After doing a little research I was thinking about trying a CLC PSU arrangement in my F5. Need some help calulating the size of the choke.
600V transformer
33,000uf caps X6
I figure the stock 4x.47ohm configuration is close to this, resistance-wise:
0.51mH 14 AWG Perfect Layer Inductor 266-325
This is 14g air coil is rated at 800w power handling. What kind of power handling does a CLC choke need to cover? The rating of the transformer? Is something like this too small?
Jantzen 0.50mH 18 AWG Air Core Inductor 255-230
600V transformer
33,000uf caps X6
I figure the stock 4x.47ohm configuration is close to this, resistance-wise:
0.51mH 14 AWG Perfect Layer Inductor 266-325
This is 14g air coil is rated at 800w power handling. What kind of power handling does a CLC choke need to cover? The rating of the transformer? Is something like this too small?
Jantzen 0.50mH 18 AWG Air Core Inductor 255-230
I kindof had the same question when I built my F4.
The answer I always got was that I needed an inductor in the .12Ω range with power handling of whatever your rail current will be (mine is 4A).
Any inductance that you have will be a benefit to smoothing the supply.
My tube amp for example uses a 6H inductor in it's power supply but it only has the current capability of 200mA.
Finding an inductor with that high of an inductance, low Ω & 4A rating will be very spendy.
And then you need 2 of them.
The answer I always got was that I needed an inductor in the .12Ω range with power handling of whatever your rail current will be (mine is 4A).
Any inductance that you have will be a benefit to smoothing the supply.
My tube amp for example uses a 6H inductor in it's power supply but it only has the current capability of 200mA.
Finding an inductor with that high of an inductance, low Ω & 4A rating will be very spendy.
And then you need 2 of them.
The power rating of a Perfect Layer inductor really applies for its use in a speaker crossover, and has nothing to do with its ability to handle a power supply. I'm not sure that there is is a clear way to specify the inductor, but consider the current it carries and the DC resistance of the particular part. Plug it into PSU Designer 2 as a combination of inductance and resistance (I don't remember whether it allows you to specify the DCR of the inductor) With appropriate characteristics of your transformer, rectifiers, capacitors and inductors you can get a good model of your potential PSU.
In the case of the two inductors presented by Hikari, the 18 gauge inductor is definitely too small. One of the benefits of using CLC is that there should be better ripple reduction with less voltage drop than CRC. Choosing an inductor with higher DCR means higher voltage drop. I'd go with 14 gauge or bigger inductors and be sure to allow enough ventilation to keep it cool as it dissipates a couple of watts. Buy some magnet wire and wind your own 10-12 gauge? or try http://www.northcreekmusic.com/NorthCreekCoilPrices.PDF
In the case of the two inductors presented by Hikari, the 18 gauge inductor is definitely too small. One of the benefits of using CLC is that there should be better ripple reduction with less voltage drop than CRC. Choosing an inductor with higher DCR means higher voltage drop. I'd go with 14 gauge or bigger inductors and be sure to allow enough ventilation to keep it cool as it dissipates a couple of watts. Buy some magnet wire and wind your own 10-12 gauge? or try http://www.northcreekmusic.com/NorthCreekCoilPrices.PDF
You'll save quite a lot of copper by winding on a no.26 powdered iron toroidal core (yellow/white). Air core only really makes sense when you need perfect linearity and no core losses, neither much matter here.
There's another downer for air cores - they radiate your ripple noise as magnetic energy, so you'll need to keep them distant from any sensitive audio circuits. Far better to tie up that energy safely in a ring.
There's another downer for air cores - they radiate your ripple noise as magnetic energy, so you'll need to keep them distant from any sensitive audio circuits. Far better to tie up that energy safely in a ring.
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When the F5 circuit first came out I made a copy from parts on hand. I used 25 watt 2 ohm ceramic resistors. They are 2 1/2 x 1/2 x 1/2 inch. I wound 3 layers of 16 gauge magnet wire on them. Paralleled with the resistor the total was less than 0.2 ohm. Some calculation seems to show that 7 layers would give 1 mh but the ohms double. They sit between 10k uf on the xformer side and 20k uf on the amp side. Didn't measure the inductance but the DC looks better on the scope than the stock 4 x 0.47 ohm. I liked it enough to use it with a second F5 and a BA3.
I have used air core inductors in the rCLC of some Power Amps.
I can clearly see the "rounding" of the ripple being fed to the amplifier.
1mm diam 50 to 100 turns (~50uH to 150uH + ~0r2) to give this attenuation of the HF component in the nominally DC supply.
The r of the inductor is what generates the heat. r = 0r2 with 2A of bias dissipates ~0.8W, peanuts ! Even 4A of bias results in ~3W of dissipation.
I can clearly see the "rounding" of the ripple being fed to the amplifier.
1mm diam 50 to 100 turns (~50uH to 150uH + ~0r2) to give this attenuation of the HF component in the nominally DC supply.
The r of the inductor is what generates the heat. r = 0r2 with 2A of bias dissipates ~0.8W, peanuts ! Even 4A of bias results in ~3W of dissipation.
Most of N.P.s published DIY writings suggest about 2mH Air Core for CLC. Although CRC is also a filter, the rounding of the ripple by the CLC without lots of loss or increasing supply impedance, is an important function to the spectrum of "Quiet" in the supply noise. Not just getting rid of 50-60 cycle stuff but, the higher frequencies involved in the cap charging pulses and maybe even diode bridge noise. The parasitic leakages etc. of the big inductor may still pass higher frequencies. So, a smaller inductor or resistor still has value, without inducing excessive losses.
Thanks guys.
Looks like an air core of this size is about $25 or so. I see why more people are not using CLC. Because it's expensive! I'll keep my eye out for some cheap air cores to play with.
What led me down this path was I started experimenting with PSU mods and found they make a big difference. I am running 3x33,000uf computer grade caps per rail and had a 4.7uf bypass cap on the final set of caps. I picked up some cheap 10uf poly caps and bypassed all the elecrolytics in the PSU with them. I wasn't expected much of a change but it was significant. So my thought was moving to CLC would also change things, hopefully for the better.
Looks like an air core of this size is about $25 or so. I see why more people are not using CLC. Because it's expensive! I'll keep my eye out for some cheap air cores to play with.
What led me down this path was I started experimenting with PSU mods and found they make a big difference. I am running 3x33,000uf computer grade caps per rail and had a 4.7uf bypass cap on the final set of caps. I picked up some cheap 10uf poly caps and bypassed all the elecrolytics in the PSU with them. I wasn't expected much of a change but it was significant. So my thought was moving to CLC would also change things, hopefully for the better.
I don't see the price as a big turn off, if you're building 1 amplifier and 50$ brings you quite an improvment on PSU performance than it might be worth the extra price. 50$ in a 500$ build is not that much more!
ps: where did you them at 25$ I've seen such inductors at least at 30-35$ each
ps: where did you them at 25$ I've seen such inductors at least at 30-35$ each
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Is there a upper limit for the inductance?
This looks like a nice afordable option
You can get double the inductacne for a little more $
This looks like a nice afordable option
You can get double the inductacne for a little more $
the ones i find goes for around $35-37 a pc. 14AWG 2-2.2mH and 0.3-0.39ohm
and one might need 4 of them (dual mono or mono Blocks). at around 2pounds a pc, it can be an expensive shipping too
and then there is taxes of course.
you get 20pc 0.47ohm 3W resistors for $10. and no extra shipping charge. so i will say that it is a hugh extra cost to use inductors.
in my case, a dual mono amp build will cost me $150 for the aircore coils. an extra $50 in shipping. and 25% taxes on top of this. that comes out at $250 for the coils alone.
and one might need 4 of them (dual mono or mono Blocks). at around 2pounds a pc, it can be an expensive shipping too
and then there is taxes of course.you get 20pc 0.47ohm 3W resistors for $10. and no extra shipping charge. so i will say that it is a hugh extra cost to use inductors.
in my case, a dual mono amp build will cost me $150 for the aircore coils. an extra $50 in shipping. and 25% taxes on top of this. that comes out at $250 for the coils alone.
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but why use air coil?
An iron core inductor will give you a lower price and better lower resistance.
Check these out
Or these
With shipping and tax you should be around 125€/150$ and lower resistance too!
An iron core inductor will give you a lower price and better lower resistance.
Check these out
Or these
With shipping and tax you should be around 125€/150$ and lower resistance too!
but why use air coil?
An iron core inductor will give you a lower price and better lower resistance.
Check these out
Or these
With shipping and tax you should be around 125€/150$ and lower resistance too!
Once you have the DC current flowing to the Load, how much effective reactance will you left with small cored coils, Saturation is always a problem with a high permiability core.. Air core coils do not have the Saturation problem.
I think the Tiny metallic cores will be useless in Power Amplifier supply duty.
The power supply Choke I have handy at 18mH weighs 2.5Kg. It was designed for
CLC duty.
With core coils take of core saturation. EDIT: Pardon me, I overlooked Art's post.
I went for four Mundorf BI100 2.2 mH 0.27 Ohm. You'll find similar one here:
Mundorf feron-core coils homepage
Currently I'd go for these:
https://www.intertechnik.com/Shop/Cross-over-parts/Inductors/Bar-core-inductors/1768,en,78
Even better, this price is hard to beat:
https://www.intertechnik.de/Shop/Fr...spulen/Trafokern/_FE96-30-180_1768,de,75,3519
I still have several suitable coils in my spare box, but all of these just come in pairs
and for dual mono amps I unfortunately need quads. Same with old coils on ebay.
Most do come in pairs. However, this would be sufficient if you just plan to build a
stereo amp. There are lots of them from recent loudspeaker projects.
I went for four Mundorf BI100 2.2 mH 0.27 Ohm. You'll find similar one here:
Mundorf feron-core coils homepage
Currently I'd go for these:
https://www.intertechnik.com/Shop/Cross-over-parts/Inductors/Bar-core-inductors/1768,en,78
Even better, this price is hard to beat:
https://www.intertechnik.de/Shop/Fr...spulen/Trafokern/_FE96-30-180_1768,de,75,3519
I still have several suitable coils in my spare box, but all of these just come in pairs
and for dual mono amps I unfortunately need quads. Same with old coils on ebay.
Most do come in pairs. However, this would be sufficient if you just plan to build a
stereo amp. There are lots of them from recent loudspeaker projects.
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No you won't ! Chokes with ferrite cores will not have any inductance to speak of once DC passes , you'll end up with little more reactance than the DCR . Laminated/gapped chokes are what is required or if you can tolerate the DCR (and cost of the copper) , air core . Hammond 159ZJ 10mH 5A is probably suitable for the smoothing choke
316a
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