Re: Choked
Thanks James, it give us a good look into these chokes.
What amazed me is the low capacitance for such a high # of turns.
By any chance can you see through the end of the outer insulation as how many layers of insulation this might have or if it looks like a perfect lay with insulation on each leyer?
James D. said:
Thanks James, it give us a good look into these chokes.
What amazed me is the low capacitance for such a high # of turns.
By any chance can you see through the end of the outer insulation as how many layers of insulation this might have or if it looks like a perfect lay with insulation on each leyer?
I'm kinda jumping in late on this thred but here is an observation I have from when I built my first version of the 26 line stage. For the plate load I used 2 156C's in series. They are cheap enough!
If I remember the numbers correctly (was 2 years ago) the -3dB points at both ends of the frequency range moved out. The LF -3dB point moved from 15hz to 7hz and the HF -3dB point moved from 30K to 90K.
The lower frequency increases as the inductance is doubled, the upper frequency increases as the capacitance of the chokes is in series and is roughly half that of a single choke.
The reason for the upper moving so much is like marketing numbers.... With the 156C's there was a dip at 50Khz then the response rose at 70K where the self resonance was at, then droped again. With one choke the dip at 50K was -4dB, With 2 chokes in series the dip was only -2dB.
Another cool trick that can be done using 2 chokes in series- if you stack the chokes and wire them correctly they become a hum bucking choke. Using my Weller soldering station as a magnetic signal source 2' from the chokes, when one choke was flipped upside down there was a 20dB reduction in received hum.
I mounted the chokes on standoffs that were the same height as the chokes with the chokes bottom to bottom. To see a picture of the double choke install look in the images section of my webpage. The one with the chokes is "26 preamp bottom side"
Hope this rambling is of some use...
Gary
http://home.pacifier.com/~gpimm/
If I remember the numbers correctly (was 2 years ago) the -3dB points at both ends of the frequency range moved out. The LF -3dB point moved from 15hz to 7hz and the HF -3dB point moved from 30K to 90K.
The lower frequency increases as the inductance is doubled, the upper frequency increases as the capacitance of the chokes is in series and is roughly half that of a single choke.
The reason for the upper moving so much is like marketing numbers.... With the 156C's there was a dip at 50Khz then the response rose at 70K where the self resonance was at, then droped again. With one choke the dip at 50K was -4dB, With 2 chokes in series the dip was only -2dB.
Another cool trick that can be done using 2 chokes in series- if you stack the chokes and wire them correctly they become a hum bucking choke. Using my Weller soldering station as a magnetic signal source 2' from the chokes, when one choke was flipped upside down there was a 20dB reduction in received hum.
I mounted the chokes on standoffs that were the same height as the chokes with the chokes bottom to bottom. To see a picture of the double choke install look in the images section of my webpage. The one with the chokes is "26 preamp bottom side"
Hope this rambling is of some use...
Gary
http://home.pacifier.com/~gpimm/
Gary,
Very interesting. Thanks for the link! But, where are the schematics for all those amps? You're just teasing the reader...
How do you like your 30/31 amp? I'm building a 31 push-pull right now, with #30's for gain duty. Phase splitter will be the Hammond 124B, when I get around to ordering one.
Yes, not enough has been said about paralleling chokes! It seems like a near perfect solution to any frequency response concerns, no? The only drawback is the increased DCR.
Joel
Very interesting. Thanks for the link! But, where are the schematics for all those amps? You're just teasing the reader...
How do you like your 30/31 amp? I'm building a 31 push-pull right now, with #30's for gain duty. Phase splitter will be the Hammond 124B, when I get around to ordering one.
Yes, not enough has been said about paralleling chokes! It seems like a near perfect solution to any frequency response concerns, no? The only drawback is the increased DCR.
Joel
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