Waking up in a Class D world.

[agedhorse]

As a general comment on musicians not hearing bass reflex cabs farting out (stated by agedhorse), I really wonder if that applies to the members of Talk Bass....

The sound of coils hitting the back plate or excessive cone flexing is horrendous and totally un-musical, especially in scenarios when the amp is still operating in its clean range. It sounds nothing like tube saturation, ss-grind or any type of intentional, pleasing overdrive I can remember hearing - rather quite the opposite! I can not remember any rack effect or pedal with a setting to emulate "cone creasing" or "fart out".

Thus I find it very strange if anyone with at least a clean-ish basic tone would not immediately identify and react to that audible distress call... Especially among the members here, many characterized by curiousity, analysis, gear comparison, preparations and general concern about their tone and rigs.

Once you have bottomed out a modern speaker (and many vintage speakers too), and you hear that noise, damage has been done, usually catastrophic, to the bottom of the bobbin, but also to the fibers in the spider, and depending on the cone geometry, possibly the cone edge ("creasing the cone").

It is entirely possible (and much more common) to damage a speaker without going as far as bottoming it out.

 

[Al Kraft]

Well, I am an engineer, too, and please understand that you can design audio components (especially speakers) to tolerate different levels of abuse. VC dimensions, underhang/overhang geometry, gap to coil ratio, gap tightness, suspension properties etc.
Most pro gear users prioritize performance/"user error tolerance" differently than your local pub cover band, which reflects in the products.

I agree that design plays a big part, and that user knowledge and respect for the designed operational envelope is also equally, if not more important. As an engineer we both know that we can only do so much in design to protect the gear of deliberately abusive users from themselves...no matter what field of engineering design we're talking about.

 

[Ephminus]

Relax @AlexanderB my post was a joke and no one else is on a personal attack against you. I'm pretty sure The Aged Horse has had his hand in many successful speaker designs, not to mention the decades he spent servicing and analyzing the fallen.



But would you let him in otherwise?

I’m not sure, does Jimmy M eat a lot of gassy food?

 

[BadExample]

I’m not sure, does Jimmy M eat a lot of gassy food?

From his experience, I gather he's a frequent traveler. Most travelers have a pretty bad diet routine, eating what's available on the road. So just guessing, yes, I think @JimmyM likely eats a lot of gassy food. But that is only a guess. I've never heard him state either way. For all we know, he may be an avid user of butt-tic-tacs and only lets out minty fresh back end gasses. No disrespect to Jimmy, I have nothing bad to say about him.

Edit: Almost ten pages now. Next page we can REALLY go OT. Them's da rules!

 

[AlexanderB]

Once you have bottomed out a modern speaker (and many vintage speakers too), and you hear that noise, damage has been done, usually catastrophic, to the bottom of the bobbin, but also to the fibers in the spider, and depending on the cone geometry, possibly the cone edge ("creasing the cone").

It is entirely possible (and much more common) to damage a speaker without going as far as bottoming it out.

I think your reply is too generic to be applicable to the OP's question. While I too have seen odd failures to transducers that were not exceeding Xmech, I still say most reflex loaded systems will start sounding really bad before you hit the level of irreversible damage. For bass horns, bandpass, TL, any mid driver or HF driver etc, excursion is just one of many failure modes.

Since I have used that specific cab for many years, and in all sorts of contexts, I still say this: using SS amplification within the conservative area of Pro Audio "rule of thumb"; 100-150% of the cabinet's continuous rating, in standard bass tuning and no octavers, that cab will give years of trouble free service. My two SVT-410HLFs will distort just right before the clip light illuminates on the amp (at around 900W per cab).
So a "500 W" amp will compromise on clarity, articulaton, bass extension etc, while the "750/800 W" models will probably give a much more satisfying experience, without straining the cab.

 

[JimmyM]

No, rather that people are highly irrational. The exact same message will be treated very differently, depending on who the messenger is. Jimmy M is much more popular here (and I like him, too) than I am, so his words carry more credibility, even if we say the same thing.

You don't think Andy hammers me if I say something inaccurate or he's not in agreement with? He's done it for years! Trust me...the only reason he ever lets me slide on a topic is if he's getting sick of hearing me.

And BTW, I still stand by my "Use your ears" comment, although I usually add "use your common sense," too. It's something I say to people who I think are newbs just to get them to think about what they're doing a little more instead of merely going by numbers. Now I have heard of speakers blowing without giving any warning, but it's been my experience that the existence of xmech in a speaker (the zone between xmax and blowing a speaker where the speaker is being pushed out of its magnetic gap) does give a warning in the form of what guitarists have called "cone cry," which is a fancy euphemism for "distortion." But you can still damage your speaker when you reach this zone, and you can skip right over it if you're not careful. But all that means nothing to someone who wants to know why they blew their cab when they "followed the numbers," so I tend to simplify it.

And I am often gassy (like today), especially since becoming mostly vegan, but I don't weigh 25 lbs so they are right to keep me off elevators.

 

[agedhorse]

I'm just sharing my experiences based on long term history of tens of thousands of drivers in real world applications by real world bass players. I stand by my comments as an accurate representation, with plenty of examples of such damage here on TB where players tend to be more sophisticated than average.

 

[ThisBass]

No offence, but this sounds like parroting to me. I am getting tired of explaining fairly basic stuff here, while certain "truths" seem to persist forever.

How do YOU think a limiter works? Even basic limiters will limit voltage swing. Voltage drives excursion. With the dynamic nature of electric bass signal contents, excursion damage (torn surrounds, cone creasing, coils hitting frame) is more likely than overheating, at least for multiple transducer, reflex cabs. A high pass filter and a voltage limiter will offer a fine protection for most users, and is very common.

Even some low cost PA amps offer built in power management today. There you can configure HP filtering, voltage limiting, average power limiting etc. Limiting average power sent to speaker is very useful for certain cabinet types (ie. horns, bandpass, sealed etc), where failure modes are different to bass reflex ones, and there might be little or no audible warning that the system is overdriven.

For most of all limiter implementations (even for most of all digital processed ones)

During normal operation, the clip limiter does not affect the audio signal and is, in fact, inaudible. It will allow brief clipping of peaks, activating only when continuous, hard clipping occurs. The clip limiter will then reduce the audio signal (up to 10dB) to minimize clipping. When clipping ends, the clip limiter will deactivate and cease its gain reduction.

That's exactly the words how QSC explains the way how a limiter works
Here you are (page #24)
Invalid Link Removed

 

[AlexanderB]

For most of all limiter implementations (even for most of all digital processed ones)

During normal operation, the clip limiter does not affect the audio signal and is, in fact, inaudible. It will allow brief clipping of peaks, activating only when continuous, hard clipping occurs. The clip limiter will then reduce the audio signal (up to 10dB) to minimize clipping. When clipping ends, the clip limiter will deactivate and cease its gain reduction.

That's exactly the words how QSC explains the way how a limiter works
Here you are (page #24)
Invalid Link Removed

I fully agree! That is a clip limiter (used to "safeguard" how an amplifier operates). I am recommending a regular limiter, which can be set to whatever signal voltage the operator not wishes to exceed.

 

[ThisBass]

I fully agree! That is a clip limiter (used to "safeguard" how an amplifier operates). I am recommending a regular limiter, which can be set to whatever signal voltage the operator not wishes to exceed.

Limiters can't limit instantaneous. Same property is for compressors as well.
Both, limiters and compressors, belong to the family of time lag loop controlled audio processing tools.
At first of limiting process the signal at the output must be "averaged" for a distinct time period just to "calculate" an average for the comparator input.
As the limiter (and also compressor) needs some time for "averaging" the audio signal before the limiting process actually can start up to gradually gain down the signal the limiter already had let pass some signal unprocessed to the output.

It makes no difference to which number the limiter damps down the signal. The big spikes of transients and furthermore a couple of cycle periods of a every beat will NOT be limited thus will be amplified with full power.
If you play a 4/4 bar and play 1/4 beats then the amplifier will push full power for a short time period with every beat. If the amplifer power is large enough to exceed the driver Xmax then driver Xmax will be exceeded with every beat. If the amplifier power was large enough to hit Xlim then the driver will be damagd and destroyed shortly.

During normal operation, the clip limiter does not affect the audio signal and is, in fact, inaudible. It will allow brief clipping of peaks, activating only when continuous, hard clipping occurs. The clip limiter will then reduce the audio signal (up to 10dB) to minimize clipping. When clipping ends, the clip limiter will deactivate and cease its gain reduction.

edit
some folks might think that digital processing might improve the reaction time of limiters and compressors but, its nothing but a mathematical issue that limiters and compressors can't process the signal instantaneous.

 

[DigitalMan]

All I know is that if I was on an elevator and the weight capacity was rated at 1,500 pounds and we had the weight up to 1,475 pounds...I wouldn’t let Jimmy M on the elevator.

I would let Jimmy on the elevator while I step out and wait for the next one.

 

[Ephminus]

You don't think Andy hammers me if I say something inaccurate or he's not in agreement with? He's done it for years! Trust me...the only reason he ever lets me slide on a topic is if he's getting sick of hearing me.

And BTW, I still stand by my "Use your ears" comment, although I usually add "use your common sense," too. It's something I say to people who I think are newbs just to get them to think about what they're doing a little more instead of merely going by numbers. Now I have heard of speakers blowing without giving any warning, but it's been my experience that the existence of xmech in a speaker (the zone between xmax and blowing a speaker where the speaker is being pushed out of its magnetic gap) does give a warning in the form of what guitarists have called "cone cry," which is a fancy euphemism for "distortion." But you can still damage your speaker when you reach this zone, and you can skip right over it if you're not careful. But all that means nothing to someone who wants to know why they blew their cab when they "followed the numbers," so I tend to simplify it.

And I am often gassy (like today), especially since becoming mostly vegan, but I don't weigh 25 lbs so they are right to keep me off elevators.

I don’t know a whole lot about speakers and cabinets except for the fact that when I plug them in and turn them on it allows me to hear my bass. LOL
So I just follow the ratings listed on them.
My SVT HLF-410 has been my main cab for about 10 years now and I’ve been trying to find a new amp that gives me flexibility and dynamics.
That’s why I’ve been looking into the Markbass EVO1.
It’s 500 Watts and 4 ohms and has two blendable channels with twelve bass amp emulations, if I’m remembering that clearly.
I really like the idea of having built in overdrive/distortion cuz why do guitar players get to have all the fun.
Do you have any idea if DSP effects the power into the cabinet at all, being that it’s not using tubes to achieve that sound?
I’m not sure if I’m asking that question correctly though.

...and by the way, instead of the elevator, maybe we should just take the stairs. As long as I get to walk ahead of you. Hahaha!

 

[DigitalMan]

Do you have any idea if DSP effects the power into the cabinet at all, being that it’s not using tubes to achieve that sound?

No effect for all practical purposes. The DSP is all happening at the preamp stage.

 

[Mantis Tobaggan]

Is an SVT CL world

 

[seamonkey]

Multidriver self powered cabinets can sure do a lot as far as tonal balance and safety limiting.
Some might wake up when they can see it gets rid of a lot of the worry of matching amplifier power to driver power.
Adding a sub is still a good idea to prevent the power alley in the important bass frequencies.

QSC has a new line of affordable cardioid subwoofers that actually use power from one amp to reduce the output in a desired direction.
That is going to really confuse some when they see huge power used for subs, when half the power is for steering purposes

 

[AlexanderB]

Limiters can't limit instantaneous. Same property is for compressors as well.
Both, limiters and compressors, belong to the family of time lag loop controlled audio processing tools.
At first of limiting process the signal at the output must be "averaged" for a distinct time period just to "calculate" an average for the comparator input.
As the limiter (and also compressor) needs some time for "averaging" the audio signal before the limiting process actually can start up to gradually gain down the signal the limiter already had let pass some signal unprocessed to the output.

It makes no difference to which number the limiter damps down the signal. The big spikes of transients and furthermore a couple of cycle periods of a every beat will NOT be limited thus will be amplified with full power.
If you play a 4/4 bar and play 1/4 beats then the amplifier will push full power for a short time period with every beat. If the amplifer power is large enough to exceed the driver Xmax then driver Xmax will be exceeded with every beat. If the amplifier power was large enough to hit Xlim then the driver will be damagd and destroyed shortly.



edit
some folks might think that digital processing might improve the reaction time of limiters and compressors but, its nothing but a mathematical issue that limiters and compressors can't process the signal instantaneous.

I do not know where you get this data from, but it remains incorrect. There is no "punching through" of voltage spikes in the sub-60 Hz frequencies where we might see problems with over excursion on this cab.
50 Hz is 50 periods per second, yielding a 20 ms duration per cycle; 10 ms for half a cycle and 5 ms from zero to one peak. Even the lowly Alesis 3630 compressor can be set to an attack time of 0.1ms. Modern, digital processor units cost very little and offer both peak and RMS limiting, even with "look ahead" function. Sure, there will be audible artefacts when the signal is limited, but it will sound no worse than the "farting out". Obviously, simiar technology is already built into some integrated power modules...

 

[ThisBass]

I do not know where you get this data from, but it remains incorrect. There is no "punching through" of voltage spikes in the sub-60 Hz frequencies where we might see problems with over excursion on this cab.
50 Hz is 50 periods per second, yielding a 20 ms duration per cycle; 10 ms for half a cycle and 5 ms from zero to one peak. Even the lowly Alesis 3630 compressor can be set to an attack time of 0.1ms. Modern, digital processor units cost very little and offer both peak and RMS limiting, even with "look ahead" function. Sure, there will be audible artefacts when the signal is limited, but it will sound no worse than the "farting out". Obviously, simiar technology is already built into some integrated power modules...

Proper Limiter design means best audible performance versus best "protecting" performance. That's nothing but a mathematical and also "audible" certainty.
You may set the Alesis 3630 to 0.1msec time constant but then get (soundwise) totally impractical performance for audio applications

 

[ThisBass]

My "go to" pre amp since about 20 years is a super clean, solid state, rack mount EBS 1V2. Originally, I used a LabGruppen Lab 1000 power amp. Heavy and low on output.
A number of years ago, I upgraded to a QSC PLX 1804, occasionally using a PLX 3602, if I intend to use active filtering for bi-amping, or high pass.

Either one of those QSCs will drive the SVT-410HLF into distortion, so proceed with causion and be prepared to cut back on the volume if things sound stressed.

By the way, I use pedals to get some dirt in my sound, when needed.

I don't think the QSC amplifiers provide variable time constants for the limiter.
These limiters are designed to provide best "trade of" of protecting goals versus audible performance as "all porpuse" PA amplifiers.

 

[ThisBass]

I'm on the way to become a theoretical "nitpicker"
Even an impractical time constant of 0.1 msec for the limiter (or compressor) can't protect from amplifier clipping. Transients come sudden with a pretty highish steep that can't be predicted with sine wave considerations for the fundamental. So I claim (theoretically) that even 0.1 msec can't savely protect from (very short period) amplifier clipping IF the signal is real audio program material or a electric bass guitar

 

[AlexanderB]

I don't think the QSC amplifiers provide variable time constants for the limiter.
These limiters are designed to provide best "trade of" of protecting goals versus audible performance as "all porpuse" PA amplifiers.

I wonder if there is a pattern of a slight lack of reading comprehension on your part? I have not mentioned any limiters in MY amps. In fact, I typically use no dynamics processing at all.