Simple way to determine effect of combining cabs?

[asingardenof]

I've done a search and couldn't see anything on this topic, but if this has been answered before, please feel free to point me at the relevant thread.

 

I was wondering if anyone had developed/discovered a simple spreadsheet or website that can tell you, for given inputs of speaker size and configuration, sensitivity, resistance, etc. what the effect on volume would be of combining different speaker cabinets. I appreciate that if you have two identical cabinets then this is relatively simple, but as this may not occur often it would be useful to be able to have a ready reckoner/rule of thumb guide for doing this which would help determine whether it's worth doing. This may only be hypothetical as there are many real-world factors that could influence the results, but it would be good to have a starting point. If I understood the science I'd be happy to look into this, but this would be a far easier task for someone with more experience than me.

[fretmeister]

Not that I've heard of.

I'd be surprised. The number of possible combinations of cab designs made in the last 50 years must be into the tens of thousands.

[Woodinblack]

1 hour ago, asingardenof said:

I was wondering if anyone had developed/discovered a simple spreadsheet or website that can tell you, for given inputs of speaker size and configuration, sensitivity, resistance, etc. what the effect on volume would be of combining different speaker cabinets.

 

Almost certainly not, because there is nothing simple about that.

[Bill Fitzmaurice]

I understand the science, and that's why my advice is never mix cabs. Doing so is just like what Mama Gump said about a life and a box of chocolates: "You never know what you're going to get".

[asingardenof]

Just now, Woodinblack said:

 

Almost certainly not, because there is nothing simple about that.

Fair enough - as I say I'm not up to speed with the science behind it, but it seems like something that could be useful if anyone had the inclination and time to look into it.

[asingardenof]

3 minutes ago, Bill Fitzmaurice said:

I understand the science, and that's why my advice is never mix cabs. Doing so is just like what Mama Gump said about a life and a box of chocolates: "You never know what you're going to get".

Legit. My plan is to eventually have to matching cabs so it won't be an issue. For now I'll save my back and just take the one to each gig and hope for the best.

Edited December 5, 2022 by asingardenof

[Dan Dare]

Such a "simple spreadsheet" would be impossible to produce. Too many variables. For it to be in any way useful, one would need to audition every conceivable combination of cabs, drivers, etc. Probably better to just try things and see whether they do the job for you or not.

[BigRedX]

Other thing that you can't predict is that when you use two different cabs they will produce different sounds in different places in a room, depending on the projection/dispersion/beaming characteristics of the cabs combined with the acoustics of the room. This is yet another reason why mixing cabs is not a good idea.

 

It's become a strange situation that for bass players the bigger and more impressive the gigs you play, the less important your choice of cab(s) becomes. The vast majority of gigs I have done over the past 20 years have had sufficient PA support for my rig (when I was still taking one to gigs) to be little more than a personal monitor, albeit a very impressive looking one. And for anything but the very smallest of stages it didn't even have sufficient dispersion to cover the whole stage, so I would be relying on the monitors to hear myself as soon as I stepped away from in front of my rig. As a result my conventional rigs got sold and replaced with a Helix and FRFR, and the latter is mainly used for band rehearsals.

Edited December 5, 2022 by BigRedX

[Woodinblack]

1 hour ago, asingardenof said:

Fair enough - as I say I'm not up to speed with the science behind it, but it seems like something that could be useful if anyone had the inclination and time to look into it.

 

The fact that in all of recent history with many hundreds of thousands of people using cabs and wondering what various ones sounded like together, that there is no such thing probably tells you more about it than the science!

[asingardenof]

7 minutes ago, Woodinblack said:

 

The fact that in all of recent history with many hundreds of thousands of people using cabs and wondering what various ones sounded like together, that there is no such thing probably tells you more about it than the science!

An excellent point!

[asingardenof]

1 hour ago, Dan Dare said:

Such a "simple spreadsheet" would be impossible to produce. Too many variables. For it to be in any way useful, one would need to audition every conceivable combination of cabs, drivers, etc. Probably better to just try things and see whether they do the job for you or not.

I did acknowledge that it would only be a rough guide and a starting point, not a final definitive answer. 

[Bill Fitzmaurice]

3 hours ago, Dan Dare said:

Such a "simple spreadsheet" would be impossible to produce. Too many variables. For it to be in any way useful, one would need to audition every conceivable combination of cabs, drivers,

It could be done, but not by auditioning cabs. If you have the full specs on cabs it is possible to predict how they'll work together. The problem there is that full specs, including FRD, Z and phase response charts, aren't available for any cabs.

[itu]

5 hours ago, asingardenof said:

I did acknowledge that it would only be a rough guide and a starting point, not a final definitive answer. 

As our grand old amp/speaker man @Bill Fitzmaurice told you, the amount of parametres, out of which most are not published by manufacturers (because they probably aren't even measured), are needed to make even a faint guess. Check wikipedia or any source that describes T/S parametres (Thiele/Small, not theile or anything else). That's a good starting point to understand this mess.

 

An anechoic room (measurement system included) would be your friend, as well as the possibility to measure the individual cabs/components, i.e. the cabs.

 

If the combination would work with the same loudness, we might start from sensitivity. If you could measure the system's sensitivity, you could find components that work together in a similar way. Then another area could possibly be the frequency response. But these already require quite a lot of equipment, as well as the ability and knowledge to use them. And that anechoic room would help.

 

I know some hifi components have been measured, but the requirements differ very much. They are after flat response while PA (which include bass) systems start from high sensitivity and loudness. Companies want specific sound from different points of view, and that also limits the functional comparison: "Bad" response, respected sound?

 

OK, if this has been slightly rough, let's start from an easy specification:

Impedance is usually qualified as one number, but it actually changes while the frequency rises. Can you mix different impedances?

If you say "No", please explain.

If you say "Yes", we want to hear your educated comments.

[Phil Starr]

I'd go even further on the impossibility of any 'simple table', quite apart from the size of such a table. If you limited yourself to the 200 most popular bass cabs a table of 40,000 combinations would take a lot of searching

 

It would be theoretically possible given enough data to predict the frequency response on axis of any given combination and to give indications of the off axis responses but would you need a greater level of detail to predict how each combination would interact with a range of rooms amplifiers and basses. You'd need a huge amount of detail though and the 'answer' to how it sounds would be just as technical and detailed as the questions. The big problem would be ow to interpret the data. The language we have to describe sounds is so vague and other people's perceptions so variable that a guide would be no more helpful than most restaurant reviews on Trip Advisor. How often is the best place to eat the sandwich bar that does a good sausage sandwich and not the Michelin starred restaurant and it's snail porridge? And, who is to say who is right.

 

If you want to know who makes the best coffee then you need to go and taste it yourself. (I make it myself btw), but you might not like black strong Americano so me giving you the weights temperatures and pressures won't help you make anything other than the coffee I like. Ultimately if you really want to mix speakers you need to do the listening yourself. 

[BigRedX]

40 minutes ago, Phil Starr said:

Ultimately if you really want to mix speakers you need to do the listening yourself. 

 

And if your cabs are for the listening benefit of your audience you also need to get out front around the venue to listen to how the sound changes in different locations. It's no good having a rig that sounds great when you're stood a couple of feet away from it and crap everywhere else, because you are the least important person from the PoV of sound. It's your audience you should be aiming at. That's why my on-stage requirements are simply that I can hear that I am in tune and in time with the rest of the band, let the PA do the heavy lifting sound-wise and trust the PA engineer will make me sound awesome FoH.

[asingardenof]

OK, so the answer is a resounding "of course not, you utter buffoon". Never mind.

[Woodinblack]

1 hour ago, asingardenof said:

OK, so the answer is a resounding "of course not, you utter buffoon". Never mind.

 

No, the answer is 'Good question, but no you can't for reasons'. Its not a stupid question, its just a no!

 

[BassmanPaul]

One pairing that you can take to the bank is never mix a 4x10 with a 1x15.  It always puts the single 15 in danger as it fails to keep up with the more capable 4x10.

[fretmeister]

On 05/12/2022 at 21:19, itu said:

As our grand old amp/speaker man @Bill Fitzmaurice told you, the amount of parametres, out of which most are not published by manufacturers (because they probably aren't even measured), are needed to make even a faint guess. Check wikipedia or any source that describes T/S parametres (Thiele/Small, not theile or anything else). That's a good starting point to understand this mess.

 

An anechoic room (measurement system included) would be your friend, as well as the possibility to measure the individual cabs/components, i.e. the cabs.

 

If the combination would work with the same loudness, we might start from sensitivity. If you could measure the system's sensitivity, you could find components that work together in a similar way. Then another area could possibly be the frequency response. But these already require quite a lot of equipment, as well as the ability and knowledge to use them. And that anechoic room would help.

 

I know some hifi components have been measured, but the requirements differ very much. They are after flat response while PA (which include bass) systems start from high sensitivity and loudness. Companies want specific sound from different points of view, and that also limits the functional comparison: "Bad" response, respected sound?

 

OK, if this has been slightly rough, let's start from an easy specification:

Impedance is usually qualified as one number, but it actually changes while the frequency rises. Can you mix different impedances?

If you say "No", please explain.

If you say "Yes", we want to hear your educated comments.

bit harsh, and unnecessarily sarcastic. It’s a valid question to ask.

[asingardenof]

On 05/12/2022 at 21:19, itu said:

As our grand old amp/speaker man @Bill Fitzmaurice told you, the amount of parametres, out of which most are not published by manufacturers (because they probably aren't even measured), are needed to make even a faint guess. Check wikipedia or any source that describes T/S parametres (Thiele/Small, not theile or anything else). That's a good starting point to understand this mess.

 

An anechoic room (measurement system included) would be your friend, as well as the possibility to measure the individual cabs/components, i.e. the cabs.

 

If the combination would work with the same loudness, we might start from sensitivity. If you could measure the system's sensitivity, you could find components that work together in a similar way. Then another area could possibly be the frequency response. But these already require quite a lot of equipment, as well as the ability and knowledge to use them. And that anechoic room would help.

 

I know some hifi components have been measured, but the requirements differ very much. They are after flat response while PA (which include bass) systems start from high sensitivity and loudness. Companies want specific sound from different points of view, and that also limits the functional comparison: "Bad" response, respected sound?

 

OK, if this has been slightly rough, let's start from an easy specification:

Impedance is usually qualified as one number, but it actually changes while the frequency rises. Can you mix different impedances?

If you say "No", please explain.

If you say "Yes", we want to hear your educated comments.

Something like "even then it's not practicable to do what you're suggesting" would have done, no need to be a Richard about it.

[itu]

1 hour ago, fretmeister said:

bit harsh, and unnecessarily sarcastic. It’s a valid question to ask.

 

37 minutes ago, asingardenof said:

Something like "even then it's not practicable to do what you're suggesting" would have done, no need to be a Richard about it.

I am sorry if my answer was considered sarcastic, or offensive. I tried to open up the topic slightly more. I studied acoustics years ago, and spent time in four anechoic rooms. Measuring took time, and as there were lots of parametres to consider. The results could be manipulated very easily, starting from microphone or speaker distance and placement.

 

Anechoic rooms were very practical, because they helped to remove room effects from measurements.

 

In the university I saw lots of mic and speaker measurements made (and I made some myself, too), but that took nearly a year and the results were something like tens of speakers: frequency response, sensitivity, etc. It was clearly lots of work, and the university sold (note: money was involved!) the results to a local hifi magazine. But that was very long ago.

[asingardenof]

3 minutes ago, itu said:

 

I am sorry if my answer was considered sarcastic, or offensive. I tried to open up the topic slightly more. I studied acoustics years ago, and spent time in four anechoic rooms. Measuring took time, and as there were lots of parametres to consider. The results could be manipulated very easily, starting from microphone or speaker distance and placement.

 

Anechoic rooms were very practical, because they helped to remove room effects from measurements.

 

In the university I saw lots of mic and speaker measurements made (and I made some myself, too), but that took nearly a year and the results were something like tens of speakers: frequency response, sensitivity, etc. It was clearly lots of work, and the university sold (note: money was involved!) the results to a local hifi magazine. But that was very long ago.

Thanks for clarifying, and apology accepted. I realise I have a lot to learn about such matters so am keen to soak up as much information about it as I can!

[Bill Fitzmaurice]

Start here: https://blog.soton.ac.uk/soundwaves/

 

We have difficulty understanding sound because of our assumption that sound waves behave in the same fashion as light waves. They don't. Not only do speakers as sound sources not behave like lamps behave as light sources, they behave differently at every frequency. That means the first step in knowing how speakers work is to learn how sound waves work. That would be easy if anything about sound waves was intuitive, but almost nothing is. Much of what intuition tells us is incorrect.

[asingardenof]

Yeah, I watch the Barefaced Youtube channel and try to understand but it's tricky for a muggle like me!

 

My only real experience of such things is where, in my day job as a highway design engineer, I've done noise assessments to determine if noise barriers are required adjacent to motorways, but that was relatively simplistic (albeit I'm sure the formulae were developed by some serious boffins at TRL who smoked pipes and suchlike) compared to modern acoustic modelling methods.

[Chienmortbb]

On 05/12/2022 at 14:10, BigRedX said:

And for anything but the very smallest of stages it didn't even have sufficient dispersion to cover the whole stage,

This important, and if you tried to add another cab on the other side of the stage, you will have peaks and troughs in the low end. This is one of the reasons the LFSys* cabs are so good. The dispersion is such that on small/medium-sized stages, the whole of my 5 piece can hear me.

 

37 minutes ago, asingardenof said:

some serious boffins at TRL who smoked pipes and suchlike)

As Dr Who said when trying to explain some phenomenon or other "it's a wibbly, wobbly, timey, whimey sort of thing". There is a science behind it, but it is complicated enough with "identical" cabinets. The results with different models is unpredictable. You need either a wireless system or long leads to walk out into the auditorium and hear the peaks and troughs you have created.

 

*I have an LFSys Silverstone, and although I count @stevie as a friend, there is no financial benefit to me recommending them.