Ouroboros said:
Ok, then how they put on same amplifier 2-4-8 ohms on output?
Classically Itech series amplifier of Crown wich says safe loads of 1-2-4-8 ohms on each channel...
How they do that?
They designed it to 1 ohm, then apply feedback after the filter.
But since you build a sub amp, pre-filter feedback, you don't have to design the filter this way. Trust me! ~20 uH is a good value, but there is no equation to calculate it!
Against ringing, you can use an RC damper in parallel with output. Rl+C3. C3=2 uF is enough, there will be more residual, but it doesn't matter at all! (But you have to use polipropilene foil capacitor!)
Ouroboros!
This is a sub amp, operating at 125 kHz! Why would you set fc=35 kHz?
But since you build a sub amp, pre-filter feedback, you don't have to design the filter this way. Trust me! ~20 uH is a good value, but there is no equation to calculate it!
Against ringing, you can use an RC damper in parallel with output. Rl+C3. C3=2 uF is enough, there will be more residual, but it doesn't matter at all! (But you have to use polipropilene foil capacitor!)
Ouroboros!
This is a sub amp, operating at 125 kHz! Why would you set fc=35 kHz?
Pafi said:
Ok, got it, do you tell me to put some resistor seried with C3, I will try it (against speaker missing ringing).
And, if I want to modify feedback to be Post Filter,what will be the difference?
Presumimg I want to transform that amp in a fullaudio amp?
Carrier will be by ex 250 Khz, for full audio, I think it's enough...
I observed on Crown K2, is post filter feedback, and they used triangle carrier on pin 3(+) input, instead mine wich is on pin 4(-) input...
No, you need an other capacitor, with the same value, in series with a resistor which has the same resistance as the load, and then you have to connect this parallel with the output.
Series connection as in the linked page can also work, but that is more expensive, and bigger (because you need twice as much capacitance for the same result).
You ought have to make some tiny, but very important modifications, but I'm afraid I don't have time to share the know-how.
So
So, I received from the producer, exact parameters of mine Dark Blue Cores :
G1W 88S540 :
What's your opinion?
Is or isn't , suitable for classD Output filter?
Can anyone tell , for 20uH, at how mant amperes it will saturate?
Also I can buy some of these cores:
Cores in material grades:
N (60ui),
Z (125ui),
S (140ui),
NH (60ui),
ZH (125ui)
SH (140ui).
So, wich will be the best for classD inductors?
So, I received from the producer, exact parameters of mine Dark Blue Cores :
G1W 88S540 :
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
What's your opinion?
Is or isn't , suitable for classD Output filter?
Can anyone tell , for 20uH, at how mant amperes it will saturate?
Also I can buy some of these cores:
Cores in material grades:
N (60ui),
Z (125ui),
S (140ui),
NH (60ui),
ZH (125ui)
SH (140ui).
So, wich will be the best for classD inductors?
Core saturation is a function of amp turns. Inductance is a function of Al. So for a desired inductance and peak current, find a core with a suitable Al and NI (amp turns) rating. Cores with lower Al have higher saturation NI capability.
So, searching in the offer that I received, I looked at those cores:
And:
Question:
Are those cores suitable for output coils?
If yes, second question is, wich of them G2B83 or G2B93 is the best?
From what I understand from the producer, their cores are pretty liniar till 1 Mhz freq.
Thank you all, and wait for some answers!
An externally hosted image should be here but it was not working when we last tested it.
And:
An externally hosted image should be here but it was not working when we last tested it.
Question:
Are those cores suitable for output coils?
If yes, second question is, wich of them G2B83 or G2B93 is the best?
From what I understand from the producer, their cores are pretty liniar till 1 Mhz freq.
Thank you all, and wait for some answers!
DjLeco!
From datasheet G1W 88S540 seems to be usable. There is no saturation characteristic, but I think it can work up to about 1000 A*turn, so you can use it as a 20 uH, ~65 A coil. It will be warm, but not too hot (~6 W core loss at 180 V supply). Not perfect, but quite good. If you use 2 of them, then they can be used up to ~90 A, with the same core loss.
From datasheet G1W 88S540 seems to be usable. There is no saturation characteristic, but I think it can work up to about 1000 A*turn, so you can use it as a 20 uH, ~65 A coil. It will be warm, but not too hot (~6 W core loss at 180 V supply). Not perfect, but quite good. If you use 2 of them, then they can be used up to ~90 A, with the same core loss.
Yes.
Thank you Pafi.
And between the two cores, G2B83 or G2B93 ,wich is the best for output inductor?
The G1W 88S540, is no longer produced, I have just couple of them, so I must take (order)one from two, so be,G2B83 or G2B93?
Thank you Pafi.
And between the two cores, G2B83 or G2B93 ,wich is the best for output inductor?
The G1W 88S540, is no longer produced, I have just couple of them, so I must take (order)one from two, so be,G2B83 or G2B93?
They are quite similar, G2B93 is a little better than G2B83 (lower core loss), the overall performance is almost identical to G1W 88S540.
Can I ask you how much do they cost?
Can I ask you how much do they cost?
Pafi said:
Mine G1W 88S540 is R50 core , the G2B93 and G2B83, are R58 cores, so sure those are better.
Momentan I doesn't know their price, I'm waiting for answers on email from the producer...
Diameter alone doesn't tell much. Your G1W has lower permeability, which is good, and it has higher area, which is also good.
Pafi said:
So, from how much you know now about mine G1W 88S540 core, can you approximate, at how many amperes will saturate for 30uH inductance?
Yes, I could, but you must be able to do that also.
Basic equation: L= Al*turns*turns (in nH) ->
turns= suare root of (L/Al)
Current*turns=1000 A (approximately), you must divide it by turns to get the saturation current.
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