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Introducing the PowerReg

Discussion in 'd.i.y.' started by teddy_pardo, Sep 27, 2007.

  1. teddy_pardo

    teddy_pardo Trade: Teddy Pardo

    Following the TeddyReg and as a results of many nights and weekends of experiments, here comes the PowerTeddyReg. It is based on the same concept but can deliver several amperes (depending on selected dropout and heat sink) and has much lower output impedance.

    Here is the circuit

    [​IMG]

    Components are


    R1 = 3.4K
    R2 = 150R
    R3 = 40-60K
    R4 = not required
    R5 = 40-60K
    R6 = 100-250R

    C1 = 0.1uF X7R Ceramic (optional)
    C2 = 10-20uF Tantalum
    C3 = 10-20uF Tantalum
    C4 = 33uF Tantalum
    C5 = 0.2-0.3uF X7R Ceramic
    C6 = 10-20uF Tantalum/Oscon

    T1 = SK117 GR
    T2 = BC550C
    T3 = D45H11
    LR1 = LM317

    Note that with a FET transistor and Sziklai-pair the dropout on the VBE is minimal (less than 1Volt) therefore the output voltage is mainly determined by the LM317.

    This regulator can be used for power amplifiers and the effect it has on the gainclone is quite astonishing. I have used a pair of these regulators (positive and negative) per channel, powered by a single 120VA transformer and cheapo miniature 10.000uF capacitors. Results are jaw dropping, it's comparable if not superior to many high end power amps discussed in this forum including my own one.

    A complete one-channel power amp including heat-sink, two regulators, and a trimmed GainClone PCB can fit in a 6x6x6 cm module. Isn't it cute?

    [​IMG]

    [​IMG]

    [​IMG]

    My next project: a miniature active cross over using these modules. Stay tuned...

    Enjoy, Teddy
     
  2. yairf

    yairf pfm Member

    Teddy
    You should trademark your "product" names, who knows... :)
     
  3. MarkW

    MarkW Best Sounds Ever

    Teddy

    Interesting stuff and nicely done. How does the GC sound with this psu arrangement?

    Mark
     
  4. new naim boy

    new naim boy pfm Member

    Teddy: Would you recommend the PTR for the SB3?
     
  5. Agent_Cooper79

    Agent_Cooper79 pfm Member

    Teddy, I am very impressed!

    Couple of questios though;

    Can the amp really still deliver the same power as with "real" PSU-caps? The reason I am asking this is the fact that the cap in the VBE looks like a bigger cap but can't really store the energy of the real cap.

    What is the reason for omitting R4, is it because you have a FET at the base of the VBE?

    Looks like fantastic work, thanks for making it available!

    /Magnus
     
  6. teddy_pardo

    teddy_pardo Trade: Teddy Pardo

    Don't know. I would assume yes but no way to try it.
     
  7. teddy_pardo

    teddy_pardo Trade: Teddy Pardo

    Yes, it can easily deliver enough power to drive a 50W power amp, maybe even more. When fully driving the power amp, the ripple looks much better on the oscilloscope than any other large capacitor combination. It sounds much better too.

    R4 is usually used to create some dropout on the VBE, in this case since the collector is connected to the rail, the LM317 takes care of the VBE dropout.
     
  8. Baki

    Baki Active Member

    Hi Teddy,
    excellent work indeed.
    I've been experimenting a lot and implemented more than 10 VBE based regs (alone, before and after linear regulator) in my cdp and integrated amp.
    One question seems inevitable.
    When to implement TeddyReg and when PowerReg?
    For example, what is your recommendation regarding the regulation of cdp opamp output stage (low power consumption, but low output impedance could be beneficial...)?
    Best,
    Baki
     
  9. teddy_pardo

    teddy_pardo Trade: Teddy Pardo

    Use PowerReg only when you need power. The TeddyReg has better regulation as it has two levels of regulation the LM317, followed by the VBE. On the PowerReg the power transistor is connected directly to the raw rail. It's still very quiet, but probably not as much as the other.
     
  10. PigletsDad

    PigletsDad pfm Member

    Another point:

    The PoweReg only has low impedance when you draw a lot of current from it; at low current drains the transistor impedances are quite high. A fair rule of thumb is that the output impedance will be 26Ohms divided by the output current in mA.
     
  11. Puffin

    Puffin pfm Member

    What would need to be altered to give an output voltage of 12vDC ?
     
  12. Nuuk

    Nuuk pfm Member

    Set the LM317 to output 13 volts. That is done by selecting the correct resistors.

    If you go to Decibel Dungeon and download the hi-fi caluclator, you will find it has a section to calculate the required resistor values.

    In this case 200R/2k would give you around 13.75 after the LML317 and about one volt less than that after the power reg circuit. Or you could use a trimmer to get 212R/2K for 13 volts after the LM317.
     
  13. Puffin

    Puffin pfm Member

    nuuk. Thanks for that I had considered a trimmer or maybe a 7812 in place of the 317 ?
     
  14. Pulse Studio

    Pulse Studio TubeTech

    Teddy wouldn't the reg be better served as a " K " series variable voltage affair?
     
  15. maxlorenz

    maxlorenz pfm Member

    Hi Teddy,
    It's me again :p

    I am buying the parts for PowerReg and TeddyReg.
    Questions:
    1) You run your chipamp around 28VDC, wright?
    Could the LM317 in your configuration be settled to >35VDC?

    2) I got dizzy trying to find JFETs :(
    I found 2SK117-BL (BL instead of GR)
    http://www.ampslab.com/PDF/2sk117.pdf
    and 2SJ103-Y as P-channel JFET (audio amp instead of "low noise audio")
    http://www.ampslab.com/PDF/2sj103.pdf

    Are these OK?
    They are $20USD per 20 units.

    Thanks,
    M
     
  16. teddy_pardo

    teddy_pardo Trade: Teddy Pardo

    Yes, I'm running it at around 28V, or even less. Be aware that when you use regulators you need less voltage as in the case of non regulated the voltage drops when the amp uses more current while in regulated it doesn't.

    You can run it at 35V too, just make sure you're using the right capacitors (50V or more).

    In both cases, make sure you have good heatsinks.

    117-BL work as well, I use them too sometimes

    Never tried the 2SJ103, but in any case the Y/GR/BL versions has an effect on the VBE dropout (Y is more dropout, BL is less). If you are using different types for the pos ans neg regulators you'll have to measure and adjust using the resistors in order to achieve symmetrical voltage.
     
  17. Harthold

    Harthold pfm Member

    I am entertaining the idea ofbuilding a chipamp like yours in the snap and definitely use Power Teddyregs. I've fitted your "best" Teddyregs mod(Sziklai) but just after Les's TPR's (with easy voltage adjustment and very good sonic results).
    Now my question is about that Gainclone of yours. Are you using Tantalum instead of Panansonic FC just close to the chip for all filtering? What values?
    Thanks Teddy
    Harthold
     
  18. teddy_pardo

    teddy_pardo Trade: Teddy Pardo

    Yes, I'm using 10-30uF tantalums but mainly because they are small in size. I also have small 0.1uF X7R ceramic capacitors in parallel.
     
  19. maxlorenz

    maxlorenz pfm Member

    Thanks Teddy for your previous answer (post #16)

    Now that I bought 600 tantalum caps I wonder why do you (and every EE writing application notes) prefer them sonically on PS and regs :D
    I am studying here and there some articles to see how this is, because they are not particularly low ESR.
    Is it a physical characteristic? like use of carbon and silver...or the dry nature..or the resin dipped nature?
    Or is it an electronic characteristic? like stability at high freqs?

    Thanks again,
    M
     
  20. teddy_pardo

    teddy_pardo Trade: Teddy Pardo

    For me there are two main reasons:

    1. They are small in size
    2. Their impedance/frequency curve is relatively flat, that is their impedance don't rise dramatically at high frequencies which makes them a good fit for paralleling a ceramic capacitor without oscillation/ringing risk

    There's an additional reason which is probably a derivative of #2, they sound better...

    Teddy
     

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