Biyang - CH-8 Analog Chorus  [schematic]

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tube-exorcist
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Post by tube-exorcist »

:scratch: How does it come that I can´t see any bias-trimpot on the pcb? Maybe Dirk can lead me in the right direction an tell me where it is located ?
"I've noticed there's an inverse relationship between cost of gear and talent. If you need the most expensive gear to get decent tones, then you suck as a player."

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Post by Dirk_Hendrik »

No clue why you cannot see it since we don't share the same set of eyes. I for sure don't see one and cannot remember having said so. However, where did you jump to the conclusion there a) would be a bias trimmer and b) you need one.
Sorry. Plain out of planes.

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tube-exorcist
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Post by tube-exorcist »

Oh here I read this:
Dirk_Hendrik wrote:
fedeza wrote:hi there. I just bought this pedal, and I have a nasty problem: when I play it through a clean amp, the sound becomes distorted. Like a saturation, but in the same volume level.
Could I do something? I'm thinking to throw it to the trash!! :cry:
Fender3D above is right. The first thing to do would be to verify your chorus is correctly biased. I find it hard to expect that a pedal in this price range, probably built by production employees with a minimal salary, goes through a quality control that ensures all products that leave the factory are optimally set up.

So,
get a sinewave, get a scope,
and readjust the BBD bias.
"I've noticed there's an inverse relationship between cost of gear and talent. If you need the most expensive gear to get decent tones, then you suck as a player."

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Post by fedeza »

Dirk_Hendrik wrote:No clue why you cannot see it since we don't share the same set of eyes. I for sure don't see one and cannot remember having said so. However, where did you jump to the conclusion there a) would be a bias trimmer and b) you need one.

You are not helping... do you wanna start to?

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Dirk_Hendrik
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Post by Dirk_Hendrik »

tube-exorcist wrote:So,
get a sinewave, get a scope,
and readjust the BBD bias.
[/quote]

Still nowhere did I say a trimmer was involved to do this.

Fedeza,
I was helping. I've told you what you need to do. Seemingly you want to have someone who is going to hand you step by step instructions in a silver plate and meanwhile you just sit and wait.
Sorry. Plain out of planes.

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fedeza
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Post by fedeza »


Still nowhere did I say a trimmer was involved to do this.

Fedeza,
I was helping. I've told you what you need to do. Seemingly you want to have someone who is going to hand you step by step instructions in a silver plate and meanwhile you just sit and wait.

Nice way "TO HELP".....

Do you want to be, good person, earn the sky, rich, famous, and reach the full HAPPINESS?... GO FOR IT!

AAAHHH! Are you waiting concrete answers? on a silver plate?

Nice way to give advices!

Still waiting for any information, data, schem, link, or anything else to solve that problem more than "Study" "go for it" "diy" or any generic else.
Thanks all

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Post by Dirk_Hendrik »

Chill!
What have you done yourself yet? So far nothing apparently, other than getting angry someone is not willing to meet your expectation spend an hour to spell it out for you.
That's my whole bloody point. I'd be more than willing to help you out but not in a "you tell me what to do but I don't want to spend any effort to understand what I need to do".

- did you make arrangements to be able to work on your chorus yet? Meaning a signal generator and an oscilloscope in, for example, a soundcard application form?
- Have you even punched the letters "BBD bias" into google and spend some time reading what these guys mean?
- Have you gotten yourself a MN3007 datasheet copy so you know what the inputs and outputs are so you know where to measure?
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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Post by lolbou »

fedeza wrote:Still waiting
Might take long indeed to have your chorus actually chorusing. :roll: You dig first! :secret:
Dirk_Hendrik wrote:- Have you even punched the letters "BBD bias" into google and spend some time reading what these guys mean?
+1 Search here too (as Dirk's mentioned before), and have a look for flanger alignment too, since BBD bias happens here too...
tube-exorcist wrote:How does it come that I can´t see any bias-trimpot on the pcb? Maybe Dirk can lead me in the right direction an tell me where it is located ?
I know that you know that a fixed value resistor can do the trick, making the bias being somewhat random... Why this sudden smartassness? :scratch:
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

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roseblood11
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Post by roseblood11 »

As the biyang is a clone of the Boss CE-2, anybody should be able to have a look at that schematic, find out how the trimpot has to be added to the Biyang, and maybe read the instructions and build reports at tonepad or generalguitargadget, I'm pretty sure that there is an easy to follow instruction about biasing..

I totally agree with Dirk-Hendrik: I'm really happy if I can help others, but if I realize, that someone is just to lazy to learn the basics, I'm out.

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Post by fedeza »

Dirk_Hendrik wrote:Chill!
What have you done yourself yet? So far nothing apparently, other than getting angry someone is not willing to meet your expectation spend an hour to spell it out for you.
That's my whole bloody point. I'd be more than willing to help you out but not in a "you tell me what to do but I don't want to spend any effort to understand what I need to do".

- did you make arrangements to be able to work on your chorus yet? Meaning a signal generator and an oscilloscope in, for example, a soundcard application form?
- Have you even punched the letters "BBD bias" into google and spend some time reading what these guys mean?
- Have you gotten yourself a MN3007 datasheet copy so you know what the inputs and outputs are so you know where to measure?

I didn't do any of those things. So those tips are the ones that i'm waiting for.
Don't get me wrong, and I don't need to chill lol. Don't think I am fighting here, just the opposite, I am looking for answers/clues/tips call-it-as-you-want.
More than those things will help me.
regards

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Post by wildschwein »

I like these pedals. I had a grey box Arion SCH-1 on my board but I really prefer the tone of the Biyang. The Arion had a cold and robotic tone -- I think the CH-8 is much warmer sonically. Sold the Arion off (for really decent money).

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Post by freefrog »

I've tweaked one of these.

The 4.5v DC line was providing 4.72v and there was no bias pot: the 10k trimmer between two 4.7k resistors usually found in CE2's is absent. There is just two 10k resistors instead. They are those named "R1" and "R2" close to the DC barrel.

The DC line traced from between these two resistors is easy to find on the other side on the PCB and hosts several testing points, where it's easy to implement additional resistance...

In this case, I've used a 470k pot parallel to the 10k resistor to ground.

If the voltage had been too low, I would have melt the 10k SMD resistor to ground and replaced it with another resistor of higher resistance or trimmer to ground....

I've also changed the caps of the tone control and added some low pass capacitance to ground to make the sound warmer but it didn't totally cancel the hiss inherent to the circuit... That said and for the record, it's also possible to cut one of the tone caps and to change the tone pot in a mere mix control (knowing that the tone control already works like a mix between two chorused signal filtered differently and that IME, one side of the circuit sounds better than the other: in the case of the pedal mentioned here, the "bass" side gives a richer chorus than the treble side of the tone pot ).

More later about this maybe and/or on request: not enough free time to share more now.

HTH at least. :-)

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