[Fred_fred2004]

Spot on

 

[millwood]

Quote:

Originally Posted by Jules /img/forum/go_quote.gif When someone ask you why you are suggesting a modification, responding by saying even a high school dropout would recognize why makes people think you are a smart ass, or an idiot. People are reading on here to learn, not to be insulted by you.

that a-hole approach is needed to talk to a-holes.

Quote:

Actually, it will effect the gain at the opamp output pin, but not at the output as drawn.

but isn't the gain on the output what we are discussing about?

while your conclusion is right, do you know why that's the case?

Quote:

I have yet to find one post of his where he was helpful and non-combative.

I cannot be held responsible for your ignorance.

Quote:

There is absolutely no advantage in using a resistor greater than 100ohm for R5.

wrong answer. you are out.

 

[rembrant]

This message is hidden because millwood is on your ignore list. =bliss

 

[TzeYang]

good lord.

Before even making ad hominem attacks why don't you guys analyze and understand the point Milliwood is trying to make? He sounds arrogant but all his points are relevant and valid.


1) R2. Increasing this value increases the susceptibility to noise due to the high impedance at the input. Johnson noise for instance. Lowering it is usually a better method to combat noise but since most of the people uses a 10K pot so we want the value here to be at least 100k to prevent the pot from loading it too much. He's right about the 47k. You can try it but I would still go for 100k to be safe. I use 470K at most and there was never any issue with noise. Your personal layout skill here matters.

2) R5. All your HD650s K701s and so on are designed on a common headphone's standard source impedance (120 Ohms). If anyone of you paid attention to Meier's desktop amplifiers you'll realize that you have a High Z OUT headphone jack. It's configured to be at 120Ohms (120 Ohms series resistor). It's a matter of taste. It does not matter if it goes up to 120 Ohms. You help reduce noise and other issues too. Although, ideally the output impedance should be as low as possible.

 

[rembrant]

Quote:

1) R2. Increasing this value increases the susceptibility to noise due to the high impedance at the input. Johnson noise for instance. Lowering it is usually a better method to combat noise but since most of the people uses a 10K pot so we want the value here to be at least 100k to prevent the pot from loading it too much.

Right, which is why advocating the use of anything lower is absurd. You tell me where I can buy a 5kohm dual log pot and I'll start useing 50k
Quote:

R5. All your HD650s K701s and so on are designed on a common headphone's standard source impedance (120 Ohms). If anyone of you paid attention to Meier's desktop amplifiers you'll realize that you have a High Z OUT headphone jack. It's configured to be at 120Ohms (120 Ohms series resistor). It's a matter of taste. It does not matter if it goes up to 120 Ohms. You help reduce noise and other issues too. Although, ideally the output impedance should be as low as possible.

Again, this is correct and why it is recommended to use as little resistance as is required.

Most of us know and understand these limitations. The last thing we need is some one with a horrible attitude either restating or refuting our statements while insinuating that we are all undereducated and beneath them.

As far as I'm concerned, he can either get a clue or get out.

 

[millwood]

Quote:

Originally Posted by rembrant /img/forum/go_quote.gif Most of us know and understand these limitations. The last thing we need is some one with a horrible attitude either restating or refuting our statements while insinuating that we are all undereducated and beneath them.

what you know and what you think you know are two different things.

 

[Pars]

Hmmm. Not sure that was warranted as he/she could have potentially made some valuable contributions (with a massive attitude change, as in not being an ******). But I guess it didn't surprise me too much.

 

[TzeYang]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Hmmm. Not sure that was warranted as he/she could have potentially made some valuable contributions (with a massive attitude change, as in not being an ******). But I guess it didn't surprise me too much.

You're right though. I don't know if he had some personal problem with this forum or what.

Quote:

Originally Posted by rembrant /img/forum/go_quote.gif Right, which is why advocating the use of anything lower is absurd. You tell me where I can buy a 5kohm dual log pot and I'll start useing 50k Again, this is correct and why it is recommended to use as little resistance as is required. Most of us know and understand these limitations. The last thing we need is some one with a horrible attitude either restating or refuting our statements while insinuating that we are all undereducated and beneath them. As far as I'm concerned, he can either get a clue or get out.

It's fine to use 47k for your 10k pot. Some BJT amplifiers uses lower value ground resistors so the input bias is not overly low (Ib =/= 0).