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Is the shunt regulator much better than the 78xx series?

post #1 of 17
12/7/09 at 1:48pm
Thread Starter 
just wondering, how much better is a shunt regulated power supply, comparing to the common 78xx series chips?
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post #2 of 17
12/7/09 at 2:06pm
I'm currently planning a balanced Gamma2, and would be also most interested in what people had to say to this.
Greetz Ava
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post #3 of 17
12/7/09 at 2:26pm
Shunts seem to be very well regarded for certain areas, but to my understanding you need to have an idea of the current draw of the load.

There is a few designs in the Power Supply section of DiyAudio. I might through the very long threads over there.
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post #4 of 17
12/7/09 at 5:30pm
Quote:
Originally Posted by AudioCats View Post
just wondering, how much better is a shunt regulated power supply, comparing to the common 78xx series chips?
Not an answer to your question but there are better series linear regulators than a generic 78xx.

LM1086 or LT1086. Even the LT1086 is only a few dollars for the part.



Linear Technology - LT1086 - 1.5A Low Dropout Positive Regulators Adjustable and Fixed 2.85V, 3.3V, 3.6V, 5V, 12V
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post #5 of 17
12/7/09 at 7:04pm
Thread Starter 
it will be used in a DAC, the current draw won't be too much, 150mA max, so it is practical to actually use shunt regs.

on the LT1086, is it better because of the low drop out or lower noise/output impedance?
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post #6 of 17
12/7/09 at 8:00pm
Quote:
Originally Posted by AudioCats View Post
it will be used in a DAC, the current draw won't be too much, 150mA max, so it is practical to actually use shunt regs.
Assuming you feed the shunt regulator with a CCS, 150mA draw is into the territory where the CCS portion is not quite trivial. The standard 10M45 and DN2540 are likely not up to the task. Other higher current depletion mode mosfets are harder to find in small quantities. LM317 based CCSes are really not very good, and oscillate very easily. BJTs that will source that much current have a too low hfe to make a really good CCS. This leaves you with a big mosfet (usually + BJT.) The CCS on the drain in this design is a good starting point (adjust R16 and leave out R17 for more reasonable current): http://www.firstwatt.com/downloads/F...-manual-sm.pdf

Quote:
Originally Posted by AudioCats View Post
on the LT1086, is it better because of the low drop out or lower noise/output impedance?
My experience is that they are actually audibly worse.
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post #7 of 17
12/8/09 at 1:57am
Shunt regulators are somewhat attractive for very low current draw applications, or else the "pass" CCS or resistor will burn heat as well as the shunt portion of the regulator.

I've built a few shunt regulators in past projects, using fully discrete parts as well as using ICs like the TL431, but the load requirement is finicky. You really do need to know how much current your load will draw, and design accordingly. The shunt current must not be so high as to cause a heat meltdown, but it needs to be higher than your maximum load current in order for the circuit to stay in good regulation. The series resistor or CCS need to be sized to handle the combined currents of the shunt and the load. If your load is variable, then it might be impossible to implement a good solution without oversizing everything and run it really hot.
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post #8 of 17
12/8/09 at 5:19am
How about INA134?
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post #9 of 17
12/8/09 at 6:05am
Quote:
Originally Posted by K3cT View Post
How about INA134?
umm that's a differential receiver mainly used to convert differential signal to SE.unless am mistaken
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post #10 of 17
12/8/09 at 6:35am
quite a few people on the diyaudio forums are using the shunt reg section of the dc coupled pass b1 clone. There is a second round of the group buy going on now.
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post #11 of 17
12/8/09 at 10:59am
Check out Salas' and Ikoflexer's thread about the Simplistic LV shunt regulator at diyaudio. Derived from Salas' HV shunt that was develloped first and built by quite a number of people (including me ).
I am using the HV shunt in two of my headphone amplifiers, they work flawlessly at around 80mA consumption and sound better than everything I tried so far...
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post #12 of 17
12/8/09 at 11:04am
I've read the Salas thread and he states that his LV reg has been used for up to 3A.
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post #13 of 17
12/8/09 at 11:08am
Quote:
Originally Posted by dsavitsk View Post
Assuming you feed the shunt regulator with a CCS, 150mA draw is into the territory where the CCS portion is not quite trivial......
Quote:
Originally Posted by amb View Post
I've built a few shunt regulators in past projects, using fully discrete parts as well as using ICs like the TL431, but the load requirement is finicky......
I wonder whether either of you well-versed gentlemen have an opinion on the Placid from TPA? It seems to be highly configurable for load current and voltage, and capable of pretty high currents.

I have built myself one for powering the I/V stage of my DAC project. I have tested it as low as 50mA and up to 200mA without a load - the shunt heatsinks get pretty damn toasty at 200mA, but it seems to work well throughout this range.
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post #14 of 17
1/4/11 at 2:50am

Dear all,

 

can I feed my headphone amp with Shunt Regulator?

I affraid the output of shunt regulator will be too big for the amp and can break my amp or cans. :(

 

How about Shunt regulator compared with sigma11?

which one is better?

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post #15 of 17
1/4/11 at 9:15am

see post #11

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