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Accuracy & precision issues won't likely be with REW (or any other software tool). It will be subject to the software inputs - In this case the sound card and the signal generator. elwood625 is using the Akitika signal generator (which is very good), so the limiting factor is probably the noise and distortion that the Behringer UM2 sound card contributes. I couldn't find any specs on this though.
A higher-end Focusrite Clarett sound card would probably provide a lower noise and distortion floor, but its going to set you back 10 to 20 times the price of the Behringer.
There's an excellent active thread that discusses all the other little details that factor into the dialing in your equipment for REW: Howto - Distortion Measurements with REW
That Akitika signal generator looks very tempting, but a bit overpriced especialy when looking inside. Plus getting rid of that potentiometer could only help reduce further distorsions (going for a fixed 1V output for example)
Are schematics available? Doesn't look very complicated to build...
Just thinking loud...
Are schematics available? Doesn't look very complicated to build...
Just thinking loud...
I have to disagree. 
The Akitika 1kHz oscillator kit at $79 seems like a great deal to me. Its specified distortion is less than 2 ppm (.0002%), which is quite low for the price. To diy one with such low distortion would not be easy.
A fix output level would not be too useful. For instance if you want to check a preamp output at 1V rms, you would need an input signal that is less than 1V rms as the preamp will have gain. Different preamps have different gain so a variable output is definitely useful.
The Akitika 1kHz oscillator kit at $79 seems like a great deal to me. Its specified distortion is less than 2 ppm (.0002%), which is quite low for the price. To diy one with such low distortion would not be easy.
A fix output level would not be too useful. For instance if you want to check a preamp output at 1V rms, you would need an input signal that is less than 1V rms as the preamp will have gain. Different preamps have different gain so a variable output is definitely useful.
Hi Ben Mah,
Reading your post, on second thought, I have... to agree with you
Well, I can't help thinking that it could cost half of that, but I understand indeed now the convenience of a potentiometer when having different units to measure and 2ppm is indeed not bad at all.
Hmm, have a some computers and a Behringer lying around, one day maybe...
Thanks
Claude
Reading your post, on second thought, I have... to agree with you
Well, I can't help thinking that it could cost half of that, but I understand indeed now the convenience of a potentiometer when having different units to measure and 2ppm is indeed not bad at all.
Hmm, have a some computers and a Behringer lying around, one day maybe...
Thanks
Claude
Since you have computers and a Behringer, all you need extra is the REW software and a couple of cables to connect everything together and you can test your preamp. REW can have the Behringer output a 1kHz signal so a stand alone oscillator is not mandatory.
For amplifier testing, you will need a power resistor for load and a voltage divider network so that you don't overload your Behringer. It so happens that Akitika has schematics for a diy voltage divider on their website.
For amplifier testing, you will need a power resistor for load and a voltage divider network so that you don't overload your Behringer. It so happens that Akitika has schematics for a diy voltage divider on their website.
Well, thought I was going to have a completed B1K today until I realized the frontplate of the Galaxy 2U black chassis has a 3/8" thick front plate. The threaded shaft of the ALPS Pot I bought won't clear it. I even had it wired and was ready to install. When I look online, none of the ones I see including the ALPS Black Beauty seem to have enough thread to get a nut on the outside. Any suggestions of an Attenuator that will work with this faceplate? Help!
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I had this same problem with the chassis I ordered. I looked through the pile of wood I had in the garage until I found a piece that was thin enough - it was easier for me to drill out to the appropriate thickness so i could mount my volume pot...
My solution is here.
My solution is here.
You know, if you buy a chassis designed to be used for audio projects, would it be too much to ask them to design them where components would work? Could they not imagine a need to mount a volume control through the front plate? I mean good grief...
Eric, that was a good idea and looks good. But I have all black brushed front components.
you can take a look here at Store to get general idea , then look at Modushop by Hi-Fi 2000 | Contenitori per Elettronica | Electronic Enclosures | Hi Fi Chassis what is available directly
if interesting , contact them and ask for additional work on holes etc.
Gainluca and Staff - they know their ****
if interesting , contact them and ask for additional work on holes etc.
Gainluca and Staff - they know their ****
I have a bronze flanged bushing on the way. I'll drill/tap the ID of the bushing for the thread of the Pot and size the hole in the faceplate for the OD of the bushing. It should just screw in and hold it. Looks like enough of the turning shaft will protrude to allow a knob on it. Good thing my other hobby is supporting my drag race car. My 160mph DIY hobby.
Hi Ben Mah,
Thanks for the tips!
Measuring the B1 Korg could be really fun, as future DIY projects. I didn't know the Behringer could be triggered to output a 1kHz signal. What quality is that then? 2ppm distorsion aswell, I doubt it, but is it really usable?
I am wondering beacause, humm... I had a look at the specs of the Codec used inside the Behringer and they are miserable. Something like 90dB S/N, worst than my very old ART DI/O using an AKM Codec... Under these circumstances, I must confess I struggle to understand how the Behringer can be used to measure what we want (say at least noise floor at -110dB, PS peaks in the -90dB region and harmonics distorsion aswell). Wouldn't a proper 24 bit high spec ADC be suitable for our mesurements given the level of what we want to measure? That ADC could be a project...
Regarding the power resistor for load for the power amp, well I already have them (unused) and voltage divider should be easy DIY. It appears I have nearly all of it, but perhaps time LOL - Oh, and the power amp to test, that should be a project to come...
Many thanks again
Claude
Thanks for the tips!
Measuring the B1 Korg could be really fun, as future DIY projects. I didn't know the Behringer could be triggered to output a 1kHz signal. What quality is that then? 2ppm distorsion aswell, I doubt it, but is it really usable?
I am wondering beacause, humm... I had a look at the specs of the Codec used inside the Behringer and they are miserable. Something like 90dB S/N, worst than my very old ART DI/O using an AKM Codec... Under these circumstances, I must confess I struggle to understand how the Behringer can be used to measure what we want (say at least noise floor at -110dB, PS peaks in the -90dB region and harmonics distorsion aswell). Wouldn't a proper 24 bit high spec ADC be suitable for our mesurements given the level of what we want to measure? That ADC could be a project...
Regarding the power resistor for load for the power amp, well I already have them (unused) and voltage divider should be easy DIY. It appears I have nearly all of it, but perhaps time LOL - Oh, and the power amp to test, that should be a project to come...
Many thanks again
Claude
The Behringer won't be a 2ppm, but it should be less than the preamp that you are testing. It may not be good enough to get an absolute value, but it is good enough for diy testing to get an idea of where you are at, and to establish a baseline so that when you do further tweaking you can see whether you are reducing or increasing the distortion.
You can also do a loopback test by feeding the output into the input to check on the Behringer self noise and distortion.
I think for casual diying, it will give you useful information and would be educational.
You can also do a loopback test by feeding the output into the input to check on the Behringer self noise and distortion.
I think for casual diying, it will give you useful information and would be educational.
Here is what you need:
HIFI 2000 Contre facade separation pour boitier Slimline 2U - Audiophonics
Christophe