4558 upgrade and Cowbell tuning alternative

Hi,

I just completed the Yocto and to my suprise everything worked from the start. I would like to recommend replacing the 4558 in the master section with an Analog Devices AD712 which sounds far superiour in my opinion.

Also, since I´m not the lucky owner of a scope, I found it easier to connect a multimeter with frequency counter and measure R44 to 540 Hz and R55 to 800 Hz which are the original Roland values.

Best Wishes,

-Stefan

AD712JN,
AD712JR,
AD712AQ,
AD712SQ
or AD712KN?
Which is the right one please?

There's an existing topic about the master amp:
Master op amp substitution? => viewtopic.php?f=16&t=162&p=1002

As for cowbell, tuning, you can get really close by ear.. I checked it with a scope afterwards and I was only 0.05ms off.

Do you have a before/after sound comparison of the op amp?

SK001 wrote:Hi,

I just completed the Yocto and to my suprise everything worked from the start. I would like to recommend replacing the 4558 in the master section with an Analog Devices AD712 which sounds far superiour in my opinion.

Also, since I´m not the lucky owner of a scope, I found it easier to connect a multimeter with frequency counter and measure R44 to 540 Hz and R55 to 800 Hz which are the original Roland values.

Best Wishes,

-Stefan

How do I measure Hz? Got a MM with Hz. Where do I probe? The red to the resistor... R44. The black to.... GND? Nowhere even close to 540Hz with this method. Around 350 Hz where he trimpot ends. Even worse with the other one.

I got 130Mv at the noise section without even modding it though. =)

Ok. So I tuned my Yocto by ear towards my real 808. Everything sounds Ok to me now and pretty damn close, except the Cowbell which is totally off.
(The cymbal is also not so spot on but acceptable)

First the Yocto... then my 808....
https://soundcloud.com/lostyears/cowbel ... to/s-M757m

The trimpot can't find any spot near the real thing. Any ideas here what is wrong or how to improve it?

Just tried this:
"Adjust TM1* up to a period of 1.85ms. If TM1* adjustment range is not large enough for this period change the value of R44 * per a resistor of 100Kohm. (supplied in kit)

Adjust TM2 * up to a period of 1.25ms. If TM2* adjustment range does not allow you to get this period change the value of R45 * per 68kohm. (Supplied with the kit)."

Did not help, the pitch is not the problem? It just sounds nothing like a 808 cowbell.

Solved my problem. D4 in the wrong direction.

Set TM1 to 540 Hz.

I guess you mean R45 not R55 for TM2 right?
Says so in Rolands service manual.

drifter7508 wrote:Just tried this:
"Adjust TM1* up to a period of 1.85ms. If TM1* adjustment range is not large enough for this period change the value of R44 * per a resistor of 100Kohm. (supplied in kit)

Adjust TM2 * up to a period of 1.25ms. If TM2* adjustment range does not allow you to get this period change the value of R45 * per 68kohm. (Supplied with the kit)."

Did not help, the pitch is not the problem? It just sounds nothing like a 808 cowbell.

These are not in the Cowbell section or am I blind? http://www.e-licktronic.com/en/content/33-cowbell

EDIT: They are in the Cymbal circuit http://www.e-licktronic.com/en/content/34-cymbal

viewtopic.php?f=16&t=714#p5676