Jump to content

justin

Manufacturer/MoT
 View Profile  See their activity

  • Posts

    6,665

  • Joined

  • Last visited

  • Days Won

    36

 Content Type 

Posts posted by justin

  1. and now for something completely different part 3

    in Do It Yourself

    Posted

    600 or 680 can be used. 680 will be slightly higher front end gain

    300 is correct

    4.2k is just higher gain than 1.9k

    I don't remember what the 50k and 25k are -- SS feedback resistors? if so also just higher vs lower gain

    If only using SS, it's possible you can eliminate the 4.2k, as long as there is still another resistor in parallel with it. what you would do is measure the gain with and without the SS feedback resistors, and choose values so you have ~6dB less gain with the SS feedback resistors installed

  2. and now for something completely different part 3

    in Do It Yourself

    Posted · Edited by justin

    you may be hearing residual DC offset from the amp boards at the time the relay engages, as it can take a short time for the servo to null this voltage completely - possibly longer than the delay on your power on relay. 

    things you can try:

    - use ground as the input signals to the protection board, do you still get turn on noise?
    - measure the DC offset at the time the relay engages
    - significantly increase the delay of the relay
    - measure the min. +/- DC voltages that cause the protection circuit to engage, for each channel
    - lower the threshold of protection

  3. and now for something completely different part 3

    in Do It Yourself

    Posted · Edited by justin

    I cant even tell if this is a stupid question but where are your heatsinks? if you try to power it even for a short time without heatsinks the bias is going to be very unstable

    On 10/7/2024 at 5:20 AM, kevin gilmore said:

    you need to measure the voltage across q36  should be about 5 volts. if not adjust rv2 and if that is not enough change r36

    3.6V sounds right to me, 5V would probably result in about 700mA bias

  5. finally an electrostatic transportable

    in Do It Yourself

    Posted

    The output ripple voltage of a DC/DC converter is often specified at a 20 MHz frequency to provide a more comprehensive view of the high-frequency noise performance. Here's why:

    1. **Switching Noise and Harmonics**: While the switching frequency of the converter might be relatively low (e.g., hundreds of kHz), the switching process generates high-frequency harmonics. These harmonics can extend well into the MHz range, and measuring at 20 MHz helps capture the impact of these high-frequency components.

    2. **Measurement Standardization**: Specifying the ripple at 20 MHz has become a common industry practice. It provides a consistent benchmark for comparing the performance of different converters. It also ensures that any high-frequency noise generated by the converter is accounted for.

    3. **Real-World Performance**: In real-world applications, the DC/DC converter might interact with other components that are sensitive to high-frequency noise. Measuring ripple at 20 MHz helps ensure the converter will perform well in a wide range of conditions and with various loads.

    4. **Electromagnetic Interference (EMI)**: High-frequency noise can contribute to EMI problems. By specifying the ripple voltage at a higher frequency, manufacturers provide a clearer picture of potential EMI issues, which is crucial for compliance with regulatory standards.

    Overall, the 20 MHz specification helps designers understand the converter's behavior across a broader spectrum of frequencies, ensuring more reliable and noise-resistant designs.

  6. Universal output HP amp with custom Lundahl transformers

    in Do It Yourself

    Posted

    This is all that was provided:

    I think I would prefer to use our 2.5kg (5lb.)
    > transformers, as the high voltage secondary needs to have a lot of insulation
    > to keep capacitances down.
    > 
    >               Spec:
    >               Transformer for SE amplifier, size as LL1620 etc.
    > 
    >               Primary 1.2k impedance, 280V anode voltage,
    > standing DC current 200 - 300mA (you will need to specify)
    >               Input signal power around 10W
    > 
    >               Secondary 1 (electrostatic speaker) 1600V P-P
    > (turns ratio 1 : 6).
    >               Does this output need a centertap for offset
    > voltage or for ground reference?
    > 
    >               Secondary 2 (low sensity headphones) , 15W
    > into 50 ohms -> approx. 27V rms (turns ratio 3:1 for 1.2k : 50)
    > 
    >               Secondary 3 (6 ohms loudspeaker and sensitive
    > headphones), 15W into 6 ohms -> approx. 10V rms (turns ratio 14:1 for
    > 1.2k:6)

     

    3729_SE_connections.pdf

  7. Universal output HP amp with custom Lundahl transformers

    in Do It Yourself

    Posted

    I met Per Lundahl at Capital Audio Fest last year, and in trying to figure out what I could use I'd have for Lundahl transformers I asked about winding something that can drive e-stats, planars, low impedance, speakers from separate taps. I had also just bought a bunch of 6336B dual triodes, so thought that might work. The transformers came and many months went by but finally rigged something up. 

    Basically right now it's just 6336B with both triodes in parallel, running about 200mA with a B+ of 260V. There's an e-stat output that steps up, and also 50 ohm and 6 ohm outputs. The grid voltage is set by a bunch of 9V in series.

    The black box in the middle on top of the Wendy's napkin is a little 4W 12V to 600V DC/DC converter for the e-stat HP bias.

    I'm actually driving it from the headphone jack of a Ray Samuels Raptor right now 🤣 Have sound coming out but no chance yet to do much further testing 6336b-lundahl-universal.jpg

     

    • Like 7

  16. Roon, Just Roon

    in Home Source Components

    Posted · Edited by justin

    On 7/18/2024 at 8:26 PM, Voltron said:

    I fully admit to being mostly out of it on the state of streaming and Roon especially, but I'm confused by your decision to get the Nucleus One and the miniDSP SHD, because the description of the latter makes it sound duplicative. In that setup does the Nucleus One run Roon software and manage your files and then the miniDSP SHD is your dac and preamp? Without the Nucleus One, would you need a computer even if you have the miniDSP and network drives?

    If I already have a dac and preamp, can I just get the Nucleus One and a drive to run Roon and play files, along with Tidal, Qobuz or Spotify through it and into the existing system that is not Roon ready? I guess my question boils down to that--does the output from the Nucleus One still require a Roon ready dac/streamer/preamp?

    if you still have the Brooklyn Bridge you can use it with a Roon core..if a device isn't Roon certified, you can still use it if it supports AirPlay, Chromecast, or USB (by plugging it into a computer or a WiFi/LAN to USB adapter aka 'Roon end point'). Computers don't need to be Roon certified and this includes this like NUCs

    get on Roon now!

    • Like 1

  19. and now for something completely different part 3

    in Do It Yourself

    Posted

    Last year I ordered a lot of different boards of KG's amps/PSUs and had someone here put them together as a project. One of them was this 6DJ8 hybrid that uses the triple output buffer of the CFA3. Single-ended output only. There was 1 missing trace on the board that prevented it from working, found and fixed that, so possibly nobody had assembled one of these before. Problem is there's a substantial hiss (very easily audible with even sensitive planars, something like 0.3mV rms of 'white noise'. The +100V is coming from a TL783 regulator, tried AC, DC, batteries for heater, different grounding, gate stopper resistors, feedback caps, w/out servo..exhausted a lot of stuff but couldn't get more than a few % improvement on the noise. Anyone have ideas?

     

    th.PDF

    gilmore-liquid-legend.jpg

  20. Audio companies behaving badly.

    in Miscellaneous

    Posted

    On 7/15/2024 at 9:32 AM, spritzer said:

    I think dCS are just in the same boat as MSB, super high prices yet you get better performance on the stuff from China that is a 1/10th the price. 

    Now on the subject... there are too many stories out there but I'll never buy anything made by Focal - just stay away from that trash heap of a company in general.  Another is Hifiman... though I did order the new Mini Shangri-la but I really should have waited as there are plenty for sale used in China right now. 

    I only saw ~2 min of the video but I assume it had something to do with measurements, my favorite part though is people wanting expensive, exotic gear that sounds different, but then acting surprised when it measures objectively worse than a Hospital DAC

    • Like 2

  24. And now what did you do TODAY?

    in Off Topic

    Posted

    43 minutes ago, Dusty Chalk said:

    Yeah, me neither.  It's right up there with 9/11 didn't happen, moon landing didn't happen, and the earth is flat.

    And to be clear, I am not saying that something terrible isn't happening in Gaza, I'm just explaining my issues with -- let's call him Marley -- Marley's ham-fisted closed-mindedness.

    05z7B3KMxe3FWjAaqmPTCGo-4..v1569491072.p

    • Confused 1

  25. The Headcase Stax thread

    in Headphones

    Posted

    8 hours ago, TammerDown said:

    Stax has removed the L300 and Sr-007 mk2 from their website. Looks like it wasn't just the 007a after all. 

    That's true. I ordered a few more pairs of SR-007MK2 after finding out about this, but that's it. I have no idea if it's being replaced by something else.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.

  I accept