Leave the music input as it is now, and connect the output of the amp to the PC aux input as shown in the picture below.
Need to say, this can give you wrong result, because of residual. This will interfere with the soundcard ADC sampling frequency and distort the measurements. I have seen somewhere the AES recommendations about the FFT/THD analyzer input filter for class D amp parameter measurements. Ideally, this filter should be used here.
I gotta build that circuit with the resistors and caps?
Or just Headphone input and Aux input connections are enough.
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Without these resistors and caps you will produce the short circuit for some of the half bridges in your amp via the PC Gnd connection, and deliver the 20V wave into soundcard aux input, where usually it is designed for 0.7-1V only...
Allright I will produce another circuit-board for this and take the output of this into the microphone jack input of the PC.
SpeactraPlus Manual tells me the audio you are trying to measure should be connected here or into Line-In.
Okay, I have simplified the schematic slightly, so it will be not so hard to build it.
This should work too, I think... Attachments
Also does it matter which capacitor I connect to which leads of the jack?
At this moment I'm thinking the capacitor for Phase Leg A goes to the positive Input and the Phase Leg B cap goes to the ground Input.
Am I Correct?
Edit: I'm glad there's room in my own board to do this. I'll use those IC socket's holders that hold the IC Pins to add the resistors and capacitors.
At this moment I'm thinking the capacitor for Phase Leg A goes to the positive Input and the Phase Leg B cap goes to the ground Input.
Am I Correct?
Edit: I'm glad there's room in my own board to do this. I'll use those IC socket's holders that hold the IC Pins to add the resistors and capacitors.
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Yes, it is ok so.
Ideally it is needed to use the op amp here to convert the differential input into single output, but it is real overkill for this project...
Okay, I have simplified the schematic slightly, so it will be not so hard to build it.
:S
You mean 20 Watts?? Have you heard about the Ohm's Law?
There is no need to use such a power resistors...These can be usual smallest 0.125 watts carbon or film resistors.
You mean 20 Watts?? Have you heard about the Ohm's Law?
These can be usual smallest 0.125 watts carbon or film resistors.
Ok. My Bad..
Edit: Oh Hell, too much reading on that manual. I'll just perform the THD v.s Freq test and I'll go from there.
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81bas at the moment I am using some crap speaker. Would it be wise to invest in a speaker with tweeter, mid-range and woofer all in one?
Also It's loud and I mean really Loud. I wasn't expecting to build anything loud as this. But at max volume the speaker or amplifier to me sounds like it's clipping.
Only way to test for sure is like the 4 Ohm resistor test you said and crank the volume all the way to see if it clips or not.
Also It's loud and I mean really Loud. I wasn't expecting to build anything loud as this. But at max volume the speaker or amplifier to me sounds like it's clipping.
Only way to test for sure is like the 4 Ohm resistor test you said and crank the volume all the way to see if it clips or not.
How do you plan to demostrate your amp with a single 'crapy' speaker?
You need some good speaker for about 50-100 watts, to show, how your amp produces almost 70 watts RMS into 4 Ohm from a single 20 volts rail without a single heatsink! How do you plan to demostrate your amp with a single 'crapy' speaker?
Any suggestions? lol
And the speakers are 8 Ohms as well mate ( well the crap ones I am using now anyway).
Without You, Ledmania and a few others replying in this thread. I'd be a goner by now.
Kudos to you sir
You are welcome!
For which power are they rated? Please, post the photo of them here
You are welcome!
For which power are they rated? Please, post the photo of them here
I'm not too sure mate. These are like old, pulled from the attic sorta speakers.
All I know from the label on the back is that it's a 8 Ohm Speaker. I will post the picture of the speaker tomorrow with the brand name. Though that brand is dead now I think.
And Also the THD vs Freq graph if i figure out the software as well.
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Here's the picture of the speaker
http://img33.imageshack.us/img33/9614/speakerq.png
It's brand is called 'Thorn'.
All I know is that it's a 8 Ohm speaker. But that's about it.
http://img33.imageshack.us/img33/9614/speakerq.png
It's brand is called 'Thorn'.
All I know is that it's a 8 Ohm speaker. But that's about it.
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