firework company has provided the music on a CD, the CD player and the transmitter, so all I have had to do is take their mono music.

I did have a rider for a job which required a USB interface from a list of a dozen or so back in about 2016. I could have borrowed one but thinking it would be useful to have I purchased one, I think it's made by Radial and supposedly plug and play. Man with PC turned up late, plugged USB in but it didn't work out of the box as promised. I plugged in one of my transformer isolated leads which of course worked exactly as expected, one £10 lead and it worked, it wasn't three leads and an expensive box that didn't work as predicted.

I had previousely connected it to my laptop so yes I know it worked, however it bounced around in my kit unused until this summer while having a sort out I passed it to someone who needed one.

One of the festivals I did I ended up with 5 acts devices. 4 happily used the 3.5mm jack which worked fine. One insisted on using their own interface, unfortunately it was a cheap one with fixed output leads on phono's and adapters, (phono to 3.5 jack, 3.5 jack to 1/4 jack, 1/4 jack to XLR) supplied by the act into the snake, only one act had any noise problems which I assumed was more to do with the horrible line of adaptors and presumably unbalanced signal. We also had DI boxes but he wanted direct into line inputs.

I know it appears I'm slagging off interfaces, however I'm truly not. I do recognise the improved performance over many devices inbuilt soundcards and they have their places, especially now many laptops have only a single 3.5mm jack. (and of course many Apple [and probably others] products have none) but to date I've only had one 'situation' with a device with no 3.5mm port and the only solution to that was wireless.

One sound effect mid 90's for teleportation we had 'bouncing' across the stage and lit lights with disco sound to light units from it, on the screen we could see what looked like distinct left and right signals but coming out of the jack was not as clean. we got round it by burning a CD and playing it on a CD player which worked like a dream. From that one situation I started becoming aware of such shortcomings but that is the only time it's bitten me, on later kit I've found it far more controllable (Or rather my PC capable colleagues have).

 

In conclusion I've found using the 3.5mm jack has been more reliable when interfacing visitors kit.

Edited December 27, 2022 by sunray

[sunray]

4 hours ago, J Pearce said:

(or a macbook whose headphone outs always seem to be trustworthy),

 

The funny thing is I find users of macbooks seem to be more defensive of their 3.5mm socket.

[Stuart91]

23 hours ago, Brian said:

I have come across various laptop which helpfully, sometimes, 'blends' the stereo signal to reduce the image width (a bit of L into R and vice-versa).

I came across a related problem with someone using an iPad to send split tracks. They had click on one side and the track itself on the other. There seemed to be a linked compressor acting on both channels, and since the click was running very hot the track was ducking regularly. Took a bit of head-scratching to figure out what was going on. 

[sunray]

1 hour ago, Stuart91 said:

I came across a related problem with someone using an iPad to send split tracks. They had click on one side and the track itself on the other. There seemed to be a linked compressor acting on both channels, and since the click was running very hot the track was ducking regularly. Took a bit of head-scratching to figure out what was going on. 

Did you get to a solution with the ipad?

[Stuart91]

7 minutes ago, sunray said:

Did you get to a solution with the ipad?

Not really (it was in the middle of a pretty fraught turnaround between bands). We just got him to reduce the overall level so that he wasn't hitting the internal compressor/limiter, and gained both channels up a little more at our end to compensate. 

What really took the time was his insistence that it couldn't possible be his iPad and our gear must be faulty... 🙄

[themadhippy]

22 minutes ago, Stuart91 said:

What really took the time was his insistence that it couldn't possible be his iPad and our gear must be faulty.

even thought it happened at his previous 37 gigs ,and the only mention of previous problems is at the load out .

Edited December 28, 2022 by themadhippy

[sunray]

Just now, Stuart91 said:

Not really (it was in the middle of a pretty fraught turnaround between bands). We just got him to reduce the overall level so that he wasn't hitting the internal compressor/limiter, and gained both channels up a little more at our end to compensate. 

What really took the time was his insistence that it couldn't possible be his iPad and our gear must be faulty... 🙄

Oh yes it's never their part...

 

I had something similar recently with the stereo backing track for a performerwith drums (very loud) one side and everything elsse the other, the 'plan' being to be able to balance it at performance. Most worked fairly well as the compression delay kept it fairly consistant but for the early part of 'Drove All Night' the dum dum beat pulled the other track down and allowed it to rise again before the next beat.

Nothing I could do about it, especially during the performance, but of course it was my fault🥴

[sunray]

12 minutes ago, themadhippy said:

even thought it happened at his previous 37 gigs ,and the only mention of previous problems is at the load out .

no... Really?