Roland TR-808 Cowbell Rebuild

Re:Roland TR-808 Cowbell Rebuild by S_A_P on Saturday May 07, 2022 @09:10AM (#31294202)

I’ve owned a few 808s and sampled all of them. They were indeed all different sounding. The cowbells are one exception and sounded more like the 2 Live Crew example. Most of the variation was in the hi hat and cymbals. Which IIRC is 6 square waves and a noise source.

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Re:Roland TR-808 Cowbell Rebuild by chriscjcj on Saturday May 07, 2022 @09:32AM (#31294304)

Very interesting! Thank you! I did a little looking and found this FWIW...

I noticed in OP's post that the two frequencies for the cowbell are 540hz and 800hz (although I don't see where this is denoted on the original schematics.) But we'll assume they're accurate numbers.

While a perfect fifth is a difference of 7 semitones, this produces a difference of only 6.804 semitones. It would seem that its designers didn't have a perfect fifth in mind.

Also, 540Hz is C#5 -45 cents and 800Hz is G5 +35 cents. So neither note seems intended to correspond to any natural key.

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Re:Roland TR-808 Cowbell Rebuild by dahart on Saturday May 07, 2022 @02:50PM (#31297376)

> While a perfect fifth is a difference of 7 semitones, this produces a difference of only 6.804 semitones. It would seem that its designers didn't have a perfect fifth in mind.

Remember that 7 semitones is not a perfect fifth. (Note this depends on your definition of perfect fifth, some people allow for being close, since equal temperament is so common.)

While a perfect fifth is a 3:2 ratio of frequency, seven semitones isn’t exactly 1.5, it’s more like 1.498.

800/540 is ~ 1.48, so I definitely agree the designers weren’t going for a fifth, very likely they wanted some beat interference to give it a nice metallic warble.

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Re:Roland TR-808 Cowbell Rebuild by chriscjcj on Saturday May 07, 2022 @10:08PM (#31300562)

You are correct sir.

I was speaking (a bit erroneously) in the context of an equal tempered scale. (I think.)

Indeed, the natural overtone series is the proper context for a true perfect fifth.

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Re:Roland TR-808 Cowbell Rebuild by max-m on Saturday May 07, 2022 @09:47AM (#31294400)

One of the diagrams shows the frequencies as 1.85ms and 1.25ms, 540.5 and 800 Hz respectively.

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Re:Roland TR-808 Cowbell Rebuild by smoyer on Saturday May 07, 2022 @11:29AM (#31295313)

In the original circuit,the same RC network is used for both the attack and decay so that circuit will indeed produce a 1:1 mark:space ratio.

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Re:Roland TR-808 Cowbell Rebuild by JKCalhoun on Saturday May 07, 2022 @12:23PM (#31295991)

Curious about the term "1:1 mark:space ratio" since it was also in the article. I would have used the term "50% duty cycle".

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Re:Roland TR-808 Cowbell Rebuild by smoyer on Saturday May 07, 2022 @04:22PM (#31298201)

I purposely repeated the OP's wording but since we're talking about an astable multivibrator,frequency and duty cycle (in percent) makes sense. I did a lot of circuit design for communications systems and I associate the words mark and space with ones and zeroes in a frame/word.

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Re:Roland TR-808 Cowbell Rebuild by JKCalhoun on Saturday May 07, 2022 @05:00PM (#31298535)

I wondered if it was an English (not American) phrasing.

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Re:Roland TR-808 Cowbell Rebuild by greenyoda on Saturday May 07, 2022 @11:23PM (#31300980)

More on the origins of the terminology here: https://en.wikipedia.org/wiki/Mark_and_space

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