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David Waelder

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About David Waelder

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  • Birthday January 1

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  • Location
    Los Angeles
  • About
    Production Mixer
  • Interested in Sound for Picture

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  1. Chinhda employed a clever approach to this engineering challenge on his Small and Medium carts. He is no longer able to build any new carts, of course, but I can share his simple design with the group. The smaller carts employed a sub-frame to hold the recorder and mixer. Battery power, accessories, boom pole holders and the like were on the main frame but the module with the recorder was detachable so it might be used in an insert car or similar application. Chinhda designed a mechanism to hang and secure that sub-frame so it might be attached at either of two preselected (and adjustable} heights. The sub-frame had two frame rails of his own construction that ran across the back of the sub-frame. You can get a sense of this in the image of the sub-frame mounted high (ChCart_SubFrameHigh.jpg). There is a blue frame piece at the top of the sub-frame. It's made from a right-angle extrusion and the metal is about a quarter-inch thick. A matching frame piece is attached to about the mid-section of the sub-frame. Those frame pieces can be hung on hooks attached to the 80/20 frame of the cart. Whether the sub-frame is hung on the lower or upper frame piece determines the working height of the equipment. A second set of hooks, similar to the hanging hooks but mounted pointing down, could then be slid down to engage another frame rail and tightened, thus locking the sub-frame into position. Raising or lowering the sub-frame is a job best handled by two people. However, it can be easily accomplished in under two minutes. If there is real interest in this bit of engineering, I'll stop by the shop to see if I can photograph some of the hooks and other hardware. David
  2. While not unexpected, the news is heart wrenching. Sympathy to his family and to Jeff who all suffer a great loss. David
  3. Some time back I needed to purchase a new set of headphones and I set up a test to audition the various candidates. I tested three or four models and don’t recall exactly which ones. I set up a boom pole on a stand with a boom cradle on the Audio Services showroom floor. (That tells you how long ago this was.) I had a Schoeps hypercardioid at the end of the pole advantageously aimed at the speaker. Then I positioned myself about four feet from the speaker so I might test the performance of the phones by periodically removing them and listening directly. Only one set of phones closely approximated the sound of direct listening: the Beyer DT-48’s. All the others clearly colored the sound. Now, the Beyers have some known liabilities: They are somewhat lacking in extreme low end reproduction making it challenging to listen for hums. They clamp one’s head in a vise. And, of course, they are Ferrari or Rolls Royce expensive. But for truthful reproduction of speaking voices, they are the best (or were then). Eventually, I migrated to the Sony’s. Comfort over long hours began to trump absolute fidelity. And, with experience I reasoned that I could interpret the Sonys appropriately. David
  4. The quandary of having to pay heavy import duties does present a challenge. Given that restriction, I would approach the matter differently. The Ramsey antenna you are using (the green circuit board shark fin) is a perfectly capable antenna. From my own tests, it has comparable performance to units from PSC, Lectro and others. It’s not very attractive, it has sharp edges and you must construct your own mounting hardware. But as an antenna, it’s fine and it’s available very cheaply. I suggest that you purchase several additional Ramsey antennas and rig them so that a single antenna serves only two radios. (Of course, with diversity radios you’ll need two antennas for two radios.) With a cluster of antennas, you’ll need to split the signal only once per antenna. That’s a minimal loss (3dB) that would not require any amplification at all. If your six radios are all diversity, you would employ six antennas and that is a bit of a cluster but all your hook-up hardware could be first class and the cost would be manageable. David
  5. There are a good many Lithium Ion batteries in common use for location recording. Many power supplies for recorders and accessories use NP-1 batteries. While Nickel Metal Hydride batteries are still available and in use, most NP-1's today are Lithium Ion because of the design's light weight and greater capacity. Aaton Cantar recorders, both the X2 and the X3 are usually powered from Lithium Ion batteries - a proprietary design for the X2 and a type 2054 cell for the X3. I don't know of any nasty incidents that have been determined to be caused by Lithium cells but there was a very serious fire on a dive boat in the Channel Islands off the California coast that may have been caused by overheated batteries. The boat was out on a diving excursion and anchored off the coast of Santa Cruz Island for the night. A fire started in or near the galley and spread throughout the boat very rapidly. The crew attempted a rescue of the passengers but were driven back by intense heat and flames. Most of the crew were able to evacuate but one crew member and thirty four passengers died in the fire. Early suspicion centered on the many batteries for underwater lights and cameras that were being charged in the galley and also in the sleeping quarters. From reports there were many batteries and multiple power strips. An investigation has so far been inconclusive. Here are links for more detailed information: https://ktla.com/2019/09/27/investigators-finish-examining-dive-boat-conception-find-no-cause-of-fire-that-killed-34-people/ https://laist.com/2019/10/03/dive-boat-conception-fire-coast-guard-sleeping-rules.php https://en.wikipedia.org/wiki/Sinking_of_MV_Conception David
  6. Yes, that’s a known issue with the Neumann mikes. However, it doesn’t seem to be related to the noise issue. That seems to be some sort of incompatibility between circuits but the particulars remain a mystery. (At least to me) This problem was one of the reasons I stopped using phantom power supplies, like the Denecke 48v unit, in favor of the Sound Devices MM series preamps. At a distance of a dozen years I no longer accurately remember the sequence of attempted remedies. I’m not sure if use of MM preamps was a remedy or if the issue wasn’t resolved until I acquired the Sennheiser 8050’s. David
  7. That is, indeed, a good line of inquiry. And, it was one of the first things I investigated. That’s not it.
  8. Regrettably, I never did identify the cause of the noise I heard with some Neumann mikes in a radio boom situation. I did learn that the shotguns (KMR 81 & KMR 82) are electronically different than the shorter mikes but I don't recall how they differ. The Audio Ltd device is probably worth a try but I'm not sure that the noise came from RF interference. Rather, I think it was some sort of incompatibility between the components. But, worth a try. I acquired a set of Sennheiser 8050's and the mysterious noise problem was never heard from again. David
  9. It has been awhile but I think that Location Sound carries NATO plug interfaces in their rental inventory. Even if you are not close enough to easily rent through LSC, it would be worth a phone call to inquire. They might be able to share a source with you. (I acquired a couple of adapters for a film about the Reno Air Races, both NATO and an alternate configuration. I think I got them through LSC but the project was ten years ago. I turned them over to the production company at wrap. It was an L.A. company specializing in 3D productions and they may still have the things. I might be able to dig out contact info if locating the connectors proves difficult.) David
  10. Very nice work and an imaginative response to the challenge. David
  11. I didn't recognize the mike until I saw the picture of it. (It's been a very long time since I used an MKH 435) As it happens, I own an MKH 435; I've had it for more than twenty years. It's a very nice microphone with, as I recall, pretty good reach and some of the characteristics of a hypercardioid. But there is a liability that I should bring to your attention if you still have the option of returning your purchase: Sennheiser no longer makes the capsule used in the MKH 435. If the capsule were to require replacement for any reason, you would not be able to make a good repair. You could choose to install another capsule but the microphone would never again perform as it was originally designed. Capsules can last a very long time, and your purchased example may have many years of service left, so this may not be an issue for you. David
  12. You might try exploring the catalog of Lord Mounts to see if there is a suitable shock mount that might be fit inside your tube. https://www.lord.com/products-and-solutions/vibration-and-motion-control/industrial/isolators/plateform-mounts The Lord Company makes a dizzying assortment of shock mounts so this may be a rabbit-hole assignment. They made the small mounts that Chinhda used to shock mount equipment shelves on some of his carts. They also made the engine mounts for the B-17 bomber and I believe that the Brooklyn Bridge floats on Lord Mounts. A surprisingly big company. David
  13. Very clever. I’ve seen cupholder mounts before but never one that incorporated a double shockmount. This looks like a very promising device. I think it may be a bit big but reducing size and bulk is a refinement you can work out in subsequent iterations. You might also consider incorporating a mini-Noga arm in the design for greater flexibility in mike placement. (Deviating from the objective of reducing size, I know.) David
  14. Maybe. (Spoken with the inflection of the Liberty Mutual Insurance ads. "Is this a lug wrench?") Laying duplex cable out in the sun is a fairly common practice to sort out kinks - or used to be before radio booms were common. It never seemed to harm the duplex but, admittedly, that is more robust cable. A little hesitation regarding cooking equipment in the noonday sun is the reason I suggested only an hour or two of exposure. Monitor the progress and pull them in if they get too hot. As always, YMMV. David
  15. I used to work regularly with Marc Gilmartin. He used a rack that permitted hanging each lavalier mike so it might stretch out. A small clip from a stationary store affixed at the bottom provided just enough weight for a gentle stretch. He did this regularly and claimed it kept the cables slack and free of memory coils. If your cables already have memory coils baked in, you might want to hang them outside in full sun for an hour or two. I think the rack Marc used was a commercially available product used by sound studios to keep patch cables sorted. Marc probably modified the slots to accommodate the thinner mike cable. David
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