What are you using to amplify your double bass?

[chrkelly]

What a thread!

I think the main thing for me would be for the cab to be reasonably light and have a very small footprint, the vast majority of gigs where I need an amp are pit gigs where it's being used just to beef up my acoustic volume. I think that's the main reason the GK microbass combo remains so popular, decent sound and it can fit anywhere. A few of the pits on a recent tour were so small I was struggling for space for my aguilar db112. I always try to play without an amp wherever possible though and just send my dynb straight to the desk.

For the big gigs though it's a completely different story. For rock etc. I found that I couldn't use the house floor monitors at all (too many feedback issues) and had to rely on my backline. Best cab for that was my Bergantino HS410. I used an SWR 8x8 for a while too and always hired a SWR Goliath 4x10 for touring. The cab must have a very tight bass and be used with a fairly neautral sounding head. Not doing those type of gigs much anymore though but I think smaller speakers are definitely the way to go for those volumes.

[alexclaber]

[quote name='jakesbass' post='345825' date='Dec 4 2008, 07:18 PM']...bass players that express preference for slightly smaller speakers, generally 10s or 12s...

...You may successfully argue that technically, a 15 [i]can[/i] produce the desired characteristics, your potential downfall is that in my experience they also display unfavourable characteristics that DB players do not like.[/quote]

The big challenge with doing anything different is the marketing, not the engineering!

Here's something to get your head around - and this is the fundamental challenge! The nominal diameter of a loudspeaker is one of the least important characteristics describing how it sounds. The concept I'm considering here is taking a very high-end hi-fi speaker approach and applying it to live instrument amplification. So if you listened to a really fantastic hi-fi you would neither know nor care how large the woofers were.

[quote name='jakesbass' post='345825' date='Dec 4 2008, 07:18 PM']The ultimate judgement is the sound. So I would say use a research process that starts from a perspective of what sounds DB players want to hear as a minimum standard, and what do they dislike.[/quote]

Minimum standard is easy to achieve - but more dislikes would be useful to know.

There is a very clear reason why double bassists don't like 15" bass guitar cabs and that is because most of them are particularly poorly designed (or not designed at all...) Most cabs are too small for the speaker they contain and this issue is exacerbated with a larger speaker. And then if you're trying to make a cab cheap enough and light enough for a double bassist to buy it then you're unlikely to put a big enough magnet on the speaker to give you strong midrange response. Therefore most 15" cabs you'll have heard sound boomy (undersized box) and muddy (lack of magnet strength). That's an over simplification but it is the essence of the problem.

Back to the 2-way open-baffle concept, most of your tone would actually be coming from the smaller midrange speaker - the 15" woofer would solely be concerned with producing the lows, and these lows would be produced as an immediate velocity wave, not the usual pressure wave which transforms into a velocity wave.

Very interesting comments from everyone - I shall keep working on this and if there's anyone near me do get in touch to test the prototype if/when it's done!

Alex

[jakenewmanbass]

[quote name='alexclaber' post='345928' date='Dec 4 2008, 09:57 PM']Minimum standard is easy to achieve - but more dislikes would be useful to know.[/quote]
Do note that I suggested that as a starting point
[quote name='alexclaber' post='345928' date='Dec 4 2008, 09:57 PM']Therefore most 15" cabs you'll have heard sound boomy (undersized box) and muddy (lack of magnet strength). That's an over simplification but it is the essence of the problem.[/quote]
It may be an over simplification to someone as acoustically aware as yourself, but to me it's a cogent explanation of what I've heard for years. (the exception being my peavey BW 15")
[quote name='alexclaber' post='345928' date='Dec 4 2008, 09:57 PM']Very interesting comments from everyone - I shall keep working on this and if there's anyone near me do get in touch to test the prototype if/when it's done![/quote]

I'm not too far, and have plenty of friends in Brighton so could always justify a trip to you Alex.
Keep us posted mate and thanks for a very interesting thread.
Jake

[synaesthesia]

[quote name='guyl' post='344926' date='Dec 3 2008, 11:17 PM']I wouldn't be too dismissive of a 15" speaker. Isn't the "box" on an upright acting as a bass speaker anyway? And that's about 2ft wide.

Never played through a cab with a rear facing speaker. Doesn't that cause trouble when your playing in a corner or against a wall?[/quote]

The measurement of the Bass's width has nothing to do with performance of typical speaker sizes.

[BassBod]

Its worth talking about "lows" with double bass amplification. Piezo's (used by most) produce a lot of very low stuff, (more than you'd ever hear acoustically) and can be a real problem even though you can't hear it directly. I've seen the cone on my CXL110 jump just from damping the strings! So if you are looking to reproduce the acoustic sound its worth thinking about?

The low cut (or high pass?) filter on the Acoustic Image preamp works, but it seems a bit crude to me? I guess it really designed with the combo "downward" speaker design in mind.

[bassace]

Also bear in mind that the further away from the speaker - ie in the audience - the more you hear the lows and the less the highs. So in addition to getting a good tight bottom (I can't believe I said that) you still need a rig that gives a strong sound right up to the thumb position if poss. When I set up on stage I look first for something like a Fender Jazz sound - yes really! - and then I tweak the preamp to bring the sound back to URB. I don't start with a lot of boom.

When I started out I used a Leak HiFi amp for many years with a custom preamp my brother built for me. I used to make my own speaker enclosures and used an 18" Goodmans. I thought it was great but looking back it must have been terrible! There was one rock band in town that had a bass enclosure so big that they put a door in the back and hung the band suits in it. Thank goodness for the 10" Wizzy.

[chris_b]

Alex, you're trying to emulate the process of sound creation from a double bass, but surely what traditional instrument makers and players are really interested in is the sound projected from the front, to the audience. A complicated solution might be more interesting but might not get the best results.

[alexclaber]

[quote name='BassBod' post='346162' date='Dec 5 2008, 09:45 AM']Its worth talking about "lows" with double bass amplification. Piezo's (used by most) produce a lot of very low stuff, (more than you'd ever hear acoustically) and can be a real problem even though you can't hear it directly. I've seen the cone on my CXL110 jump just from damping the strings! So if you are looking to reproduce the acoustic sound its worth thinking about?

The low cut (or high pass?) filter on the Acoustic Image preamp works, but it seems a bit crude to me? I guess it really designed with the combo "downward" speaker design in mind.[/quote]

That is a very good point! The highpass filter on the AI preamp isn't crude at all, these kind of steep active filters are the best way to deal with unwanted lows, which is why you find similar highpass filters on all decent PA systems. Trying to control the very low response through cab design doesn't really work because the only options are sealed cabs which reduce cone excursion but as a result also reduce LF sensitivity or ported/transmission line/bandpass/horn cabs all of which unload below a certain frequency but do give more sensitivity down to that point.

[quote name='bassace' post='346189' date='Dec 5 2008, 10:07 AM']Also bear in mind that the further away from the speaker - ie in the audience - the more you hear the lows and the less the highs. So in addition to getting a good tight bottom (I can't believe I said that) you still need a rig that gives a strong sound right up to the thumb position if poss. When I set up on stage I look first for something like a Fender Jazz sound - yes really! - and then I tweak the preamp to bring the sound back to URB. I don't start with a lot of boom.[/quote]

Have you ever wondered why the further you get from the speaker the more you hear the lows and the less the highs?

The main reason that this occurs is that although the on-axis frequency response of your cab may be fairly flat the power response of that cab is not. Power response is the sum total of all the output from a speaker in every direction across the frequency spectrum. So how does this relate to a typical cab?

Lets look at a typical 1x12" cab with fairly flat response between 100Hz and 3kHz. The low frequency output is omnidirectional so you get equal output both backwards and sideways as you do to the front. The midrange output is directional but still well dispersed, so it occurs only to the front but is spread broadly to both sides of the forwards direction. The treble output is more directional, being in a more narrow cone beaming from the centre of the speaker. So if we say that the total midrange energy coming from the speaker is equal to 100dB then the total LF energy will be four times that (due to backwards and left and right output) which will be 106dB. And the treble energy is in a much more narrow cone, so probably only about 89dB. So although the on-axis frequency response is fairly flat the power response is stronger in the lows and weaker in the highs.

Now if you play outdoors or in anechoic chamber then all you'll hear out in the audience (assuming no PA support) is the roughly on-axis forwards response. But if you play indoors then some of that energy that isn't on-axis will be reflected and will add to the direct output, hence the sound gets less and less clear and more and more bottom heavy as the proportion of reflected vs direct sound increases.

With an open-baffle speaker you reduce the power response in the lows by removing sideways output whilst increasing the power response in the mids and treble by improving the dispersion. So theoretically this kind of speaker should allow you to have a much more similar sound onstage compared to out front. The downside of an open-baffle woofer is that you lose a whole load of output in the lows because of the cancelled out sound to the sides, hence the need for a larger woofer to move enough air (but because this woofer isn't in a conventional cab is doesn't have a typical 'sound').

[quote name='chris_b' post='346216' date='Dec 5 2008, 10:32 AM']Alex, you're trying to emulate the process of sound creation from a double bass, but surely what traditional instrument makers and players are really interested in is the sound projected from the front, to the audience. A complicated solution might be more interesting but might not get the best results.[/quote]

I'm not so sure - I thinkthe sound of an acoustic instrument is the whole sound you hear from it and that will be a combination of direct and reflected sound. I may be barking up the wrong tree but I just have a feeling... I don't like complicated solutions - I'm a complete minimalist at heart so always try to design down to the minimum complexity without noticeable detriment to the performance (hence my RIM Custom 5 being like it is and the same with my cab designs!)

If anyone wants some more reading on the concept of open-baffle speakers, pop along to [url="http://www.linkwitzlab.com"]http://www.linkwitzlab.com[/url] - the man knows his stuff!

Alex

[BassBod]

Thanks Alex - great discussion. Can't wait to see what you come up with.....