Amplification for Rock 'n' Roll Band

[yorkshiremike]

Hello guys,

I'm fairly new to playing double bass. I've played electric bass for 40 years but Db for just 12 months. I started off playing in bluegrass sessions. No problem in acoustic sessions.

I've played a 50s country revival show in theaters using a TC 2 x 8 combo again no problem.

I've now been asked to play in a 50s Rock 'n' Roll band. Playing the style isn't a problem, I don't slap.

I'm having a problem getting sufficient volume without feedback. I am using a shadow pickup.

Suggestions have included;
Taping up the f holes which we have tried but doesn't help too much.
Using an Eq box, I have a Behringer 6 band bass eq we haven't tried yet.

Another suggestion has been a compressor.

Any suggestions please, I've suggested that we turn down on stage, it was met by looks of disbelief.

[TheRev]

Are you using a pre-amp between your pickup and the amp input?
Piezo pickups like the Shadow will work straight into the amp input, but the impedance mis match between the amp input (typically 0.5-1MOhm) and the impedance that the pickup works best with (~10MOhm) can result in a thin sound, which you then try to boost with some bass eq, which then makes you more prone to feedback.
More importantly, many preamps come with a high pass filter control - I find this essential in reducing the subsonic frequencies which are usually the main culprit in causing feedback.

[TPJ]

Have you thought about using a mag pup for the rock gigs? Might be an easier way to combat the dreaded feedback.

[yorkshiremike]

Reverend,
Thank you for your suggestion. The shadow pickup has a battery volume and a tone contr4ol on it. I thought it might be active, I'll try using the bass eq box as I believe that has a pre amp in it.

TPJ
A mag pickup that's another area to look at. Have you any suggestions as to makes and placement? I believe that a lot of players mount them at the end of the fingerboard.

[TPJ]

[quote name='yorkshiremike' timestamp='1489317212' post='3255927']
TPJ
A mag pickup that's another area to look at. Have you any suggestions as to makes and placement? I believe that a lot of players mount them at the end of the fingerboard.
[/quote]

Kirvo are from the states, Schallers you can get from Thomann, Armstrong make some in the UK. They all go on the end of the fingerboard, but you need to use strings with metal in them. Also, the Bassmax pups seem to be a bit less prone to feedback, just depends on where you are standing in relation to your amp and PA etc... You want to try and keep the bass away from your speaker at higher volumes to help reduce the chance of feedback. The FDeck preamps are very handy too as they have high impedence input, an adjustable high pass filter and a phase switch...all the eseentials There was a guy in the uk that would clone them for a good price, not sure if he's still making them.

Edited March 12, 2017 by TPJ

[TheRev]

[quote name='yorkshiremike' timestamp='1489317212' post='3255927']
Reverend,
Thank you for your suggestion. The shadow pickup has a battery volume and a tone contr4ol on it. I thought it might be active, I'll try using the bass eq box as I believe that has a pre amp in it.


[/quote]

What model Shadow pickup do you have? The RB rockabilly pro system comes with a 2 channel preamp with a subsonic filter and a low cut control. Both those controls are designed to help prevent feedback.

[javasound]

Apologies if you know the following already but ...

Feedback is caused by the pickup attempting to amplify the sound from the speaker - which has already been amplified. You get a swiftly increasing cycle of amplification which produces the familiar feedback sound. Feedback is usually caused by over sensitivty to a particular frequency - and this is the frequency that the feedback produces - so if its a high squeal, there is too much top end, if its a low hum, too much bottom end.

One thing you can do is to use a graphic equalizer to cut the frequency which is feeding back - and the more bands you have in your graphic, then the more successful this will be. So if you are getting a low feedback, try experimenting with cutting some of he low frequencies.

The trouble with using a graphic to cut the feedback is that is very easy to end up with a thin sound - as you are taking frequencies out of the equation. The other thing you can look at is reducing your on stage sound. If you have a pa, put the bass through that as well as though your on stage amp. You can then reduce he volume of your amp so that it is loud enough for you to hear, but it doesnt have to be loud enough for the audience - they will hear it through the pa.

A good preamp is a must - and as other posters have said, if you have a good preamp, then the amp is receiving a strong re signal, so doesnt have to boost it so much, which will mean less feedback potential.

A final more radical solution - if you cant put the bass through the pa, put he bass amp/speaker in front of you pointing away from you towards the audience. This will reduce the feedback but of course you wont be able to hear yourself so easily. If this becomes a problem use a second amp set at a quieter volume pointing back at you. If you are using an amp purely for monitoring, then you can position it as close to you as possible. I use a MarkBass Traveller speaker (which is pretty small) on a stand so I can get it close to my ears which means I dont need it excessively loud.

Hope this all helps

[yorkshiremike]

Thanks to all for the suggestions.

The problem seems to be mainly low end feedback.

I'll try the little Behringer 6 band Bass Eq. This may give both eq and pre amp.
I'll also try taping some bass guitar pickups on just to see if the strings work well with mag pickups.

I had the strings fitted just after I bought the instrument and I can't remember the name. I believe they might be nylon core with a steel wrapping.

I've suggested that we don't play as loud. It doesn't seem to have gone down well.

[ivansc]

Worth reminding yourself that the punch from any bass instrument starts a lot higher up the frequency range than you think.
For me, punch starts around 250 cycles which is probably well above where you have been getting feedback. Might be worth borrowing a multiband graphic EQ just to find out exactly where you are feeding back.

[TheRev]

[quote name='yorkshiremike' timestamp='1489535537' post='3257809']
I'll also try taping some bass guitar pickups on just to see if the strings work well with mag pickups.

I believe they might be nylon core with a steel wrapping.


[/quote]

You'll most likely need steel core strings to use a magnetic pickup as there's not enough metal mass in the wrap to generate a useable current.

[yorkshiremike]

Thanks for the suggestions and information. I haven't had chance to try any of them yet.

[artisan]

The actual bass can make a major difference too.
My old Strunal was a total nightmare for feeding back,a total nightmare,I had everything damped & an extra sound post but still had problems.
My Duke however is nothing like as prone to feedback,I do still cover the f-holes on a loud stage though as it is a major help when cranking the volume.
BTW if you tape the f-holes you need at least 5 layers of gaffa tape for it to work.
As for magnetic pickups - for me yuck,I hated both the sound & feel of the steel strings.
I run through a GK MB800 Fusion,everything set flat apart from the bass control which is set around the 9 o'clock position (bass cut) & can play stood in front of the amp at pretty high volume with no feedback.

Edited March 21, 2017 by artisan

[fatback]

In a similar situation to you (and with a loud drummer) I found raising the cab 18 inches or so (on a low stool or table) was a huge help. Raising too high will lose you volume. If there's a house PA, I raise it to chest level on a keyboard stand for monitoring.

As for EQ, you really need a notch filter for best results.

I added an Armstrong mag p/u (excellent), but you do have to use metal strings. In the end, i rarely had to use the mag, but it did give me confidence that I could switch over if problems with the piezzo got unmanageable.

All part of the fun.

[paddy109]

There's a Fishman Platinum Pro Eq in the for sale section - these are pretty good and helping to eliminate feedback issues.