Nice info
But could be hard to get
I doubt they sell to private customer
And not in small quantities either
Around here such things usually works the way that IF they have e stock of a certain item fore a big customer, it may be possible to buy a few
Or they sometimes forward you to one their big customers
If lucky you can beg to buy a few out the backdoor
I once bought a huge 3foot heatsink that way
On a request on custom trafos, the same thing, but really way too expencive
But could be hard to get
I doubt they sell to private customer
And not in small quantities either
Around here such things usually works the way that IF they have e stock of a certain item fore a big customer, it may be possible to buy a few
Or they sometimes forward you to one their big customers
If lucky you can beg to buy a few out the backdoor
I once bought a huge 3foot heatsink that way
On a request on custom trafos, the same thing, but really way too expencive
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And go here too.
Class D audio amplifier
I am developing a full bridge Class D amp and will be using the gapped toroids for the filters. That is why I know a bit about these parts. I do have a friend that can get samples from Ferroxcube. I have also developed an XL (2007) spreadsheet that automates that Ferroxcube app. note for class-D filter component calculations. It even tells you how many turns to use on that core of the gapped toroid and helps with finding the wire size to use. Helps with wire losses too. I'd be willing to send you the spreadsheet but it is at work and I won't be there until monday. It is not documented well and somewhat of a work in progress since it was for my own consumption. Send me an email at: stoc005<at>att.net with your address and I will send it. I will convert it to Excel 1998 since 2007 is so bizarre. I'll send a schematic of the amp so far as well. It's kind of rough. It is similar to the UcD type amps with analog feedback taken after the L-C filter plus it is self-oscillating at 300-500Khz.
On a related note about component values for output filters. With the LTSpice simulations I've done on these filters and the amps that drive them, I've pretty much decided that the correct impedance to design towards is 6 ohms. An 8 ohm filter is just wrong for a 4 ohm load and a 4 ohm filter is wrong for an 8 ohm load. 6 ohms seems like a reasonable compromise since most single speakers start out at around 8 ohms and end up a bit less, after the crossover and zobel(s) networks are added in the speaker. I use zobels for crossover design since it levels the impedance you have to work with for the crossover filters. With that taken care of, a Class D amp should only be connected to one speaker at a time, IMHO. Paralleled speaker pairs on the amplifier should not be allowed, I think.
Bill
Class D audio amplifier
I am developing a full bridge Class D amp and will be using the gapped toroids for the filters. That is why I know a bit about these parts. I do have a friend that can get samples from Ferroxcube. I have also developed an XL (2007) spreadsheet that automates that Ferroxcube app. note for class-D filter component calculations. It even tells you how many turns to use on that core of the gapped toroid and helps with finding the wire size to use. Helps with wire losses too. I'd be willing to send you the spreadsheet but it is at work and I won't be there until monday. It is not documented well and somewhat of a work in progress since it was for my own consumption. Send me an email at: stoc005<at>att.net with your address and I will send it. I will convert it to Excel 1998 since 2007 is so bizarre. I'll send a schematic of the amp so far as well. It's kind of rough. It is similar to the UcD type amps with analog feedback taken after the L-C filter plus it is self-oscillating at 300-500Khz.
On a related note about component values for output filters. With the LTSpice simulations I've done on these filters and the amps that drive them, I've pretty much decided that the correct impedance to design towards is 6 ohms. An 8 ohm filter is just wrong for a 4 ohm load and a 4 ohm filter is wrong for an 8 ohm load. 6 ohms seems like a reasonable compromise since most single speakers start out at around 8 ohms and end up a bit less, after the crossover and zobel(s) networks are added in the speaker. I use zobels for crossover design since it levels the impedance you have to work with for the crossover filters. With that taken care of, a Class D amp should only be connected to one speaker at a time, IMHO. Paralleled speaker pairs on the amplifier should not be allowed, I think.
Bill
Tn26/11-3c20-a201, tn23/14/7-4c65
We might have to settle for one of these which are in stock.
TN26/11-3C20-A201
TN23/14/7-4C65
Also, I wonder why they show their inductors wound so loosely?
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We might have to settle for one of these which are in stock.
TN26/11-3C20-A201
TN23/14/7-4C65
Also, I wonder why they show their inductors wound so loosely?
Much better containment from the toroid air core
The toroid air cores do exhibit much better containment than the cylinders but still leak a little more than the T106-2 cores. Even the type 2 cores are not as silent as you might think. Are they leaking from the leads? The original little smd shielded bobbins were dead silent. Anyone care to try their amp and report back? Maybe all of our hand wound cores leak a little. I am listening with an AM radio tuned between stations to the switching frequency. Turn your amp on and off and listen to the difference.
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This amp is giving me the best sound I have ever had though, and it is the cheapest, running off of a single $32.00 smps.
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The toroid air cores do exhibit much better containment than the cylinders but still leak a little more than the T106-2 cores. Even the type 2 cores are not as silent as you might think. Are they leaking from the leads? The original little smd shielded bobbins were dead silent. Anyone care to try their amp and report back? Maybe all of our hand wound cores leak a little. I am listening with an AM radio tuned between stations to the switching frequency. Turn your amp on and off and listen to the difference.
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This amp is giving me the best sound I have ever had though, and it is the cheapest, running off of a single $32.00 smps.
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@sendler
Try some air toroids out of more reasonably sized wire and pop them into a set of hacked off pipe caps and solder them together.
No iron distortion.
No radiation.
It looks like you're off the deep end of milliohms with that wire.
Edit: You're never going to get a leak-free toroid because the windings are not perfectly uniform and everywhere.
Edit2: What is the RDSon of the output transistors?
Try some air toroids out of more reasonably sized wire and pop them into a set of hacked off pipe caps and solder them together.
No iron distortion.
No radiation.
It looks like you're off the deep end of milliohms with that wire.
Edit: You're never going to get a leak-free toroid because the windings are not perfectly uniform and everywhere.
Edit2: What is the RDSon of the output transistors?
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Air core Class D inductors??
I think air core inductors are going in the wrong direction. You want a very low DC resistance for these inductors. One way to achieve that is to use large diameter wire. Next, use a core that produces the desired inductance with as few turns as possible. Now, pick a magnetic material and mechanical configuration that allows you to create the inductor you desire without causing saturation of the magnetic material at the level of DC/AC (audio) current that it will see. Plus the core should confine the magnetic field such that radiated energy is tolerable. If the inductance collapses because of magnetic saturation, the filter no longer works as designed.
Air core inductors use too much wire. The DC resistance is higher than necessary. This will cause a lower damping factor on the output of the amplifier. The bass will be less controlled (dare I say "flabby" or "less tight"??) than it could be with a higher damping factor. Yes, people listen to AM, which is why you need to keep the stray magnetic fields under control. Air cores just radiate too much, unless you completely shield them magnetically.
I think air core inductors are going in the wrong direction. You want a very low DC resistance for these inductors. One way to achieve that is to use large diameter wire. Next, use a core that produces the desired inductance with as few turns as possible. Now, pick a magnetic material and mechanical configuration that allows you to create the inductor you desire without causing saturation of the magnetic material at the level of DC/AC (audio) current that it will see. Plus the core should confine the magnetic field such that radiated energy is tolerable. If the inductance collapses because of magnetic saturation, the filter no longer works as designed.
Air core inductors use too much wire. The DC resistance is higher than necessary. This will cause a lower damping factor on the output of the amplifier. The bass will be less controlled (dare I say "flabby" or "less tight"??) than it could be with a higher damping factor. Yes, people listen to AM, which is why you need to keep the stray magnetic fields under control. Air cores just radiate too much, unless you completely shield them magnetically.
Listening is the important step
That's the problem. You can't think what something will sound like. You have to build the circuits and listen to them. That's what the whole DIYaudio forum is about and why modified gear can sound way better than stock. Whether it's a DAC, an amp, a cable, passive component, whatever. If the shortest wire was the best then every loudspeaker would have a massive core with a few turns of wire on it for all of their inductors. But they don't. They all use air core unless the value is too large. 10,000 times the values we are dealing with in class D.
I have three identical amp boards. One with the 20ga. type 2 toroids and one with the 20ga. cylindrical air cores and the air cores sound much more transparent even though I can't use them because of EMI. The big 14ga. air core toroids destroy the sonics of either one and have emissions on par with the type 2. It's not just me. The forums are full of class D people who have listened various (and unknowingly noisy) air cores and I have yet to read a single post where they preferred the type 2 core which is otherwise the de facto. Too bad the forum search doesn't consider "air" to be an important enough word to find as it would be easier to read about.
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That's the problem. You can't think what something will sound like. You have to build the circuits and listen to them. That's what the whole DIYaudio forum is about and why modified gear can sound way better than stock. Whether it's a DAC, an amp, a cable, passive component, whatever. If the shortest wire was the best then every loudspeaker would have a massive core with a few turns of wire on it for all of their inductors. But they don't. They all use air core unless the value is too large. 10,000 times the values we are dealing with in class D.
I have three identical amp boards. One with the 20ga. type 2 toroids and one with the 20ga. cylindrical air cores and the air cores sound much more transparent even though I can't use them because of EMI. The big 14ga. air core toroids destroy the sonics of either one and have emissions on par with the type 2. It's not just me. The forums are full of class D people who have listened various (and unknowingly noisy) air cores and I have yet to read a single post where they preferred the type 2 core which is otherwise the de facto. Too bad the forum search doesn't consider "air" to be an important enough word to find as it would be easier to read about.
Wow! Bob Cordell likes air cores
Wow! Bob Cordell likes class D air toroids. Great link stinius.
Gapped ferrite core
If you want to use a gapped ferrite core, then better to buy such core that you don't need to saw. There are plenty of them.
If you want to use a gapped ferrite core, then better to buy such core that you don't need to saw. There are plenty of them.
I suggested this already in the other thread but it fits better here.
The Wurth coils are the best coils I tried so far for my system with the Shure 2x100 amps.
They are better than 10uH air cores that I took out of my Charlize and
many others that I bought and wound.
For the price you should at least try them in your system.
They do equally well with my full Horn-system, KRK monitors or Fonken.
Greets,
Klaus
The Wurth coils are the best coils I tried so far for my system with the Shure 2x100 amps.
They are better than 10uH air cores that I took out of my Charlize and
many others that I bought and wound.
For the price you should at least try them in your system.
They do equally well with my full Horn-system, KRK monitors or Fonken.
Greets,
Klaus
Ordered
Thanks for the tip Klaus. As you have found the output coil is the key that can unlock the superiority of class D. I ordered the Wurths that you like from Digikey and will report at the Sure 2X100 thread here.
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http://www.diyaudio.com/forums/class-d/143669-sure-electronics-new-tripath-board-tc2000-tp2050.html
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Thanks for the tip Klaus. As you have found the output coil is the key that can unlock the superiority of class D. I ordered the Wurths that you like from Digikey and will report at the Sure 2X100 thread here.
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http://www.diyaudio.com/forums/class-d/143669-sure-electronics-new-tripath-board-tc2000-tp2050.html
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Once a board is installed in a metal case, isn't that shielded? So the emi pollutions shouldn't be anymore a problem. What do you think about?
Add wire
Yes the Wurth XXL coils are my favorite as the sonics are very close to an air core with some advantages of much smaller size and less EMI. Much better sound than the undersized type 2 cores that everyone uses. More loss than the air cores though so battery users will find less run time. Just add some solid core wires to the Wurth coils and fit them down to the board as best as possible.
IMO, the properties of a high perm ferrite with a gap are different than a lower perm ferrite unless you really get lucky. I do some work with high Q resonant inductors (non-audio) and nothing can beat the gapped ferrite for maintaining the Q under power.
Sawing a gap is easier than one might think. I use a thin copper or brass wheel with some silicon carbide grit slurry in a dish on the bottom, and the part gravity fed from the top. There are also inexpensive diamond saws if you want to go that route. Check the lapidary supply places. If you're paying more than $10 for a nice 4" diamond saw, you haven't found the right place.
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