So I have some kind of schematics AV400 from A.Holton and I dont know is this is good schematics: in the text it stays that you use irfp240 but in the schematics in the same "pdf" file there are 2SK1530 mosfets ?!
So can that schematics be used with irfp and 2SK without any changing in the schematics: 2SK are lateral and irfp240 are vertical mosfets
So if second stage has enough current to drive irfp can the same scehmatics be used with 2SK without any change ?
I would post his schematics here so I dont know is it legal or not?
please if you have good working schematics isnig IRFP-s can you send it here: velikigrizli@gmail.com
Concerned to Auasi amplifier: it uses daul voltage supply : so it can be difficult to buld when using SMPS with feedback
Can Quasi amplifier work ONLY at +/- 70V
About AV400 Holton : What is the purpose of Q19 and Q20 from the schematics:
It wolud be much easier if I wolud post the schematics here...
So can that schematics be used with irfp and 2SK without any changing in the schematics: 2SK are lateral and irfp240 are vertical mosfets
So if second stage has enough current to drive irfp can the same scehmatics be used with 2SK without any change ?
I would post his schematics here so I dont know is it legal or not?
please if you have good working schematics isnig IRFP-s can you send it here: velikigrizli@gmail.com
Concerned to Auasi amplifier: it uses daul voltage supply : so it can be difficult to buld when using SMPS with feedback
Can Quasi amplifier work ONLY at +/- 70V
About AV400 Holton : What is the purpose of Q19 and Q20 from the schematics:
It wolud be much easier if I wolud post the schematics here...
The Quasi amplifier in the thread "Power Amp Under Development" only uses the 2 main rails, I.e. +/- 70 volt rails. The third rail was dropped during the thread so it will be quite suitable to use with your SMPS.
Cheers
Q
PS. I have not built Holton's AV400 but I'm sure it would sound great. He is well known and respected in Australia for his amplifier designs and one of his designs has been featured in the major local electronics magazine. So you can choose knowing both will be great.
Cheers
Q
PS. I have not built Holton's AV400 but I'm sure it would sound great. He is well known and respected in Australia for his amplifier designs and one of his designs has been featured in the major local electronics magazine. So you can choose knowing both will be great.
Hi medogrizli,
Answers to most of your q. about are in the thread already. You really had to do more homework. Mr. Holton's work is not in the public sector now. Don't post it openly. But the guys who have encountered it knows what you are talking about and would answer you if they want to. You can use irpf instead of the 2sk/j's and that had been answered too less than a week ago but I am not too sure if that's your q. or someone's on this subject.
Answers to most of your q. about are in the thread already. You really had to do more homework. Mr. Holton's work is not in the public sector now. Don't post it openly. But the guys who have encountered it knows what you are talking about and would answer you if they want to. You can use irpf instead of the 2sk/j's and that had been answered too less than a week ago but I am not too sure if that's your q. or someone's on this subject.
Quasi vs. Holton, obviously the amplifiers are different but both are excellent and they look like they may have a few similarities. As of yet I have not heard Holton's.
I think it is crude to sum it up this way but here goes:
A) Holton can provide you a kit approach and you must purchase the design from him. He can provide you key options to go with your purchase. He is well respected. Holton can provide the board.
B) Quasi offers you his design fully. You get to build at your own risk and skill level. Seems more exciting to me plus no charge is cool. It is fully scalable to your own desire. Q gains high respect also. If you don't want to make the Q board, you can have it manufactured.
However, Quasi’s amp comes with more support if you chose to use the DIY site as you build it. If I was Holton, I would discuss those things only in private emails to protect intellectual property.
I think you should build both and compare them? Aussie vs. Aussie!
Then you will be the expert!
Less talk more building!
Cheers,
Shawn.
I think it is crude to sum it up this way but here goes:
A) Holton can provide you a kit approach and you must purchase the design from him. He can provide you key options to go with your purchase. He is well respected. Holton can provide the board.
B) Quasi offers you his design fully. You get to build at your own risk and skill level. Seems more exciting to me plus no charge is cool. It is fully scalable to your own desire. Q gains high respect also. If you don't want to make the Q board, you can have it manufactured.
However, Quasi’s amp comes with more support if you chose to use the DIY site as you build it. If I was Holton, I would discuss those things only in private emails to protect intellectual property.
I think you should build both and compare them? Aussie vs. Aussie!
Then you will be the expert!
Less talk more building!
Cheers,
Shawn.
Build both
Use one power supply and try both? Financially no big difference to try two amplifiers. When you build the case and the power supply twice, well, that's when the money doubles.
Seriously, try both designs and good luck with your decision.
Shawn.
medogrizli said:Using only N- channel has some "theoretic" advantages
Board is not problem to make
Use one power supply and try both? Financially no big difference to try two amplifiers. When you build the case and the power supply twice, well, that's when the money doubles.
Seriously, try both designs and good luck with your decision.
Shawn.
Re: Build both
But mosfets are not so cheap and I cant say the difference by ear I am not "audiophile" my ears are not so sharp: for difference you nead measuring equipement:
So if quasi has small distorsion etc. then its ok:
is there any way to use irfp240 in the quas amplifier : I have tons of these
irfp240 is 200V mosfet, max voltage will be ok ,but other characteristic I am not sure what do you think
momentarily I have +/- 50V supply for trying and testing: Can both Holton and Quasy work on that woltage correctly ?
TomWaits said:
Use one power supply and try both? Financially no big difference to try two amplifiers. When you build the case and the power supply twice, well, that's when the money doubles.
Seriously, try both designs and good luck with your decision.
Shawn.
But mosfets are not so cheap
and I cant say the difference by ear I am not "audiophile" my ears are not so sharp: for difference you nead measuring equipement:So if quasi has small distorsion etc. then its ok:
is there any way to use irfp240 in the quas amplifier : I have tons of these
irfp240 is 200V mosfet, max voltage will be ok ,but other characteristic I am not sure what do you think
momentarily I have +/- 50V supply for trying and testing: Can both Holton and Quasy work on that woltage correctly ?
TomWaits said:
Exactly, and he had the nerve to say I had a face of trouble?
IRFP240 looks nice, I wish I had lots. You don't have audiophile ears but it sounds like you want a set. Everything is good. Flip a coin?
Less talk more building!
Shawn.
But what with the soar : irfp240 is 200V mosfet with different gate capacitiance irfp450 is 500V mosfet...
Hi Med,
it is two days since I pointed you to Bensen's spreadsheet and the link in there to do the calculations for SOAR.
You are still asking the same questions.
When are you going to do some of your own homework?
Ask us, how to insert the SOAR data, or how to use a spreadsheet, or why do I need to know the transformer voltage. Anything to show us you have at least read the reference.
There is nothing wrong with admitting you don't understand it. We can help you overcome that.
But YOU have to make a start.
it is two days since I pointed you to Bensen's spreadsheet and the link in there to do the calculations for SOAR.
You are still asking the same questions.
When are you going to do some of your own homework?
Ask us, how to insert the SOAR data, or how to use a spreadsheet, or why do I need to know the transformer voltage. Anything to show us you have at least read the reference.
There is nothing wrong with admitting you don't understand it. We can help you overcome that.
But YOU have to make a start.
SOAR is hardly the determining factor here. Since MOSFETs do not have secondary breakdown problems, SOAR is calculated only from the dissipation and it's derating, i.e. what kind of heatsink you have and how well you can thermally interface the MOSFET case to it.
The fact that IRFP450 has 190W max dissipation vs IRFP240 150W max is not very signifficant for your power levels. Either will have SOAR that any BJT can only wish for.
The determining factor, however, is the gate capacitance, and in fact, Cgd plays a major role here (this is especially relevant to quasicomplementary amps).
Although the Cgs of the IRFP450 is more than twice as large as that of the IRFP240, it's Cdg is 4 times smaller.
Cdg appears enlarged 1+(gm * Rload) times and in parallel to Cgs due to miller action. The fact that the IRFP450 has slightly larger gm does not offset the 4 times higher Cdg of the IRFP240. Because of this, the capacitance presented to the driver is approximately N * Cgs + N^2 * Cgd * gm * Rload where N is the number of parallel transistors. Note especially the N squared term in the second part of the equation!
Here is a breakdown of Cin in nF:
1 pair: IRFP240 15.5nF, IRFP250 7.44nF
2 pairs: IRFP240 59nF, IRFP450 24.5nF
3 pairs: IRFP240 131nF, IRFP450 51nF
4 pairs: IRFP240 230nF, IRFP450 87.4nF
In other words, driving 3 pairs of IRF450 is approximately equal to driving 2 pairs of IRFP240.
3 pairs of IRFP450 can statically (DC outut) dissipate 570W and handle 42A of output current, while 2 pairs of IRFP240 can statically dissipate 300W and handle 40A of output current. For larger number of pairs, the IRFP450 is a clear winner.
Under AC output with net DC=0, dissipationand current output can be up to double as the top and bottom half of the output stage share current and power dissipation equally. If you have a sufficiently large heatsink to use most of the smaller max power dissipation of the IRFP240, you can use 2 pairs of these for an output of about 120W into 8 ohms, or 240W into 4 ohms, in a quasi style amp.
EDIT - see my post below, this was based on a comparison of a Fairchild IRFP240 and ST IRFP450. parameters can differ a lot depending on who the manufacturer of the same marked part is!
The fact that IRFP450 has 190W max dissipation vs IRFP240 150W max is not very signifficant for your power levels. Either will have SOAR that any BJT can only wish for.
The determining factor, however, is the gate capacitance, and in fact, Cgd plays a major role here (this is especially relevant to quasicomplementary amps).
Although the Cgs of the IRFP450 is more than twice as large as that of the IRFP240, it's Cdg is 4 times smaller.
Cdg appears enlarged 1+(gm * Rload) times and in parallel to Cgs due to miller action. The fact that the IRFP450 has slightly larger gm does not offset the 4 times higher Cdg of the IRFP240. Because of this, the capacitance presented to the driver is approximately N * Cgs + N^2 * Cgd * gm * Rload where N is the number of parallel transistors. Note especially the N squared term in the second part of the equation!
Here is a breakdown of Cin in nF:
1 pair: IRFP240 15.5nF, IRFP250 7.44nF
2 pairs: IRFP240 59nF, IRFP450 24.5nF
3 pairs: IRFP240 131nF, IRFP450 51nF
4 pairs: IRFP240 230nF, IRFP450 87.4nF
In other words, driving 3 pairs of IRF450 is approximately equal to driving 2 pairs of IRFP240.
3 pairs of IRFP450 can statically (DC outut) dissipate 570W and handle 42A of output current, while 2 pairs of IRFP240 can statically dissipate 300W and handle 40A of output current. For larger number of pairs, the IRFP450 is a clear winner.
Under AC output with net DC=0, dissipationand current output can be up to double as the top and bottom half of the output stage share current and power dissipation equally. If you have a sufficiently large heatsink to use most of the smaller max power dissipation of the IRFP240, you can use 2 pairs of these for an output of about 120W into 8 ohms, or 240W into 4 ohms, in a quasi style amp.
EDIT - see my post below, this was based on a comparison of a Fairchild IRFP240 and ST IRFP450. parameters can differ a lot depending on who the manufacturer of the same marked part is!
quasi said:
Thanks, but unfortunately the figures are only right for a given manufacturer of MOSFETs.
I have just checked how various types of MOSFETs with the same designation differ across manufacturers.
Here is a small comparison: Fairchild IRFP240 has 160pF Cdg, while IRF IRFP240 has 130pF. Cgs is more or less the same. However, with the IRFP450, things canbe DRASTICALLY different. ST IRFP450 has Cgd only 40pF, while IRF IRFP450 has 340pF - a factor of 8.5 times larger!!! To make matters worse, it's gm is also higher, 17A/V at 11A vs 15A/V for the ST version.
Using these figures, replacing IRF IRFP450 with IRF IRFP240 is not only possible, but highly recomended!!!
In any case, it is clear from my first post that reducing Cgd (also known as Crss) is af high importance for quasicomplementary amps, including your design. Sometimes chosing the manufacturer of a supposedly equivalent part may be the key to achieving this goal.
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