Magazine Archive

Home -> Magazines -> Issues -> Articles in this issue -> View

Sample & Hold Modification

Provides Note Bender



A modification of the Sample and Hold circuit in the Keyboard Controller of my synthesizer provides a note bender. This effect is used extensively by Jan Hammer (with Jeff Beck), Patrick Moraz (Yes) and Roger Powell (Utopia). It is used the same way as a guitarist bends a note.

The problem with using the pitch control as a bender is that once you have bent a note you must again "find" the correctly tuned location. Using the fine tuning modification, Polyphony 3/76, does not completely solve the problem. It can be used to bend notes down in pitch but not up (zero resistance is the least you can go). This means that you would have to compensate for a "full on" position on the fine tune control by raising the coarse adjust. This greatly diminishes the range of the keyboard.

To get around this I replaced the 1800 ohm resistor that is in parallel with the pitch control with a 1000 ohm slide pot in series with an 820 ohm resistor. Together they are in parallel with the pot. When the pot is "full on" there is around 1800 ohm (close enough). However, as the pot is moved toward zero resistance the series combination approaches 820 ohms thus allowing more current. I've found that when using the keyboard on the middle pitch range (16') that it allows a bend of about 2 half steps which is perfect for most applications. It also is fun to use.

Raising the pitch control to the next octave diminishes the range of the bender since the pitch control itself is approaching zero resistance. But on the 16' range it is a great effect.

A rotary pot would work but I used a slide pot since it's easier to "feel the bend" and return to normal after the bend. One disadvantage to a slide pot, though, is cutting the panel.


More from these topics


Browse by Topic:

Electronics / Build

Maintenance / Repair / Modification



Previous Article in this issue

How To Make An EGG Mod


Polyphony - Copyright: Polyphony Publishing Company

 

Polyphony - Jul 1977

Donated & scanned by: Mike Gorman

Feature by Barry Nesmith

Previous article in this issue:

> How To Make An EGG Mod


Help Support The Things You Love

mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.

If you value this resource, you can support this project - it really helps!

Donations for June 2022
Issues donated this month: 0

New issues that have been donated or scanned for us this month.

Funds donated this month: £49.00

All donations and support are gratefully appreciated - thank you.


Magazines Needed - Can You Help?

Do you have any of these magazine issues?

> See all issues we need

If so, and you can donate, lend or scan them to help complete our archive, please get in touch via the Contribute page - thanks!

If you're enjoying the site, please consider supporting me to help build this archive...

...with a one time Donation, or a recurring Donation of just £2 a month. It really helps - thank you!
muzines_logo_02

Small Print

Terms of usePrivacy