Any prob using 2 Midgets separated on stage

[fatback]

I use one Midget on a stand for my upright (to avoid feedback), but seem to lose a good deal of low end volume that way. Wondering if a second Midget in front of me would give me the extra oomph I feel I need.

But would that cause any kind of phase problem?

Haven't a clue about these things, so your thoughts much appreciated. Amp is an EA Doubler 550.

[chris_b]

[size=4]Can't you reduce feedback by putting foam plugs in the F holes?[/size]

[Clarky]

[sup]Two midgets on stage can get nasty[/sup]

[sup][attachment=94147:tv1-1.jpg][/sup]

[LawrenceH]

[quote name='fatback' timestamp='1322574550' post='1452848']
I use one Midget on a stand for my upright (to avoid feedback), but seem to lose a good deal of low end volume that way. Wondering if a second Midget in front of me would give me the extra oomph I feel I need.

But would that cause any kind of phase problem?

Haven't a clue about these things, so your thoughts much appreciated. Amp is an EA Doubler 550.
[/quote]

Separating bass speakers is generally a bad idea...witness the classic 'corridor of bass' when bands use the one-sub-a-side setup for PA - gives a very uneven, location-dependent response. For controlling feedback without losing low-end you may be better off using something like a gramma pad that keeps the speaker low down, and/or putting the pin on something that provides similar isolation. Mechanical coupling to the floor is different to acoustic coupling obtained by being close to a surface. This will only work if firstly it is not mechanical coupling that is giving you the low end (tends to be 'boomy' and centred on a particular frequency) and secondly if the sheer volume of the low-end isn't what's causing the feedback. In that case you may have reached the inherent limitations of double bass and need to look into notch filters or foam inserts on the bass itself, I seem to remember Clarky had a thread discussing this?

[fatback]

@ Clarky... I was wondering whose resistance would crack first

@ Chris & Lawrence

I thought maybe the separation wouldn't be a good idea. Pity.

In fact my bass is as feedback resistant as could be hoped for, i think, as long as the speaker isn't directly behind the body. In that case, raising the speaker is the only option - some of these 'stages' are so small and/or crowded I'm literally a metre away from the speaker. The ideal would have been one speaker raised behind for monitoring and another in front for extra bottom.

I'm pretty sure what's happening is that the loss of acoustic coupling means I lose bottom, and the temptation to boost the low then swallows watts. I can get enough volume as long as I don't do that and instead work with the mids.

All is compromise, i guess.

Thanks for your thoughts

Edited November 29, 2011 by fatback

[dave_bass5]

[quote name='Clarky' timestamp='1322576325' post='1452920']
[sup]Two midgets on stage can get nasty[/sup]

[sup][attachment=94147:tv1-1.jpg][/sup]
[/quote]

LOL, i was going to use the Stone 'enge scene from Spinal Tap but this is funnier.

[Clarky]

[quote name='fatback' timestamp='1322577500' post='1452965']
@ Clarky... I was wondering whose resistance would crack first

@ Chris & Lawrence

I thought maybe the separation wouldn't be a good idea. Pity.

In fact my bass is as feedback resistant as could be hoped for, i think, as long as the speaker isn't directly behind the body. In that case, raising the speaker is the only option - some of these 'stages' are so small and/or crowded I'm literally a metre away from the speaker. The ideal would have been one speaker raised behind for monitoring and another in front for extra bottom.

I'm pretty sure what's happening is that the loss of acoustic coupling means I lose bottom, and the temptation to boost the low then swallows watts. I can get enough volume as long as I don't do that and instead work with the mids.

All is compromise, i guess.

Thanks for your thoughts
[/quote]
Maybe something downfiring like an Acoustic Image cab (which would also come in handy as a sole cab for those quieter gigs, should you ever do those)?

Or cheaper still (and what I did) get a Mackie C200 passive 10" speaker and stand, use that as the head-height speaker, and couple it with Midget on ground (in my case it was an Acoustic Image or Wizzy speaker on ground).

Edited November 29, 2011 by Clarky

[thumperbob 2002]

gramma pad- you will be surprised.

[fatback]

[quote name='thumperbob 2002' timestamp='1322580385' post='1453055']
gramma pad- you will be surprised.
[/quote]

I have actually used auralex strips under the cab for electric gigs on boomy stages, and I've tried it with the upright but it doesn't reduce feedback at all when the speaker is behind the bass. And imo life is too short to fiddle with my notch filter.

@ clarky, don't you get the same phase type probs that Lawrence is talking about? If you don't, it would certainly be a cheaper solution than two midgets (although I'm mad to hear what that would sound like. Awesome, I guess.).

[Clarky]

[quote name='fatback' timestamp='1322587810' post='1453215']
I have actually used auralex strips under the cab for electric gigs on boomy stages, and I've tried it with the upright but it doesn't reduce feedback at all when the speaker is behind the bass. And imo life is too short to fiddle with my notch filter.

@ clarky, don't you get the same phase type probs that Lawrence is talking about? If you don't, it would certainly be a cheaper solution than two midgets (although I'm mad to hear what that would sound like. Awesome, I guess.).
[/quote]

I didn't notice any phase problems but the gigs concerned were bl**dy loud with 14 of us and me standing next to a sousaphone player! I used the floor speaker more for the drummer and the head-height Mackie for me

[pbass67]

Just an observation that my midget doesn't like being off the floor, the only time its not sounded 'right' was in a pub on a seat. Lost low end. Done loads of other gigs with it on floor and its been great, albeit on electric bass. Don't know nothing about phase issues though, so I'll leave that to those that do.

[alexclaber]

With two cabs you could do something cunning by separating them and putting the bass body in a null point but that's much more effort than using a notch filter! On which subject, you'll probably get the best results from the notch filter by taking out the dominant resonance of your bass, which will be the same frequency regardless of the room. So find out where it is once and then remember it for future applications.

We're just tooling up some wedges for mechanically isolating and tilting bass cabs so they might help - cab on the floor for more boundary reinforcement but tilted up so you can hear the higher frequencies better.

[fatback]

[quote name='alexclaber' timestamp='1322733195' post='1454929']
With two cabs you could do something cunning by separating them and putting the bass body in a null point but that's much more effort than using a notch filter! On which subject, you'll probably get the best results from the notch filter by taking out the dominant resonance of your bass, which will be the same frequency regardless of the room. So find out where it is once and then remember it for future applications.

We're just tooling up some wedges for mechanically isolating and tilting bass cabs so they might help - cab on the floor for more boundary reinforcement but tilted up so you can hear the higher frequencies better.
[/quote]

Interesting point about the resonance frequency. All the same, I'm not sure I'd want to risk the cab on the floor in these situations as putting it on the stand always works, and there's never time to muck about.

@ pbass - that's exactly my experience. Maybe a more powerful amp is needed to crank up the lows with eq?

Alex, is the Midget especially dependent on boundary reinforcement because of its small size (probably a dumb question, I know)?

[Bill Fitzmaurice]

[quote name='fatback' timestamp='1322743247' post='1455141']


Alex, is the Midget especially dependent on boundary reinforcement because of its small size (probably a dumb question, I know)?
[/quote]No more than any other cab, as all react to boundaries in the same fashion. To be accurate, you aren't losing lows with the cab elevated. That would require lifting it at least 5 feet off the ground. You're reducing boundary loading in the midbass. Using a parametric EQ to notch out the feedback, rather than lifting the cab, would have the benefit of giving additional headroom in the amp and speaker, as it reduces the amp output in the notched bandwidth. It would also give you a bigger bottom, as being able to dial in the precise frequency, notch width and amount of gain reduction will stop the feedback with minimal effect on other frequencies.

[fatback]

[quote name='Bill Fitzmaurice' timestamp='1322746072' post='1455240']
No more than any other cab, as all react to boundaries in the same fashion. To be accurate, you aren't losing lows with the cab elevated. That would require lifting it at least 5 feet off the ground. You're reducing boundary loading in the midbass. Using a parametric EQ to notch out the feedback, rather than lifting the cab, would have the benefit of giving additional headroom in the amp and speaker, as it reduces the amp output in the notched bandwidth. It would also give you a bigger bottom, as being able to dial in the precise frequency, notch width and amount of gain reduction will stop the feedback with minimal effect on other frequencies.
[/quote]

Thanks, Bill. The cab on stand is chest height, so not so far off 5 feet. Do you lose midbass at lesser elevations?

Unfortunately, I don't see using the notch filter as very practical in the kind of situations we play in most often, ie tiny stages and no soundcheck; just stand up and play.

I'll certainly look for that resonating frequency of the bass, as Alex described, but I can't see the speaker on the floor close behind the bass body ever being other than a problem. Luckily, the cab on stand approach is workable, as long as I don't need to get much louder, as I'd reach the amp's limits (with one cab) pretty quickly.

Edited December 1, 2011 by fatback

[LawrenceH]

[quote name='fatback' timestamp='1322763158' post='1455625']
Thanks, Bill. The cab on stand is chest height, so not so far off 5 feet. Do you lose midbass at lesser elevations?

Unfortunately, I don't see using the notch filter as very practical in the kind of situations we play in most often, ie tiny stages and no soundcheck; just stand up and play.

I'll certainly look for that resonating frequency of the bass, as Alex described, but I can't see the speaker on the floor close behind the bass body ever being other than a problem. Luckily, the cab on stand approach is workable, as long as I don't need to get much louder, as I'd reach the amp's limits (with one cab) pretty quickly.
[/quote]

If you used a notch filter that was centred on the resonance of the bass body that would stay pretty constant so you wouldn't need to adjust for each soundcheck, as Alex says. Behringer used to do a cheap little DSP device called a Shark, I think they probably still do, that has an adjustable notch filter with variable Q (filter width). With something like that you could work out the problem frequency at a practice/at home and just leave it in your signal chain, bypassed if you liked until needed.

To understand boundary effects it's important to recognise that there are two potential aspects - reinforcement and cancellation. The former is due to the boundary effectively acting to constrain the directions in which waves can propagate. The latter is due to reflections from the boundary coming back out of phase and cancelling out the wave from the listener's persective. A cab 5 feet from a boundary will have a primary cancellation around 55Hz-ish, this frequency will be raised as the cab gets closer to the boundary. Raising a cab up high has the effects of both lowering the frequency below which boundary reinforcement occurs, and introducing cancellations, each of which will reduce output. Bear in mind also, that the double bass's output is probably not that low frequency so both midbass cancellations and loss of boundary loading could each be contributing. Walls also count as boundaries.

Edited December 1, 2011 by LawrenceH

[fatback]

Thanks Lawrence. I see the point about losing both low and low mid. That would fit.

On the notch filter side, i do have one on my amp (fixed narrow Q)and I also have one on a DHA pedal (variable Q). I'll definitely try to find the bass's resonance, but i still can't see me risking putting the cab on the floor, having a problem and having to muck with EQ. I hate the pressure of solving techie stuff in the minutes before the gig. Absolutely does my head in.

In short, not brave enough. I think I'll stick with the stand - 100% hassle-free.

[Bill Fitzmaurice]

[quote name='fatback' timestamp='1322763158' post='1455625']
Thanks, Bill. The cab on stand is chest height, so not so far off 5 feet. Do you lose midbass at lesser elevations?
[/quote]Yes. There's actually a cancellation notch where the difference between the distance from the speaker to the bass and the reflected wave off the floor to the bass is 1/2 wavelength. You can vary the frequency of that notch by both speaker and instrument placement, IMO rotating a knob is far more practical.