Here are some interesting videos related to PA and sound reinforcement systems. Wikipedia defines that a public address system (PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound source or recorded sound or music. The term, sound reinforcement system generally means a PA system specifically for live music or performance. A sound reinforcement system for a rock concert or other large event in a stadium may be very complex.
A brief history of live sound reinforcement
Stage Left Audio – Event Video 11
Dave Rat about his sound engineering for the Red Hot Chili Peppers live tour 2016
LIVE SOUND SUBS SUBWOOFER PLACEMENT & CONFIGURATION: LR, Center, Cardioid, End Fire (Pt1)
Look inside D&B, L’Acoustics and MicroWedge Monitors
DJ Sub and Speaker Placement For Dummies
Cardioid Subwoofers and Nexo Technology Part 1
Time Lapse of a Large PA Audio Sound System Setup for Rock & Roll
#38 – Arena line array system walk-through
How to Set Up a Simple PA System
Sound System Tuning Step-by-Step using TRACT and Smaart
Audio 101- How to do a pro sound check.
984 Comments
Tomi Engdahl says:
The same sound from multiple sources is an unnatural event
https://www.youtube.com/watch?v=VHjdh-Vka-g
Demonstration of how to reduce comb filtering and audio interference issues from sound reinforcement systems.
00:00 Into
0037 Same sound from multiple points in space
01:40 Same signal vs different signal interactions
02:11 Multiple sounds from the same point in space
03:05 Unnatural sound assets and issues
04:05 Demo description
05:16 Single speaker pink noise
05:39 Same pink noise to two speakers
06:07 Same pink noise to two speakers with polarity reverse one speaker
06:26 Same pink noise to two speakers
06:32 Two different pink noise generators to each speaker
07:02 Two different pink noise generators to each speaker with one speaker polarity reversed
07:20 Summary
09:00 Multiple pink sources for measuring sound systems
09:26 Outro
Tomi Engdahl says:
How To Eliminate Microphone Feedback | 5 Must-Know Tips
https://www.youtube.com/watch?v=z2ceO8D_MUw
0:00 – Introduction
0:16 – What Causes Microphone Feedback?
1:03 – Tip #1
2:32 – Tip #2
3:19 – Tip #3
5:20 – Tip #4
6:26 – Tip #5
7:31 – Bonus Tip (Tip #6)
7:49 – Subscribe To Audio University!
Tomi Engdahl says:
World’s Top 10 Most Viral Songs? – We’re Doomed
https://www.youtube.com/watch?v=v8Dtc_s7FKc
Tomi Engdahl says:
Powersoft Webinar Dave Rat
https://www.youtube.com/watch?v=J81R2IvDX6Y
Dave Rat of Rat Sound has built a reputation as one of the top live sound gurus in the world, working with artists including Nirvana, Rage Against the Machine, and Blink 182. In his webinar, Dave Rat will explain the setup for the 2016 Red Hot Chilli Peppers world tour, discussing how to maximise amp technology for one of the world’s biggest rock bands. A particular highlight of this session will be a focus on the Rat Sound SuperWedge, which has been specially-developed by Mr Rat and is driven by Powersoft X4s. Exploring the idea behind the monitor and the manufacturing process, as well as the routing and power requirements together with how the X4s have aided the design.
Tomi Engdahl says:
Gain Before Feedback on EAW MicroWedge, L-Acoustics and D&B Wedges
https://www.youtube.com/watch?v=wI_3WYHS71c
00:00 Intro and description of products to test
00:32 Test decryption
01:14 level test matching
01:54 Distance matching
02:17 Mic test D&B M2
02;44 MicroWedge 15
03;11 L-Acoustics 115XT
03:30 MicroWedge 12
03:50 increase level to match feedback
05:50 Measure output levels
07:01 Summary of levels
07:16 All at 103db
09:07 Outro
Tomi Engdahl says:
Do TALENT shows use auto tune?! DON’T believe everything you hear!!!
https://www.youtube.com/watch?v=whKfSollIw8
On the agenda tonight we’re taking a look at an audition from ‘The X Factor’ here in the UK to see if it was auto-tuned!
TIME STAMPS –
0:00 Start
1:24 Performance
4:06 Analysis Start
6:34 Respectability? Credibility?
8:21 Trying to ‘get away with it’?
8:54 All About the TV (from personal experience!)
11:04 Vocal Waveform Analysis
15:59 Throwing Off the Scent
18:14 The Judges
Tomi Engdahl says:
Can you combine multiple XLR cables?
https://www.youtube.com/watch?v=sA4C2HLx8Hc
XLR balanced interconnects are the best sounding connections between stereo equipment when high performance audio is concerned. But what if you do not have the proper length of cable? Can you connect two or more?
Viewer comments:
I think it largely comes down to the quality of the connectors and the consistency of impedance in the cable segments.
If the connectors are top notch and the impedance is consistent along the run, the two segments effectively become one longer run with the combined cable characteristics (resistance, inductance, parasitic capacitance) of the two segments. As always, interconnect quality counts. My preference is to build interconnects from scratch with excellent connectors and overspecified cable. The Grateful Dead used a lot of Belden #83393 (single pair 20AWG tinned copper with aluminized polyester shield) and that’s what fed Jerry’s McIntosh MC-2300.
This man knows his stuff. You can answer that question from an engineering perspective. I would not recommend connecting cheap low quality xlr cables in a chain though, only the high quality ones in my opinion. Check the wire gauge, shielding, soldering and connectors for a good high quality cable.
Do keep in mind that the XLR Cable and connections is an almost 70-year old design:
https://en.wikipedia.org/wiki/XLR_connector
Tomi Engdahl says:
Are Expensive XLR Cables Worth It? (FAQ Series)
https://www.youtube.com/watch?v=A0TlrpVCRgw
What’s the difference between an $8 and $50 XLR cable? Do $50 mic cables make your recording sound better? Why pay so much for a cable? In this video, I address those questions and demonstrate the difference in shielding and test if there is any difference in tone based on the XLR cable you’re using.
00:00 – Introduction
00:15 – An Answer To The Question
01:06 – Build Quality
02:41 – Shielding Performance Measurement
06:05 – Noise Floor Measurement
07:50 – Do Cables Affect the Tone of Recording?
10:05 – Warranty of Cables
10:42 – Why Are Cables More Expensive?
11:05 – Who Should Buy Expensive Cables?
13:30 – Outro
NOTE 1: The frequency response measurements only cover 20Hz – 20kHz which is all most podcast producers and at home studio producers will encounter. The results may differ if you record high resolution with the intention of slowing down the audio. For most people 20Hz – 20kHz is more than sufficient.
NOTE 2: For non-reviews I typically record unprocessed audio and process in post. Here I mistakenly recorded the processed audio for my spoken word portions, and that processing was not good, so this is not a good representation of the sound of this mic. Sorry about that.
Tomi Engdahl says:
Choosing Digital vs Analog Audio – X32/M32 AES50, Routing Latency (Public)
https://www.youtube.com/watch?v=hSYXAV-rpOg
Lets clarify digital vs analog advantages. Looking at AES50 Latency and also testing for internal latency differentials.
Tomi Engdahl says:
Are they auto tuning GREAT singers? YES AND WE CAN SEE IT!
https://www.youtube.com/watch?v=OBk7BnIA12c
Do TALENT shows use auto tune?! DON’T believe everything you hear!!!
https://www.youtube.com/watch?v=whKfSollIw8
Tomi Engdahl says:
Powersoft super LFE 40inch impression.
https://www.youtube.com/watch?v=7PIwKCgSyKw
Super LFE 18inch vs 40 inch
Binaural recording. Please listen with headphones.
Tomi Engdahl says:
Test AES3 performance with numerous XLR connections
https://www.youtube.com/watch?v=oasD75TsCeQ
Was curious to see if using lots of short cables would adversely effect transmission distance of AES 192Khz.
Interesting. I think the problem arises from people using bad interconnects of course if they’re bad they’re going to cause signal degradation, if they’re reasonably good quality and taken care of they shouldn’t make a difference.
Tomi Engdahl says:
Testing AES3 maximum cable lengths down CAT5, Audio Snake and Mic Cables
https://www.youtube.com/watch?v=v-qoZPKsLDs
Comparing various lengths of mic cable, AES cable, snake cable and Cat 5 cables with AES 48, 96 and 192 Khz.
Tomi Engdahl says:
Heat Bends Sound
https://www.youtube.com/watch?v=_lB8e9OY0-U
The heat from humans at a concert refracts sound up and away from from the audience. Here is a demo using a heat gun to alter the path of sound waves. This phenomenon of sound being refracted by heat can cause substantial variations in the quality of the sound at concerts and other gatherings.
Tomi Engdahl says:
Basic Vocal EQ – How to Fix Your Vocals (Body, Nose and Harshness)
https://www.youtube.com/watch?v=qYdj_Ngb9gg
Basic Vocal EQ – This “How I Produce” video is the start of a new Vocal Production series. In this video we look at, vocal EQ basics and how to EQ a problem vocal.
Targeting the main problem frequencies in vocals, we go through how to fix muddy vocals, how to fix nasal vocals and how to fix harsh vocals and approximate frequency ranges for these problems. We also look at giving vocals a breathy tone and how to hear and identify frequencies.
Topics and Timings:
1. Intro (0:00 – 1:03)
2. Vocal Tone (1:03 – 2:02)
3. How to Use EQ (2:02 – 3:23)
4. Problem Frequencies (3:23 – 5:21)
5. How to Fix Muddy Vocals (5:21 – 8:15)
6. How to Fix Nasal Vocals (8:15 – 10:32)
7. How to Fix Harsh Vocals (10:32 – 13:13)
8. How to Achieve a Breathy Sound (13:13 – 15:11)
9. High Pass Filters (15:11 – 16:32)
10. The “Sweeping” Method (16:32 – 19:14)
11. Final Thoughts (19:14 – 20:26)
https://www.puremix.net/ear-training.html
Tomi Engdahl says:
Audio Mixer Buying Guide | A Checklist Before You Buy!
https://www.youtube.com/watch?v=RFGiAD3lFto
Which audio mixing console should you buy? What should you look for in an audio mixer when shopping? Are some mixers better for beginners and others for more advanced users? In this video, I’ll help you determine which mixer you need based on budget, application, skill level and more. Whether you’re looking for an audio console for live sound, a home studio, or streaming, this video will help you choose the right mixer!
00:00 – Introduction
00:22 – Which Type Of Mixer Do You Need?
03:38 – 3 Key Factors For Choosing A Mixer
04:02 – Key Factor #1
06:48 – Key Factor #2
08:10 – Key Factor #3
10:06 – Subscribe To Audio University!
Mixing Console User Guide:
https://audiouniversityonline.com/mixing-console-tutorial/
Tomi Engdahl says:
How to Build an IEM Rig Using the Behringer XR18 or Midas MR18 – In Ear Monitor Rig
https://www.youtube.com/watch?v=xT9gTBFxvZk
How to build an In Ear Monitor rig using the Behringer XR18 or Midas MR18. IEMs are becoming increasingly popular for musicians. More and more bands are creating their own ear rigs so that they can go anywhere there is a provided sound system and use their own monitor rig while a tech mixes Front of House. Of course, it also works for using your own PA as well.
Besides the consistency of having the same monitor system gig to gig, there’s also the efficiency that comes with the rack packaging to speed up setup and tear down. Also, with much of the rig staying connected, there’s less chance for mispatches and other problems. And with proper labeling, an easier time troubleshooting if there is an issue.
Really, the process shown here could also work for the Behringer X32R as well. And the concepts work with any monitor mixing system.
While the example is using wired beltpacks, if there are wireless IEMS being used, then it’s just a matter of connecting the XLR Aux outputs to the transmitters instead of the wired beltpacks.
This video is a live sound tutorial for musicians and techs wanting to understand the concept of an in ear monitor rig and how it all connects and interfaces with the house PA.
The concept of a separate monitor system with a split to the house sound system is something that has filtered down from large scale concerts and arena shows to smaller venues as the technology has reached a point that the needed equipment is in the budget of many musicians these days.
Having an ear rig is great for festival shows where setup and soundcheck time is limited, and having your own, preset in ear mons is a major time-saver and performance booster.
Tomi Engdahl says:
Universal Audio’s LUNA vs $1,000,000 Gear
https://www.youtube.com/watch?v=F1mzXWf4OEw
Song Performance: Victor Indrizzo, Sean Hurley, Steve Maggiora, Greg Pajer, and Katie Ferrara
Today we are at Sunset Sound Studios in my one of my FAVOURITE rooms to record in, and we are doing the ultimate test! We will be comparing the Sunset Sound Console to the Universal Audio LUNA DAW.
Designed for seamless integration with Apollo audio interfaces, LUNA is UAD’s free Mac‑based recording application that lets you do music recording, audio editing, composition, sound design, and more ‑ all in real time, and with big analog studio sound.
Few studios in the world have contributed as much to the sonic imprint of music culture as Los Angeles’ Sunset Sound Studio. Sunset Sound Recordings was opened in 1958 by Tutti Camarata, then director of recording for Disney Studios. The space’s slanted floor and uneven walls gave it ideal acoustics, and soon the studio was busy recording Disney classics like “Mary Poppins”.
All the rooms and equipment have been carefully maintained since their construction in the early 60s, so their sonic imprint has remained exactly the same as they were when Sunset’s iconic sessions were tracked.
In the video, we compare a recording in this iconic room to the exact same song done through the LUNA DAW with our good friend and Academy Member, Melissa Bell.
Tomi Engdahl says:
Powersoft K20 DSP 18kw
https://www.youtube.com/watch?v=F2LLumFRIl8
Tomi Engdahl says:
The Matterhorn – Worlds Largest Subwoofer
https://www.youtube.com/watch?v=o36Kp6veJ6c
The most powerful sub ever created. It was born out of a military request and is housed in a 20′ x 8′ x 8′ shipping container. 40 drivers, 40,000 watts of self powered and built in generator to boot.
Tomi Engdahl says:
Make Your Voice Sound Better – Vocal EQ Zones
https://www.youtube.com/watch?v=pjMCyLsRNig
This video is an in-depth look at post-production EQ for dialogue. This could be for a podcast, voice over or YouTube video where you want the audio to sound professional. I will be breaking down the frequency spectrum into 6 zones to keep the video focussed. These zones should be used as a guide only and will have to be adjusted to your dialogue or voice. I would never suggest copying exactly what I do and I hope you use your ears to guide your final EQ choices. These techniques work with condenser and dynamic microphones and with all room sizes.
►Timestamps
0:00 – Intro
1:10 – 0Hz to 50Hz
2:10 – 50Hz to 200Hz
6:40 – 200Hz to 600Hz
9:00 – 600Hz to 4kHz
10:00 – 4kHz – 8kHz
12:00 – 8kHz+
Tomi Engdahl says:
Copper Wire vs Midas M32 vs Behringer X32 (Public)
https://www.youtube.com/watch?v=YYsWJhUtwlk
No matter how great digital audio is, a short copper wire blows it away for pure transmission of wide frequency response, low noise, reduced latency and pretty much every spec we can measure. The question is whether those differences are relevant.
Viewer comments:
The increased rippling in the tops and bottoms of the square wave seen when the frequency is increased is an inherent distortion due to Nyquist and anti-aliasing filters. The higher frequencies needed to create the sharp edges of a square wave at ~11k and up are above Nyquist and are thus filtered out by the anti-aliasing filters, thus the ripple is seen.
Tomi Engdahl says:
Moving the Studer mixing board
https://www.youtube.com/watch?v=9e_y3mcNOTo
Here’s a flashback to 2019 when we moved in the Studer mixing board of Neil Young’s.
Tomi Engdahl says:
One of the Rodecaster Pro’s Most Important Features: Mix Minus
https://www.youtube.com/watch?v=axg0XpPgl1U
Here’s a quick and simple rundown of how to use mix minus with the Rodecaster Pro, both via USB Mix Minus and with the mute/solo buttons on each channel. Mix minus is a great tool for listening to input sources without including them on your final recording or output.
•Chapters:
0:00 – What Is Mix Minus?
1:07 – USB Mix Minus on the Rodecaster Pro
2:09 – Using the Mute and Solo Buttons for Mix Minus
3:31 – What About Multitrack Recording?
Tomi Engdahl says:
A brief history of live sound reinforcement
https://www.youtube.com/watch?v=XvwMc3cF1jA
A presentation that I put together recently for a group of university students in Singapore. We normally don’t go into this type of detail when training new sound engineers but I made an exception for this class
The structure of this presentation is based largely on a pair of excellent articles written by Andy Coules for prosoundweb.com – links to these articles can be found below.
Hope you enjoy this little look into where our industry came from. Voice over recorded with a Shure SM86.
Tomi Engdahl says:
Which vintage mode sounds best? – Focusrite vs Solid State Logic vs Universal Audio
https://www.youtube.com/watch?v=DeJQPZ3Y8cM
In this video I will play some audio samples and compare the differences of the modes designed to color the audio on the Focusrite 2i2 3rd Gen, Solid State Logic SSL 2 and Universal Audio Volt interfaces.
00:00 Intro
00:58 Audio Samples
02:40 Comparison
04:38 Conclusion
Tomi Engdahl says:
CREATIVE CRIBS: Abbey Road Studio Two
https://www.youtube.com/watch?v=5QskQHxvB_Q
Spitfire Audio co-founder Christian Henson takes a deep dive into the most famous recording location in the world: Abbey Road Studio Two. Guided by Abbey Road’s Head of Audio Products Mirek Stiles, follow along as they take you through the history, unique gear and curiosities of this studio, home to some of the most legendary recordings by The Beatles, Pink Floyd, Radiohead and many more.
Contents:
00:00 – Entering The Room
5:08 – The Pianos
7:27 – The Echo chamber
9:19 – The Mic cupboard
17:54 – The Control Room
Tomi Engdahl says:
Advantages of Amplifier Bridged Mono Mode (Public)
https://www.youtube.com/watch?v=HYbvA1DOR9A
Lets take a look at what happens when an amp is operated in bridged mono mode, look at the advantages and similarities to balanced lines and the way houses are powered.
00:00 Intro
00:37 What a bridged mono switch does
01:17 Bridging amps without a bridged mono switch
02:28 Bridging two separate amps into a single mono amp
03:43 Minimum impedance of stereo vs bridged
05:00 Comparing stereo into 8 ohms vs bridged into 16 ohms
10:24 Speaker line loss in stereo vs bridged mode
12:57 2 wire vs 4 wire line loss
13:57 Advantages of higher voltage outputs
14:23 Series vs parallel speakers and speaker failures
15:55 Bridged mono, balanced lines and single phase residential AC service
18:41 Outro
Are bridged amps true monoblocks?
https://www.youtube.com/watch?v=ts-n9qpyfCY
If you bridge a stereo amplifier into a mono amplifier is that the same as a dedicated monoblock amplifier like PS Audio’s BHK amplifier?
Tomi Engdahl says:
What Are The Different Outputs Of An Audio Mixer?
https://www.youtube.com/watch?v=Zdl3_3Zf5F4
What’s the difference between the main outs, aux outs, and matrix outputs on a mixer? How about the direct outputs? When should you use an auxiliary output or matrix instead of the main mix outs? In this video, you’ll learn about the most common outputs on audio mixing consoles and how to use them.
0:00 – Introduction
0:17 – Main Outputs
1:09 – Direct Outputs
1:53 – Aux Outputs
3:29 – Matrix Outputs
4:48 – Subscribe To Audio University!
https://audiouniversityonline.com/mixing-console-tutorial/
Tomi Engdahl says:
Analog vs Digital Audio | The Truth About Which Is Better…
https://www.youtube.com/watch?v=1YviIsCbT9Q
What’s the difference between analog and digital audio? Is vinyl better than CD or MP3? What makes one better than the other? In this video, you’ll learn about the benefits and drawbacks of analog and digital audio. By the end, you’ll be able to answer these questions for yourself.
TIMESTAMPS:
00:00 – Intro
00:14 – Analog Audio Explained
01:24 – Digital Audio Explained
02:55 – Analog vs Digital Audio: Pros & Cons
03:19 – Noise
04:30 – Fidelity
07:50 – Aliasing
08:55 – Harmonic Distortion & Non-Linearity
10:52 – Production & Editing
12:33 – Portability & Durability
13:36 – (Free) Speaker Placement Guide
14:08 – Subscribe To Audio University!
Tomi Engdahl says:
Analog vs Digital Audio: Which Is Better?
https://audiouniversityonline.com/analog-vs-digital-audio/
Tomi Engdahl says:
Does Audio Gain Knob Sound Different Than Attenuation Fader? (Public)
https://www.youtube.com/watch?v=chgovyDUxx4
I chat about the differences between gain and attenuation, setting power amp input levels, self powered speaker levels, do a demo showing the differences is sound and discuss a common myth.
00:00 Intro
00:18 The two ways we control audio level
00:35 First thing a mic or input signal encounters
01:02 Controlled and fixed gain stages
01:55 Difference between gain and attenuation (fader)
02:47 Pan pots attenuate sound to left or right or both
03:25 Attenuators only cut, even if there is markings showing boost
04:57 Gain stages boost
05:23 Volume levels of power amps
07:00 Mixing console out levels vs amp inputs
08:14 Reducing hum or buzz with amp levels
09:03 Setting volume levels on self powered speakers
10:17 Do gain pots and faders sound different?
11:42 Test setup to compare gain vs attenuator
13:01 Lots of gain minimal fader vs minimal gain and lots of fader
14:37 Clipping vs non clipping signal
17:10 Outro
Tomi Engdahl says:
Scoping & Loading Down M32 & X32 Max Output (Public)
https://www.youtube.com/watch?v=vBGKPz1qTNg
Unbalanced vs balanced line input to the scope when measuring.
Does a tiny Behringer Xenyx 802 really put out over twice the output voltage than the fancy dancy digital X32 or M32 consoles do before clipping?
What happens to the outputs voltages when multiple inputs are driven?
Lets take a look!
00:00 Intro
01:55 Why are the tests not the same as previously?
04:00 Balanced vs unbalanced scope measurement
06:05 Comparing maximum outputs and metering of X32, M32 and Xenyx
08:55 Test outputs when loaded down
12:55 Outro
Tomi Engdahl says:
Servodrive Contrabass mechanism in action
https://www.youtube.com/watch?v=8oqt9LbSvpQ
Visual look inside the servodrive contrabass subwoofer. in stead of a voicecoil its using a DC permanent magnet Motor for driving the 2 opposite 15″cones.
Tomi Engdahl says:
Gemini XGA5000 amplifier repair PT1
https://m.youtube.com/watch?v=a-6H51WFKVw&feature=youtu.be
Tomi Engdahl says:
Behringer FLOW 8 v11749 First Look – Pre/Post Fader Mon Sends Firmware Update!
https://www.youtube.com/watch?v=4bCBHNbmXjs
Tomi Engdahl says:
The Best Concert Sound Sub Drivers and Enclosures
https://fohonline.com/articles/tech-feature/the-best-concert-sound-sub-drivers-and-enclosures/
Tomi Engdahl says:
How to Coil Cables | The Over Under Technique
https://m.youtube.com/watch?v=cpuutP6Df84
Tomi Engdahl says:
The NEW Mackie thrash 215 review and teardown! What’s $350 get you?!
https://m.youtube.com/watch?v=6spx8Kq_79g&feature=share
Tomi Engdahl says:
Take Apart Behringer X32 & Midas M32 (Public)
https://www.youtube.com/watch?v=Oms2ypKaSPo
Lets figure out how to take apart a Behringer X32 and Midas M32 and compare the insides!!
00:00 Intro
00:38 Behringer X32 disassemble
03:10 Midas M32 disassemble
05:33 Side by side compare inputs and outputs
06:55 Fader differences
08:10 Encoder and switches compare
13:36 Fader motor compare
14:33 Summary and outro
Tomi Engdahl says:
Audio Gremlins – When Off is Bad (Public)
https://www.youtube.com/watch?v=hYRjGUyw6Io
In this video I hunt down an audio gremlin that can bite you even when the gear is off.
00:00 Intro
00:25 Setup
01:20 300 Hz tone test Xenyx
01:44 300 Hz to Xenyx and X32
02;10 Off test
02:32 Summary overview
03:35 Lower volume test
04:25 Outro
Viewer comments:
You are changing the impedance on the hardwire split when you plug into the Behringer, even though it’s off there is still circuitry that you are connecting to.
Hardwire splits should never be used to connect a monitor board because the FOH board and monitor board will interact just that way.
I would like to see the results of that same test with a transformer split, please.
Ok, will show the transformer split results. I did test shortly after doing the video
Dave
I love your videos you get into some interesting stuff. (Whoever thought we’d be looking at behringer as serious product but it is.). I use 2X 32 consoles with two sets of stage boxes with a transformer split in front of the stage boxes. I didn’t want an off console and other split issues to cause problems. I’m now going to have to check and see if it gets through the transformers using two sets of stage boxes……
In tests I have done since the video I show the issue passer right through the transformer as expected
Dave, you come up with some very interesting problems. I’d like to know what is going on inside the x32 with power on and off that would cause this.
Some people have posted what they believe is happening and why in the comments.
Transistors do change their impedance based on how they are biased. The question I powder is which mic pre amps do it and which do not and how many of each are out there and which consoles have which and why.
tompettytribute
2 days ago
I’m sure this is caused by the same protection diodes that you ran into when you were doing clipping experiments, and were seeing how the a console clipped at very low gain prior to the clip indicator coming on. The clipping at the front end prior to the ADC can be caused by input protection devices like diodes, which will be connected to the input and then one each to supply and ground. When there is no supply (unit off), you now have essentially back to back diodes to ground. That will cause clipping on both side of the waveform starting at (roughly) 1.4Vpp (basically 2 diode drops). Lower the signal well below that and you won’t see it. Because the didoes turning on at the waveform peaks drastically momentarily drop the impedance on the input, it will affect anything else directly connected to that input. It will also impact things behind a transformer, as transformers do not provide total impedance isolation, although the impact will be a bit reduced. Bottom line is, don’t ever plug any signals into active circuitry gear that is powered off – you are asking for trouble. Of course others have mentioned that hardwire splits can potentially cause issues due to parallel impedance so should never be used, but that is a little drastic. If you understand your source impedance and the console input impedance, and how multiple impedance terminations on a single line interact, then using hardwire splits is fine in many instances. If you don’t understand all that, then it’s safest not to ever use hardwire splits. But as you can see, even with transformer isolation, you still need to understand this kind of stuff.
would have to see the schematic to know for sure…
It seems to be certain mic pre designs and for the end user the importance is not really the design as much as awareness that off gear can be different than on gear
woh that’s an interesting and useful find. Wonder if other digital consoles cause the same issue or if it’s just the X/M32.
The QU16 does it but not as much. Have not tested any other digital consoles yet
Good demonstration Dave.. it’s a simple explanation if you know transistor theory… on the input circuit there would be an operational amplifier (op amp) with differential Input ( converts balanced to unbalanced to feed into the Analogue to digital converter) .. Inside that operational amplifier is many transistors .. the makeup of those individual silicon transistors have a junction that will work like a diode between the base and the collector or emitter (depending if its NPN or PNP) .. so the junction of that transistor will just act like a diode which requires 0.6volt to jump the junction .. then the signal will flow down via maybe another transistor then down to earth .. loading up the signal generator… Hence why the signal sounds ok at low levels because the signal isn’t jumping the transistor (diode junction) cause the signal isn’t reaching the forward voltage level of 0.6volts, .. but when you turn up the signal level the input transistor(s) in the op amp start conducting and most likely either short or ground the signal in the op amp causing the signal generator to load up ..and cause all sorts of funny sounds . Yes it would happen on most boards with Operation amplifier inputs.. unless your mixer has a small relay that disconnects the input signal from the input op amps for this very purpose.
And it only happens with some pre amp designs and not others.
And most importantly, I think you will find that no owner’s manual warns you and yet nearly no one knows it happens.
My curiosity led me to look at the schematic for the input circuit. There are a couple of descrite transistors before an op-amp. But there are diodes on the input that would normally be reverse biased when the + and – 15v supplies are active. I guess they are over voltage protection for the input. But, when the +&- 15v is missing (power off) they will conduct at 0.6v are are likely to produce the distortion you demonstrated. Interesting how a protection circuit actually backfires under certain circumstances.
I also looked at the schematic for the M32. You’ll get the same distortion with that console too. And probably with the X/MR18 series.
Interesting and thank you Ken!
The same is true of many ICs. They’ll have clamping diodes to protect them from overvoltage input. But with the power off, the input signal is now trying to power the board.
Very interesting (but annoying) way to create soft clipping
Do you have a technical explanation of why this happens? Since it only happens above a certain voltage, I suspect the input impedance of the X32 drops when it’s switched off, causing the little console to distort since it can’t deliver the current at these voltages into the lower impedance.
I’d sure like to know where it drops to, maybe I’ll put my X32 on the DATS to see. A higher quality output stage will possibly not distort in this scenario, maybe try replacing the Xenxy with the M32 and see if the issue still appears, the M32 will probably be able to drive it still.
I’ve done tests and other videos you might want to look at.
The Xenyx actually has a much better output stage than the M32 or X32.
But that’s all beside the point because the issue in the real world would arise when plugging in a DJ mixer or CD player or some sort of music player or any other line level input which could have any type of medium low or high quality output
it’s input protection devices on the console inputs, that are connected tot he internal power supply. When the internal power supply is off, they clip at +/- 1 diode drop, rather than only when the input level exceeds the internal power supply level.
Does this show up with other outboard rack gear like compressors, effects, etc. when their power is off?
I noticed happen years ago with an outboard gear unit but don’t recall what it was.
I’d need to be tested but as far as I can tell it’s a type of input design that does it more than other types.
a lot of outboard gear has bypass relays, so when the unit is off (or power fails during the show) inputs are connected directly to outputs
hey Dave.. are you sure this would happen with ISO splitters ? my experience with them is whatever is behind the transformer doesnt affect the direct signal ? also i realize the value of a test like this is to be informed but the scenarios where this would negatively impact things seems fairly small.. if a venue has a monitor desk and you were forced to run monitors from FOH, couldn’t you just turn the monitor desk on without it being used ? also if there were two digital desks id say first option would probably be a tablet for monitors to avoid the need to repatch anything.. with that said its still handy to see these tests and know how gear behaves.. thanks.
Yes, I tested it. For the test I used a radial transformer iso split box, and as expected, similar result.
Though the losses in the iso split diminished the impact slightly.
I highly doubt anyone who would use Y-cable splitters to split between FOH and monitors is paying enough attention to understand or care about the impedance changes caused by the second board, let alone in a position to be in charge of a venue with separate FOH and monitor boards, because using Y-cables to split a signal is a pretty serious rookie mistake. Plus, if you have an X32 for monitors and an X32 for FOH, using any kind of analog splitter makes absolutely no sense because by the time you’ve spent enough to split 8 channels, you’ve already spent more than you’d need to spend on the single AES50 cable you’d need to connect the two X32s to each other in order to split the signals digitally. The X32 is by no means the only digital board on the market, but it seems to be the most common (and, as the owner of an X32 Rack, I think it’s popular for very good reason, it’s a fantastic board), so the hypothetical of a setup with two X32s not only seems realistic, but it’s probably actively put in practice by plenty of venues and sound companies so bringing up the X32′s capability of sharing inputs with other X32s via AES50 seems extremely worth mentioning.
A Y cable is the same as a hardwire spilt and the same issue happens also with a transformer split as well.
Making assumptions like that are quite often flawed. As you get more experience and exposure in this industry you will find the vast array or setups and reasons for them are astonishing.never under estimate the creative and not smart ideas that people implement
There are many installations using hardwire or transformer splits for various reasons. Some have a mix of analog consoles and digital, some have accomodations for artists to bring in consoles and tie in, some have recording consoles that are only 9cxasionally used that have seperate mic pre amps and the list goes on and on.
And with the instability of AES50 for ling runs over 80 meters, a hardwire snake is often necessary.
And the issue is not an x32 issue, it is an issue that many boards exhibit
Tomi Engdahl says:
Does Audio Gain Knob Sound Different Than Attenuation Fader? (Public)
https://www.youtube.com/watch?v=chgovyDUxx4
Tomi Engdahl says:
Metering and Audible Clipping – Behringer X32 vs Allen & Heath QU16 Clip (Public)
https://www.youtube.com/watch?v=NctemYCNO9g
Lets look at the differences in the way input and output signal levels and clipping is displayed on a Behringer X32 vs an Allen and Heath QU16
How Audible is Digital Audio Bit Depth Resolution? (Public)
https://www.youtube.com/watch?v=-G8-RvUxldo
In this video I use signal nulling to try and see if we can hear differences in bit depth resolution of a higher and lower level signal.
00:00 Intro
00:53 Digital vs analog volume based resolution
02:04 What levels should we set:
02:26 Test setup
04:40 Console gain structure
05:58 Cancelling signals with optimal gain
06:58 Lower gain, higher fader cancellation
08:00 Sonic difference between higher gain and lower gain
12:00 The sound of clipping
12:30 Cancellation with other signals
15:36 Summary
16:45 Outro
Tomi Engdahl says:
How to Correctly Fig 8 Wind a Cable and it is not a Straight Figure 8
https://www.youtube.com/watch?v=jgq8-4m133o
It can desirable to wind a cable in a figure 8 to reduce inductance related heat in power cables, to fit a large cable in a case, or to reduce inductance related signal degradation in audio cables to name a few.
Turns out that winding a straight figure 8 is not optimal and does little to nothing in altering the inductance build up compared to a coiled cable. In this video you can hear the effects of inductance build up of coiled and Fig 8 cable as well as see it on an analyzer. I will also show you how to wind a cable figure 8 (perhaps better called a figure 80) such that there is little to no inductance build up.
Viewer comments:
Even after doing live sound for a number of years, I kinda love the fact that you can gain new knowledge on something as simple as coiling a cable.
Only downside is telling house crews or touring crews how & why to do it, and watch them look at me like I’m mad! haha
Right! Who woulda thought? I learned something when I saw the issue and pondered till I sorted a solution. I am sure this is a known practice that just has not propagated as well as it should
Today I learned.
The downside with all this isolation is Dave is not Working.
The Upside is he has time to to educate the rest of us!
Very interesting. Another benefit I also see with this method of fig8 is since you aren’t going across the middle each time it doesn’t make a mountain in the middle and lays flatter.
Yes and for big cables to fit in cases, it is common for techs to wind in this manner or close. But they typically strive for an 8 and settle with some rings to fit, rather than striving for the correct ballance
Thanks Dave. Way back, I used to figure 8 the multicores and then fold together into the roadcase. It was only 50 metres long, so when in use, it was always fully extended. Whilst being fascinated by most of your videos, the one that stuck out for me was “in nature you never hear the same sound coming from two locations” and leading onto how you insert pink noise into a system. So obvious yet I had never thought of it. I also love that you still mix in analog. Thank you from Australia and please keep them coming!
We do this with power feeder as well; the idea being that a straight coil causes inductive buildup, and therefore heat. I’m not sure that this is true, at least to any practical extent. From Dave’s comment elsewhere, he says it’s only useful where multiple leads are concerned.
Tomi Engdahl says:
Understanding Phase and the Physics of Sound
https://www.youtube.com/watch?v=GohIVYK1bzQ
Jason Rodd (the sonic experience)
In this video I explain some basics about sound itself, and how that knowledge helps in understanding phase. I demonstrate how phase issues can occur while recording, and how they can be taken care of.
Tomi Engdahl says:
Over-Under Cable Wrapping
https://www.youtube.com/watch?v=NYb2n6_UPEQ
Tomi Engdahl says:
Understanding Digital Stageboxes
https://www.youtube.com/watch?v=qBJHcxNvCGQ
Learn about analogue and digital stage boxes, the difference between them, how to connect them and practical uses for both
Tomi Engdahl says:
Behringer X32 – AES50 Digital Snake Cable Build – EtherCon Connector
https://www.youtube.com/watch?v=02dksd-eTzg
NOTE: Behringer does now state that this cable needs to be a grounded Cat5E cable. You can find this requirement in the manual for the S-16 on page 6. The build process of the EtherCon connector is still the same for a shielded or non-shielded cable. If you are purchasing a network cable for your use with a digital snake, please find a shielded cat5 cable.
Today I am showing you guys how to build a robust ethernet cable for use with the Behringer X32 AES50 Digital Snake.
Once built you can employ this for use in connecting your Behringer X32 mixer to another X32 for use with a monitor console setup, or with connecting your Behringer X32 with the Behringer S16 stage box (not released yet when this video was made).
The EtherCon connector used is the Neutrik NE8MC-B.
Note: the P16′s do not use an EtherCon type connection, only a normal Ethernet connection. Only the AES50 uses the EtherCon type connection, however a normal ethernet cable will connect into an EtherCon connection, just it is not as robust.
Tomi Engdahl says:
HOW Live! Webinar: Signal Flow of a Mixing Console
https://www.youtube.com/watch?v=Z7P-Lu5T_ng
In this webinar, our House of Worship Product Specialist Evan Hooton will walk you through the general layout and signal path of a mixing board used in a House of Worship scenario. In addition, we’ll learn about inputs, outputs, EQ, the Aux section, subgroups, and more!
Tomi Engdahl says:
Inside Meyer Sound Lab’s New Flagship PANTHER Line Array
https://www.youtube.com/watch?v=OxQwumADjSE
A brief tour of Meyer Sound’s new flagship PANTHER line arrays. Shipping in February, 2022, Panther combines two long-excursion 12” woofers and 3” compression drivers with four channels of onboard Class-D powering fed from a dual (analog/Milan AVB network) input module. Designed for large-scale touring and installs, three models offer different horizontal dispersion: the 95° PANTHER-M; 110° PANTHER-W; and 80° long-throw PANTHER-L. PANTHER produces nearly the same power and headroom as LEO in the footprint of LYON, yet weighs just 150 pounds and are capable of max 150dB SPLs. All have IP55 weather protection-rated enclosures and integrate with Meyer Sound’s existing 900-LFC and 1100-LFC subwoofers. A range of flown rigging, ground-stack and transport options are available.
For more information, visit: https://meyersound.com/product/panther