The Stax I thread

Discussion in 'Headphones' started by knerian, Mar 28, 2016.

  1. BenjaminBore

    BenjaminBore Friend

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    Thanks @JimL. In terms of non-DIY more affordable amps would I be right in thinking Mjolnir Audio in Iceland would be my best bet? If so can anyone comment on their range, or what would be a wise minimum entry point for the 007 and 009?

    I just wandered in there for a demo, I was never at risk of blindly dropping 4k on whatever amp they happened to use to drive the 007/009. Everyone’s feedback has been highly educational. It’s only ever an upside, and one of the great things about posting here.
     
  2. JimL

    JimL Tongues KG's hairy starfish for fun

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    Mjollnir Audio is definitely a reputable builder, however his prices are somewhat high due to high import duties on parts to Iceland. Any of his amps from the KGST and KGSS upwards are capable of driving the 007s. You may have preferences for tube vs solid-state sound which would incline you towards one amp or another. Note that all of the tube amps are actually hybrid with solid state input and intermediate stages and tube outputs.

    You may be able to find a builder in GB who could give you a better price. I believe @headinclouds used to do builds but I don't know if he still does. If you check over on HF you may be able to locate a builder in GB, or at least contact someone there who could let you listen to to a good Stax set-up.
     
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  3. Madra

    Madra Acquaintance

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    @JimL , given the choice between a SRM-313 and an SRM-006tii (supposedly an updated T1) which one would you recommend to drive a Lambda Pro Signature. The 006tii will be used unmodded, at least for a while.
     
  4. BenjaminBore

    BenjaminBore Friend

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    Thank you, that’s very helpful. I think I heard @headinclouds has retired from building amps now.

    I forgot to ask about energisers. What kind of performance can one reasonably expect from them? If they are viable how powerful an amp is needed to get the most out of them?

    Lastly I saw a comment from a few years ago suggesting, I think to @sorrodje, using an adapter to drive one with a Schiit Mjolnir 2. Which puts out 16w rms p/chan 8w rms p/chan @ 32ohms, and just so happens to be my primary amp. Would it be worth trying, and if so would it be safe. For example I’ve seen comments made by @schiit saying not to use it with speakers. I can’t remember the exact terminology used but it was something like certain components would run too hot as they weren’t designed to handle the reactive load/mechanical feedback from speaker drivers.
     
    Last edited: Jun 19, 2018
  5. JimL

    JimL Tongues KG's hairy starfish for fun

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    Haven't heard either one, so I have no subjective opinion on the sound. Either should be adequate to drive a Lambda series headphone, but they likely have different "flavors" - the SRM-006 probably a bit smoother due to the tube output stage. I know Muppetface likes the T1 for Lambda series headphones.

    So the adapter/energizers are basically transformers that step up the voltage (and step down the current) from a speaker amplifier. They also include a bias supply for the diaphragm. I think the general consensus is that a dedicated amplifier does a better job overall, but the energizer is an inexpensive way to get started. I don't know about the Schiit Mjolnir specifically, but I think the potential issue there is the amount of current required, as the Mjolnir is designed to drive headphones down to around 32 ohms whereas most speakers are rated at 4-8 ohms, so it is likely to run out of current fairly quickly, depending on how loud you listen.

    I would recommend trying an old Stax energizer, however most of them only have sockets for the old "normal" series (6 pin socket) rather than the new Pro series (5 pin sockets). An old energizer can be converted to a Pro series by installing a new bias supply and blocking the center pin in the output socket (so you can't accidentally plug in a normal bias headphone by mistake). Occasionally, a Stax SRD-7 Pro will show up on eBay (you can tell because it will have a 5 pin socket). I haven't priced any recently but as I recall they usually run around $250 USD.

    The Woo WES has had issues with putting in the wrong value bias supply output resistor (Stax currently uses 4.7 meg or 5.1 meg), and iFi iESL uses a HV battery bias supply, which is IMHO an expensive solution to a non-existent problem. I'm sure iFi Audio will disagree, but the Gilmore amps all use basically the same bias supply design as the Stax energizers, and nobody complains about their bias supplies being inadequate. Another issue that spritzer identified is that they put a capacitor after the bias supply output resistor, which is a no-no. Stax do not do this, and they have been building electrostatic headphones for over 50 years, so they have figured out a thing or two and it is wise to follow their example.
     
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  6. gepardcv

    gepardcv Almost "Made"

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    On the subject of the iFi iESL, I heard one paired with an iCAN Pro with an SR-007. All the knobs looked set correctly to me with respect to bias and gain, but with volume maxed out, it was maybe as loud as a Carbon with the volume knob set to 10 o’clock. It wasn’t my unit so I did not experiment with the settings further, but concluded that it’s either a broken device or a broken design.
     
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  7. kevnin

    kevnin #facetweeting - Friend

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    I have an SRD7 pro and an SR007, and I used to use a Mjolnir2 to drive it. I can't speak to any potential long term ill effects as I only used it for a short time, but it worked fine. I didn't have any issues getting to loud volume. I compared it to a 727 w/feedback mod. The energizer was a bit behind in performance, particularly in bass texture and resolution, but the difference was smaller than I expected. Given the price difference, and the fact that the 727 doesn't drive the 007 perfectly anyway (bass is still little loose), I think its a perfectly valid strategy to use an energizer while you save up for a higher level amp. (and make sure estats are really the way you want to go)
     
    Last edited: Jun 20, 2018
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  8. JimL

    JimL Tongues KG's hairy starfish for fun

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    According to spritzer, the iESL has a step-up ratio of either 1:16 or 1:32. This compares to the old Stax boxes, which, again according to spritzer, had a step-up ratio of 1:25. When you consider that the average speaker amp has about 20X gain, this works out to 320x to 640x voltage gain from a line source, which is close to the gain from a KG amp - around 500x to 1000x. Perhaps it was set at the lower gain (higher impedance on the right hand knob), or alternatively the amp didn't have enough voltage. Still, it should have been the responsibility of whoever was demonstrating it to have it set up correctly.
     
  9. gepardcv

    gepardcv Almost "Made"

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    It was running from a Pro iCAN, not a speaker amp. I will not swear to it, but I think its gain was set to 9dB, with impedance on the iESL set to 64ohm. As for setup, the owner showed the unit off with an SR-009, which I did not try, so I don't know if it was loud enough. I brought my own 007 to try with it — this was before spritzer's discovery of the capacitor on the bias line, otherwise I'd never have plugged my headphones into it. In any case, while the owner had no way to set it up properly to work with a 007, I find it hard to believe that it would work properly with a 009, either.
     
  10. phaeton

    phaeton Acquaintance

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    Hi, new staxer here :D .. well, actually not new, in the past I had a 507+323 combo, but sold them a while ago. And I have used a 009+BHSE for a long time (not mine unfortunately)
    I just got a 009 (almost new, only 100hrs) and I will use a T1W (fully reconditioned) for now.
    I have quickly gone through this thread, but still don't have a clear idea: can you old'n'wise staxers out there suggest a good tube amplifier for 3k max (new/used/demo/whatever)
    I like trasparent, fast, precise sound with a touch of warmth (and you can see my other cans & amps down here, to get an idea....)
    any help highly appreciated :bow:
    rgrds
    mike
     
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  11. numbercube

    numbercube Acquaintance

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  12. JimL

    JimL Tongues KG's hairy starfish for fun

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    The T1W is a good starter amp for Staxes, although it is better suited for Lambda series headphones IMHO. However, when the SR007 first came out Stax sent it around to reviewers with the T1S, which is essentially the same amp, so.....

    The Woo GES (based on an old Gilmore design) the new Woo amp, the Trilogy H1 and the Aristeus are pure tube designs, however the latter three are beyond your budget. The Trilogy is also grossly overpriced IMO, as it is based on the simplest stat amp tube circuit around.

    If you are willing to DIY, or can find someone to build it for you, the SRX Plus and the Kevin Gilmore Megatron are two amps that use only tubes for amplification, although they do use some solid state in the form of current sources and loads to set the operating conditions. The Megatron is significantly more complicated than the SRX Plus, and I would guess than commissioning a build would be over your budget. The Megatron also runs about 200 watts consumption as opposed to less than 60 watts for the SRX Plus.

    Otherwise, most of the commercially available "tube" amps are actually hybrids, as they use solid state amplification stages as well as tube amplification - your T1W is an example of this, as is the Blue Hawaii, the KGSS Grounded grid, etc. I am not familiar with the Alpha Centauri mentioned in the post by @numbercube, but looking at the pictures on their website it appears to be a hybrid also, with solid state front end and 6SN7 outputs, so it is likely no more powerful than your T1W, as the 6CG7/6FQ7 output tubes used in the T1W have pretty much the same electrical specifications as the basic 6SN7 tube used in the Alpha Centauri - the 6SN7GTA/B used in the SRX Plus has significantly higher voltage and power limits, although it is still relatively puny compared to the EL34 tubes used in the Blue Hawaii for example.

    The problem with most tube electrostatic amps is that they use plate resistor outputs. As a consequence of this, more than two thirds the signal current is wasted in the plate resistors, and consequently is not available to drive the headphones, which is the object of the exercise. This also increases distortion. So, for example, modifying a T1 by replacing its plate resistors with good solid state current sources significantly improves its drive capability and reduces distortion, resulting in better bass control and punch and more extended highs.
     
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  13. phaeton

    phaeton Acquaintance

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    Many thanks for the replies, appreciated.

    So, suppose I can do some soldering, and suppose I know what's an IXP10M45S, would it be so difficult to arrange a CCS on the plate of the outpit tubes in the T1W? Where I can find some info/instructions?

    Also, given 3K seems to be not enough even in the used market, let's widen the scope to every kind of ES amplifier that can drive the 009 to full potential with a touch of warmth (to be clear, I like the BHSE but only with Mullard XF tubes)

    thanks!!
     
  14. phaeton

    phaeton Acquaintance

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    Don't bother, have found your post about the T1 mod, very interesting!!!
     
  15. JimL

    JimL Tongues KG's hairy starfish for fun

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    The HF Stax Thread III also has a discussion of the mod between me and @Muffinhead starting about p. 923.
     
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  16. phaeton

    phaeton Acquaintance

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    tnks :bow:
     
  17. maverickronin

    maverickronin Friend

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    I'm having some trouble with my SRM-T1S and was hoping someone would be able to help me diagnose it remotely.

    For a few days in a row the balance was changing pretty wildly every time I turned it on and I had to readjust the split pot. When I finally decided i hadn't accidentally unbalanced it that many times in a row I decided it was time to switch out the tubes.

    I put in a set of NOS RCA tubes I'd been saving for the occasion. I let them burn in for about 12 hours and then went to set the trim pots for the section balance and ground offset. The problem was that the section balance just way, way off. Too much for the trim pot to compensate. After zeroing the ground offset the left channel is still high by ~110 volts and the right by ~10.

    I put in a pair of new production Electro Harmonix, let them burn in and got the same thing. Switched their channels, got the same thing. Switched the channels of the RCAs, put the original tubes back in, and then switched their channels but still got the same results for every combination.

    I know a little bit about the theory, but not enough to troubleshoot it by myself.

    Sound fixable to anyone?
     
  18. Scubadude

    Scubadude Almost "Made"

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    I recently joined the Stax clan with a new in box SRS-2170. Glad to see some love for the baby Stax sets above. I've been warned it is a gateway drug and it is quite addictive. Makes the HD800 sound slow and muddy ... Much like a well-driven K1000 which is the closest comparison in my collection. But at a much higher price.

    Won't be caught Stax-less ever again!
     
  19. Ardacer

    Ardacer Almost "Made"

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    I know right? It really makes hd800 seem like a slouch. So silly.
     
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  20. Madra

    Madra Acquaintance

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    I recently revisited Stax with a Lambda Pro Signature and a 006tii amp. I bought the Signatures in the mid nineties, used them for a couple of years with a lowly Yamaha integrated, then moved on to 2 channels.
    I started using them a couple of months ago, with a newly acquired 006tii and I am enjoying the combination a lot (and kicking myself for keeping them unused in a closet for more than 20 years!!!), to the extent that I am using my 2 ch system less and less.
    I was out of the headphone world for that long and lack experience with modern cans (bar the hd650), but before buying the signatures, I auditioned the AKG K1000, some Jecklin Floats and ended choosing the Stax.
     
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