Last night I tried replacing the 0.2 Ohm res with L||R network in ser. with the output. The res is 10 ohms/1W and I put 8 turns of wire (24AWG from a network cable) on top of it. My GC is even more civilized now. So I do recommend using it. It protects from instability in the HF range much better that the 0.2 res no matter the type of speakers. Also it allows me to go higher with the FB resistors for better DC offset (I'm using 4.7k/100k) without ill effects.
So I recommend using the L||R with high cap PSU.
Just my observation.
Greg
So I recommend using the L||R with high cap PSU.
Just my observation.
Greg
This may or may not be due to the inductor as it really has very little inductance. What you are hearing is IMO the effect of removing some nasty ceramic resistors (which really sound like sh**) and replacing them which a much better sounding, slightly inductive wirewound resistor. I have been using similar resitors but wound to cancel the inductance for many years and they sound better than even boutique high power resistors.
analog_sa said:
Interesting.
Do you know the internal contruction of the wirewound resistors?
How do you cancel the inductance externaly?
Winding in the opposite direction?
Here we go again, discussing the resistors' polarity.
😀
Hi Carlos
A good discussion of winding methods can be found here
I have only used conventional insulated copper (wire wrap or magnet wire) bifiliar wound and the ends connected in reverse phase. Of course you get only half the resistance this way. It seems like a more economical solution to follow Sully's suggestion from the quoted thread.
As i intend rebuilding my GC with 3886 following all your recommendations i guess it's winding time again 🙂
A good discussion of winding methods can be found here
I have only used conventional insulated copper (wire wrap or magnet wire) bifiliar wound and the ends connected in reverse phase. Of course you get only half the resistance this way. It seems like a more economical solution to follow Sully's suggestion from the quoted thread.
As i intend rebuilding my GC with 3886 following all your recommendations i guess it's winding time again 🙂
analog_sa said:
I remember that thread, it's very interesting.
I never considered building my own resistors.😛
"If you want to make an apple pie from scratch,you must first create the universe."
(c) Carl Sagan
If you seriously consider buying high-power Caddocks per example, spending 10 min to wind your own may actually seem appealing 🙂
Tom probably spends longer but he is really a perfectionist.
analog_sa said:
there was an item in the Linear Tech magazine (I think, correct me if I am wrong) on calculating R for current shunts by designing them on the PCB.
what are you using for resistance wire.
and another completely irrelevant sidebar discussion on resistance wire -- the reason that "toasters" in the U.S. in the 1950's lasted so long was that GE and Westinghouse bought up large stocks of government surplus nichrome wire -- the kind which was used in flying suits (and tested to a high standard) -- you couldn't kill one of these things -- us cynics believe that in order to get the market for small appliances moving they substituted inferior wire as part of programmed obsolescence. my mother uses the same toaster she received as a wedding present in 1949.
Programmed obsolescence is very real and accelerating. We got a basic steam iron about 10years ago. It lasted about 7years. Since then we have had to replace one every year.
Every time I go into my local repair shop I see huge flat screen TVs piling up, with about one or two years on the clock. Our ex rental TV is still going strong after 10years.
Quite frankly it disgusts me.
Shoog
Every time I go into my local repair shop I see huge flat screen TVs piling up, with about one or two years on the clock. Our ex rental TV is still going strong after 10years.
Quite frankly it disgusts me.
Shoog
I was told by somebody in the trade that washing machines are designed to last just two years.
Given the amount of energy involved in making these items, and then diposing of them and then recyling the parts, this is nothing short of environmental suicide!
Given the amount of energy involved in making these items, and then diposing of them and then recyling the parts, this is nothing short of environmental suicide!
As i already mentioned in this thread i use wire wrap kynar insulated wire or just magnet wire. Nichrome seems way too non-linear to expect anything nice and soldering it is pretty much impossible. That's the stuff that 'white coffin' resistors use and they all sound atrocious to my ears.
I first started winding sub one ohm resistors at the time i was into discrete SS amps and noticed that the addition of emitter resistors always brought the sound down. With home made resistors the difference was barely perceptible.
Apparently mine has a design fault 🙂 Or it's just too old.
What's wrong with that anyway? If i was a manufacturer i'd make sure all products self destructed a day after the warranty expired.
jackinnj said:
Everything lasted longer and there were people to repair and parts available for replacing.
In 1989~1990 I repaired computer motherboards and monitors.
Now you don't repair. You trash it.
Talking about lasting longer, look at modern cars.
Older cars with decades old had the original carb in shape.
On new cars it is very common to have problems with the electronic injection/ignition in a question on 2~3 years.
Specially when warranty expires.
And they don't repair it.
They just replace the "black box" and ask you a huge amount of money.
carlosfm said:
I built up a quickie amp today using LM3875 with 2Kohm and 100 ohm feedback resistors as previously shown:
😀Re: Re: Improving the Non-Inverting chipamp
😎
How much dc-offset?
jeff mai said:I built up a quickie amp today using LM3875 with 2Kohm and 100 ohm feedback resistors as previously shown:
😎
How much dc-offset?
Re: Re: Re: Improving the Non-Inverting chipamp
About 4mV on both channels. This is less than the other chip amps I've built by quite a bit. I think all the others were 10 - 30mV
carlosfm said:
About 4mV on both channels. This is less than the other chip amps I've built by quite a bit. I think all the others were 10 - 30mV