Testing/recording cabs 115 112 210 212... all things being equal

[warwickhunt]

I have in my possession an array of cabs which I was going to record to assess / demonstrate their similarities and/or differences.  Now none of this is going to be scientific or setting out to prove a point; purely that I have them and someone 'might' be interested in the outcomes.  

 

Genz Benz 2x12 NeoX - 4 ohm

TC Electronic RS 2x10 (x2) - 8 ohm

Aguilar DB 1x12 (x1 no tweeter x2 with tweeter) - 8 ohm

TKS 1x15 - 8 ohm

 

My initial thoughts are that I'll need to position the mic in the same reference point on all cabs (close mic, off-axis) and that I'll obviously feed the cab with the same amp on flat settings (not EQing to suit a particular cab); I think it would be prudent for me to use a recording of me playing (a looper might be easiest) to eliminate any variance in my playing. 

 

However, I started to wonder about the fact that some of the cabs have 2 drivers v's 1 driver and one of the cabs (Genz Benz) is a 4 ohm load.  I could run a pair of TC cabs to get me 4 ohms, likewise a pair of Aguilars but the TKS would be stand alone so would I need to tweak the volume to get relative parity... but then I'd need to consider variance in sensitivity.  

 

I think as it is unscientific and for fun I just need to decide if I'm going to pair cabs where they match to give 4 ohms, with the exception of the TKS which will just have to suck it up OR I could do all 8 ohm cabs and leave the Genz Benz as is and see how that compares... thoughts/votes?  

 

[itu]

How about pink noise and one meter distance from the cabs? Looper is of interest, but I still would add some pink.

[Bill Fitzmaurice]

First and foremost do the testing outdoors, well away from any buildings or walls, otherwise at least half the result will be from the room. Some years ago there was a much ballyhooed  'subwoofer shoot out' where the results were totally useless, as the room response dominated the results. Second, don't place cabs near each other. An unused cab acts as a bass trap. It's best to leave the mic in one spot and then place each cab in the same place one by one. The mic should be at least two meters out from the cab location, preferably more. 1m/1w is how the charts are shown but that's an extrapolated result. Danley Sound Labs, for instance, measures at 10 meters with 100 watts, which is the equivalent of 1m/1w. Finally, measure on axis and 45 degrees off-axis. Off-axis is where differences between various configurations will be most evident.

[warwickhunt]

Oooof that throws up some questions.    

 

Outdoors OK.

Mic 2m - 10m from a cab... am I going to need to crank the gain to silly levels to get a good signal?  

Mic 45 degrees off axis @ 2 - 10m AND outdoors - do I leave the gains where they are or do I try to match to on axis levels?  

 

Biggest issue though is that I'm imagining that I'd need to run my amp at a very rough approximation of what I guess 100w is... I've no way of measuring if my amp (likely my Thunderfunk 550) was outputting 100w at any given setting on the input or output gains.  

[warwickhunt]

Thinking it through that would be the most scientific way Bill but most cabs are used in rooms so maybe that isn't an issue for a bit of 'fun' so long as I follow your other guidance (no other cabs, same position).

[Bill Fitzmaurice]

You'll be surprised how loud 2.83v is at 2 meters. BTW, you can't accurately measure pink noise with a volt meter as it will bounce quite a bit. Get it close and leave the amp set at the same volume with each speaker. If you want to calibrate the result you'd do that with a 1kHz sine wave at 2.83v. Measuring at 45 degrees is simple, just rotate the cab.

[stevie]

Outdoors in the North East in January? Good luck with that.

 

However, I don't think @warwickhuntsaid anything about measuring - only recording.

 

 

[Downunderwonder]

7 hours ago, Bill Fitzmaurice said:

You'll be surprised how loud 2.83v is at 2 meters.

Also how surprisingly not nearly as loud at 50 hz as it is at 100hz with the same small signal.

[Chienmortbb]

12 hours ago, Bill Fitzmaurice said:

You'll be surprised how loud 2.83v is at 2 meters. BTW, you can't accurately measure pink noise with a volt meter as it will bounce quite a bit. Get it close and leave the amp set at the same volume with each speaker. If you want to calibrate the result you'd do that with a 1kHz sine wave at 2.83v. Measuring at 45 degrees is simple, just rotate the cab.

Much of what you say is true but as you know, using 2.83V for all cabinets will give  the impression that the 4R cabinet(s)  a. 3dB advantage. To put us another way, 2.83V gives 1 watt at 8R and 2 watts at 4R.  

[warwickhunt]

10 hours ago, stevie said:

Outdoors in the North East in January? Good luck with that.

 

However, I don't think @warwickhuntsaid anything about measuring - only recording.

 

 

 

LOL  That has been going through my head all night... maybe in April I'll try this scenario. 

 

You are also correct I'm not talking of measuring or analysing; my initial thought was 'How different will each cab *combination of cabs* sound if close mic recorded?'  I know they sound quite different sat in front of them but if they were recorded and no clue given, could another bassist readily identify a 10/12/15" driver?  BTW I'm confident the answer is NO, however a lot of folk will declare they want X, Y or Z size driver to get more top/mid/bottom.

 

[Downunderwonder]

28 minutes ago, Chienmortbb said:

Much of what you say is true but as you know, using 2.83V for all cabinets will give  the impression that the 4R cabinet(s)  a. 3dB advantage. To put us another way, 2.83V gives 1 watt at 8R and 2 watts at 4R.  

Halve the voltage. Job done.

[ahpook]

Looks like a fun project. Keep it as unscientific as you like 👍

[Chienmortbb]

4 minutes ago, ahpook said:

Looks like a fun project. Keep it as unscientific as you like 👍

The problem with that is that if a cab is louder, it will sound better. All things being equal, the 4R cab is likely to "win". Of course all cabs are not equal when it comes to sensitivity, so it is possible that an 8R cab will "win" the sensitivity battle, but the 4R cab has a built-in advantage UNLESS you are using a valve amp and setting the transformer taps correctly.

 

You could of course use a sound level meter and adjust the outputs to be equal at a given frequency, but that brings two unknowns into the project.

 

So just try it and publish your thoughts. It will not be scientific, but it might be fun.

[stevie]

Nearfield recording isn't a great idea because you won't fully capture the contribution of the port and the tweeter. I'd suggest putting the mic about two metres away. Bill's suggestion of placing the test object in the same place in the room is sensible. Recording at ear height could be interesting, as could recording with the cabs turned facing 45 degrees from the mic - but let's not overcomplicated what sounds like a fun project.

 

In a perfect testing scenario, amplifier power would be adjusted to account for the different cab impedances. But there again, a 2x12 is going to sound louder than a 1x12 even if the impedance is the same. I'm looking forward to this. It's just a shame you don'f have an LFSys cab in the line up. 😁

[Bill Fitzmaurice]

4 hours ago, Chienmortbb said:

Much of what you say is true but as you know, using 2.83V for all cabinets will give  the impression that the 4R cabinet(s)  a. 3dB advantage. To put us another way, 2.83V gives 1 watt at 8R and 2 watts at 4R.  

True. However, there's a benefit to testing with the same amp settings. Power doesn't define how loud a cab goes, voltage swing does. While power varies with the load impedance voltage swing does not. So if your intent is to see which cab will go louder with a given amp you test them with the same voltage input.

Quote

Halve the voltage. Job done.

Halving the voltage results in one-quarter the power. Also, in most cases otherwise with identical drivers save one is 8 ohm and the other is 4 ohm the 4 ohm driver actual impedance is usually more than half that of the 8 ohm driver. There are too many variables involved to truly know how much power the cab is actually being driven with. When you use voltage as the benchmark there are no variables. For this reason testing is never done with a specified power, as there's no way of knowing how much power is being applied. It's different at every frequency. Testing is always done with a specified voltage. When the result is called 1m/1w that's a calculated figure, and not a particularly accurate one. For instance, this charts the power into an 8 ohm speaker at 2.83v. How many watts? There's a thousand answers, one for every frequency.

[tauzero]

As @stevie says, if you close mic it, you lose any contribution from other drivers and the port. Consider a typical pub gig - the front row of audience (so the ones who are messing up your sound to the people behind them by being big bags of water with cloth wrapped round them) are hopefully at least 2m away from your cab, so you really want to know roughly what it'll sound like to them. A mic at 2-3m distance, and absolutely consistent placement of mic and cab in the room (which ideally should have some soft furnishings) should give some decent recordings. Your idea of using a pre-recorded piece rather than playing the same thing for each cab is a very good one.

[Phil Starr]

On 07/01/2024 at 14:44, warwickhunt said:

I have in my possession an array of cabs which I was going to record to assess / demonstrate their similarities and/or differences.  Now none of this is going to be scientific or setting out to prove a point; purely that I have them and someone 'might' be interested in the outcomes.  

 

Genz Benz 2x12 NeoX - 4 ohm

TC Electronic RS 2x10 (x2) - 8 ohm

Aguilar DB 1x12 (x1 no tweeter x2 with tweeter) - 8 ohm

TKS 1x15 - 8 ohm

 

My initial thoughts are that I'll need to position the mic in the same reference point on all cabs (close mic, off-axis) and that I'll obviously feed the cab with the same amp on flat settings (not EQing to suit a particular cab); I think it would be prudent for me to use a recording of me playing (a looper might be easiest) to eliminate any variance in my playing. 

 

However, I started to wonder about the fact that some of the cabs have 2 drivers v's 1 driver and one of the cabs (Genz Benz) is a 4 ohm load.  I could run a pair of TC cabs to get me 4 ohms, likewise a pair of Aguilars but the TKS would be stand alone so would I need to tweak the volume to get relative parity... but then I'd need to consider variance in sensitivity.  

 

I think as it is unscientific and for fun I just need to decide if I'm going to pair cabs where they match to give 4 ohms, with the exception of the TKS which will just have to suck it up OR I could do all 8 ohm cabs and leave the Genz Benz as is and see how that compares... thoughts/votes?  

 

This is the sort of experience I've tried to give people at the South West Bass Bash for the last few years. Over the years we've tried all sorts of things to try and make it a fair test but in the end it's just a bit of fun, there are too many variables to control. So, yes please to the mic being well back from the cab in the 'audience' area, directly in line with the cabs and in as non-reverberent a space as you can manage. Outdoors would be good and as far away from any walls as possible. Then think about amplification. Most bass amps are highly coloured so we take the bass straight through a desk and a PA amp. The problem is that any frequency irregularities in the amp are going to flatter some speakers more than others. Any peak in the amp that lines up with a peak in the speaker is going to make that bit of the spectrum really jump or if the speaker is weak there the amp will fill in the gap. Come to that some speakers will work better with some basses. So many variables

 

Finally you need to think about volume. Some cabs are going to be louder than others, fundamentally we prefer loud sounds and due to the way our hearing works louder boosts the bass and treble we hear more than the mid-range. At the bass bash I've tried to make sure the sound levels are the same from each speaker turning the amp up and down to match the sound levels, I've even tried using sound level meters to match volumes. Just swapping speakers with the amp settings unchanged will tell you mainly just how loud they are, if you wnat to know how good they sound then you need to set the amp each time for equal volumes. Or do both as two separate tests

 

I think this is going to be a lot of fun for all of us, don't worry if it isn't the most scientific study ever done, there's far worse on You Tube and we all still lap it up. I'm sure you and we will all learn something. I can't wait to see what you do

[Chienmortbb]

There are so many things to agree on and so many things to argue on this thread that I am bowing out. Try it and let us know your thoughts afterwards, It will be fun, and we can then start "discussing vigorously" again.🤣

[warwickhunt]

Cheers for all of the thoughts, feedback and solid scientific knowledge.  I am well aware that if you were going to draw conclusions from this bit of fun it would be absolutely pointless!  It is not a case of me trying to prove/disprove anything but it is interesting (if that is the right word) when you have a set of cabs and you spend timing swapping and changing just one variable (the cab) and in some cases you can see how conceptions/misconceptions can be created.  This idea isn't new but when I had a bass playing friend around we were actually blind testing (NOT 'testing') our Kemper profiles (and making profiles) through various devices and in the process the cabs became as much a focus as the profiles.  Nothing deadly serious, just interesting to both of us.

 

I think in the short term (possibly next week), I'm going to clear my music room (5m x 5m) a bit and do a fun/casual recording of the 4 cabs BUT I think I'll do it as 2/4 separate challenges (not going to call it a 'test', as it isn't); I'll do it with 8 ohm singles + the GB 4 ohm cab @ 2m but also @ 4" (where you might mic a cab from for live work) but I'll also do the other option as 4 ohm loads with the TKS 8 ohm cab (at the same distances).  It makes sense if I have everything in situ I may as well do multiple variables before I pack it away.  That way if there is a variable induced by me it'll be the same on all (i.e. recording level, positioning etc).  

 

Sound source - Oooooh I'm with @Phil Starr that an amp might flatter a particular cab, which might be my choice of cab/amp BUT it might not be everyone's ideal partnership.  However, I have the option to use my Thunderfunk (550w solid state), EBS HD350 (250-350w solid state), Tech Soundsystem Blackcat (1000w valve preamp [tonestack EQ] C;donkey D power) or my Fishman Plat Pro preamp pedal which is quite neutral sounding into the power stage of one of the above amps.  I do have other preamps (Tech 21 Sansamp, Tonebone Bassbone, BBE Acoustimax) but I think they are more coloured.  Any amp setting would have to be on neutral, which is 12:00 for everything except the Blackcat (I'll need to research Tonestack again), with no preshape engaged (EBS EQ can be bypassed which I need to investigate what that means).

 

I'll use a bass which most folk will be familiar with as opposed to something like a Bolin or obscure Warwick; possibly my Sandberg P bass in passive mode or the Sandberg Jazz (passive Aguilar pups).  Played into a Looper to ensure consistency and using my Rode Condenser mic set at the same relative position in front of each driver.  All cabs have a tweeter but I 'think' for the close mic, I'll position it away from any horn or driver with horn included (the top driver on the TC cab); for the 2m recording I'll position the mic at the centre of the actual cab as opposed to driver or tweeter.  

 

Lots of variables and still some things I've got to think through including the actual recording process et al.  Off to do something constructive... these dishes won't do themselves!   

Edited January 9 by warwickhunt

[itu]

Please use some uncompressed format (PCM, wav...) to record your test. Any coding may ruin results.

[warwickhunt]

3 minutes ago, itu said:

Please use some uncompressed format (PCM, wav...) to record your test. Any coding may ruin results.

 

What sort of file sizes will I end up with?  I have to be aware of where I post/host them for accessibility.

 

[itu]

CD is 80 minutes and 700 MB. I don't think you need more than 2 channels.

[tauzero]

3 hours ago, warwickhunt said:

 

What sort of file sizes will I end up with?  I have to be aware of where I post/host them for accessibility.

 

 

If you record them in WAV and compress them to 320kHz MP3, that should be pretty much indistinguishable from the WAV.

[Downunderwonder]

I still reckon halving the power is a good idea for an "everything is equal when it really isn't" test when the one cab is 4 ohm and dual driver.

 

Divide voltage by square root of 2 to knobble its sensitivity advantage. Intuitively that is much more equal than letting it rip with the same voltage as the 8 ohm single driver cabs.

[warwickhunt]

2 hours ago, Downunderwonder said:

I still reckon halving the power is a good idea for an "everything is equal when it really isn't" test when the one cab is 4 ohm and dual driver.

 

Divide voltage by square root of 2 to knobble its sensitivity advantage. Intuitively that is much more equal than letting it rip with the same voltage as the 8 ohm single driver cabs.

 

You assume I have a means of measuring voltage... I'm playing a bass into an amp.