Bass Gear Magazine - Speaker Cab Tests

[detracti]

I was reading the speaker cab reviews in issue #1 the other day, and notice the low frequency is measured at -10db.

Thanks for making that qualification.

Question - Do manufacturer's published specs generally measure the low end at -10db? For some reason, I've got it in my head that most or all measure at -3db.

Thanks!

[will33]

They should qualify how they are making the measurements, -3db, -10db etc. If it's not mentioned in an ad, assume it's at least -10db. Results in a lower number, sells better, etc.

[billfitzmaurice]

Originally Posted by detracti

Question - Do manufacturer's published specs generally measure the low end at -10db? For some reason, I've got it in my head that most or all measure at -3db.

Thanks!

The AES standard for useable response is -10dB, and that's barely usable, as -10dB takes ten times the power for equal output as the 0dB reference. The bigger question is from what frequency that -10dB figure is calculated, and where that's concerned none of the cabs measured adhered to AES standards that are intended to prevent inflated claims.

[detracti]

Originally Posted by billfitzmaurice

The AES standard for useable response is -10dB, and that's barely usable, as -10dB takes ten times the power for equal output as the 0dB reference. ...

I don't remember where I picked this up, but yeah. That's why I'm asking.

[OldogNewTrick]

there has been a thread discussing this very point-
click here

for some reason there are no further responses from BGM ...
wonder why...

[spode master]

Argh downloading the spell check lost my whole thing.

I started thread on this because of their non-standard method of determining -10dB points. The good people at Bass Gear explained that they were using a 60 point average from I think 20Hz-20kHz. In the case of the neo 8 5 gives a average sensitivity that is ~8dB less than what the RMS sensitivity is in its usable bandpass. That means that its -10dB point is really -18dB.

This not a standardised method. Bill, I and others have voiced our disaproval for this method as it uses 2 unrelated numbers to determin sensitivity and -10dB point. Especially the "Bass Gear Certified tag at the bottom". I am hoping for their second issue that they go to something a little closer to AES standards.

Their current method stretches the numbers unrealisticly, and helps encourage questionable measurment practices from manufacturers of musical instrument products. As a third party Bass Gear should be a little more objective. Stretching the numbers disempowers the uneducated consumer, and it pisses off people who like to design speakers.

They do however post some good graphs so you can actually see what is happening if you know what your looking at. I like what they're doing otherwise, just would like them to stop playing manufacturers unrealistic number games.

Antone-

[Crockettnj]

and then perhaps they'd be calling some very ewll respected gear makers "to the table".

If the standards are in place, and they have been fully vetted, then use them.

[bgavin]

Unless they publish the chart, and the measurement method, the claimed specs are nothing more than bovine merde.

If you really want to separate wheat from chaff, use Danley's 100w/10m measuring technique. It produces the same chart as 1w/1m. The distance filters out all the Doppler distortion and any artificial boost from being 1m from the baffle.

With commercial bass cabs, this is a real eye opener.

[detracti]

Well, didn't mean to open a can of worms . I just figured it was a relative measurement - -10db or -3db relative to average.

I just hope they review the Aggie GS212, because I'd like to see how it stacks up against the other to 212's in that issue.

[tombowlus]

We stand by our numbers, which do state frequency response using the -10 dB points. But, the issue seems to be with the fact that we use the 1k Hz sensitivity measurement for our 'tested sensitivity', but for the frequency response measurement, we compare the frequency response against the average measured response from 20Hz to 20kHz. I agree that it would be nice to derive both numbers from the same test, but we did have lengthy discussions about this topic (and we did consult with quite a number of 'reputable outside sources' throughout the process), and we chose the numbers/test we publish for what we felt were good reasons. If you read deeper, you'll notice that we also post the average sensitivity from 281Hz to 3kHz, as well as a 'Low End Response' sensitivity, which we derive from the average sensitivity of the enclosure using the five fundamental frequencies from each string of a 5-string bass. In addition, we publish the frequency response curves.

So, on the one hand, I would argue that we set up our tests with the intention of being as helpful as possible to the average player (and perhaps, not so much with a mind for our EE readership). And as indicated, we do provide a number of different ways to illustrate the response of the enclosure. Furthermore, our test methodology was applied consistently to all of the cabs which we tested.

But, on the other hand, we definitely listen to what our readers have to say, and if we can find room for improvement, we will certainly try to do so.

Tom.

[Vinny D]

I don't see the point in Bass Gear Mag. doing anymore testing on products, so far all that is happened is everyone questioning there testing methods and crying when there beloved mfg's equipment doesn't spec. out how they hoped it would have.
With any luck they will be able too get a bunch of revenue from advertisers and just become an add magazine like the rest of them already out there.

Lets see if this speaker testing issue will turn into a 12 page ordeal like the GBE1200 did.......and is still on going.
I'm sorry...it's 15 pages.

[billfitzmaurice]

Originally Posted by tombowlus

So, on the one hand, I would argue that we set up our tests with the intention of being as helpful as possible to the average player (and perhaps, not so much with a mind for our EE readership).

Tom.

The methods used to test and rate speakers are set forth by the AES. Using a different standard of one's own making renders the results questionable at best. If the average player wants to see inflated specs that don't allow for meaningful unbiased comparisons between products they already have sources for those: the manufacturers.

As for the 'EE readership' snub, one should expect that a professionally oriented publication would have an expert in the field in charge of the testing and the reporting of the results. If that was the case this particular brouhaha would have been avoided.

[greenboy]

Originally Posted by billfitzmaurice

The methods used to test and rate speakers are set forth by the AES. Using a different standard of one's own making renders the results questionable at best. If the average player wants to see inflated specs that don't allow for meaningful unbiased comparisons between products they already have sources for those: the manufacturers.

As for the 'EE readership' snub, one should expect that a professionally oriented publication would have an expert in the field in charge of the testing and the reporting of the results. If that was the case this particular brouhaha would have been avoided.

+1000.

It's not like the AES didn't arrive at tests with decades of both ears and smarts involved in ascertaining what would be meaningful to those using systems in the real world. Second-guessing the body of expertise and FIELD EXPERIENCE the AES represents seems to indicate that the magazine can't decide if they want to follow the bass gear manufacturers' questionable haphazard marketing-driven practices, or really do the real thing.

I would suggest dispensing with the tests/data all together too, even if it is fun to play at it, and just doing the typical subjective descriptive stuff and let the ads be as important as the content -

or going for the real thing, if you have the ability to do so. Straddling both worlds seems clumsy and takes more effort in interpreting results anyway. And it would seem to be easier for neophytes to understand the results and see/hear how they actually correspond to the product performance if they weren't coming from several different approaches. Otherwise charts and numbers are just window dressing for those who don't get the big picture.

I realize the world of bass players is a different world than that of serious studio and live sound reinforcement people, but... ; }

[Kindness]

Originally Posted by greenboy

Otherwise charts and numbers are just window dressing for those who don't get the big picture.

Disappointingly this is exactly how the speaker data in first issue comes across.

[alexclaber]

Originally Posted by tombowlus

We stand by our numbers, which do state frequency response using the -10 dB points. But, the issue seems to be with the fact that we use the 1k Hz sensitivity measurement for our 'tested sensitivity', but for the frequency response measurement, we compare the frequency response against the average measured response from 20Hz to 20kHz. I agree that it would be nice to derive both numbers from the same test, but we did have lengthy discussions about this topic (and we did consult with quite a number of 'reputable outside sources' throughout the process), and we chose the numbers/test we publish for what we felt were good reasons. If you read deeper, you'll notice that we also post the average sensitivity from 281Hz to 3kHz, as well as a 'Low End Response' sensitivity, which we derive from the average sensitivity of the enclosure using the five fundamental frequencies from each string of a 5-string bass. In addition, we publish the frequency response curves.

That does seem rather over-complicated.

Surely it would be easier to measure average sensitivity over a standardised bandwidth which is applicate to all bass cabs and avoids loud tweeters causing misleading readings, say 100Hz-1kHz, and then reference your -3dB, -6dB and/or -10dB response points from that. So one number for sensitivity, one or two numbers for low frequency extension. Simple. Not flattering but honest and reliable for comparing different models.

I dare you to post response plots of maximum output and power handling with <10% THD! Can you imagine the horrified owners?

Alex

[tombowlus]

Originally Posted by billfitzmaurice

The methods used to test and rate speakers are set forth by the AES. Using a different standard of one's own making renders the results questionable at best. If the average player wants to see inflated specs that don't allow for meaningful unbiased comparisons between products they already have sources for those: the manufacturers.

As for the 'EE readership' snub, one should expect that a professionally oriented publication would have an expert in the field in charge of the testing and the reporting of the results. If that was the case this particular brouhaha would have been avoided.

The EE readership comment was not intended as a snub.

To answer your question, our technical editor, Shane Radtke is in all honesty more of an amp expert than a cab expert. But he is highly competent and has done a great deal of research with regard to the bench tests for enclosures. In addition, we did consult with numerous experts in the field of speaker design and testing. Granted, there will always be someone out there with a higher degree of expertise in any field, and certainly, you are probably one of the top people in the field of speaker design, Bill.

That being said, we are aware that our test methods and data sets are not 'AES-compliant', but that was not really our goal. We wanted to establish a fair set of tests which were useful to (and readily understood by) our readership. I strongly disagree with the statements that if our data is not 100% AES compliant, then it is entirely useless, or 'bovine merde.' In addition, we do provide a good deal of data regarding sensitivity and frequency response (see my post, above).

So, to reiterate, if we can find a way to improve our test procedures and/or our presentation of data, we will try to do just that. We certainly do welcome constructive feedback, and I appreciate the time that people have spent making suggestions as to how we should change. However, I cannot promise that we will make AES compliance as high of a priority as some people may wish.

Tom.

[greenboy]

Originally Posted by tombowlus

{...}I strongly disagree with the statements that if our data is not 100% AES compliant, then it is entirely useless, or 'bovine merde.' In addition, we do provide a good deal of data regarding sensitivity and frequency response (see my post, above).

Hey Tom,

Just to keep this real simple, if you reference everything to the same data point instead of several, the derived information becomes more accessible and trustworthy. Using one figure as the reference for one thing and another figure for another set of what should be related data is either confusing or "invisible" in a way that leads to incorrect assumptions for relative neophytes... and for those more educated, the cumulative picture seems troubling at the least.

However, I cannot promise that we will make AES compliance as high of a priority as some people may wish.

For me it's not so much AES compliance I am after as it is having all meaningful data referenced to the same points.

I'll also mention that I've always considered the potential of trade periodicals to be educational. I'm largely self-taught and better periodicals and the like have always been more than just buyers' guides for me - they've informed me and opened a larger world.

[greenboy]

Originally Posted by alexclaber

{...}I dare you to post response plots of maximum output and power handling with <10% THD! Can you imagine the horrified owners?

We've more than a few times been aghast at the specsmanship that is rampant in the bass cab manufactuer domain. So few products actually have audible performance in keeping with what the website and sales literature would suggest.

In a larger context, I think it would be instructive for everybody to see how imperfect even the best designs are, how complex audio really is, how many compromises even the best designers have to deal with, and how much thought, measurement, and R&D it takes to make even incremental advances in the art and science of gear for audio.

There would be many many surprises and a general awareness of the complex issues would begin to grow, I'm sure, as more products were scrutinized - whether talking Behringer or Meyer.

[asad137]

Originally Posted by tombowlus

We wanted to establish a fair set of tests which were useful to (and readily understood by) our readership.

I believe you did not accomplish this goal. One of my biggest criticisms from the other thread amounts to: If you take something like a typical 2-way (woofer+tweeter) cab and measure it twice -- once with the tweeter on, once with the tweeter off -- your quoted -10 dB point will change! This is a fundamental problem (no pun intended!) with your measurement methodology.

Asad

[OldogNewTrick]

Originally Posted by tombowlus

We stand by our numbers
...
So, on the one hand
....
But, on the other hand, we definitely listen to what our readers have to say, and if we can find room for improvement, we will certainly try to do so.

lawyer talk, I guess an occupational illness...
take heart, we all have them, the engineers, designers and musicians alike ....

My comments regarding the PJB Neo 8B test still stand.


As most people have pointed out, there is no point to tout comparability, when you shift the point of reference from test to test. That smacks of advertorials.

I was (still am) looking forward to BGM as an unbiased source of information on bass gear, which I cannot test/compare. That requires them to starting from a consistent point of reference.