sensitivity or frequency response for cabs?

[rpsands]

Make the chart window the active window, hold down alt and press print Screen, then paste into Ms paint.

 

[Rick James]

I also ask that this topic remain civil or I am done participating.

I haven't seen anything uncivil. This looks to me like an excuse to bail on this discussion, and get what you wanted all along, not to post charts.

 

[rpsands]

I haven't seen anything uncivil. This looks to me like an excuse to bail on this discussion, and get what you wanted all along, not to post charts.

Wow, way to go. Sounds like you're trying to give him an excuse.

In my opinion, genz has always provided slightly more reasonable specs than the competition, as well as fantastic support and a willingness to engage in discussions like this.

I'd appreciate it, personally, if you could keep markedly uncivil comments like this out of the thread. I'm really, really interested in the discussion and would hate to see it ruined by this kind of talk.

 

[bobcruz]

+1. Agedhorse's willingness to engage in this debate is a major positive.

 

[rpsands]

One thing I would like to add to the discussion:

Displacement limited power handling. I'm not sure the best way to calculate this but it would be nice if every company had power handling charts with a swept sine wave, so we could make some educated guesses.

I'm suspecting the "real" displacement limitation for bass guitar with a Neox112T for example is probably around 150 watts (figuring around 75 watts @ 40hz or so).

 

[OldogNewTrick]

fdeck (haven't seen him around here for a while ) has a sensible real world implementation in his speaker spreadsheet where he splits the power evenly over fundamental plus 3 overtones for a wave-form based power handling chart as well as a traditional sine based chart.

Makes a lot of sense to me.

 

[agedhorse]

Make the chart window the active window, hold down alt and press print Screen, then paste into Ms paint.

Not quite that easy unfortunately, it's legacy DOS based firmware that I can't even print out for lack of a working printer driver.

I use the legacy analyzer because of familiarity and user friendly averaging algorithems. It's also stand-alone (except storing data on the old PC) with all functions internal to the device. I also us an HP 339 analyzer for much the same reasons... it's something that I am comfortable with and it's user interface makes for a good design tool.

When I get a chance I will try to do the same averaging method in TrueRTA and see if I can make this work but it will by necessity by a week or two before I can devote any time to this due to my other commitments.

Rick, your comment is unjustified and pointedly rude. I never said that I wouldn't post charts, I said that I couldn't at this time. I have gone out of my way to be helpful and informative in this and other threads and would appreciate a bit of common courtesy in return.

 

[rpsands]

Digital camera maybe?

 

[agedhorse]

One thing I would like to add to the discussion:

Displacement limited power handling. I'm not sure the best way to calculate this but it would be nice if every company had power handling charts with a swept sine wave, so we could make some educated guesses.

I'm suspecting the "real" displacement limitation for bass guitar with a Neox112T for example is probably around 150 watts (figuring around 75 watts @ 40hz or so).

This is indeed a very important factor, and one reason why I am fairly conservative in power ratings as well as my recommendations against using really large amps with any speaker that has the potential for displacement limiting (one part of the power compression equation).

The thermal capacity of the driver is 300 watts RMS, the displacement begins to become non-linear at about 110Hz at 300 watts RMS which it the entry point into soft power compression as the motor fringes enough to maintain some control as the VC begins to enter the asymmetrical portion of the magnetic field. The field is not so tightly focused (as on some drivers) to create an abrupt transition into non-linearity so it's still quite useable. At 300 watts RMS we are still well away from Xmech. Preak displacement occurs at roughly 70Hz and 40Hz and is still <7mm. Driving beyond the RMS rating, power compression begins to rob much of the potential gain on almost all cabinets anyway, even if the spec's claim otherwise.

I use a special measurement tool for determining the RMS power rating, or an approximation of the onset of power compression, It resides in the Audio Control firmware of the Iasys measurement system which I use. What it does is send a duty cyle limited signal to the DUT (device under test) and measures the output, compares the two and if the difference is witin the setpoint window (amount of power compression test limit) then it steps to the next level and so-on until the measured result deviates from the expected result by the defined deviation value. I typically use 3dB (over the initial value) as the power compression level because there is a gradual increase in this value as the process goes from zero to the final value where the curve begins to knee up and the slope begins to increase more rapidly. This is the transition point and is a good indication of where the system becomes really non-linear. The algorithem naturally limits the VC temperature to what the 1/8-power dictates, and bandwidth limits the spectrum to predefined (repeatable) curves but looks at the COMBINATION of thermal and electro-mechanical parameters in a real-world type test. This is a fairly specialized test, and I have seen only a few manufacturers (high end pro audio only) do this kind of thing with their products and mostly with specific components. This is data that I can not share for propriatary reasons.

Bill, have you ever done a staged power compression test on any of your speakers? It's an amazingly revealing test, and points out some of the otherwise unmeasureable responses and realistic expectations that a speaker system is really capable of. It exposes a world of myths regarding power handling and what happens to transfer efficiency as the transition occurs.

I share this with you guys so that maybe you all can better appreciate the level of design and testing that's done (at my level anyway) as well as why this kind of detail, while part of our testing, is meaningless to present in a retail environment. I do it in part because we have a 3 year transferrable warranty, and the last thing we want to do is eat drivers damaged from a "bad" (read as unrealistic) design. I would suggest that most manufacturers do not has a warranty this comprehensive.

This forum represents maybe the most technically astute 1/10 of 1% of the bass playing population and I'll gess that even most of you find this boringly technical.

 

[agedhorse]

Digital camera maybe?

I was actually thinking the same thing... except for the MPX display makes it a bit harder than point and shoot. I'll give it a try when I get back. It may be easier just to set up the newer RTA in spite of it's user-hostile nature

 

[rpsands]

One thing I'll note: It's anecdotal, but it seems like every other bass player I talk to while gigging here in the valley is aware of Talkbass if they don't frequent it regularly. If not Talkbass, then harmonyCentral's reviews at the very least.

It's true though that most of the guys I talk to have no idea about how adding 3db of bass affects the power handling ability of their cabinet, for example. And most don't understand what frequencies mean what sounds to the ear.

But everyone I run into has dealt with challenges getting good tone, enough volume, and dispersion on stage. If they were presented with more of the data I think way more guys would grok it than you think!

 

[agedhorse]

It's true though that most of the guys I talk to have no idea about how adding 3db of bass affects the power handling ability of their cabinet, for example. And most don't understand what frequencies mean what sounds to the ear.

But everyone I run into has dealt with challenges getting good tone, enough volume, and dispersion on stage. If they were presented with more of the data I think way more guys would grok it than you think!

If they don't understand what frequencies mean what sounds to the ear, how are they going to read and interpret even more technical data? THEN, try to translate this to tone and dispersion?

I understand where you are coming from, and it's frustrating for me too, but I have answered enough e-mail support questions asking questions so basic and simple that I shudder to go through the (considerable) effort to try to quantify tone. I got an e-mail a few months ago asking where the power cord plugs into the speaker... he was trying to plug the (unpowered) speaker into the wall.

I think it's time for a beer and a nap...

 

[rpsands]

If they don't understand what frequencies mean what sounds to the ear, how are they going to read and interpret even more technical data? THEN, try to translate this to tone and dispersion?

I understand where you are coming from, and it's frustrating for me too, but I have answered enough e-mail support questions asking questions so basic and simple that I shudder to go through the (considerable) effort to try to quantify tone. I got an e-mail a few months ago asking where the power cord plugs into the speaker... he was trying to plug the (unpowered) speaker into the wall.

I think it's time for a beer and a nap...

*lol*

Just explain it in the manual. Everyone reads those, right?

 

[muddycreek]

Something that would go a long way towards people 'getting it' would be comparisons with known entities. Were somebody to START making more test results available just on their own cabs, I can see the argument that it would be misunderstood and taken out of context.

If, however, more test results were available and the testing methods were consistent and known, either the manufacturers themselves or third parties could test some widely available cabinets.

How cool would it be to see comprehensive sensitivity graphs, polar patterns at set frequencies, and power handling graphs, and compare them to the same graphs on an SVT 810, a B15, a Boogie PH115, an Eden 410, an early SWR 410, and a Bag End S15?

 

[agedhorse]

*lol*

Just explain it in the manual. Everyone reads those, right?

Yup!

 

[agedhorse]

Something that would go a long way towards people 'getting it' would be comparisons with known entities. Were somebody to START making more test results available just on their own cabs, I can see the argument that it would be misunderstood and taken out of context.

If, however, more test results were available and the testing methods were consistent and known, either the manufacturers themselves or third parties could test some widely available cabinets.

How cool would it be to see comprehensive sensitivity graphs, polar patterns at set frequencies, and power handling graphs, and compare them to the same graphs on an SVT 810, a B15, a Boogie PH115, an Eden 410, an early SWR 410, and a Bag End S15?

Yes, but even the pro audio field hasn't been able to accomplish this. EASE is about as close as we come, but much of this data is irrelevant to a typical gigging bass player.

A third party program was proposed, but never took off in part due to the expense of supporting a testing program like this.

Testing and transcribing data into useable formats takes time, a LOT of time. There really needs to be real value to a large percentage of end users for it to be viable. Really, just playing a few cabinets that have been selected for size/weight/style criteria probably yields better information regarding suitability to a particular player, playing style and instrument.

 

[rpsands]

One thing I'll say is that you know jack squat about a cabinet until you've gigged it, unless you know things like polar response, frequency response, and displacement limitations.

How a cabinet performs outside of a gig, even in a jam room type setting, tends to be quite different than on a gig. Stages are different than practice rooms, and similar. When you're moving around at a show, it's different than a small practice space.

I've seen a lot of players get into this trap; they pick size/weight/style and go play a few, like one, buy it, and it sounds nothing like they remember it in the store.

 

[agedhorse]

Agreed, our cabinets are voiced based on gigging experience and we encourage folks to try them out in that context. Bedroom wanking is not a good way to choose a cabinet unless that's the task that it's going to be doing. This, of course, applies to all cabinets INCLUDING pro audio.

 

[thudfromafar]

Perhaps a new wiki project could come out of this thread, attempting to reveal accurate specs of all the amps/cabs on the bass market? Or at least as many as possible Gotta start somewhere

 

[billfitzmaurice]

Perhaps a new wiki project could come out of this thread, attempting to reveal accurate specs of all the amps/cabs on the bass market? Or at least as many as possible Gotta start somewhere

That's been raised before and never gotten anywhere. IMO it's no mere coincidence that those who have the ability to measure their speakers are also those who build their own. If you peruse the hi-fi and home theater forums where there are separate sections devoted to DIY you'll find that the majority of those who build their own cabs also are very much into how to measure them, while few of those who buy their speakers are able to measure them.