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

[Downunderwonder]

53 minutes ago, warwickhunt said:

 

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

You can send a 100hz signal to your amp and if you have a multimeter it shouldn't be too had to access the voltage RMS reading at the speaker. Either a speakon with one end exposed to wiring or a 1//4" plug. If you are using 2V then 1.4 for the 4 ohm. At that rate it get the same nominal power but it still has a nominal 3dB sensitivity advantage from being a bigger 2 driver cab.

 

Hence why I figured on a half voltage to fully peg it back, with recognition that it was getting 1/4 of the power. 2 of any other other cabs can also use 1/4 each in a projected comparison. This way the projection is virtual but more accessible from the observations I reckon.

 

If you had two identical cabs and listened to the pair they would be way far more boomfy than the single. Cutting the pair down to 1/4 power would level them out pretty closely.

 

We have to assume all cabs are going to take something like their rated power to make any use of a DIY sensitivity to bass voltage comparison.

[stevie]

Don't overthink this, @warwickhunt A proper, scientifically acceptable comparison requires a much more stringent approach than anything suggested so far. Unless you have a degree in acoustics and an in-depth knowledge of statistics, just make recordings that are as close to what you would expect to hear as a player. Otherwise, there will always be some smart Alec quick to point out the failings in your procedure.

 

If I were doing this, I'd record each cab in the same position in the room - not too far from the back wall. I'd raise the mic to ear level, i.e. not directly in front of the speakers. I wouldn't bother with close mic'ing at all (but that's up to you), as it's not going to tell you anything useful. If you're using a recording as your source, a hi-fi amp, if you have one, would likely be a better choice than a bass amp. Probably a step too far, but a high quality full-range recording makes it much easier to discern differences/shortcomings in speakers than bass guitar on its own.

 

Ignore the complications of multiple drivers and different impedances. Just provide the information with each recording at let us, the listeners, deal with it. Keep it simple. Remember what Voltaire said about getting your knickers in a twist.

[Chienmortbb]

4 hours ago, stevie said:

Remember what Voltaire said about getting your knickers in a twist.

Don't remember that one. Was it something like if you touch the brown and blue wires at the same time, your knickers will be twisted?

[tauzero]

7 hours ago, Chienmortbb said:

Don't remember that one. Was it something like if you touch the brown and blue wires at the same time, your knickers will be twisted?

 

Don't cross the streams.

 

As volume does change perception, perhaps make recordings with gain and volume set identically for each cab, and then import each recording into Audacity and use the Normalize function to get them all to the same volume. Then use both sets of recordings, with explanations, for listening tests.

[Chienmortbb]

7 hours ago, tauzero said:

 

Don't cross the streams.

 

As volume does change perception, perhaps make recordings with gain and volume set identically for each cab, and then import each recording into Audacity and use the Normalize function to get them all to the same volume. Then use both sets of recordings, with explanations, for listening tests.

That sounds like a plan.

[stevie]

Yes, that's a nice bit of lateral thinking. It assumes that @warwickhunt is familiar with the software. If not, I'm sure someone from the forum would be happy to do the conversion.

[warwickhunt]

I have Ableton Live II Lite on my laptop.  I'm going to try and get this set up this week, so I'll familiarise myself with the software and see if I can find a function to 'normalize'.

[tauzero]

4 hours ago, warwickhunt said:

I have Ableton Live II Lite on my laptop.  I'm going to try and get this set up this week, so I'll familiarise myself with the software and see if I can find a function to 'normalize'.

 

If you can't, it's very easy in Audacity.

 

1. File | Import | Audio to import an audio file
2. Select | All (or Ctrl-A) to select the entire track
3. Effect | Volume and Compression | Normalize to normalise it
4. File | Export Audio to export the normalised file 

[Downunderwonder]

I thought the idea was to compare not make everything sound the same.

[warwickhunt]

17 minutes ago, Downunderwonder said:

I thought the idea was to compare not make everything sound the same.

 

My initial thoughts were tonal differences between cabs/drivers as opposed to volume differences between 4 / 8 ohms.

[Downunderwonder]

Tone is highly dependent on volume. At lower volume our appreciation of the bass content lessens so it sounds more thin/weedy/trebly/shouty..pick your favourite descriptor, without changing any EQ.

 

My vote would be naked truth with standard signal. 

[tauzero]

1 hour ago, Downunderwonder said:

Tone is highly dependent on volume.

 

That is exactly why I suggested what I did. One set of recordings at the different volume levels provided by the cabs, another set which are the same recordings but all normalised to the same volume. I did explain my thinking.

[Downunderwonder]

5 minutes ago, tauzero said:

 

That is exactly why I suggested what I did. One set of recordings at the different volume levels provided by the cabs, another set which are the same recordings but all normalised to the same volume. I did explain my thinking.

I must have missed the dual set presentation suggestion. Still don't see the point in normalising. It seriously masks an underperformance and the degree of boost is unknown.

[tauzero]

19 minutes ago, Downunderwonder said:

I must have missed the dual set presentation suggestion. Still don't see the point in normalising. It seriously masks an underperformance and the degree of boost is unknown.

 

Normalising eliminates the perception of tonal difference caused by volume difference. Having the original recordings at the levels that the cabs produce means that any underperformance is not masked.

 

Recording set 1 - original recordings from cabs, with amps at constant volume settings

Recording set 2 - normalised versions of recordings, eliminating volume perception issues

 

Nobody else seems to be having trouble understanding this.

[warwickhunt]

Room emptied of all cabs.  Tape marks on the floor for cab and mic position (cab 1m from rear wall / mic 2m from cab + 2m from rear wall)... nearly ready! 

 

Originally I was setting this up for fun to see if, in a real life setting (amp/cab in front of you), what differences might you expect and then actually hear if you were faced with a range of cabs of varying driver diameter.  This is skewed/compounded by the fact that every cab has a different sensitivity and in some cases an ohmage difference BUT I suppose that is part of the real world nature of my idea.  In truth it means that multiple drivers, sensitivity of drivers and the ohmage of the cab will most certainly skew any 'direct' comparison.  In real life if your 112 8 ohm cab was quieter than your 210 4 ohm cab, you'd just turn up a bit wouldn't you?

 

As per the poll result at the top I'll use single 8 ohm cabs (other than the GB212 which is 4 ohms).  

 

What I think I'll do is 1st pass I'll leave all volumes/settings the same and record as is (recording levels set to an approximation of the cab that I think is the average of all the cabs). 

 

Then I can do a 2nd pass and use the recording indicators/meters to try and get cab(s) to a matched level of input.  I do need to consider if I turn up the amp to get the meters to match or leave the amp setting and increase the gain on the recording.  I'll wait till I actually attempt this to see if I need to significantly alter the output gain on the amp, if I do I'll be sure to take notes and mention this.  It'll be a case of suck it and see but I don't want to be skewing things to advantage one cab over another... we'll see.    

 

Just as an aside I'm going to take a line out from the amp (Thunderfunk 550) and put it through my QSC K10 monitor cab.  I'll not be able to maintain equality of volume due to the monitor having the power amp.  However, using the meters in the recording software, I'll try and get it close.  I'm doing this just out of interest/curiosity (the reason for the whole thing I suppose) to see if my own perception is skewed by knowing it is a monitor and not a bass specific cab.

 

I don't think I'm going to immediately label each sample, I'll make it a blind test and then do a reveal.  

 

PLEASE this is just me with a bit of time (and cabs) on my hands, having a bit of fun and maybe it'll be of interest to a few, don't crucify me because it isn't remotely scientific; at least I'm trying to make it reasonably practicable and relevant.  

 

I reserve the right to scrap this if it turns out to be a right chew on!  LOL

[Chienmortbb]

Fill your boots. It's your thread and if people disagree they can look away. 

[warwickhunt]

 

Lets see if it worked.