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  1. NelsonVandal

    Frankenheiser (or maybe Hellheiser), way of fixing broken HD650 headband cheap and dirty

    Quote:   No, I bought a long straight bar. I used my bare hands and a couple of strokes with a small sledgehammer and bent it against a toroid transformer (a smaller one than in the picture above). It would've been better to use a cylinder with a smoother surface. I used countersunk...
  2. NelsonVandal

    Frankenheiser (or maybe Hellheiser), way of fixing broken HD650 headband cheap and dirty

    Yes, they're very comfortable. Except for the weight there's no difference. I think I was lucky to get the bend and pressure to the head to fit my head perfectly.   The weight is 350 grams so it's + 90 grams.  
  3. NelsonVandal

    Frankenheiser (or maybe Hellheiser), way of fixing broken HD650 headband cheap and dirty

    After thousands and thousands of hours my HD650's headband snapped. A complete headband is the equivalent of 160 USD + shipping costs in Sweden. The phones are so worn down it's just not worth it. I've tried to convince myself that the Denon AH-D2000 I just bought second hand sounds just as good...
  4. NelsonVandal

    AD 8066 problems

    Quote: Originally Posted by Slash47 Why you would end up with a noisy amp I do not quite see. The resistors are way too resistant, but other then that you'll end up with a nice opamp rollable cmoy. Johnson–Nyquist noise - Wikipedia, the free encyclopedia I've tried that...
  5. NelsonVandal

    Curious about 3 channel amps...

    Quote: Originally Posted by Koyaan I. Sqatsi But it doesn't entirely work as advertised. It's advertised as bypassing ground. It doesn't. That's a myth. I've never seen it advertised as "bypassing ground". I don't even know what that means. Quote: A regulated low...
  6. NelsonVandal

    Curious about 3 channel amps...

    There aren't that many ways to implement an opamp. The differencies lies in the choice of opamp, and the way the return currents are handled (you can call it the power supply if you want) - which IMO is just as important as the L/R channels: resistors/capacitors, batteries, IC or discrete...
  7. NelsonVandal

    Design Amp from the Ground Up

    There are a lot of tweaks you can do to alter the sound of SS amps. The choice of transistors have a major influence. You can even alter between bipolar, JFET and MOSFET if you make the design versatile enough. By adding CFP and/or cascode the sound is altered. You can also play around with...
  8. NelsonVandal

    Amp inputs

    Quote: Originally Posted by compuryan I would expect the RCA to be better sonically. Of course the difference would be small and immeasurable. It is measurable (crosstalk). I wonder if it's audible?
  9. NelsonVandal

    the Pimeta-V2 thread

    Just to illustrate what happens in this circuit (I have no generic buffer symbol, so I use a discrete diamond buffer instead, but it should make no difference): with no PIMETA resistor R7, R14 in the schematic above (it looks exactly the same with a 100R resistor) with a 10k resistor...
  10. NelsonVandal

    the Pimeta-V2 thread

    Tangent, since you're not using the 1 nF cap bypassing the 10 k input resistor suggested by National I don't think 10 k is an appropriate value. Besides, the LMH6321 is inside the loop of an opamp in PIMETA and is run open loop in the data sheet. I think PIMETA is deemed to be unstable with a 10...
  11. NelsonVandal

    Case-it-yourself DAC kit

    Back on track, has someone compared it to the Zero DAC? There are a couple of different DAC's on Ebay. Most of them use CS4398, but others use PCM1793, TDA1543, AD1852 etc. As I understand it CS4398 sounds (too) detailed, forward and a bit grainy while AD1852 sounds smoother and maybe...
  12. NelsonVandal

    Case-it-yourself DAC kit

    Quote: Originally Posted by linuxworks I wish someone could show me some sound that entered your home stereo that did NOT pass thru at least 10 op amps (in the studio, at mastering, at many places) before it got to you. I know you know this but the anti-opamp crowd really makes me...
  13. NelsonVandal

    Cmoy power caps... how big?

    Thank you kvant for the EE perspective. I've heard and measured this effect, but I wasn't familiar with the formula. A low impedance point for the return currents is IMO essential for a natural stereo image. I think one must keep power supply and how the amp handles the return currents apart...
  14. NelsonVandal

    Metalised Polypropylene Caps in Cmoy - Better or Worse?

    Quote: Originally Posted by Horse The limits of a CMOY don't really lie in C2. The metallized polypropylenes are perfect. No they're unnecessary. They're large, cost money and can do nothing but degrade the sound.
  15. NelsonVandal

    Metalised Polypropylene Caps in Cmoy - Better or Worse?

    Are you really sure you need C2 at all? I think probably not. Remove it and stop worrying about capacitor quality
  16. NelsonVandal

    Design Amp from the Ground Up

    I've built several solid state amps from the ground up, without any knowledge at all - I've picked it up along the way. Looking at schematics, hanging around Diyaudio.com and playing around with LTSpice have done it for me. There are so many options. All of them will measure well and sound OK...
  17. NelsonVandal

    Cmoy power caps... how big?

    Quote: Originally Posted by gurusan He is talking about power caps..... Yes and I'm also talking about power caps. They're very much in the audio path, sinking/sourcing the return currents. That's why 3 channel amps, amps with shunt regulators or any other methods of getting a...
  18. NelsonVandal

    Cmoy power caps... how big?

    How large caps you should use is depending on the impedance of your phones. The lower the impedance, the higher the cap value. It has to do with crosstalk in the lower (and mid) registers. Capacitors in the audio pathway like the rails to ground caps in CMOY degrade the sound more than active...
  19. NelsonVandal

    DIY Mystery

    Maybe you've melted the cable isolation? That's why I prefer PTFE or silicon rubber.
  20. NelsonVandal

    Black Gate K Series Vs. Film...

    Don't use electrolytics in the signal path unless you absolutely have to. Even the BG NX Hi-Q sounds worse than a cheap polyester cap.
  21. NelsonVandal

    Questions about some simple power/volt/current...

    I agree regarding listening levels. You don't need more than 1 V for low impedance and maybe 3 V for high impedance phones. Still there are several reasons for using higher supply. The distortion generally gets lower if the supply voltage is increased. A lot of amps don't swing from rail-to-rail...
  22. NelsonVandal

    HELP with cmoy board design

    Quote: Originally Posted by DragooNArT2 good i hope you're right .I've already started to build the board and bought all the elements except the C2 caps which i cannot seem to find.I've went to several electronics shops and everyone said they didn't have any 0.1uF or 100nF caps at all...
  23. NelsonVandal

    Books/links to learning how to read schematics

    Start playing around with LTSpice. Look at what others have done, and start with some simple schematics and move on to more complex. There are a lot of schematics to be found at Diyaudio.com and all over the web. I think it's too tedious to learn it the proper way. Besides, you can never...
  24. NelsonVandal

    Advice on next build

    I haven't heard any Ultrasone headphone, but I think what you need is an amp with low output impedance and capable of a fair deal of current, preferably with a low impedance ground (as in active ground channel or shunt regulators) since the impedance of your phones is 35 Ohm. I have't heard...
  25. NelsonVandal

    Interest Check: PPAS redesign?

    I have an original PPAS with LME49720/LMH6321, and it's noisy. Gain is set to 4. It's probably noisier than the new one because of the layout without decoupling caps in proximity to the opamps. If I simulate PPAS with AD8620 (one of the least noisy JFET input opamps there is), I get a noise...
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