Ed Simon's answer is unequivocally best. If (R2/R1) = N (typically N=20) then just connect N identical resistors in series to get R2. Connect 1 resistor to get R1. Presto, identical power dissipation and identical temperature and identical temperature-vs-time dynamic behavior in R2 and R1. Thus the ratio R2/R1 does not vary with signal level, does not vary with temperature, and does not vary with time. Thanks, Ed!!
But then the equivalent series inductance increases x20, could be a serious stability issue. In my book, connecting 20 resistors in series is wrong, I’d rather connect 20 resistors in parallel (if really that many are required). A 10W feedback resistor is hardly ever required.
Thick film network designers have been doing this since the 60's. We used to buy them.
No, they (Magnet Audio) would, in your name, with your logo and name on the product:
then send it to audio magazines for review:
I can report to all here that I had this amp design prototyped for myself and recently sent to Asian Audiophile magazine for review and listen and get thier comments on the sound. They said they were able to clearly hear the character of the various preamps they had used it with..
Then set a price and advertise the product:
https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-129.html#post5464883
Now go tell everybody you would not collect anything of the proceedings, or you would donate every penny to the Panda Bear protection fund.
N.B. This is Damir’s amp, of course. You could at least have the decency to add his small business name (Verson) somewhere on the case and/or in the ads. You now have the amplifier stability matzo ball in your lap and, as any “designer” of your kind, have no clue how to address.
P.S. I have no problem with any audio commercial operation. But playing the innocent DIYer comedy role, and for so many years, while fishing here for your next product... I find this dishonest and disgusting. Your CEO opinion may of course find this a standard operating procedure.
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Damir’s amp is free. I think you are jealous because you can not design an amp as good as Damir’s amp
You mean you are not in audio business?
Here you go.
Looks good (thank-you) while I'm not so sure that connecting resistances in series should be such a good idea concerning total reactance ?
My question was too about sound quality as it is a critical point in the amp. Hence my question about the kind of resistances best to be used. ( And a little about size and aesthetic).
Show me a person without bias and I will show you a person without an opinion. Ergo, those who accuse you of bias has expressed an opinion, glass houses and all that.
From a sound quality perspective, series or parallel doesn’t matter. It is much more critical to always keep the resistor perpendicular to the Earth magnetic field and do not attempt to install the resistor using leaded solder when the moon is in the third quarter of a synodic month.
The largest benefit audio-wise is to keep the voltage drop across each R low so volt coefficient effect is reduced. Thus, series.
-Richard
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Damir’s amp is free. I think you are jealous because you can not design an amp as good as Damir’s amp
Yes, I am very jealous
. Thanks for identifying yourself as yet another supporter of Richard’s business model.
I think that power dissipation in resistors can be important, especially with feedback resistors, but I would not put 20 in series in order to balance the dissipation. Just use a large enough resistor for the main feedback resistor (out to input), larger than the very minimum, and use a quality 1% Dale or equivalent resistor. That is what I use. Rely on thermal capacitance primarily, rather than thermal resistance.
Richard: I was looking back through some 80's TAA mags, and there you were!
Richard: I was looking back through some 80's TAA mags, and there you were!
Damir’s amp is free. I think you are jealous because you can not design an amp as good as Damir’s amp
That is correct. I dont know where Waly (Syn08) has been. But seems like he has a personal mission to counter any thing and everything I say or do... right or wrong.
Damir design is being build by others, i am sure. Plus his other fine designs. All published for DIY. What I showed is my DIY effort in packaging it. The fact that I have resources available to me to build it should not be a problem for any one.
THx-Richard
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Thanks J.C.
Dale metal film is what i thought at first sight. Parallel to get 6W (dissipated power at + or - V DC). It should be enough for music. Same dissipation on each one on the two sides.
Do-you have an opinion about thick film VS oxide VS metal film ? Big difference if any on the way they sound ?
What about 2 TO-220 mounted on both side of the same radiator (a plate) ?
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I am not retired...Life is good.
If what you do from 9 to 5 is fun.... it is not work.
Jn
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