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Showing content with the highest reputation on 04/13/2018 in all areas

  1. I might need to fire my photographer, but here's something new.
    8 points
  2. 4 points
  3. We did end up buying the hand made, foam and latex free bed. It was over the top, but, after daily back pain for years, to suddenly realize my back has not hurt since the day we got it has made the price worth it.
    4 points
  4. The Copenhagen is a differential cascode circuit. The Copenhagen V uses tubes (valves) for the upper device, while the Copenhagen S uses transistors (sand). They are otherwise just about the same. It does indeed use input and output transformers (amorphous Lundahls in both cases, though the inputs can use mu metal instead). The tubes (E81L's) need not be matched at all. It is what is often called a "transconductance amp". In essence, it uses the headphone's impedance as an I/V converter, and it takes advantage of the slight Sennheiser impedance bump to make it a bit more euphonic. When used with Senns, I'd describe the sound as happy and punchy (kind of making them sound like how Grados would sound if they were not grating) - some people hate it, others love it, but it definitely has a sound. It can be linearized with the addition of some parallel resistance on the output (this is what a triode amp does except the parallel load is the tube plate impedance). Without doing that, it is not great with the Focals. Even with, they are so poorly damped that it would not be my first choice for powering them. With phones that have a flat impedance, it is pretty neutral. It's not an amp for everyone (definitely not for the objectivist crowd), but it is my favorite these days - I use a Copenhagen S with 650's for most pleasure listening.
    3 points
  5. Your inquiring public would love a central page with blurbs on all of your current amps!
    2 points
  6. The 580V voltage is for the headphones - this is sometimes called biasing the headphones. When you change the resistors on the output stage you have to adjust the currents in the output stage so that the output sits at zero volts with respect to ground - this is referred to as biasing the output stage. These are two separate things that are not related to each other except that they are sometimes referred to with the same term - "bias."
    1 point
  7. My last order from December 2017 was fine...
    1 point
  8. Pitchfork article https://pitchfork.com/news/high-definition-vinyl-is-happening-possibly-as-early-as-next-year/ The slashdot comments seem to echo your view https://yro.slashdot.org/story/18/04/12/2320221/high-definition-vinyl-is-coming-as-early-as-next-year a couple of choice ones "This scheme is a shoe-in for the 2018 "polished turd of the year" award." " Or.. now hear me out on this one... or ... we could just, you know, send the digitally converted audio, you know, without converting it back into a bumpy piece of plastic. I know this might sound radical, but it seems to me that converting analog sound to digital format then to a digital 3d map then to a laser-cut stamper then to a piece of bumpy vinyl then to a vibrating stylus and into a varying electrical current to drive an amplification system to run the speakers that you listen to might just be a little more complicated than just taking the digital format for storage and transport and converting that back into analog sound at playback."
    1 point
  9. That is a "Copenhagen V" headphone amplifier. Power supply is external.
    1 point
  10. Really. Read about it at axpona. The weird thing is you have to convert the original recording source to digital, which then gets converted into some kind of 3D topographic map which then feeds the laser based cutter which then makes the stamper ill take my non HD AAA sourced vinyl just fine.
    1 point
  11. Sent from my ONEPLUS A3000 using Tapatalk
    1 point
  12. I finally built my Blue Hawaii - a single box KG 2015 which uses the mosfets, (but I will build the BJT boards too). All GR supplies. I was inspired by a Triumph Rocket motorcycle for the chrome trim and I wanted volume indication in the dark so it has a circle of leds and a delayed pointer off the heater warm up. While I was working all this out Kevin published the Grounded Grid so I am building one of those in a similar case. Looking forward to some extended listening now. Thanks Kevin for a great design
    1 point
  13. I was able to get the 450v supply up and running. I did have one error on the board. The current source feeding the 10v reference gets up to 150 degree F, but I can add more copper around it. I think it will be just fine. I was running this with a 110mA load.
    1 point
  14. ^ Here and ready for action Sir!
    1 point
  15. About to: (Sous vided) Rack of pork
    1 point
  16. Horses for courses. As John Broskie of TubeCAD points out, series regulators are well suited for class AB power amplifiers, where the current demand on the power supply can vary from tens of mA to several amps, whereas shunt regulators are best suited for class A amplifiers where the variation in current demand is relatively limited. Arguments about which “sounds better” approach religious discussions, although it is interesting that more designers claim that shunt regulators sound “better” than the reverse – for example, Broskie, the late Allen Wright of Vacuum State Electronics, Richard Marsh, the late John Camille, designer of the Kyrie 211 SET amplifier, Lynn Olson, designer of the Amity, Raven and Karna, Kevin Carter of K&K Audio, and Frank Cooter. I think Kevin Gilmore is one of the few designers who has gone on record saying that series regulators are as good or better. Incidentally, Richard Marsh wrote an excellent basic article on power supplies for Audio Amateur magazine (1983, issue 3). Religious arguments aside, there are pluses and minuses to both approaches. In favor of series regulators, they can have excellent specifications in terms of noise, output impedance, input rejection, etc. For example, the low voltage regulators designed by Walt Jung have a lower output impedance than 0.2” (yes, one fifth of an inch) of 18 gauge wire. Of course, to achieve that performance you would have to incorporate the regulator circuit on the amplifier board, as any intermediate wiring would negatively affect the impedance. Series regulators are frequently more efficient than shunt regulators as they only require a few mA extra current draw for regulation. In favor of shunt regulators, they have a constant current draw from the raw power supply, can both source and sink current, and have a relatively simple path to ground. By using a constant current source in series between the raw power supply and the shunt, this limits the signal currents to the regulator and amplifier area, whereas the varying demands of a series regulator means that some simplified form of the signal current has to circulate between the raw power supply and the series regulator. The argument that a shunt regulator can both source and sink current is thought by some to be a major reason for its sonic superiority. However, this can be abrogated to a significant degree by placing a bleed resistor after a series regulator to bring it up to 50% of maximum load, as first suggested by Richard Marsh. This allows a series regulator to also source or sink current up to the level of its bleed current, but also decreases the efficiency advantage of a series regulator. For a phono preamp, which runs in class A, you definitely want low noise. The GRLV definitely qualifies for that. K&K Audio sells a shunt regulator kit which it claims is suitable for phono preamps, and says it is based on the Salas regulator, so I assume that it is low noise also, though without suitable measuring equipment it is impossible to know how they rank in terms of noise.
    1 point
  17. 1 point
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