Failure in Ladyada manual?

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Chris72160
 
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Failure in Ladyada manual?

Post by Chris72160 »

Hello,

i found a failure in the Ladyada manual, but i am not sure.

http://www.ladyada.net/make/x0xb0x/fab/vcf/index.html

On this page you can read, that the resonance-frequency should be around 500Hz at C1 (65,4Hz). Because of that you should apply 3VDC to R89.

In my case (and in your case?) 3VDC doesn`t lead to C1 (65,4Hz), but C2 (121,8Hz).

So should the 500Hz applied to C1 (2VDC) or to C2 (3VDC)?

Greetz Chris

"There is an 'official' tuning for the VCF. According to the Roland TB-303 manual, when playing C1 (65.4Hz) with the cutoff frequency knob set to 50%, saw waveform, and resonance knob at 100%, the resonance frequency should be 500Hz (give or take 100Hz depending on how it sounds to you). You can perform this tuning by either applying 3.0VDC to the VCO or finishing the entire assembly and using something like Keyboard mode to trigger the note. The cutoff can be adjusted by tweaking TM3."

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mmm
 
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Re: Failure in Ladyada manual?

Post by mmm »

It's supposed to be the non-transposed low C with appr. 66Hz.

Actually the TB303 service notes don't say which C it is but the diagram shows a 15ms cycle for the underlying sawtooth which means it's the lower C. Make sure that ENV MOD and DECAY are set to min and Accent isn't active.
The resonance peaks then should be 2ms (+/- 0.5ms) apart.

Chris72160
 
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Re: Failure in Ladyada manual?

Post by Chris72160 »

Hi MMM,

this means, that my suggestion was right, isn`t it?

2VDC is right, not 3VDC, or?

Greetz Chris

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antto
 
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Re: Failure in Ladyada manual?

Post by antto »

well, that's a minor detail
the VCF cutoff calibration procedure really says that you should "tune" the resonance to roughly 500Hz
it doesn't matter at what note the VCO will be oscillating

but surely 2V is the pitch for the (non-transposed) low C note

Chris72160
 
Posts: 44
Joined: Wed May 01, 2013 6:24 am

Re: Failure in Ladyada manual?

Post by Chris72160 »

Thank you.

Greetz Chris

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