LCR Inductor Q

dshortt9 · 19th March 2013, 03:31 AM

Forgive me if this question has been answered elsewhere or if is common knowledge, but what should the Q value be for an inductor meant for an LCR network. I'm thinking it should be as high as possible?
Thanks in advance.

DF96 · 19th March 2013, 11:01 AM

It all depends on the purpose of the network. Sometimes as high Q as possible is required; sometimes the Q is deliberately reduced by adding resistance.

analog_sa · 19th March 2013, 12:15 PM

Quote:

Originally Posted by DF96

It all depends on the purpose of the network.

How do you find the time to add value to most threads?

As a wild guess i would venture it is the type of network used in phono preamps.

DF96 · 19th March 2013, 12:41 PM

Maybe, but 'analogue source' covers a lot of possible uses for LCR networks as it includes tapes and radios too.

FoMoCo · 19th March 2013, 01:32 PM

Quote:

Originally Posted by dshortt9

Forgive me if this question has been answered elsewhere or if is common knowledge, but what should the Q value be for an inductor meant for an LCR network. I'm thinking it should be as high as possible?
Thanks in advance.

Unless the designer intended a certain Q (and they shouldn't have) higher is better.

However, you should analyze the part of the circuit the inductor is in. A lot of circuits do not need a hi Q and you'd be wasting your money to seek out the highest Q possible.

Without seeing the circuit there is no definitive answer.

dshortt9 · 19th March 2013, 03:13 PM

The inductor is for phono equalization like the Tango LCR600.
Link to more information: passive RIAA LCR unit

FoMoCo · 19th March 2013, 04:03 PM

Quote:

Originally Posted by dshortt9

The inductor is for phono equalization like the Tango LCR600.
Link to more information: passive RIAA LCR unit

My personal opinion is that it's not horribly important. Anything above, say, 10... I'd think shunt capacitance would be more important given the high value of the inductors.

DF96 · 19th March 2013, 04:30 PM

The network designer would allow for Q in his design (at least, he ought to). You just have to use the same Q as he designed for. If he doesn't specify Q, then maybe he hasn't thought about it.

This sort of problem does not arise with RC networks, as real capacitors are much closer to an ideal capacitor than any real inductor is to an ideal inductor. The claim in the link about RIAA accuracy only being achieved with LCR is nonsense and can be completely ignored.

morinix · 19th March 2013, 04:34 PM

Quote:

Originally Posted by dshortt9

Forgive me if this question has been answered elsewhere or if is common knowledge, but what should the Q value be for an inductor meant for an LCR network. I'm thinking it should be as high as possible?
Thanks in advance.

Gonna' build your own inductors?

dshortt9 · 19th March 2013, 04:45 PM

Thanks, I could not find the answer to this question anywhere else. It is more a question of minimum Q and shunt capacitance that does not cause problems at audio frequencies. That put me in the right direction. Now I just need to find the right inductors. That will be more difficult.

19th March 2013, 03:31 AM	#1
dshortt9 diyAudio Member Join Date: Apr 2001 Location: Milwaukee, Wisconsin	LCR Inductor Q Forgive me if this question has been answered elsewhere or if is common knowledge, but what should the Q value be for an inductor meant for an LCR network. I'm thinking it should be as high as possible? Thanks in advance.

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19th March 2013, 11:01 AM	#2
DF96 diyAudio Member Join Date: May 2007	It all depends on the purpose of the network. Sometimes as high Q as possible is required; sometimes the Q is deliberately reduced by adding resistance.

19th March 2013, 12:41 PM	#4
DF96 diyAudio Member Join Date: May 2007	Maybe, but 'analogue source' covers a lot of possible uses for LCR networks as it includes tapes and radios too.

19th March 2013, 03:13 PM	#6
dshortt9 diyAudio Member Join Date: Apr 2001 Location: Milwaukee, Wisconsin	The inductor is for phono equalization like the Tango LCR600. Link to more information: passive RIAA LCR unit

19th March 2013, 04:30 PM	#8
DF96 diyAudio Member Join Date: May 2007	The network designer would allow for Q in his design (at least, he ought to). You just have to use the same Q as he designed for. If he doesn't specify Q, then maybe he hasn't thought about it. This sort of problem does not arise with RC networks, as real capacitors are much closer to an ideal capacitor than any real inductor is to an ideal inductor. The claim in the link about RIAA accuracy only being achieved with LCR is nonsense and can be completely ignored.

19th March 2013, 04:45 PM	#10
dshortt9 diyAudio Member Join Date: Apr 2001 Location: Milwaukee, Wisconsin	Thanks, I could not find the answer to this question anywhere else. It is more a question of minimum Q and shunt capacitance that does not cause problems at audio frequencies. That put me in the right direction. Now I just need to find the right inductors. That will be more difficult.