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Showing content with the highest reputation on 03/24/2016 in all areas
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3 points
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A couple things. Put simply, a choke is an inductor and an electrostatic headphone looks kind of like a capacitor. Look in any electronics textbook and you will see that when you connect an inductor with a capacitor you get a resonant circuit, which means you can have a peak in the frequency response at the resonance frequency. I said the headphone looks “kind of” like a capacitor. It doesn’t exactly resemble a capacitor because it makes sound, which means it uses power. The power spectrum of music is highest in the mid-bass to lower mid-range areas (approximately 50-300 Hz). The impedance of a choke rises with frequency, which means that it requires more current to drive it at low frequencies, exactly where the headphone is requiring the most current and voltage to make music. This increases the distortion of the output device. The largest commercial plate choke I have found runs around 200H. This has an impedance around 25 kilohms at 20 Hz, rising linearly with frequency from there so at 40 Hz its impedance is 50 kHz, which is a typical resistance for a stat amp plate resistor. So at the lowest bass frequencies it requires/diverts more current from the headphone than a typical plate resistor. This is all based on an ideal choke, ignoring the possible resonances and other imperfections of a real world device. With a resistor load, you don't have the possibility of a peak in the frequency response but the resistor requires curent to drive it through the whole frequency spectrum. In fact, with a resistor load, the amplifier actually wastes more current (and power) driving the resistor than driving the headphone. By comparison a really good current source load demands a negligible amount of current, which means all the standing current of the output device is available to drive the headphones, which is what you want. As I said elsewhere, it converts an amp for driving output resistors to an amp for driving headphones. It is simply a better technology. This is why Stax has used current source loads in its solid state amps in place of resistor loads since the 1970s.3 points
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2 points
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Next weekend (Fri/Sat) I'll be lending a hand at; Electroacoustics Festival 2016. My school is pretty big on experimental music and this is the second year Foothill College is hosting this. I'll be recording this year (board to laptop and surround mic to portable recorder) so it's a step up from running the concession stand. So, if you're in the Bay Area and enjoy being challenged by something new, come by and check it out. http://www.electroacoustica.org/2 points
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Saw that pic from Knucks in his thread with the three guys and the laser light show, thought it was Muse, so did a Google image search. Turns out it was Tool. "Fuck me, they're still together?!?!" So now watching a Tool (Full Concert) on YouTube. Maybe if they quit touring, they'd get around to the next studio album. Maybe not, though. They open with a cover. Not that there's anything wrong with that.2 points
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I would like to invite everyone to CanLanta 2016! Saturday May 21st at the place we've had the past couple big Atlanta meets, which has been a nice venue. I'll copy from the post on HF, but Tyll is coming back to Atlanta for the first time in a long time, and we're excited to have him back. I hear through the grapevine that there are some premiere d-_-b approved, but not sure it's public knowledge yet, so I'll let that MOT speak up if he's so inclined. John M and the boys in Atlanta have done a lot of work getting this off the ground, and I think it's going to be a nice event. Travel Team, let's make it happen. **BRENT** Canlanta 2016: It’s been about three years now since we had a proper headphone meet in the Atlanta area, so mark your calendars folks because the next event is now official. The primary sponsor of this event the Audio Video Club of Atlanta. Date: May 21st, 2016 9:00am-6:00pm Where: Marriott Century Center 2000 Century Blvd NE, Atlanta, GA 30345 Travel and hotel discounts: There will be a limited number of discounted rooms available at a price of $109. Currently the number of rooms at the accommodation price is capped at ten. If this fills up we have the option of negotiating additional rooms at the special rate. If you plan to stay at the hotel please pm me so that I can keep a running count. Vendors: (if there are any vendors not on the list who would like contact me via pm (matttcg) Beezar Audio (confirmed) Headamp (confirmed) Mr. Speakers (confirmed) The vendor list is growing quickly. I will hold off on the list until we have the confirmations. Special Guest Speaker: We are happy to announce that Tyll Hertsens will be giving a series of talks during the meet. Come meet the Grandpapa of headphonedom. Misc: Although there will be plenty of vendors at the meet, we encourage attendees to bring their own gear. Tables and access to power outlets will be provided. Feel free to show up without any gear if you’d just like to join in for a day to check out new gear and talk with other members and vendors about the hobby. The event is free of charge to individuals. Please keep in mind that you always want to treat equipment belonging to others with respect and care as if it were yours and you paid lot's of money for it. If you are unsure about how to use something, always ask. Never relocate any equipment from someone’s table without their express permission. Please post in this thread if you are planning to attend and list the equipment that you’ll be bringing and I’ll compile and list to add to the beginning of the thread. The ballroom will be available for setup purposes early Saturday morning, 7:00 am, for vendors and attendees to setup their gear. Parking: Parking is available at the hotel and is free. Please be sure to always keep expensive equipment secure. Please do not leave expensive equipment locked in your car. Get Social: Please spread the word about this meet and let’s make this a great event for everyone. Check it out on FaceBook: https://www.facebook.com/CanLanta2016/ Food: You’ll be on your own for lunch but there are plenty of places to eat within a few miles of the event. As always, please do not bring food or drink near anyone’s equipment.1 point
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1 point
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Nope, I even asked Jack if it was working correctly and he looked at me with a puzzled look and said "this is the upgraded version". Yeah....1 point
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I didn't spray the entire board, but I used a conformal pen to specifically insulate the high voltage pads that face upwards (ie though the ventilation holes in the top plate. I've used conformal spray on boards that will or might be working in a damp environment - like wet level damp. It is common on mil spec stuff for that reason.1 point
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If builder decide to use only one series of resistors, then one should probably choose 1/2W. Othervise most of them could be 1/8W.1 point
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Ah - thanks for the heads up. With something of that vintage I'll be looking carefully at the rats nest before I even turn it on, particularly dried out electrolytics and the such. It has apparently shipped, so will soon see what I've taken on. Just restored a pair of PRO4AA's. They were in fact the first headphone type I ever bought back in 1974; I recalled they were pretty good so I picked up a cheap pair on eBay. Fairly good condition all said. Foam damping in the cups was dust, so have used a chunk of speaker damping in each after cleaning out the cups. Dried out hardened fluid pads which I've replaced with Brainwavz (bit of a struggle, but I wasn't taking no for an answer). Then the cable that goes through the headband went intermittent - so I've spend a fun hour or two replacing that. Not perfect in sound quality by a stretch. Excellent bass extension, but evidence of a midrange hump and recessed treble. That was in a shootout with (old) Beyer DT990 and AKG K701 both owned since new. All in all I rather prefer the DT990 in terms of overall balance - the K701 is just too bright, kind of the opposite problem of the PRO4AA. But all in all, given the date I bought my original pair and what else was on the market at that time, I think I chose wisely with the old PRO4AA.1 point
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1 point
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Apparently I've stumbled into a heavy Tom Petty binge. Hard.1 point
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Here's a video from our radio station KFJC. Some very cools stuff from Robert Rich.1 point
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Trying to imagine why it would be posted in the thread full of awesomeness. Were they dressed as led zeppelin? Halloween concert? Looks like Maynard is out with Puscifer until at least June..... So another 2 years before a new album?1 point
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It's quite simple. Look at all the values in the schematic and look at the wattage rating. Is 300v across a resistor even possible?1 point
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Hey, I didn't know it was your Birthday David, happy birthday. Going back to dust I get a thin film of really fine dust over my system desk every day. If I don't wipe it in a week it starts looking like a some ageing special effect you see in old movies Ha Ha. Price I have to pay for living near the sea and in a dry climate. I was more worried about my 009s than my amps, so I use a nice 'stuffed bird' display case, looks ok I think, maybe a bit odd? I cut a few small holes in the top to equalise humidity, and my 007s got a bit of mould on the leather cups using the bell jar. Seems fine now, and keep the dust off them plus I can gave longingly at them when not on my head.1 point
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1 point
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I'm starting to use Evernote more and more for just about anything with text. So far it has all the notifications and reminder features I need. And it's nice to have access to it from anything, anywhere.1 point
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I have to thank Doug again for doing such a wonderful job on the amp. It definitely exceeded all my expectations.1 point
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in case it wasn't clear, I was kidding. I figure since mine is number 7 that any additional dust isn't going to matter.1 point
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I just wanted to add that Doug let me build one of these (populating the PCB, only) and I've been listening to it for the last few weeks. Basically, I begged him because showing off the T3 at headphone meets was not working well with the DACs I had. I needed something Summit-Fi as a source, but didn't have it. The Walnut v5 solved the situation in spades. Before anyone asks - I would not recommend it as anything but a custom build from Doug. I built it myself, but it took weeks of preparation. I got two new pairs of $45 tweezers, a hot-air re-work station and other tools, too. I took several days to practice on some of my scrap Beezar DACs. I still made mistakes when I attacked the Walnut. I finally got it working, but I'd have to say it was the most challenging build I've ever done, bar none. Again, I'm just talking about the PCB. Anyway, the sound is absolutely exquisite using a T3 and HD800. I've never experienced sound at this level before and actually owned it. Thank you, Doug!1 point
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1 point
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Not to be portenteous, but otherwise it will be lost. Oral history dies with its participants, like poor Chu.1 point
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Tyll, this is just a random thought, but have you ever thought of writing a piece on the Genesis of the hobby. You are the only person who could do it justice.1 point
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Absolutely! Well said, Dan. Tyll, I know that wasn't your intention in either forwarding that heartbreaking email to Kevin in an effort to help, or in writing that beautiful tribute and posting it for everyone who loves the headphone hobby to see, or indeed in filling us in regarding this sad back story... it's not about you, and I get that. Yet, Dan's comment is the only conclusion that we can possibly draw from that chain of events and from so many similar actions on your part that have illustrated time and time again that you are indeed a good man and a blessing to all of us. Thanks for all that you do for the hobby. Didn't want to wait around until you bite the dust to say so.1 point
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Not your typical fare for this thread but my wife surprised me with this today. It's pretty cool. Sent from my iPhone using Tapatalk1 point