Understand DI Boxes, Impedance and Transformers Part #1

Part 1 of Chatting about DI boxes, impedance and such
Part 2 - • DI Boxes, Impedance an...
00:00 Intro
00:40 Signal levels
02:14 Types of cables and signals
03:34 Impedance
07:38 Transformers
09:09 Wrap up
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[@RaquelFoster]

Dave reminds of of my favorite teacher - my high school physics teacher who was in a band. That guy had lessons that involved launching mice on model rockets and lighting matches with a rifle. The best was when he told us to make a musical instrument and play it in class.

[@DaveRat]

Honored!

[@TotoSonic89]

Nice way to explain it with the sticks.... I never used it to explain it, but it makes sense and is easier to understand to non-technicians. Aguante Dave!

[@DaveRat]

Cool cool and thank you Toto

[@greenanoleenterprises-demo5502]

A refreshingly uncomplicated treatment! I wish I'd experienced that 9 minutes of explanation years ago. Can't wait for part 2.

[@DaveRat]

Awesome!

[@caleykelly]

Took the words out of my mouth Green. Thanks as always Dave!

[@DaveRat]

Thank you!

[@zerokoolTV]

Dave you are very Masterful in explaining complex stuff in a much easier way to understand. Thanks dude. This is great stuff

[@DaveRat]

👍🤙👍

[@ToddWCorey1]

Thanks, Dave! As someone with a mechanical engineering background, I thought the impedance analogy was perfect.

[@DaveRat]

Awesome and thank you! I am always apprehensive when presenting analogies that have not been vetted to KZbin public. Not getting slammed makes me very happy

[@luc5580]

As a beginner sound engineer this is very helpfull! Thanks Dave you don't know how much this means to me! :)

[@DaveRat]

Awesome and thank you Luc

[@therobdenton]

Fulcrum! That is the best analogy for a transformer I have heard. I'm really looking forward to your next episode on this. I hope you can touch on how matching (and skewing) the input/output impedance affects frequency response. Thanks for doing these videos.

[@DaveRat]

Thank you Rob!

[@CoastalBreed]

Another Gem from the Guru himself💪 Good stuff.

[@DaveRat]

Thank you!

[@michael_emm]

Love it. The basics at it's best.

[@DaveRat]

Thank you Michael

[@pettera.eriksen9109]

I can not describe how much your videos mean to me and my understanding of why i do things the way i do

[@DaveRat]

So cool, thank you Petter!

[@darrendevereux5666]

Hey Dave, discovered your channel from the behind the scenes video at Slane videos. I just wanted to say thanks a million for uploading these wonderful insightful videos. Very much appreciated, and look forward to watching more. All the best!

[@DaveRat]

Thank you Darren!

[@MrNicknayme]

I LOVE this! Some interresting knowledge, that are more on the tech side, but are a great supplement to having musicality and knowing when to use some gear. More, more, MOOOORE! ;)

[@DaveRat]

Awesome. Thank you Nick!

[@chikkenyo]

Thanks Dave. I'm always pleased to watch videos from a dude that sounds like a transplant surfer dude that really knows their stuff, and has a good way of explaining it. Electronic engineering should not be an esoteric 'sport'. It's PHYSICS, dude!!

[@DaveRat]

Thank you!

[@TomCee53]

Oops, I should have watched this one first. Great stick analogy. The thickness of the stick could have been emphasized. You mentioned loss, but maybe another video, for not all transformers are created equal. (Live vs studio)

[@DaveRat]

Cool cool

[@erniesanders3724]

Just stumbled upon Dave the other day. Mind blowing the amazing information he shares. Love this guy. Awesome skills.

[@DaveRat]

Thank you Ernie!!

[@Audiosyntax]

I love when Dave uses props in his videos. It is important for audio enthusiasts to understand exactly what is happening when they run their audio through a DI box. These little transformers are one of the few pieces of pro audio gear that you will commonly see in the gig bag of any musician. Great vid!

[@DaveRat]

Awesome and thank ypu!

[@EcBaPr]

awesome thanks Dave.. the example with the sticks waving makes it easy to understand..

[@DaveRat]

Excellent! So happy the analogy works!

[@tylerkeeton17]

So. much. Cool. Content! Thanks as always Dave!

[@DaveRat]

Thank you Tyler!

[@nattyphysicist]

I love this. Pure poetry

[@DaveRat]

Appreciated, makes me happy the rough analogy seems to convey.

[@BermanSound]

Good demo. Thanks dave!

[@DaveRat]

Awesome and thank you and great to see ya in the zoom chats

[@mwintersteinsmith]

An excellent and informative video. Thank you Dave 🐀 😎

[@DaveRat]

Thank you Martin!

[@MrMercho4416]

Thanks Dave

[@DaveRat]

Thank you Dave!

[@DMKahn]

Thank you for this, awesome visual representation

[@DaveRat]

Thank you!

[@miguelpozoblock4223]

Awesome,thanks!!

[@DaveRat]

👍

[@bradwalker1259]

I think a useful analogy is that low impedance signals have high 'stiffness' and high impedance signals have lower 'stiffness'.

[@DaveRat]

Cool, yes that works, thank you Brad

[@russellszabadosaka5-pindin849]

Those were awesome metaphors for explaining high & low impedance. Thanks man!

[@DaveRat]

Thank you Russel!

[@russellszabadosaka5-pindin849]

@Dave Rat yr welcome, thanks for replying.

[@DaveRat]

👍

[@Scottjcpp]

Awesome. Wanted to see this subject. Psyched for what's to come :-)

[@DaveRat]

Tomorrow or sat it should be up!

[@ThunderBassistJay]

I really like the example with the stick. 👍 Due to capacitance, long guitar cables, in combination with the high impedance of a pickup, tend to attenuate high frequencies. With a DI box close to the guitar, this problem is solved. In other words, the RC time constant improves. This is an advantage of an active guitar as well.

[@DaveRat]

Excellent and thank you for the info good stuff

[@ThunderBassistJay]

@@DaveRat You're welcome. I started out as an electronics engineer, who worked with transmitters and stereo modulation, more than 40 years ago. From there I switched to managing a temperature calibration and research lab. At 50 I learned to play the bass, so my approach is mostly technical. 😊

[@DaveRat]

Awesome and very cool!

[@JulianFernandez]

thanks so much

[@DaveRat]

👍

[@nischalrokka103]

Great video : ) Much love from nepal 🇳🇵

[@DaveRat]

Awesome! Hello Nischal! And cool cool, Nepal!

[@wm8123]

your stick example is actually electronically not incorrect. Is exactly this thing. Very nice example, i have to remeber this, when i explain it to someone else. The frequency denpening part is than another thing^^. But yeah, simply you can break it down to the mechanical principle :-) thank you

[@kevinpetit9886]

Great video. 🙂👍❤

[@DaveRat]

👍

[@stu-po]

Your "seesaw" example is actually very clever.

[@DaveRat]

Awesome and thank you

[@violadrums]

Man your info is the best. I trust your word and love that you do these things for the wanna be sound guys. Thank you

[@DaveRat]

Awesome thank you!

[@OwlProducer]

Freaking great explanation :)

[@DaveRat]

Awesome and thank you!

[@leonline3424]

Great vid , thanks, could you please make a comparison video with cheap/entry level Active and non active DI's versus semi pro versus pro DI's? Would love your take on this subject , cheers :)

[@dlcarburetor]

Feel free to get deeper on this topic if you'd like. I recent started using the ART DTI to connect small music sources to a mixer over long runs of balanced line. Been getting good results but don't fully understand what's happening "inside" the lines and devices.

[@DaveRat]

I have one more vid to release and will work on a third in the series

[@giovannimercuri5168]

I am sure it will be a detail you cover in the future episodes of the series...but, do you intend to cover the difference between the active and passive DI boxes? I have heard varying opinions and different "rules of thumb" for when to use one vs. the other and have dorked around a bit with the JDI and the J48 from Radial...just still not sure I am in a position to know if the transformer based solution or the active one is better suited for one thing or another. Anyway, hope to hear your thoughts on all that! Thanks again for all the great content.

[@DaveRat]

Interesting, I cover some but will ponder a vid covering more

[@dighawaii1]

can haz part 2? Thanks for these!

[@DaveRat]

👍 I will release part 2 next weekend

[@djgalawak]

ola, nice way of explain. which ratio you recommand for drum machine (big sub, punch), synth. rec in apollo solo. jensen, lundhall, cinemag.. best vibes

[@DaveRat]

Hmmm, I personally try to avoid transformers except if absolutely needed for problem solving

[@clownhands]

Hi Dave, I love your analogies for conveying engineering concepts with intuition. I was hoping you could apply your science communication skills to a simple question that has been bothering me for ages: In power engineering, we use a transformer at the source and to step up voltage (and step down current) to maximize the efficiency of long distance power transmission. In audio engineering, we do the opposite; step down the source’s voltage and step up the current to maximize the efficiency of long distance signal transmission. How would you explain in an intuitive way to, say, a high school physics student, why power vs audio engineers do the opposite? Thanks, Brian

[@DaveRat]

Interesting! Maybe a bit of clarification in that audio does not step down voltage and up current per se, but rather things like mics are typically already low voltage higher current right off the voice coil. I will think on this further but off the top of my head I would say the power transmission is driven by minimizing loss and the goal is to transmit max watts. For audio the driving factor is optimizing frequency response, minimizing HF loss and with the exception of post power ams, loss of voltage or watts is not a significant concern. Losing 1/2 the power of an audio signal is no big deal as long as we stay above the noise floor. So... For audio signals, low impedance is critical. Our enemy is capacitance. For power generation higher impedances rolling off high frequencies I advantageous as it helps filter noise. So narrowing it down, audio wants low impedance which is a high current low voltage scenario compared tolong distance power generation, high impedance low current is optimal. But,,, audio does use the power generation concept for 70 volt lines, where we do exactly the same thing as power, transform up to high voltage and transform back down at the speaker. But it does not sound great So from that perspective, if transmission of power is the goal, high voltage low current If transmission of accurate wide bandwidth signal is the primary goal, then lower impedances are preferred, which ruslts in higher currents and lower voltage, Great question and will ponder and simplify

[@johnnatangonzalez5986]

Gracias por traducir a español 👌🏻

[@DaveRat]

Denada, y Buenos Jonathan!

[@IanSzot]

Hey Dave can I suggest a quick comparision between cheap and expensive DI boxes? How they change sound and stuff like that. I know the "industry standard" that everyone loves is the Whirwind IMP 2 and the Radial boxes but I do wonder what is different in them (components and sound quality) compared to a cheap Behringer DI and if it's worth the extra cost

[@DaveRat]

Good idea, will add that to my list of vids to do

[@tarun.krishna]

What's your thoughts on using AES cables to send analogue signals for the PA ?

[@DaveRat]

All good we do it all the time. We use analog over cat5 soundtools products for analog return snakes as well as analog backup to the delay clusters and pretty much anywhere. Shielded Cat5e cable actually carries analog better than audio snakes

[@tarun.krishna]

@@DaveRat Thank you so much.

[@dzaring]

Hey Dave, thanks for you video. I like your style. You dumb it down enough for me to get it. I'm a ham radio operator and deal with impedance difference. With the high power 100W or even 1kw the standing wave reflection can be damaging. Are you concerned about SWR? How would you detect it? What could you do about it? Thanks. 73's KA9WAP

[@DaveRat]

Great to meet you David and awesome questions. So cool ponder the challenges across differing fields. Yes we do face standing wave challenges in the audio world but in a differing way. First, SWR is an issue between the rf amp and antenna so the parallel for audio would seem to be between amp and speaker. Between amp and speaker we don't really encounter swr issues but some something similar called back EMF does occur, though not a huge issue except in some more esoteric subwoofer designs. That said, for pro audio the standing wave issue occurs acoustically with sound waves bouncing around the room or venue. This is a significant issue in reflective and reverberant rooms and spaces and we can go do great lengths to dampen the standing waves and reflections using sound proofing and by altering angles on parallel surfaces. The standing wave and reflection issue also is a factor impacting speaker enclosure design, microphone design and just about everything acoustic. Basically a 3D version of what you face between amp and antenna except we just get bad sound and SWR in ham can damage the RF amp. Unfortunately, I don't have much guidance in resolving the SWR issues in ham, but will ponder it. Thanks again David!

[@dzaring]

@@DaveRat Thank you so much for the quick response. In the ham world, we use and antenna tuner to cope with the SWR. The tuner is an impedance matching devices that make the antenna look like it's the correct length for the frequency being delivered.

[@DaveRat]

I wish our solution was that easy!

[@caspermaster-com]

Thanks. I would like to know the practical implications of low/high impedance. I undarstand the level differences ex. that a preamp wants to see like -60db as you say, but I don't undarstand if there are any practical implications in terms of sonics and function for low/high impedance in itself :)

[@DaveRat]

Hmmm, well a guitar pickup is lhigh impedance because there are many many winds of wire around the magnets that pick up the magnetic fluctuations from string motion. Using less winds of wire would give less output, needing more gain on the guitar amp. Quite high gain preamps are more expensive and tend to need to be balanced, also more expensive and complex. So simple and cheap tends toward high impedance. Low impedances or more specifically the low voltages that tend to accompany low impedance signals are more challenging to work with but can offer higher fidelity and are less susceptible to cable capacitance and HF roll off it causes.

[@caspermaster-com]

@@DaveRat Thanks!

[@DaveRat]

👍

[@tims.227]

Are there 3D files available of the cool tiny monitor box? Thank you for your nice videos, i learned a lot from them. Greetings from Germany

[@DaveRat]

Thank you! I may share 3d files at some point, still working on them

[@tims.227]

@@DaveRat ok thank you very much.

[@WorshipShed]

I want to know more about Impedance

[@DaveRat]

Hmmm, what cha want to know!

[@ohyau2]

I was hoping you were going into the differences in imputing an acoustic with a piezo pickup vs a bass or keys, why one DI doesn't fit all.

[@DaveRat]

I will work on a video for choosing the right DI

[@SUKAGALIH49]

nice shirt

[@DaveRat]

Garbage!

[@josefbuckland]

I think your PARANOID it does not belong in the trash. Lol. Butch Vig what a producer!

[@DaveRat]

Ha! Great sounding, and yes Garbage

[@AntwhaleNearfar]

Why do I think you were once affiliated with The RHCP? 🤔

[@DaveRat]

I mixed sound for them for 27 years

[@LoffysDomain]

What is a di box?

[@DaveRat]

DI stands for direct input. A DI box is a direct input box that allows the 1/4" outputs of electronic musical instruments and amplifiers to connect directly into the XLR inputs of mixing consoles or other gear. Electronically a DI box converts a high impedance audio signal to a low impedance audio signal. DI boxes can be passive transformer designs or active electronic designs who are combination of the two. In addition to impedance matching instrument outputs to mixing board inputs, DI boxes also provide round loop isolation which can help with eliminating and buzz from grounding issues.

[@shatteredsquare]

current sounds like torque, , high impedance sounds like a little F1 engine that makes all its horsepower at tens of thousands of RPM but very little torque, low impedance sounds like a geared down tractor that can pull anything but it's only a couple hundred horsepower

[@DaveRat]

That works

[@Hipyon]

He missed the crucial point you can run low impedance into high but not high and low when impedances are matched you get maximum power transfer at 50% efficiency Power transfer would make a good video the maths is quite simple The graph quite pretty and the sweet spot you're looking for

[@DaveRat]

Cool cool, I cover a bit of that in vid 2 where I show how to use a DI box backwards to boost signal voltage and show sagging when plugged into a low impedance input

[@OtherTheDave]

@@DaveRat That sounds like it’ll be interesting. I’ve used a pair of passive DI boxes (with one backwards) to kinda fake an SGI, but I haven’t tried using them to boost voltages.