[n_maher]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif Also, you will want to mod the output to the pre-amp outs if you decide to do it. I added a capacitor to that output. Not a high value at all, but it did make a difference.

What do mean, that you added a cap to the preamp output? Did you add this in series with the coupling cap that is already on the headphone output? Please elaborate.

 

[jbloudg20]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif What do mean, that you added a cap to the preamp output? Did you add this in series with the coupling cap that is already on the headphone output? Please elaborate.

I think she removed the coupling caps :facepalm:. At least that was her goal, as stated a few times.

Good thing she'll only ruin those POS cheap speakers

 

[-=Germania=-]

^ Dude - seriously you need to read before you comment.

I didn't remove any caps. I simply added stuff to an RCA out from a swicthed headphone jack.

It is kind of like so:

FYI Guys, I am using different output capacitor values than the rest of you. Mine are 220uF on output instead of 470uf

 

[jbloudg20]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif ^ Dude - seriously you need to read before you comment.

^ Dude- seriously you need to not only use quotes, but better explain yourself before you spout off. I was not the only one who was confused as to what you posted. I wouldn't remove the output caps without a servo implemented.

 

[n_maher]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif I didn't remove any caps. I simply added stuff to an RCA out from a swicthed headphone jack. It is kind of like so:

That's a low pass filter, although I'm not quite sure it works as simply as you have it drawn since in reality you have both a high pass and low pass filter on the output when using your preamp outputs.

 

[-=Germania=-]

opps wrong cap value:
Corrected:

Also you are right about it being a low pass filter, but it works a bit differently since it is directly connected at the output where it is also being grounded.

 

[jbloudg20]

So the next logical question in my head, is why are you implementing a bandpass filter for your preamp?

 

[-=Germania=-]

That filter has it cut off well above the audible range, so it does not mess with the audio signals passing through the amp.
You dont get a 1db drop until 80,000 Hz even based on calculations. It does work a little differently the way it is situated, but the basic principle applies.

It does give it a "push" factor and some more impedence to work with, making a better pre-amp out - None of the distortion that you would have if you used the amp as a direct input to your power amp.

 

[n_maher]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif It does give it a "push" factor and some more impedence to work with, making a better pre-amp out - None of the distortion that you would have if you used the amp as a direct input to your power amp.

I'd like a bit more explanation of how you figure that adding resistance on the output is going to reduce distortion. It may have quieted the noise floor on your amp but I'm not sure that's the same thing.

 

[dsavitsk]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif It does give it a "push" factor

I don't think I want an amp that drives me from my home. What exactly do you mean.

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif and some more impedence to work with, making a better pre-amp out

I don't know what this means, either.

 

[-=Germania=-]

Well, to me it seems that one of the reasons that this amp has trouble being used as a straight pre-amp is because of the output impedence and potential feedback.

What this does is bumps up the impedence, reduces feedback, and gets rid of output noise for use as a pre-amp (at least in my current system).

Having the high pass and the low pass filter in that configuration does something pretty unique as far as a balancing act between the two. I also found out that it only works well if done directly at the plug with very short resistor leads. Using the master ground and not the one sent to the plug makes a difference as well in terms of the noise - one less signal path I suppose!

I am sure thae there is more than can be done other than this simple circuit that will improve this aspect, but I have the next Millet Build concerning my mind at the moment with some changes I want to make and doing the math to figure it out.

The "push" word has to do with dynamics. There is greater dynamics, not greater noise.

Also, please note that I have the dial set at 10 o'clock and my amp at 5/8 power. That matches the output from the internal D/A converter that I was comparing it against.

I should note that using this pre-amp output from the combo previously described sounded better than using the internal D/A converter as well as just using the output of a modified Zhaolu.

 

[FallenAngel]

Just built one of these, sounds very nice, surprisingly nice for the price actually. I made mine a little more extreme in terms of parts

Alps RK27 POT
VitaminQ coupling caps
Muse FG output caps

 

[n_maher]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif Well, to me it seems that one of the reasons that this amp has trouble being used as a straight pre-amp is because of the output impedence and potential feedback. What this does is bumps up the impedence, reduces feedback, and gets rid of output noise for use as a pre-amp (at least in my current system).

Higher output impedance has never been something described to me as a positive and you'll have to clarify for me how your mods reduce feedback, I don't know what you mean there.

Quote:

Using the master ground and not the one sent to the plug makes a difference as well in terms of the noise - one less signal path I suppose!

I'm afraid I need more explanation here to - what "master ground" are you referring to? All grounds in the amp are the same thing. There is no ground sent to the plug.

 

[dsavitsk]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif Well, to me it seems that one of the reasons that this amp has trouble being used as a straight pre-amp is because of the output impedence and potential feedback. What this does is bumps up the impedence, reduces feedback, and gets rid of output noise for use as a pre-amp (at least in my current system). Having the high pass and the low pass filter in that configuration does something pretty unique as far as a balancing act between the two. I also found out that it only works well if done directly at the plug with very short resistor leads. Using the master ground and not the one sent to the plug makes a difference as well in terms of the noise - one less signal path I suppose! I am sure thae there is more than can be done other than this simple circuit that will improve this aspect, but I have the next Millet Build concerning my mind at the moment with some changes I want to make and doing the math to figure it out. The "push" word has to do with dynamics. There is greater dynamics, not greater noise. Also, please note that I have the dial set at 10 o'clock and my amp at 5/8 power. That matches the output from the internal D/A converter that I was comparing it against. I should note that using this pre-amp output from the combo previously described sounded better than using the internal D/A converter as well as just using the output of a modified Zhaolu.

This is 100% nonsense. It isn't even worth a point by point refutation as not one word of it makes any sense.

And I'm still waiting on your cable measurements.

 

[-=Germania=-]

I will take pictures.
If any of you have enough courage to try it - let me know.
Unless you actually try it and think it makes stuff sound worse...I don't see the sense in arguing this.

"Master Ground" as in directly to the ground plane instead of the ground on the switched 1/4 jack.

I will get onto the cables once school starts, but we don't start until almost the end of this month.