P3 Adjustment for the average Hobbyist

[silasmellor]

Do it! That looks very respectable. What cable did you use for loop back?

 

[MEPER]

I used exactly this one:
Køb Jack kabel - Stereo - 0.75 m på Av-Cables.dk
They ship very fast......got it two days ago. Stereo jack cable.

 

[wintermute]

I tried with a test cd (some old technics one I have with no idea what the tones actually are) tonight as the source, though I could only find 400hz tones on it. If I changed ARTA's generator to 400Hz (but turned it off) then it gave me proper distortion figures. When the generator was set to 1Khz (and turned off) it told me the THD was 100%

So yeah an external source should work but make sure the generator in ARTA is set to the same frequency as the generator

Tony.

 

[MEPER]

OK....that is a very good information

 

[Russellc]

Yes the 2i2 is a proper sound card which is connected via USB. But performs the same basic functions as a PCI or pcie sound card. The main advantage of going with USB is that it is portable and can be used with a laptop.

There are some things I prefer about using a pci card (I find the gain knobs on the 2i2 really finicky to adjust), but the portability and being able to use a laptop running off battery are the main reasons I went with a 2i2.

edit: the main advantage of using a laptop (apart from portability) is that you can completely eliminate the PC as a source of ground loops.

Tony.

Am I correct in assuming that if I use 212 there is no reason to worry about sound card specs/quality that is in laptop?
Thanks,

Russellc

 

[Russellc]

It was just a loop back test......so output back to input to check how ARTA works and also get a feeling for how clean the built-in test generator is.


I wonder if it is possible to work with an external test generator in such a setup with ARTA.

Thanks.
Russellc

 

[Itsmee]

Am I correct in assuming that if I use 212 there is no reason to worry about sound card specs/quality that is in laptop?
Thanks,

Russellc

Correct, your not using it.

 

[Russellc]

Correct, your not using it.

Thanks, I am beginning to grasp this a lot better. Soon as back in town ordering the 212 from focusrite.

Russellc

 

[Russellc]

nope

EMU 1212 is way too complicated (12 channels out , same in)

any smaller EMU , less channels .... that's better

if one is happy having only SE in/outs , choice is much easier - buy any 2hand Audigy , for instance ....... and you're good

Second hand audibly are cheap, tempting, but many here are using focusrite, probably should bite bullet on one of them...path being cleared here.

Russellc

 

[KevinHeem]

So yeah an external source should work but make sure the generator in ARTA is set to the same frequency as the generator

In Arta, look to the far left in the second tool bar. There's a drop down menu that says "Gen" next to it. Select "External".

 

[wintermute]

So there is!! Cool thanks!

 

[hirscwi]

Great thread. I've been wondering about adjusting P3 on my F-5 and BA3 (used as a preamp). It seems to me that I should be able to use my newly acquired QuantAsylum QA401. It has a THD option. Should that make it easy to adjust P3? If I understand correctly, I'm not aiming for the lowest THD but rather for either desired 2nd or 3rd harmonics - correct?

 

[MEPER]

I think 6L6 video shows that if adjusted to lowest THD it is all almost only 3rd harmonic. If adjusted a little "off".....I can't remember in which direction…...the THD is a little higher but almost only 2nd harmonic.

 

[hirscwi]

I think 6L6 video shows that if adjusted to lowest THD it is all almost only 3rd harmonic. If adjusted a little "off".....I can't remember in which direction…...the THD is a little higher but almost only 2nd harmonic.

Thank you. I didn't see that video. Which thread is it?

 

[Dennis Hui]

Try here:

Adjusting P3 - a video

 

[KevinHeem]

It seems to me that I should be able to use my newly acquired QuantAsylum QA401.

Umm...yeah, that's the perfect tool for adjusting P3. It has selectable 20dB attenuation so you should be able to test/adjust the F5 or BA-3 preamp just fine.

 

[hirscwi]

Thank for all the information. It's just what I need.

 

[nashbap]

So I bought a Focusrite 2i2 2nd gen and have started experimenting a bit.

Loopback seemed good similar to what Wintermute posted earlier.

When testing a preamp or a poweramp NP says measure at 1 watt output. Do I need a load and of what R across preamp output? Same question for poweramp.

Thanks.
nash

 

[Itsmee]

BA3 already has a load on the output, try various 'load' values down to 1K, no power amp input should be that low.
Power amp, 8R, 4R and maybe 2R.

 

[Russellc]

So I bought a Focusrite 2i2 2nd gen and have started experimenting a bit.

Loopback seemed good similar to what Wintermute posted earlier.

When testing a preamp or a poweramp NP says measure at 1 watt output. Do I need a load and of what R across preamp output? Same question for poweramp.

Thanks.
nash

Nice I am a little behind. I spent my current play money on one of zenmod's M25 kits, so I am a week or two out from getting my 212. I guess I could put it on a card and pay off in week or two.....

Russellc