sensitivity or frequency response for cabs?

[tombowlus]

Of all people, given your experience, you should know how arbitrary 'measurement' is regarding bass gear....

Absolutely! That is an excellent point, actually. Without consistency in measurement conditions, methods, equipment, etc, comparing results may very well be more prejudicial than probative.

Tom.

 

[R Baer]

The arguments presented here against flat don't make any sense to me...

I don't think anyones arguing that there is anything wrong with flat response if that is what works for you, but IMO, it's the color of our amps and cabs that gives us the wide array of choices to choose from when buying a bass amp. If the Holy Grail of Bass Amps was a perfectly flat amp through a perfectly flat cab, then all the manufactures would produce only that and in return, all our amps would then sound the exact same. IMO, it's all those little subtleties and variances from the pristine that give your rig a personality.

Personally, I'm with the guitards on this one. I like amps, cabs and instruments that have a personality and I have always enjoyed the never ending quest for the perfect mix of equipment in search of the ultimate tone.

 

[fdeck]

For me, specs are just the tip of the iceberg. This may be just a personal compulsion of mine (quite likely, in fact), but I am keenly interested in understanding how gear works, in as much detail as possible. Specs, if they are honestly reported, give me an insight into the designer's intentions.

 

[Calaverasgrande]

The flat as ruler thing was really popular back in the 80's and early 90's for bass amps. You know back when tweeters, graphic eqs and "parametric" eqs showed up.
Somehow tube heads have stuck around. 12" speakers are making a big comeback. There are even apostate souls that play out with no tweeters on their cabs at all! With a bass guitar!

Honestly this is one of the things that drew me into being a bass player in the first place. The elctric bass is a relatively young instrument with many different approaches and tones that are suitable.
I'm one of those guys that wants some color from my cabs. I mostly want more low end and low mid than is reasonable and I dont want hardly anything happening above 4k. So yeah, I think I can infer some useful info from a frequency plot? There are literally hundreds of cabs out there. With the advances in materials and design its harder and harder to make any kind of generalization about cabinet or driver size. So some guidance or information from the manufacturers is appreciated!
For instance, keep hearing that lots of 2x12 cabs are go just as low as any 15" cab and will deliver output on par with a 4x10. Given that the prices are usually a good compromise between the cheapness of a 15 and the cost of a 4x10 (and they are usually lighter to boot) it would be great to know what its general response curve is. Especially before I charge up my capitol one card!

 

[agedhorse]

Specs, if they are honestly reported, give me an insight into the designer's intentions.

If designers would discuss their intentions, design philosophy, approach to architecture, and operational parameters of their feature sets, the same insight could be even more accurately obtained without having to try reading between the lines.

I have tried to share some of the challenges we as designers (in general) face when choosing a design approach and path to follow. This has included on several occasions a discussion on the art of managing compromises and trade-offs to get the player as close as possible to their "ideal" amp while avoiding the all too common pitfalls like size/weight/price creep or quality decline.

 

[thudfromafar]

For me, specs are just the tip of the iceberg. This may be just a personal compulsion of mine (quite likely, in fact), but I am keenly interested in understanding how gear works, in as much detail as possible. Specs, if they are honestly reported, give me an insight into the designer's intentions.

+1 ~ I just wanna learn.

 

[thudfromafar]

If designers would discuss their intentions, design philosophy, approach to architecture, and operational parameters of their feature sets, the same insight could be even more accurately obtained without having to try reading between the lines.

unfortunately it's kind of a rare thing

 

[Calaverasgrande]

I think the "cabinet is a part of my instrument" guys will benefit a lot from the new drive for maximizing the performance of cabinets too.

Imagine the cabinet Bill or Alex could make if they were designing a voiced cabinet for monster rock tone. SVT sound in a package a third the size maybe?

I think that's what will break the doors off the market; someone comes up with a solidly engineered way to get fridge rock sounds without modeling.

EXACTLY!
I am very interested in specs of cabinets. Not because I want a perfect tone or flat tone. But because I want the best performance to weight ratio! The SVT 8x10 and similar cabs like the Mesa 2x15 TL606 style cab are great, until you hit 40 and still dont have a full time roadie crew!

I am very interested in some of the lighter, more efficient 4x12 designs or 6x10 boxes. But without any kind of graph of response I have to go track one down in a store (kinda hard for some popular models) to check out what they low end is like.
I dont have a lot of time to cruise guitar stores. I also cant afford to buy all these models one after another!

 

[alexclaber]

EXACTLY!
I am very interested in specs of cabinets. Not because I want a perfect tone or flat tone. But because I want the best performance to weight ratio! The SVT 8x10 and similar cabs like the Mesa 2x15 TL606 style cab are great, until you hit 40 and still dont have a full time roadie crew!

That's it - good specs can tell you performance (in terms of max SPL etc) but not tone! A bit like how car specs can tell you how quickly a car can travel but won't tell you what it feels like to drive.

Something on my agenda for when I have some spare time is to rent a few SVT810s from different eras and to try to take a comprehensive set of measurements (not just frequency response plots) from them to find out what's really happening. As it stands I think you could get a great SVT810 sound from a much smaller lighter cab if you used an amp modeller but I'm doubtful that you could get that tone or feel passively because of the non-linearities which would be so hard to emulate precisely. But we shall see!

 

[mulchor]

I was reminded of this thread when reading another.
http://www.talkbass.com/forum/showthread.php?t=619681

The theme of that one is frustrations in trying to get an accurate, basic spec from a manufacturer. -- Answer the question: "How much does it weigh?"

The actual weight appears to be 25% heavier than advertised, but the manufacturer doesn't even seem to know. To make matters worse, it's a brand I never see in stores (Carvin), so the consumer can't just go audition it.

My point is this. Very basic specs are inaccurate when provided by the manufacturer.

In this thread, we're talking about measurements which are actually rather complicated. E.g., how to measure it, but then also how to process it. Two people using the same equipment will come up with different answers. No one ever reports kernel size. No one ever reports data verifying that 1W input was actually 1W (and then there's the people who try to pass off 2.8V, as if the impedance were constant).

What alexclaber is talking about above (measuring a bunch of SVT810s) is a great research/development tool, and with decent empirical techniques you can measure them all the same. But those results will be specific to alex's lab.

If a lab collected and reported all the data from all the rigs in a sensible way, it would be awesome.

But if we leave it to the manufacturers, no 'fense, but we're left with nothing informative, because they can't even be trusted to get the weight right. Give them the chance to cherry-pick and your pretty graphs are LESS informative than "silky smooth with a tight solid booty."

 

[rpsands]

I think it's probably worth making a distinction between voicing and tone.

The voicing of a cabinet is easy to tell from an FR chart ESPECIALLY if you do one at 1/8th power or 1/2 power or something too (which should be done if possible imho).

 

[R Baer]

I was reminded of this thread when reading another.
http://www.talkbass.com/forum/showthread.php?t=619681

The theme of that one is frustrations in trying to get an accurate, basic spec from a manufacturer. -- Answer the question: "How much does it weigh?"

The actual weight appears to be 25% heavier than advertised, but the manufacturer doesn't even seem to know. To make matters worse, it's a brand I never see in stores (Carvin), so the consumer can't just go audition it....But if we leave it to the manufacturers, no 'fense, but we're left with nothing informative, because they can't even be trusted to get the weight right. Give them the chance to cherry-pick and your pretty graphs are LESS informative than "silky smooth with a tight solid booty."

Weight does vary from cab to cab, mostly due to weight differences in the ply. In the case of our cabs with a sprayed on coating, that can vary a little as well. Get one of the cabs made from a heavier sheet of ply that got maybe a few extra screws on the line and a little thicker coating andyou are going to end up with a slightly heavier cabinet. Just as easily, you could get one that is a little lighter.

So yes, cab weight is going to vary a little, but it shouldn't be too drastic. What we do is weigh out a few cabs from a couple different batches and base the weight on the average of the heaviest cabs.

 

[jnewmark]

Interesting discussion the last few pages, although I'll admit, I don't understand alot of it, but, did it ever get resolved about the GB Neox 112T 's specs being " impossible " ( according to BFM ), or not ? If it did, would someone point it out to me ?

 

[JimmyM]

Interesting discussion the last few pages, although I'll admit, I don't understand alot of it, but, did it ever get resolved about the GB Neox 112T 's specs being " impossible " ( according to BFM ), or not ? If it did, would someone point it out to me ?

don't know if it got resolved. andy was having a hard time converting a couple charts to a format that could be seen on here.

but as far as i'm concerned, it's resolved. why? because like i do with bill, i believe everything andy says. they're having a dispute now, but andy is a very honest dude, and this dispute doesn't change that at all for me.

 

[billfitzmaurice]

Interesting discussion the last few pages, although I'll admit, I don't understand alot of it, but, did it ever get resolved about the GB Neox 112T 's specs being " impossible "

No. And until I see the driver T/S specs that prove otherwise I stand by my opinion that no twelve in production is capable of 98dB IEC sensitivity and 95dB sensitivity at 45Hz.

 

[rpsands]

No. And until I see the driver T/S specs that prove otherwise I stand by my opinion that no twelve in production is capable of 98dB IEC sensitivity and 95dB sensitivity at 45Hz.

Bill, my modeling of a Deltalite 2512 II in a 4cf box tuned to 40hz shows -3db @ 39.5hz or so, and the rated sensitivity of the driver is 99.9db (lots more in the mids of course).

In WinISD the calculated SPL is 94.15db though.

With 1w input signal it shows 93db or so @ 45hz.

Does that sound right to you?

 

[billfitzmaurice]

Bill, my modeling of a Deltalite 2512 II in a 4cf box tuned to 40hz shows -3db @ 39.5hz or so, and the rated sensitivity of the driver is 99.9db (lots more in the mids of course).

In WinISD the calculated SPL is 94.15db though.

With 1w input signal it shows 93db or so @ 45hz.

Does that sound right to you?

94.15dB is the correct figure. 99.9dB would be an averaged broadband figure including break-up mode, a practice specifically forbidden by IEC/AES standards as it leads to a false conclusion. If one was to fudge the numbers in this case and claim 99.9dB sensitivity that means it's down 7dB at 45 Hz. But you see manufacturers doing this smoke and mirror trick all the time, quoting SPL including break-up mode but the -3dB and -10dB points without.

 

[agedhorse]

Well, here lies a big rub in what specific spec is appropriate to use and what relates most correctly to what the user is likely to experience in using the speaker with it's specific voicing. The user is not conforming to a particular published (and particularly pro audio standard where voicing is not "really" desireable) but hears the broad-band average over the bandwidth that he/she is playing, including whatever harmonics his instrument and amplifier produces. The published specs should conform to the approximate conditions that the product is likely to be used in, applied uniformly to all speakers being tested (ie. it should not be variable).

rp, what measurement conditions does your simulation calculate to... full-space or 1/2-space? Most default to full-space but some have conversions that can be made upon plotting. It's always worthwhile to verify the conversion/tab configs.

Bill, you said the numbers are impossible yet rp posted numbers that you esssentially agreed with and are pretty close to what I came up with also (using a driver/box optimization that's different than the off the shelf DeltaLite of course) and in fact it's within 0.85dB, and 99dB broadband average (we bandwidth limit a bass cabinet to about 5k because many players do not even use the tweeter which is variable from 0 to about 3dB above average sensitivity depending on the cabinet model) which agrees nicely with our 98dB/1W/1M and my simulated number of 97dB and change. We also do all of our work in 1/2-space because I have yet to see a bass cabinet used in full-space and this reflects how the product is being used. So, subtract off some simulation optimism (theoretical versus practical) but then add the 1/2-space conversion (including the primarily low frequency reinforcement) and I stand by the results as being absolutely reasonable and accurate.

As a side note, a speaker that's voiced with extended bass in full-space is likely to feel boomy or overdone (less balanced) in the bottom octave or two due to the effect of it being used in 1/2-space. While the graphed results might look "good" the voicing in 1/2-space use might not produce the expected results.

Here's an interesting bit that Peavey came up with a few years ago, this applies pretty specificly to a full range speaker (pro audio) but is worthwhile reading IMO. Invalid Link Removed

 

[rpsands]

To my knowledge Winisd models in half space; in that case, the calculated and modeled SPL @ 50hz is about 94db.

I think your transfer function is accurate, but your assumed sensitivity is what's wrong.

 

[agedhorse]

So Bill, it looks like you do measurements using 1/2-space as well. How would you spec. these speakers in the commercial world? How would you characterize the LF roll-off and sensitivity given the great differences between your mid rise and LF roll-off on the T-36? I see a 15dB difference, what would be the most fair characterization for assigning realistic (or valuable to the customer) numerical values to such a response curve?

http://billfitzmaurice.info/forum/viewtopic.php?f=12&t=11124&sid=24e381707c1c0e47f69d5c47d6e25b6c