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An Interview with Dane Tate

Including a Review of the

XQP OPTICAL DE-ESSER 531 pan60                     Let's start with some background. Would you please tell us a bit about yourself, give us some background and include topics hobbies or the things that help you to relax and wind down? Dane  I first learned about audio from a couple of guys at my church when I was about 12 years old. Later, I took over the sound system at the church, rewired part of it, etc. I studied electronics at Vo-tech in high school and received a BS in Radio, TV, & Film from the University of Oklahoma. I installed a new audio room at the J-school while there. I worked as an engineer at a voice-over studio, Irving Productions, for eight years in Tulsa, eventually worked on equipment maintenance. I did some freelance installation during those years, too. Next, I went into full-time contracting of installations and freelanced as an engineer for the TV Guide Channel for a couple of years (it was located in Tulsa, at that time). I designed the first de-esser after I left Irving Productions. Later I worked in video production, which I currently do now. I like to write and record my own music, and that is probably my hobby. I moved to Enid in 2008 and only recently bought a house here, so I've been able to enjoy working in the yard again. It has also been an adventure to convert my garage into a wood shop. pan60                        So, you are a working engineer? Dane  What I do now is video production at the community access facility in Enid, OK. We have one of maybe two full production PEG facilities in the state. We have two studios, a couple of AVID rooms, and a remote truck. I also have a Final Cut setup in my office. I direct a call-in math show that the school children watch and several remotes each month along with a bunch of odd stuff. I am also teaching a video production class as an adjunct professor for one of the local colleges. pan60                        I would love to get into video production. Maybe someday. : ) What got you into gear design? Dane  We had a rather stinky de-esser during the years at Irving Productions. However, I came up with my optical de-esser design as part of a channel strip sort of thing. It was actually the germ of a one-channel console for recording books-to-tape. It was basically a single, full-featured channel with talkback and slate and tape returns, etc. It had the features of a full-sized recording console, but with only one mic input. Curious, I know, but there wasn't much around in the mid-nineties in the realm of "controllers" like there are today, because people still used Pro Tools with consoles in most situations. We did at Irving. The book recording console was never built, incidentally. pan60                        Your de-esser was offered some years back in a 19'' format, can you tell us a bit about that? Dane  It was the Dane Optical De-esser #31. It was a single-channel, half-rack unit with built-in power supply. Very few were built and sold, but they were well-liked by a select few. The circuit hasn't changed significantly. pan60                        It seems to me that the computer revolution has made some outboard gear obsolete to many, but I see a huge return to outboard analog gear. Did this have any bearing on you reintroducing the Dane De-esser? Dane  Well, it certainly encouraged me. The main reason for the return was...wait, I have a feeling you are about to ask me another question... pan60                        What made you decide to go into the 500 format? Dane  Ah, I thought that was coming. pan60                        LOL Dane  It occurred to me a number of years ago that the 500 format was a really nice way to produce a product. The chassis was a huge expense on the #31 - it was all custom fabricated from aluminum which included engraved and paint-filled legends. There was a built-in power supply, of course, which can be a liability. I hate wall warts and line warts, though, so I never wanted to do that. I have had a 500 VPR rack for a number of years, about half full of API stuff, so it was really calling me. pan60                        Tell us about you De-esser. How does it, if at all, differ from the older 19'' rack mount version from the past? Dane  Apart from the obvious lack of a power supply, etc., it is virtually the same -- except for the use of twin VACTROLs, instead of one. The issue there is that the resistance of the VACTROLs vary quite a bit from piece to piece on the extreme low-end of the resistance range, which is where the reduction is taking place. This means that one de-esser may be more or less aggressive than the next one. The solution was found when my XQP partner, A.J. Wells, and I tried using two VACTROLs in parallel. The theory was that two would average. The resistance would be half (more reduction), but the current driving the LEDs would be split in half (less reduction), so the same basic amount of reduction should be there. Well, it works even better in practice than in theory. It's scary in fact. Otherwise, we're using pushbutton switches instead of toggles, smaller LEDs, brightly colored knobs, and laser-engraved aluminum panels. pan60                        Can you explain what is going on with a optical De-esser? Why optical? Dane  You must understand first that I am more of an operator than a designer. The design of this thing was very empirical. The optical concept is quite simple in theory, and I knew that I could figure it out just by messing around, and that's basically what happened. I knew from the start that I wanted a de-esser that was natural, not surgical. A lot of de- essers utilize very elaborate schemes in their attempts to do a tough job. You can't always reduce a sibilant - especially a whistling sound as much as you might wish. Some really creative designs have come about. I haven't used very many of them at all, but I know that the ones I have used (as well as reports from other engineers) often sound really bizarre. I didn't think that the process had to be that complicated. Also, unlike a lot of compressor designs, a de-esser should not (in my opinion) color the sound. It's not a creative tool in the same way compression can be. It's a problem solver, and it should be as transparent as possible within reason. So optical seemed like a good approach, because it results in a short and simple signal path. VCAs tend to have a bad reputation, and I didn't want to mess with those. People don't want to spend $1,000 on a de-esser for the most part, so the path is all monolithic op amps. There is an Analog Devices balanced line receiver at the input and a balanced line driver on the output. There is a large metal film capacitor on each input leg, and these are the only ones in the signal path. There is an Analog Devices AD711 buffer op amp in between the two above mentioned chips, and that's about all there is in the audible signal path. Also, there are the two VACTROL opto-isolators of course and a few scattered resistors - all metal film. The side-chain has a high pass filter to remove all the low frequency content from the gain reduction control. There is a rotary switch which selects one of three corner frequencies for this filter. They are labled X, Y, and Z, according to tradition. They are at about 3K, 5k, and 7kHz, but who cares? These frequencies were chosen from listening tests. Most de-essers cover 1k to 10k or so, but I never heard anything in the 1k range that I considered sibilance. Because we use a high-pass filter instead of a band-pass, any sibilant above the chosen position is covered. This is another example of what I consider to sound more natural. There doesn't seem to me to be a reason to hone in on a very narrow band. Reduction will only occur if a sibilant is loud enough to trigger the thing, and if a sibilant is occurring, nothing else is. This is, of course, true for a voice track - not a mix. I never intended the unit to be used on mixes. A further, technical bit of trivia is that the LED in the VACTROL is driven by a transconductance amplifier, rather than a rectifier. This makes the action very soft knee, which I think sounds better. So, for those not at all familiar with how an optical gain reduction device works, here is a brief explanation. When the signal enters the side-chain, anything below the selected frequency is filtered out. It's a multi-stage filter, by the way. Anything above that point - basically sibilance - causes the LED in the VACTROL to light up, which causes the resistance of the resistor in the VACTROL to lower. That resistor is the shunt leg in a voltage divider, and the lower the resistance there, the more attenuation occurs in the audio path. It's very simple, really. The trick to a design like this is juggling the resistance of about six different resistors in the circuit which control the amount of bite the thing takes, where the knobs point, etc. By the way, this is a feed-forward design - the side-chain takes its feed from the input of the gain reduction circuit, rather than the output. Compressors come in both varieties, and some are even selectable. However, the feed-back style doesn't work so well in a de-esser in my humble opinion. pan60                        Well everyone by now knows how I evaluate: 1.         Do I like the company and/or the man behind the company? 2.         I need to be comfortable that service is available, that the company cares about their product, and their customers, as well. 3.         And how does the product perform? Dane is a very nice gentleman and it is obvious through my contacts and dealing with him that the he cares about the customer, as well as his products. After spending a great deal of time with the Dane’s XQP 531 De-esser, I sent Dane a email: ''I like this a lot. I use this on cymbal and all kinds of things. Sometimes I just run a track through it to see what it does, and I love it. : )~ Dane, send me an invoice as I want to get a second one so I can run this on a bus. Also, get me one of your new cool distortion units -- The XQP 545 Disrupter. So, I guess I would not look at it just as a De-essor, but just a great tool. I did not care for the knobs, but, it is not a deal breaker. I do think some cooler looking knobs would be better. We both know no matter how good something is, looks also count. But, then again, it does catch one’s eye with those red and green knobs. LOL i don't know! Maybe the knobs are growing on me! I think the price is good, the service is great, that Dane is an awesome guy, and his gear is very well made at his price point. Dane, tell us about the Disrupter. Dane  The XQP 545 Optical Disrupter came about rather by accident. I took a de-esser circuit one day and removed the high pass filter in the side-chain to begin messing around with a compressor. There was distortion right away, and upon looking at it on the scope, I saw that it was asymmetrical and very smooth - no clipping. So, I began playing with it through different sources and liked the way it sounded, especially on low frequency material. A.J. and I quickly realized that the reason this was happening. I mentioned earlier that the LED in the VACTROL in the de-esser is driven by a transconductance amp. This circuit makes a varying current out of a varying voltage, which makes the brightness of the LED vary in proportion to the voltage, which results in a very smooth, soft-knee kind of gain reduction. However, there is no rectifier, so the signal is still AC. Now, in the high-frequency only area in which the de-esser operates, the distortion is not really obvious (although it can be measured). But, when dealing with the full frequency spectrum, it becomes very obvious. So, what is happening is simply that the top half of the waveform is being compressed, but not the bottom half. And it sounds really cool! It is less and less noticeable as the frequency rises, which is why it tends to be best on low frequency sources. My personal favorite is an organ patch on a synthesizer. Sometimes, these are way too clean sounding, and the Disrupter can provide it with a nice growl. The character of the distortion is smooth, because it is not actually overdriving anything, thus there is no clipping, so there is no nasty high-frequency harshness. If you are Disrupting source material that has high frequencies in it, as well as low, such as a mix, the highs will start to break up as the low frequencies are being affected. It is much the way a speaker sounds when it is being driven by excessive low frequency content. pan60                        You now have a very cool EQ out that is next on my list of 500 format gear to have. : ) Tell us a bit about the EQ. Dane  The 535 Program EQ is new. There are two production prototypes in existence, at the moment. I have one in my rack, and there is one floating around Boston with the PAD guys. I can't take credit for this design, as it is pretty much a standard active Baxandall circuit. However, I did give each band its own amplifier, so that there is no interaction between the two bands. There is therefore a dummy LF section in the HF section, as that is an integral part of the basic design. There is also a built-in high pass filter set quite low to prevent horribly excessive subsonic low end when boosting the LF band. The Baxandall EQ makes these incredibly gentle curves, which don't have an easily identified corner frequency. That point is actually beyond 20k on both of the two selectable frequencies. In fact, the frequencies, as marked on the front panel (10k / 15k and 50 / 100) are almost completely arbitrary! Not unlike the X, Y, and Z positions on the de-esser. I chose those numbers because they roughly correspond to what my mind suggests when I listen to the device. Those seem like numbers we all can relate to. But, you just have to listen to it. I think we are probably all guilty at times of "listening" with our eyes instead of our ears. I know I am. pan60                        Well, I am looking forward to getting my hands one of those EQ's. Thanks, Dane!
August, 2011
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XQP Optical De Dresser 531