Speaker Cabinet design: Interpreting Thiele-Small data, using sofware, and tuning

[bob p]

there's a component of intentionally deceptive advertising with those mega-watt Class D bass rigs. they like to puff about the mega-watt power ratings, as if that makes them superior to an old-school rig with a lower wattage rating. but it's all apples and oranges because the speaker cabinets aren't even close to being similar.

[Justin Thomas]

And those kilowatt amps seem to blow up a hell of a lot easier, too... But even if they didn't they still sound like $#!+.

Juan has outlined the history of speaker wars here before, and how we got there, and how we are stuck in a vicious circle. I will simply go back to the source. Everybody laughs at my bass rig. Until they hear it. That's good enough for me. Of course, the confidence (arrogance?) of the operator might have a part to play...

Justin

[bob p]

I think the reason that people blow up their Class D rigs is because they aren't vigilant about using the right load impedance. So many people are used to being able to mismatch indiscriminately with SS rigs, and somewhat discriminately with tube rigs, that they try to do it with Class D amps and get burned.

[Leo_Gnardo]

or better yet, just drive your stack of 15 with a pair of SVT. too much is never enough.

Saw lots of Hot Tuna shows in the 70's, Jack Casady with 3 or 4 SVT's and a stack of 18's. "There's thunder in the air!" The FOH mixer never had to stress his PA by putting bass into the mix I'm sure.

Efficient, lower-powered speakers are an absolute secret to great bass TONE. Amplification is the EASY part; making it sound aesthetically pleasing is where nearly every single modern "bass amp" falls short.

Now you're starting to sound like Rich Koerner, Time Electronics. And, you're right, both of yez. Look it up, it's on his website. Lots more interesting reading there, kool old photos too.

[Leo_Gnardo]

they like to puff about the mega-watt power ratings, as if that makes them superior to an old-school rig with a lower wattage rating.

I was reading the specs on one of those Class D amps. A thousand watts all right. For a millisecond pulse, with a 1% duty cycle. Whatever happened to specs as approved by the FTC in the early 70's? How much power can that amp turn out continuously into its rated load for at least an hour, without breaking down, popping a fuse or breaker, setting off its thermal limit switch, eh? Oh probably 40 watts or so... We're back to amp companies now able to advertise anything they want, add that to the rash of fake news.

[Dave H]

Dave H: yes, but are those efficient paper&glue speakers, or plastic&rubber "speakers?" Lots of bass players play through 2x15" whatsits...

They were paper and glue, no rubber or plastic. I used a 5F6A I made at rehearsals. It was fine.

[Justin Thomas]

Spent MUCH time perusing that web site!

Justin

[J M Fahey]

Comedy time: around 1980 I was pricing out components for a PA system, and the salesman told me the price of alnico was soaring "because of all the trouble in the alnico mines." Had a hard time not laughing at him over the phone. I waited until after we rang off. Alnico mines, indeed! Wonder where they are?

Well, he was not that far off.
There was BIG problem with Cobalt mines.
Civil war in Africa raged in Congo, doubly so because the Province where most mines are in is Katanga and Belgians pushed for its independence by arming the natives against Congo.
The official war was from 1960 to 1966 but after it ended situation got actually worse, because of bloody revenge and massacre against rebels so in the early 70´s Cobalt price went through the roof, once reserves were depleted.

[olddawg]

Trouble vs benefit. If you are a famous touring artist with a crew, personal preferences, an image, and endorsements .... yeah you are going to use what you want to use. I'm an old guy playing clubs. I worked with a bass player a while back that had a stock 60 watt Fender Rumble with a DI out. Sounded great. Another guy had one of those Marc Bass (Class D) amps with the 2x10" cab. It was ok. The current bassist is old school a with 2x15" cab and a GK. I'll be gigging this weekend with a stock Bugera v22 (badge removed, lol!) and a Weber attenuator with a mic on it. I get no complaints and I can lift it (sometimes, lol). The younger/bigger/ healthier guitarist/vocalist guy on the other side of the stage has a JCM 2000 with an oversized 4x12" sealed (directional as hell) cab, a rack preamp, a modeler rack, and a stupid noisy VHF wireless. He likes what he likes. I like what I can load ... and sound better. But sometimes I think with equipment, it's "look how big my dick is" syndrome. I've been on stage with a 5 watt Ep VJ through a 1x12" Eminence (in a 1960 Ampeg Rocket) and had the sound guy go mental with my stage volume. My take after doing this 50 years: "There are no rules and lots of fools!" Use your own ears and decide what you want to lug around.

[Leo_Gnardo]

Well, he was not that far off.
There was BIG problem with Cobalt mines.
Civil war in Africa raged in Congo, doubly so because the Province where most mines are in is Katanga and Belgians pushed for its independence by arming the natives against Congo.
The official war was from 1960 to 1966 but after it ended situation got actually worse, because of bloody revenge and massacre against rebels so in the early 70´s Cobalt price went through the roof, once reserves were depleted.

Well I knew that, and by late 70's USSR cut off selling cobalt too. What little there was left was a byproduct of nickel mining in Canada and Australia. And in the old supply & demand formula, the price went sky high. What I was laughing at was the salesman's representation of alnico as if it springs out of the ground, ready-made.

We had a similar squeeze on neodymium a few years back when China refused to continue to sell theirs. Well sure, billions of Chinese want electric cars, that's the next thing, also train motors not to mention military uses. Funny thing, there's as much neodymium as copper available in the earth's crust, it's just a matter of reaching down to get it. Haven't heard in more recent years how Nd might have become more available. Seems there's plenty of Nd magnet speakers, and everybody and his cousin bringing out more electric cars.

[Justin Thomas]

That may be true, but as a musician, I don't want to have to worry about it, for one. Two, there's WAY too much that can go against the ideal circumstances that should be factored into the equation. Whether by stupidity or necessity, "the show must go on" should be factored into the manufacturing equation. There shouldn't be such requirement for close tolerances like that. Unless it's a scam to sell more amps. Let's face it, these things re CHEAP to manufacture. Throw it away and buy a new one.

Me? I'll keep plugging my Bassman into 4/8/16 ohm cabs & not give a damn. It's got a Twin Reverb tranny, so 8 is he middle ground.

Justin

[The Dude]

@ The Dude: can you put up that little rolling on your side crying-laughing smiley-face guy emoji?......

This one?

[bob p]

my twin reverb ot has a 4 ohm tap. 2/4/8 would be ok but 16 is pretty far off.

[Justin Thomas]

But my Bassman is only 50W. So it all comes out in the wash. My point being, it ain't blown yet, after about 8 years of plugging into whatever. Class D...

Justin

[The Dude]

I think the reason that people blow up their Class D rigs is because they aren't vigilant about using the right load impedance. So many people are used to being able to mismatch indiscriminately with SS rigs, and somewhat discriminately with tube rigs, that they try to do it with Class D amps and get burned.

As an aside, I don't see this as a problem with Class D amps any more so than solid state amps of any other class. Misuse of any product outside it's design specs is a user problem- not a design problem.