Manufacturer specifications..... ???

[JKnPA]

When a company puts a product in the market and lists the specifications of that new product........ like speakers; how do we know these 'product specifications' are true?
Do companies have to submit their new product to an 'independent laboratory' for testing ?
What exactly is the process ?
Just a thought, since most of us here are not audio engineers! ...........:rolleyes:
TIA...........
John

[j_garcia]

Those measurements are based entirely on their testing and testing methods. You can look for pro/magazine reviews of specific models to see what their measurements yeild, but it is relatively safe to believe the manufacturer's ratings. However, one thing that some manufacturers do to make their numbers look better is to give you the absolute numbers (one in particular comes to mind). That means they give you the entire range of the speaker without mentioning that 30Hz is -10dB, rather than giving the -3dB numbers, which can actually tell you something. So, what you want to see is a spec like "55Hz - 20kHz -3dB", meaning the point at which the speaker's output at those frequencies is reduced by 3dB or 50%.

[JKnPA]

JG,
OK........ that is what I suspected. So we should stay with 'quality companies' especially when buying speakers!
The design of 'crossover freq.' circuits is very interesting, although
complex. I found another website explaining 'active' and 'passive' design; I assume most quality manufacturers use 'active' crossover freq. design techniques. Would that be true?
Would these 'quality companies' include schematics with their products(speakers), so we could actually see the circuit design (filters) used in the product?
Thanks again for replying..........
John

[jaxvon]

Most speakers you see on the market use passive crossovers. These use a network of inductors, capacitors, and resistors between the input jacks on a speaker and the drivers. Active crossovers split the signal after the preamp, necessitating multiple amplifiers. As for finding a schematic, most companies (heck, I don't even know of one that does) do not post crossover circuit layouts. The design of these crossovers is a big part of a speaker's sound, so releasing it into the public would be a way for the company to lose money.

[JKnPA]

That's interesting!.............:rolleyes:
The article/s stated that passive designs can be somewhat troublesome to design because of various factors.
So how do I know if the speaker I buy has active or passive 'crossover freq.' design ? What do I look for in the specifications?
Can you give me a link/s on active/passive designs ?
I'm glad we have some audio engineers here who can give technical information on these issues.
I really appreciate your knowledge & time given freely!
Thanks...........

[Buckeyefan 1]

That's interesting!.............:rolleyes:
The article/s stated that passive designs can be somewhat troublesome to design because of various factors.
So how do I know if the speaker I buy has active or passive 'crossover freq.' design ? What do I look for in the specifications?
Can you give me a link/s on active/passive designs ?
I'm glad we have some audio engineers here who can give technical information on these issues.
I really appreciate your knowledge & time given freely!
Thanks...........

Read this, it may help:

http://www.enjoythemusic.com/magazine/viewpoint/0403/aachapter43.htm

If you're really intersted in the topic -

http://users.pandora.be/airborne/speakers.html

[j_garcia]

Active crossovers are great, but they are nowhere near as cost effective as a passive network. While a passive network may be a bit tougher to design up front, the proper design can tweak the speaker to pretty much exactly the desired sound.

[JKnPA]

BuckeyeFan,
I just skimmed thru the articles, I'll read them more thoughly this afternoon. There is so much info in these articles, it takes time to 'sink in'............. :rolleyes:

JG,
From the article/s I read, the author thought 'active design' was more reliable for the reasons stated in his article..... mostly had to do with the 'output impedance ' of the amps!........... ;) See paragraph 4 in his conclusions( bottom of page).
Here is the link........ maybe you and 'Buckeye' might enjoy it, maybe not !!......... ;)
http://sound.westhost.com/biamp-vs-passive.htm

* So , will the manufacturer tell me in the specs.(@ online dealer), if the unit has active or passive design?

[jaxvon]

Unless a manufacturer specifically mentions that the speaker uses an active crossover, you can assume that it has a passive crossover. Very few speakers use active crossovers, and those that do are often quite expensive. However, if you ever decided to build your own speaker, an active crossover would be the best way to get the sound exactly right.

[j_garcia]

Consumer speakers with active crossovers would be quite rare, and those that have them are not likely to be inexpensive as Jax said.

My question is, what exactly is it you are after?

[JKnPA]

JG,
Being a retired elec. technician, I was just interested in the filter design being used in speakers. Most companies today overstate their product specifications or are somewhat ambiguous in stating facts!
Whenever I buy any electronic products, I always like to have a schematic included with the product, so I might be able to repair it when it 'fails'........ which is usually right after the warranty expirers!.......:rolleyes:
The article I read ( link I supplied), stated that active design was more reliable than passive. So I was just curious what most speaker companies employ.
I hope I answered your question..............................

Thanks
John

[jaxvon]

Unless you have a very old speaker, you're not likely to see any failure in the crossover, assuming it hasn't been abused. As for the schematic, you'll probably have to pop open the cabs and figure it out yourself, as I don't know of any speaker company that would willing give out that information.

[JKnPA]

Ok,,,,,,,,,,,, I appreciate your replies.
I really didn't think the filter designs( active or passive) would be a big secret, but I guess I am mistaken, since they have been employed for many years.
Filter design......... interesting stuff !

Have a nice weekend !