Slides from my AES Reverb presentation

I was invited by the Seattle chapter of the Audio Engineering Society to speak about reverbs and reverb design. I threw together some slides:


Pretty skeletal deck, but it was (hopefully) more entertaining when presented in person. Don Gunn helped me out with a Logic X project that accompanied the presentation. Don also listened to me when I practiced the presentation, and was graceful enough to pretend that he hasn’t heard me ranting on the same topics about 100 times before.

I think I learned more from the people in the audience at the AES presentation than anyone learned from me! It was cool to hear anecdotes from people that had worked at Lexicon and Alesis, as well as folks that had a lot of experience with plate reverbs and echo chambers. Thanks to Christopher Deckard for inviting me to speak, and thanks to everyone that attended the presentation.

About the author:

Sean Costello is the "algorithmic reverb plugin wizard" [citation needed] at Valhalla DSP.

Comments (18)

  1. WOW! That’s so cool, I really wish I could have heard your presentation! Perhaps we can arrange a reprise at an upcoming convention?

    1. If there is ever a reprise, I’d love to fill in some of the gaps in the history. There were a few folks at the talk who had worked at Lexicon and Alesis during the early days, that would be able to actually ANSWER some of the historical questions.

  2. I read this with great interest! I note that an AES timeline has the EMT250 released in 1975, not 1976. Would be nice to know which is correct.

    My question is really… what was the first commercially released (and hence used in studio) digital delay? People talk of the AMS DMX 15-80, released in 1978. But I find it hard to believe a reverb came out several years before a simple delay unit.

  3. Thanks for the slides. Very interesting comments at the end. I have been mixing for over 20 years now, and have been heavily involved with doing ITB mixes since 95. These days I do a lot of multichannel mixes. If there are reverbs out there I haven’t heard or tried I will be surprised. Your hard work shows. A number of us (mixers) agree emphatically that your offerings are among the best. For the future I am hoping you approach multichannel surround and consider the possibilities above 8 channels. I typically work in 11.1 and given what Dolby, DTS, and Auro are doing for immersive mixing, there will be a need for something that can scale up in useful ways. please feel free to contact me offsets if you’d like. All the best!

  4. The PNW AES Section did indeed record Sean’s presentation. For some reason, it isn’t posted yet on the PNW AES meeting archive website yet ( ), but I’ll see why not.

    Our October 2015 meeting will have Sean joined by former Lexicon and Alesis engineers, in a free form chat about reverbs. However, it will be at a local studio and RSVP needed due to space limits. It’ll be recorded.

    Thanks again to Sean for his participation with us!

    -Gary Louie, AES PNW Section secretary

  5. Just listened to the presentation and read the slideshow afterwards. I thought it might be boring but it wasn’t at all! Plus I think this will give me a better feel for what I’m actually listening for when I’m applying reverb and playing around with the parameters. It’s actually pretty inspiring to hear how much of what you do involves mucking about and experimenting rather than invoking scientific/mathematical superpowers. Pretty cool that we live in a day and age where you can dream up an algorithm and give it a go – even if it means that so much knowhow that could be built upon is now shrouded in secrecy.

    This also inspired a thought about the difference between Echo and reverb: Maybe one way of looking at it is that “echo” is just a name we give to a peculiar reverb pattern in which the original sound is reflected with so little diffusion and at long enough intervals that we can distinguish the original sound source in those reflections with our ears. Or maybe I missed the point of that part of your talk entirely, haha!

  6. Wow. I know nothing related to audio engineering and reverb. Yet after listening to the presentation, I’m fascinated with the subject. The way you conceptualize a space as containing very many bells…wow! It’s changed the way by which I not only view, but also listen to any room or building that I occupy!

    Thanks for opening my eyes, ears and mind to concepts of sound. And thanks for creating awesome plugins!

    For those who’ve not yet listened to the recorded presentation, I highly encourage you to check it out.

  7. Hi Sean,

    I stayed up way too late listening to your excellent AES presentation. I did some research on EMT 140 back in the ’70s, and built 3 or 4 of my own plate reverbs. On the question about the EMT 140 plate dimensions (specifically the thickness), my recollection is that the the plates were 1meter x 2 meters x 0.5 mm.

    Thanks for the excellent information and presentation. I learned lots!


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