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Posts by tomb

 With respect, "hard to drive" is not the issue ... and Grado's don't necessarily like low-impedance amps.  It's one of the reasons they get branded for harshness/tizziness and people recommend tube amps as a result.  It's not for the supposed warmth. They will always crave current.  Hence, the issue with the CMoy.  That's the thing with current pulse capability in an amp.  Unlike voltage clipping, if the current desired by the headphone is not available in the amp, you...
I don't want to sound discouraging, but:   1. Great Grados need an amp. 2. The real difference comes when you leave the SR line and pursue something like the RS-series or the PS-500. 3. I love Grados more than any other headphones, but I'm not sure I'd pay the price difference you're citing, especially with the other headphones you mention at such a lower price.   You may have better luck on ebay or pursuing the for sale section here on Head-Fi.  You might be able to...
As usual, it's best to let dsavitsk answer the technical questions.That said, it is a tube hybrid DSHA. However, the differential output devices are BJT, NPN transistors, not MOSFETs. This is the second T3 prototype built (after two T2 prototypes). The first T3 prototype used the MOSFETs. However, we found that the highs were rolled off because the MOSFETs don't present a high enough input impedence to the tubes.
 There are some turbines - and I've worked with the planes that use them - where the sonic pressure is enough to be fatal in certain circumstances. But you're right - it was a little joke. 
 JMHO, but as discussed earlier - I think that assumes compressed music and the generally available dynamic range from most studio productions.  Life-like is something else altogether. I listen to pop music all the time, it's actually my favorite (power pop to be specific), but that's a studio and producer's construct.  Back in the day, I used to despise live albums.  The sound quality was always worse and never as good as the studio version.  It was always so with live...
 I think it's more complicated than that.  What you're really looking for is what is the dB level of the softest passage that you can hear.  The dynamic range would be the difference between that level and the peaks.  I mentioned some numbers in a previous post.  The actual threshold of human hearing and pain has been referenced at about 135dB. A general average is about 50dB for the lowest levels to 120dB for popular music.  Classic orchestral music might be 20 dB for the...
 I know you usually know what you're talking about, but have you actually used one in this circuit?  I have - many times.  It seems perfectly adequate for setting a stable current through the buffer.  Maybe it's not optimum, but works fine for 30-60 ma settings.  It's not as if it's in the signal path, anyway.
This is also the buffer used in the Millett Hybrid MiniMAX. I'm not sure about R1, but the rest looks right. Note that availability of the PN4392 is almost non-existent these days. You might try a J310 for the jfet, instead. We also found it advantageous to reduce the values of R22 and R32 by half. This will give you 2X current at the output buffers and allow a much higher Class A bias.
A reasonable comment and one that can be debated ad nausea. Just a fine point, but orchestral music happens to be found on Redbook CDs. If one starts limiting the quality available at the outset by limiting adequate power, it can be hard to catch up later on. If one wants to establish limits of "just good enough," that's certainly a valid goal, but it's not one that's usually discussed around here.Anyway, there is still a wide disparity if someone is trying to use a dB...
 First of all, if all you are interested in is compressed music at a constant level, then yeah - your dB calculations are OK.  However, this isn't machinery, it's not an automobile, aircraft, or some other such vehicle where you are exposed to a constant sound level.  It's music. Music - properly recorded and properly reproduced - includes transient peaks of much, much higher than anything you're demonstrating. A violin can hit 103 dB.A 16" cymbal can hit 111 dBA trombone...
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