Jump to content


High Rollers
  • Content Count

  • Joined

  • Last visited

  • Days Won


Quad last won the day on February 9 2011

Quad had the most liked content!

Community Reputation

11 Good

About Quad

  • Rank
    High Roller
  • Birthday 10/02/1956

Profile Information

  • Interests
    audio, vintage TV
  • Location
  • Gender


  • Location
  • Interests
    audio, vintage TV
  • Headphones
    SRX-III, SR Lambda, SR Lambda Pro, SR Lambda Signature, SR Gamma Pro, SR-007, HE60 and some more
  • Headphone Amps
    Stax SRA-12S, Stax SRA-14S, Sennheiser HEV70, Precision Electronics XS2 and XH5
  • Other Audio Gear
    Stax ED-1

Recent Profile Visitors

1,669 profile views
  1. The charge up is not that noticeably slow, since the RC-time is only 0.47 s (4.7 MOhms x 0.1 microfarad). Before you start the CD, the membranes will be already fully charged if the charge build-up time would be due only to the series resistor in the bias supply. But there is a low impedance (w.r.t. the impedance of the headphone elements, which is about 1000 times larger than that of the final capacitor) in parallel of the output of the bias supply. So it certainly is not just a current source, but much more a voltage source, due to the reservoir capacity of the capacitor. I suppose that
  2. Hello bobkatz, Yes, we are talking about the same part of the schematic. But... after the resistor R403 (4.7M) you find the capacitor C417 (0.1uF). After that there is is direct line to the bias-pins on the headphone connectors. So in effect: no series resistor. Just an additional RC-filter stage in the bias supply. The schematic prior to s/n 1000 does not have this capacitor. And thus does indeed have a series resistor in the bias line. Things can easily be corrected for s/n over 1000 by just adding a 4.7M (or an other large value that you happen to have lying around) between the bias
  3. Hello bobkatz, First of all: thank you for the manuals. The notes on old manuals are always worthy of being read. Why invent the wheel twice? So in fact you did implement a kind of balance control after all. Are they sonically of the same quality as the volume control or does that not make a difference? I tend to feel that the sonic differences between volume controls are minimal. One of the main issues to me is very good tracking. The output coupling caps: the listed voltage rating is probably just what Stax had at hand. Which indeed by no means implies a necessary value. I expect
  4. Hello bobkatz, Good to see that more SRA-12S amps are still in use. You are absolutely right about the quality of the intermediate-stage amp and the phono board. Normally indeed there is no need for the additional gain, and it causes audible noise as well. Part of the cause of the noise is the high impedance of the volume control (250k if I remember well). You did the right thing by choosing a much lower value. Personally I feel that a balance control is indispensable. A lot of recordings are off balance, and my ears have some damage that needs correcting as well. My volume control ha
  5. Hi htless, Some more detailed ones would be helpful. Would it also be possible to get some high resolution pics of the EMM-1 -module? top and bottom and some at an angle to see the components and mechanical construction better? Maybe some day I will try to rebuild it..... if I can get enough info on it, that is. And I will try to make a JB-1 (line level input) module. Just to have a nice view at the back of the SRA-14S, and see the appropriate led light up on at the front panel..... Thanks. best wishes
  6. Hi Birgir, Yes, somehow I feel that you are (again) right. Onto the other Stax equipment the usual text is screenprinted. Nothing on this one however... Thanks again. Hello htless, Thanks. That would be appreciated. And yes I had found this japanese site some time ago. No detailed pics of the SRA-14S. They also have a section with brochures/user manuals. The links to the brochure of the SRA-14S (2 pages) do not work.... Maybe someone has an original brochure of the SRA-14S. A copy or high-Q scan would not go amiss I would not even say no to an original one Let'
  7. Hello htless, Thank you for your additional information and your photos ! All very interesting stuff. The PS-3 power is made specifically to use as a phono pre-amp unit with one of the available SRA-14S cartridge modules as a head-amp for one of the SRM-amplifiers. This way you could create a (I presume very high quality) phono input on a line-only amplifier. Probably a good way for Stax to sell the separate modules. The PS-3 cost about a quarter of a complete SRA-14S in Japan. All pictures I have seen so far from an SRA-14S are with an outboard dedicated power supply unit. Mine
  8. Thanx! Yes I am very happy to have the SRA-14S. I always wanted an SRA-12S and an SRA-14S. Well, now I have both of them! Let's hope someone can help me to a service manual for it. Then I can restore it to original glory....
  9. Yes, that is also what I have always assumed. Thanks for the information on the switches. No s/n, but the sticker or plate could have been removed someday. Even at a prototype you would expect some indication. Since I never saw pictures of an SRA-14S with internal power supply, there is very little to compare to. There is no text "Serial No._____" on the back, like on the "standard" version. Although I knew on beforehand that there was no s/n on it, I still bought it. Always wanted to have an SRA-12S and an SRA-14S..... Well, I have both now As soon (or not soon....) as I have
  10. Hi padam, Thanks, our posts have crossed each other. I already found the user manual some time ago. Nice to have, since usually it is also difficult to get hold of. All the best.
  11. Hi Spritzer, Here they come. The IS amplifier is on a separate board, with somewhat lower gain than the SRA-12S. That is a good thing. Less noise also. The gain without the IS is sufficient though (as is the case with the SRA-12S, i.e. 60dB), and then there is no audible noise at all. All switches are connected by flat bowden cables to the front. Not easy to service this way. Do you happen to know any reports about bad switches? It is not (yet) clear to me why there are so many cut traces and added bridge/jumper wires on one of the switch-boards. (Maybe on the other switch-board
  12. Finally I was able to acquire an SRA-14S and it has arrived now! No phono equalizer modules however. A previous owner had been cutting copper tracks on the input/switching pcb and added a lot of wires (in different places than the cut traces). Neatly done, but still.... Maybe he had some problem with the switches? So restauration will be a major undertaking without documentation. Can anyone help me with the service manual and/or schematic diagrams? That would be highly appreciated. Paper copy or electronic, everything is welcome. The headphone amp looks at first glance like th
  13. Congratulations Birgir !! I am jealous already...... This is definitely THE amp we all would like to have. No chanche of building one without the schematics I am afraid.... Looking forward to seeing a detailed comparison with the other famous amps. Enjoy it ! Quad
  14. Thanks for your help Birgir ! (Is there anything at all that you do not know about Stax?) Best wishes.
  15. Hi all, Recently I acquired a replacement Stax cable. Could anyone determine for which type(s) ear speaker it is intended? (Just curious to know it....) Some characteristics (see picture of the cable): * the continuous and dotted lines are gold coloured * the cable is matt black * the length from the tip of the connector pins to the feedthrough at the speaker side is approx 2.39 m * the overall width of the cable is 13 mm * the connector is a 5-pin gold plated type I might use it for a SRX-mkIII (or mkII with torn membranes I have to repair) after a planned conversion to a p
  • Create New...