With OPA552 this basic circuit would pretty much start smoking.
We are able to push supply voltage near +-30V but it would produce so much heat that those output transistors are unable to sink all that heat...
I didnt even try. But I made it class AB.
Now, I have it running nicely
It sounds as great as it should but I need to design PCB for that amp, its so much fun if you can try many opamps with it, they all sound different.
If I compare OPA27GP to OPA551 I cant hear many differences only maybe the OPA27 has a bit better highs but thats it, they sound very similar.
In class AB the output power is nearly 40W RMS at 4R, I cant really measure RMS but its close.
Im going to be off from this for a while, I started building VSSA...
I need something to compare it to... Yet Im unable to do any measurements, I dont have much tools... Soldering iron and multimeter, thats it.
We are able to push supply voltage near +-30V but it would produce so much heat that those output transistors are unable to sink all that heat...
I didnt even try. But I made it class AB.
Now, I have it running nicely
It sounds as great as it should but I need to design PCB for that amp, its so much fun if you can try many opamps with it, they all sound different.
If I compare OPA27GP to OPA551 I cant hear many differences only maybe the OPA27 has a bit better highs but thats it, they sound very similar.
In class AB the output power is nearly 40W RMS at 4R, I cant really measure RMS but its close.
Im going to be off from this for a while, I started building VSSA...
I need something to compare it to... Yet Im unable to do any measurements, I dont have much tools... Soldering iron and multimeter, thats it.
If you make a resistor divider and and buffer opamp you can use your computer and soundcard as a simple scope using Visual Analyzer.
This way you can actually see what your signal looks like and measure its AC characteristics and THD as well as Frequency response using other programs like HOLMimpulse and REW.
In this thread I designed one to measure the output of my amps and measure step-up transformers for ESL's for up as high 10Kv going directly into my computer,
A TEST JIG FOR FINDING ESL STEP-UP TRANSFORMER PARAMETERS
A TEST JIG FOR FINDING ESL STEP-UP TRANSFORMER PARAMETERS
Even though I have a scope I can't measure THD with it, and this method actually was better than using my scope in some cases when it could pick out the signal buried deeply in the 3.0mv residual noise floor.
This same setup can be used to precisely measure capacitors and inductor's as well as resistors with a different configuration of the interface input opamps.
I show such examples of this powerful free software in this thread here,
http://www.diyaudio.com/forums/software-tools/212908-exploring-visual-analyser-va-3.html#post3383659
This is the beginning of the thread,
http://www.diyaudio.com/forums/software-tools/212908-exploring-visual-analyser-va.html#post3028849
It is an amazing tool and very accurate once you learn to calibrate and use it.
It is very well suited for audio use.
I have used it with every type of sound card that I have and they all produced great results.
But of course the better the card you have the better your results will be as you are limited by your cards sample rate.
Still good enough for audio though.
The newest version that is out can be found in the forum section of their website and so far it is the most stable version yet.
There is a x86 and a x64 versions available.
Visual Analyser 2011 XE
You will have to sign up to the forum in order to get the latest ones.
Just love this program, Do give it a try.
It beats not having a scope at all.
I rarely have to power up my scope now unless I am working with faster signals.
Wave Spectra is another great scope program as well that does FFT's (THD) but it doesn't have the measuring capability that VA has, although you can only do AC measurements with a sound card.
The link to WaveSpectra and many more of these type of programs can be found in these threads but if you can't locate them let me know and I will dig them up for you.
Cheers !!!
jer
This way you can actually see what your signal looks like and measure its AC characteristics and THD as well as Frequency response using other programs like HOLMimpulse and REW.
In this thread I designed one to measure the output of my amps and measure step-up transformers for ESL's for up as high 10Kv going directly into my computer,
A TEST JIG FOR FINDING ESL STEP-UP TRANSFORMER PARAMETERS
A TEST JIG FOR FINDING ESL STEP-UP TRANSFORMER PARAMETERS
Even though I have a scope I can't measure THD with it, and this method actually was better than using my scope in some cases when it could pick out the signal buried deeply in the 3.0mv residual noise floor.
This same setup can be used to precisely measure capacitors and inductor's as well as resistors with a different configuration of the interface input opamps.
I show such examples of this powerful free software in this thread here,
http://www.diyaudio.com/forums/software-tools/212908-exploring-visual-analyser-va-3.html#post3383659
This is the beginning of the thread,
http://www.diyaudio.com/forums/software-tools/212908-exploring-visual-analyser-va.html#post3028849
It is an amazing tool and very accurate once you learn to calibrate and use it.
It is very well suited for audio use.
I have used it with every type of sound card that I have and they all produced great results.
But of course the better the card you have the better your results will be as you are limited by your cards sample rate.
Still good enough for audio though.
The newest version that is out can be found in the forum section of their website and so far it is the most stable version yet.
There is a x86 and a x64 versions available.
Visual Analyser 2011 XE
You will have to sign up to the forum in order to get the latest ones.
Just love this program, Do give it a try.
It beats not having a scope at all.
I rarely have to power up my scope now unless I am working with faster signals.
Wave Spectra is another great scope program as well that does FFT's (THD) but it doesn't have the measuring capability that VA has, although you can only do AC measurements with a sound card.
The link to WaveSpectra and many more of these type of programs can be found in these threads but if you can't locate them let me know and I will dig them up for you.
Cheers !!!
jer
Haha! Ive tried that Virtual analizer... Mostly its signal generator...
Built a pair of pretty much High-end speakers and needed to measure frequency response.
Got it done fairly well, wonderful program..
I almost got it how to get it working as oscilloscope
I'll try to make it work...
Any circuits for that buffer?
Built a pair of pretty much High-end speakers and needed to measure frequency response.
Got it done fairly well, wonderful program..
I almost got it how to get it working as oscilloscope
I'll try to make it work...
Any circuits for that buffer?
Last edited:
I wish I could edit my post but still I just have to ask for advice..
I dont know what to do with those grounding trackes and power traces that go to the opamp. The trimmer... maybe I can use fixed resistor?
There isnt alot of current flowing thru but yeh ..
http://s6.postimg.org/6lre8fa1d/my_new_idea_Mihkus.png
I dont know what to do with those grounding trackes and power traces that go to the opamp. The trimmer... maybe I can use fixed resistor?
There isnt alot of current flowing thru but yeh ..
http://s6.postimg.org/6lre8fa1d/my_new_idea_Mihkus.png
An externally hosted image should be here but it was not working when we last tested it.
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