Newbie question: What makes bow 'screech'?

[danonearth]

Hi, I am just beginning to bow my upright bass, and sometimes I get a 'screech' if I rotate the bow on it's side and play the string with the edge of the hair... I am interested in 'why' this happens? As I actually really like the 'effect' (it's kind of like 'feedback' on an electric guitar) and want to use it when I choose to, but I am just curious why bowing with the tilted edge of the hair does this?

Thanks!

[zbd1960]

I'm a cellist, not a double-bassist, but I would suspect lack of rosin. Does the bow skitter over the strings? That indicates lack of consistent grip, which means either lack of rosin, or the hair is worn. You can get it if the strings get caked with rosin, which is why you need to clean the string by giving them a rub with a clean dry cloth after playing. Now if you were talking underhand baroque grip on a violone...
This vid is violone played with a baroque bow: [url="https://youtu.be/CunZ_ciJ6bI"]https://youtu.be/CunZ_ciJ6bI[/url]

And this one is played with an underhand bow, but nearer to Renaissance style bow: [url="https://youtu.be/hbYfSAtuR6E"]https://youtu.be/hbYfSAtuR6E[/url]

Edited October 24, 2016 by zbd1960

[neilp]

At the heart of it, the bass has thick heavy strings and it's not easy to make them "speak" quickly and evenly. One of the ways you can get the screeching noise is if you don't have enough grip on the strings. This could be worn bow hair, not enough rosin or not enough of the ribbon of hair contacting the string. Could also be caused by tension in the bow arm, bow too near the bridge and moving too fast, or the bow stroke not being perpendicular to the string. Inconsistent weight in the bow stroke, poorly set-up instrument, unsuitable strings, old and useless rosin, the list goes on. This is why there's so little point faffing with strings etc etc to try to get your "tone". It's almost always nothing to do with perceived problems with strings or set-up, much more likely poor technique.

[Trimmo91]

What he said

Edited October 25, 2016 by Trimmo91

[DanOwens]

I'd have thought it was something to do with the string's nodes. If you travel the bow along the string either towards the bridge or nut, does it change the sound?

[BaconCheese]

You get this sound more easily when you play close to the brigde and when using the space near to the tip of the bow.

[danonearth]

[quote name='neilp' timestamp='1477358022' post='3161726']
At the heart of it, the bass has thick heavy strings and it's not easy to make them "speak" quickly and evenly. One of the ways you can get the screeching noise is if you don't have enough grip on the strings.
[/quote]

Thanks, everyone... I think @Neilp has explained closest to what I am experiencing (on purpose) and that is that the 'edge' of the hair does not have enough 'grip' on the strings, so it is causing them to 'screech' - as opposed to the full flat 'face' of the the hair 'gripping' the strings to get the full sound (since the bow doesn't 'skitter', and it's a new bow with good rosin, @Zbd1960

I don't think it is due to nodes or harmonics, as you suggest @DanOwens - but that is a cool idea to experiment with... and also playing closer to the bridge to get the effect I am looking for, @BaconCheese

Thanks!

cheers,
Dan

Edited October 26, 2016 by danonearth

[NickA]

Not enough gentle force to get the string moving. Getting a big heavy string to start vibrating back and forth from an excitation force at one end of it is hard to do.

The bow excites the harmonics of the string rather than the fundamental (ie the actual note you want), ie it vibrates with one or more spots not moving at all ("nodes"); exactly as if you are playing a deliberate harmonic by lightly placing a finger on a "node" (eg put your finger lightly on D on the G-string and bow gently - you will get D but an octave up from what you'd get if you push your finger right down on the finger board).

It happens by accident if you are using high tension strings (or hybrids - as I do) and bowing too near the bridge and/or with insufficient pressure or rosin. To do it on purpose use gentle pressure near the bridge.

It's something bass players normally try to avoid!

It's an interesting sound, but not sure it's repeatable enough to be used in music; who knows what note will come out! Learn some deliberate harmonics instead :¬)

[bornagainbass65]

There is a special effect that you get if you play right up to the bridge.... Ponticello
https://www.youtube.com/watch?v=Z_GrrhecEvE