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The Stax Thread III

Discussion in 'High-end Audio Forum' started by currawong, Aug 20, 2013.
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  1. Grant99
    Yes, that's it! I didn't have a torx driver that size but after I read your reply I used a very small sized drill bit...just had to tap it a few times. And was able to tap it back into with the replacement case holder. Thanks!

    The best thing about this is that you can still get replacement parts for Stax headphones...even when they are like 20 years old. I think that says a lot about what kind of company Stax is.

    Again, thanks for your help on this one, I really appreciate it!
    regards, Grant
     
  2. ciccarel
    I am at a loss of what to do. I have had planed to buy the L700 after hearing some of the great reviews. I found a great deal on a SR-507 and is the best thing I have ever heard. Great detail, good sub bass and quite comfortable. This is my first Stax experience. I am hooked. My plan was to move the 507 to my second system and find a L700. I have read everything I can find comparing the the L700 to the 507. Is the L700 better then the 507? If yes, how much?

    I guess my options are find another 507, find a good deal on L700, or save a little more for a 007.

    Any thoughts, John
     
  3. tumpux
    Just get the 007..
     
    HoloSpice likes this.
  4. Ali-Pacha
    Or not. 007 is such a different beast from the usual "hig-mids energy and presence" Lambdas show (especially 507) he could probably dislike them (or not).

    Ali
     
    GarageBoy and Thaudiophile like this.
  5. ciccarel
    Thanks for the input. I ended up buying another SR-507. I guess I'm done buying for now. In the last 6 months I bought TH900, LCD-X, DT1990 Pro, HD58X, ..., and now another Stax SR-507. I like them all for different music and moods. I think in the future I will end up with the SR-007 or some vintage. I wish it was easier to audition Stax without traveling.
     
  6. Quixote79
    you is heering the same as spitzen at other place almost best lambda ever
     
  7. Grant99
    Are the requirements for the amp to drive the SR-L700 about the same as the other Lambdas? I currently use the SR-404 & the amp I have drives them quite nicely, they sound quite good, but I've heard that L700s are another step up. But I am bit concerned that maybe my amp won't drive them sufficiently, like the SR-007 MK.2s that I have. Any experience on this or comments ?

    thanks, Grant
     
  8. JimL11
    General consensus is that any of the Lambda phones need about the same drive requirements. I might help if you were more specific about which amp you are using.
     
  9. esl63
    Hi!

    I had an old Srm-T1 lying around.
    It sounded ok on my Stax 407 Pro headphones but I thought that maybe some recapping and adjustments was needed.
    Originally there was 4*100uF Caps in the power supply. I changed to 4*680uF and it was a nice upgrade.
    Then I found that changing the anode resistors (66kOhm) to a CCS was a good thing and here is the schematic found here on muffinhead post: [​IMG]
    It works well on low current 1mA, but It went into oscillation above 4mA. Any ideas how to make it more stable?
    The top current regulator mosfet is 10M90S. Now i´m driving it on 3mA and it sounds really good. But i want to drive 4.9mA, and without oscillation....
     
  10. JimL11
    There are a couple things you could do. First, the lead length between the gate resistor and the MOSFETs must be as short as possible, so that the resistor body should be very close to the body of the MOSFET. I hardwired my CCS and the wire distance between the MOSFET body and the resistor body was less than 1 cm IIRC.

    Second, you could increase the value of the DN2540 resistor to, say 1 kilohm.

    Alternatively, you could ask Kevin Gilmore to send you a copy of his board file so you could order a circuit board and build it on that.

    Hope this helps.
     
  11. esl63
    Fixed! Thanks Jim L11!
    I put a decoupling cap on the positive terminal of 10M90s and made the wires shorter.
    Maybe adding a 150H Hammond choke in series after each CCS could give both a larger "swing" and better s/n in the higher frequencies?
    Maybe 2*150H getting 300H and get rid of the CCS is more puristic... but I am attracted by the combo of CCS and choke...
     
  12. JimL11
    Glad to hear it, although I'm not sure about the decoupling cap, as that makes a low impedance bypass at high frequencies, and the whole idea of a CCS is to have a very HIGH impedance throughout the entire audio frequency spectrum. I would try it without the decoupling cap.

    I don't think you've thought through the choke idea. The CCS has a DC impedance of at least 170 megohms according to my measurements, which should extend to most audio frequencies. so a choke won't make much difference. Also, interposing an additional resistance (from the wire in the choke) cannot increase the swing, it can only decrease it.

    Every study shows that most of the power in music is in the bass and low midrange, hence the most voltage swing is also in that range. The problem with a choke on its own is that its impedance is lowest at low frequencies, whereas an electrostatic headphone, to the degree it resembles a capacitor, has its highest impedance in the same range. This means that most of the current and power produced by the output device gets burned up in the output resistor or choke instead of going to the headphone, which is the whole point of the exercise. The big advantage of using a CCS is that the output device does not burn up any power in the loading device. This means that substituting a CCS for a resistor or choke more than doubles the effective power of the output device while simultaneously decreasing its distortion.

    In sum, adding a choke in series with the CCS will not increase the swing, is no better than the CCS on its own (remember you can never subtract noise by adding another component), and a choke by itself wastes as much or more power than a resistor in the music power range, as well as having its own problems, including resonances, stray capacitances, etc. So basically, not a good idea, in addition to costing a bunch of money.
     
    Last edited: Jan 29, 2019
  13. Grant99
    That's what I was hoping to hear. I have both Stax 006t and a McAlister Audio EA-8. The McAlister amp really makes the SR-404s come alive, they sound much better with it. But it doesn't drive the SR-007 Mk2s that I have. So I'm pondering getting an SR-L700...and wondering if my amp will drive it OK.

    thanks,
    Grant
     
  14. esl63
    The CCS amplifikation is quite high and the bandwith also. I have not calculated on the poles so I don´t know the phase margin. When i got time I want to do a spice simulation. Anyway the decoupling worked well.

    Reagarding the 150H choke. A choke supply will generate an opposite current and voltage, that in turn will feed the headphone. Giving 3dB higher voltage swing or 6dB more power than just a CCS. The voltage out can actually swing higher and lower than the power supply.... Thats way the headroom gets bigger. And as I said the secon adwantage is that at high frequencies where the impedance of the CCS is increasing, thats where the choke comes in... at 10kHz the 150 H choke will have an impedance of 10Meg ohm.
     
  15. Windseeker
    Hiya fellow STAX afficionados, here's a quick (mostly positive) note about a recent repair job on my earspeakers.

    After nearly 7 years of heavy usage, my SR-009's cable finally gave up & started to have intermittent sound problem on one channel. As I was simply too emotionally attached to it, I opted to send the cans to STAX HQ for repair.

    The correspondence process was very courteous and efficient. Repair fee (including initial check-up, cleaning, post-repair burn-in & check-up) was around USD 133 (after currency conversion) + cost for replacement parts (which of course varies). Whether that's reasonable would be a subjective opinion, but I felt it's rather fair.

    I guess the repair duration would depend on what exactly is broken. All in all, my earspeakers stayed at STAX HQ for 12 days (of course, getting the product to STAX HQ takes additional efforts, time & shipping costs etc., but that's another matter).

    At last, the eaqrspeakers are back home & I'm a happy STAX listener once again. There's no doubt that my cans have aged somewhat, but here's hoping that there's some more enjoyable life left in them...
     
    Last edited: Jan 30, 2019
    arnaud, sinkr, Pahani and 2 others like this.

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