Biasing

[peAk]

Hello all,

Can anyone explain what exactly one needs to do this and/or links to some past discussions about it? I did some searching but it seems there is a ton of info about it and maybe someone knows a better place to start. I have read the article on GPBC but it seemed that a part 2 was never created.

I am looking for info like: what you are looking for, tools needed, can it be done by ear without tools, etc. and so forth.

I have some builds coming up that will need biasing and I am not sure where to start or what equipment is essiential.

Thanks!

[jkokura]

Depends. Biasing what?

Jacob

[peAk]

I guess the first biasing I will have to do is on some chorus pedals with MN3207 and MN3007

[Govmnt_Lacky]

Usually....

Biasing a BBD based circuit requires the use of an oscope at minimum. You will need to bias the BBD input and also the BBD output. Having the oscope allows you to dial in the waveform perfectly.

Most of the time....

These adjustments can be done by ear. But... it is not perfect 

[peAk]

Usually....

Biasing a BBD based circuit requires the use of an oscope at minimum. You will need to bias the BBD input and also the BBD output. Having the oscope allows you to dial in the waveform perfectly.

Most of the time....

These adjustments can be done by ear. But... it is not perfect 

would a cheap one like this work http://www.amazon.com/Seeedstudio-DSO-Nano-Oscilloscope-v3/dp/B00BB4ETJW/ref=sr_1_3?ie=UTF8&qid=1392053298&sr=8-3&keywords=oscilloscope

or any other suggestions. Don't want to break the bank if possible.

[jkokura]

The thing about osciliscopes is that you get what you pay for, and the industry standard devices are at the $1000+ mark. You can get decent ones for like 4 or 500 bucks, but they're found used at that price more often than new.

The cheap one may get the job done, but that's not a standard tool.

Jacob

[RobA]

...
would a cheap one like this work http://www.amazon.com/Seeedstudio-DSO-Nano-Oscilloscope-v3/dp/B00BB4ETJW/ref=sr_1_3?ie=UTF8&qid=1392053298&sr=8-3&keywords=oscilloscope

or any other suggestions. Don't want to break the bank if possible.

I've got one of those. They are actually pretty slick. You need to be able to upgrade the firmware on them to get the maximum usefulness out of them and last I checked, the version three didn't have the firmware updated for it yet (it's a third party thing). Still, even without the firmware update, it's a perfectly usable little scope and works really well for investigating LFO's. That was why I got it really, so I'd be able to take quick looks at LFO's with a quick and easy tool.

But, I've biased several BBD based circuits so far and I've had no problem at all getting them to sound great. I certainly didn't feel the need to pull out the scope to bother looking to get the thing tuned to the best sounding point.

[Scruffie]

Unless you're doing multiple BBDs in series it can be done to a satisfactory level with just your ear or by using a cheaply made audio probe.

Even with BBDs in series you can do it with an audio probe, you don't need a scope unless you really want to get it spot on.

A frequency counter can be handy though and can be found on decent DMMs.