coil current rating for this amp

Leolabs · 25th July 2007, 02:03 AM

This is a current dumping amp,wonder what the require value for the carrying current rating of the 2 uH coil????

r221b · 26th July 2007, 02:16 AM

Since the current through the speaker must also pass through the inductor, using Ohm's law, 100 watts into 4 ohms is 5 amps. Therefore the inductor should be able to handle 5 amps of current. In reality, you may be able to use a lower rated inductor because you won't be running it at 100 watts all the time. I'd guess a 3 amp rated inductor would be sufficient for most uses. A 3 amp inductor will allow 36 watts continuous at the speaker. It would depend upon your actual use though. Hope this helps.

sherlock

anatech · 26th July 2007, 02:30 AM

Hi sherlock,
Figure on the peak current and allowable temperature rise in the coil. All coil charts are based on temperature rise.

Now, in this design the resistance may be important. The coil is part of a bridge circuit and represents part of the basis on how it works. Therefore, no iron allowed here. I imagine there will be a fair amount of swinging current here and you don't want resistive losses.

Of course, one is allowed to experiment. I haven't read the article Leolabs. Don't they give you ant more information on the coil? If not, look at some Quad schematics and parts lists.

-Chris

Lumba Ogir · 26th July 2007, 07:34 AM

Hi,
the comprehensive QUAD documentations and discussions may help.

I wonder why the CFP is configured for voltage gain in these amps.
Does the current dumping principle require it?

Leolabs · 27th July 2007, 02:52 AM

Thank you guys for the suggestions.But the original Quad is using NPN power transistors only as opposite to this design which use NPN/PNP configurations,wonder the working principle is still the same???

anatech · 27th July 2007, 03:44 AM

Hi Leolabs,

Quote:

But the original Quad is using NPN power transistors only as opposite to this design which use NPN/PNP configurations,wonder the working principle is still the same???

I think so. The bridge is the key, how the other mechanics are put together shouldn't matter.

-Chris

Lumba Ogir · 27th July 2007, 01:55 PM

Leolabs,

Quote:

wonder the working principle is still the same???

YES, you should definitely look at the more recent QUAD modifications and - after a careful consideration - make your choice.

http://www.dc-daylight.ltd.uk/Valve-...-405-Mods.html
http://www.dc-daylight.ltd.uk/Valve-...DCD-Mod-3..pdf

I am just interested in some theoretical details.

Leolabs · 7th August 2007, 02:12 AM

And one more question:How to calculate the voltage gain of this amp???

anatech · 7th August 2007, 02:24 AM

Hi Leolabs,
In the first picture in the article you posted. The gain will be determined by R1 and R2.

Standard op amp stuff.

-Chris

Leolabs · 7th August 2007, 02:29 AM

If so,then the voltage gain is very large!

26th July 2007, 02:30 AM	#3
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi sherlock, Figure on the peak current and allowable temperature rise in the coil. All coil charts are based on temperature rise. Now, in this design the resistance may be important. The coil is part of a bridge circuit and represents part of the basis on how it works. Therefore, no iron allowed here. I imagine there will be a fair amount of swinging current here and you don't want resistive losses. Of course, one is allowed to experiment. I haven't read the article Leolabs. Don't they give you ant more information on the coil? If not, look at some Quad schematics and parts lists. -Chris __________________ "Just because you can, doesn't mean you should" © my Wife

7th August 2007, 02:24 AM	#9
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Leolabs, In the first picture in the article you posted. The gain will be determined by R1 and R2. Standard op amp stuff. -Chris __________________ "Just because you can, doesn't mean you should" © my Wife

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26th July 2007, 02:16 AM	#2
r221b diyAudio Member Join Date: Jul 2007	Since the current through the speaker must also pass through the inductor, using Ohm's law, 100 watts into 4 ohms is 5 amps. Therefore the inductor should be able to handle 5 amps of current. In reality, you may be able to use a lower rated inductor because you won't be running it at 100 watts all the time. I'd guess a 3 amp rated inductor would be sufficient for most uses. A 3 amp inductor will allow 36 watts continuous at the speaker. It would depend upon your actual use though. Hope this helps. sherlock

26th July 2007, 07:34 AM	#4
Lumba Ogir Banned Join Date: Apr 2005 Location: Stockholm	Hi, the comprehensive QUAD documentations and discussions may help. I wonder why the CFP is configured for voltage gain in these amps. Does the current dumping principle require it?

27th July 2007, 02:52 AM	#5
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Thank you guys for the suggestions.But the original Quad is using NPN power transistors only as opposite to this design which use NPN/PNP configurations,wonder the working principle is still the same???

7th August 2007, 02:12 AM	#8
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	And one more question:How to calculate the voltage gain of this amp???

7th August 2007, 02:29 AM	#10
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	If so,then the voltage gain is very large!