[sdiy] Roland PB-300 kick: is it an 808?

[Benjamin Tremblay]

Yeah. I put  on my glasses this morning and looked at the PB-300 kick drum more closely. 
I agree, it only has the vestige of the 808 circuit and no active positive feedback. 
Fun ahead nonetheless. 

> On Nov 25, 2022, at 7:49 AM, Todd Sines <sines_list at scale.la> wrote:
> 
> Unipulse documents trigger inputs here
> https://tubbutec.de/blog/unipulse-midi-for-roland-pb-300/ <https://tubbutec.de/blog/unipulse-midi-for-roland-pb-300/>
> 
> More info here
> https://www.modwiggler.com//forum/viewtopic.php?f=78&t=234143
> 
> 
> Todd
> 
>> On Nov 24, 2022, at 8:48 PM, Benjamin Tremblay via Synth-diy <synth-diy at synth-diy.org> wrote:
>> 
>> Oh yes! 
>> It’s a square wave bass kind of like a Casio MT-40.
>> And like the MT-40 I would like to build out the timbre of the bass.
>> 
>> And of course, I would like to add MIDI triggers to the drum sounds. The PB-300 does not support that!
>> 
>> 
>>> On Nov 24, 2022, at 8:12 PM, Adam (synthDIY) <synthdiy at adambaby.com <mailto:synthdiy at adambaby.com>> wrote:
>>> 
>>> Ermagawd, dontcha just love Roland stuff from this period?
>>> 
>>> I found a SM circuit description for this thing.
>>> 
>>> Typically it uses their “swing type VCA”  and twin T networks for the drum sounds, but then it also features:
>>> 
>>> 
>>> “BASS
>>> PB-300 utilizes the CPU’s internal TIMER as an oscillator to generate BASS Notes. The signals from the oscillator for BASS Note are taken from CPU via PC7 (Pin 24).
>>> When PB-300 is played with BASS switch on, it progresses the development of BASS line in accordance with a combination of keys pressed, which is received via MIDI IN. The varying data of BASS Notes are sent from CPU via PC7 to Q4 of Voicing board, where bass tone is gated when TRIG from PB7 (Pin 16) is applied to Q2 at a certain rhythm tempo. Having colored while passing through IC1a and Q1 (LPF), bass tone is routed to BASS VOL CONT VR2.”
>>> 
>>> There’s also some wonderfully wacky stuff explaining how it will generate arpeggios from incoming midi chords, and there’s a dedicated VCA for “Nuance” (elsewhere known as Accent) from incoming midi note velocity!
>>> 
>>> Those Roland engineers! There must’ve been something in the water…
>>> 
>>> A
>>> 
>>>> On 25 Nov 2022, at 8:44 am, Adam (synthDIY) <synthdiy at adambaby.com <mailto:synthdiy at adambaby.com>> wrote:
>>>> 
>>>> Interesting!
>>>> Good basic analogue sounds - ripe for tweaking. 
>>>> 
>>>> Is there no clap? Most complex voice circuit of this era.
>>>> 
>>>> I wonder what the controls marked “Hold, Arpeggio,etc” are doing on a rhythm machine?
>>>> 
>>>> And don’t knock the DR-55!! There is no muddy live PA ever existed that could muffle that rim shot!!
>>>> 
>>>> A
>>>> 
>>>>> On 25 Nov 2022, at 7:43 am, Benjamin Tremblay via Synth-diy <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>> wrote:
>>>>> 
>>>>> It lacks any knobs, but the transistor-controlled pitch sweep, trigger circuitry, and positive feedback decay look similar to me. Am I reading this right?
>>>>> I’m looking to add some knobs to mine.
>>>>> The cymbals etc remind me of the CR-5000 but the kick looks like is just needs a little love.
>>>>> Huh I will try to dig up the schematic.
>>>>> Ben 
>>>>> 
>>>>> Benjamin Tremblay
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>>>> 
>>>> 
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