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Introducing the PowerReg

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

PowerReg.png


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_3415.jpg


IMG_3416.jpg


IMG_3417.jpg


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

Enjoy, Teddy
 
Teddy

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

Mark
 
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
 
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

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

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.
 
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
 
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.
 
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
 
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.
 
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
 
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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