Speaker Specs and Transparency

[peplepew]

What is with some of these speaker manufacturers??????? They just aren't transparent with their specs and trying to get the info from them is like pulling teeth. I asked the tech department at a manufacturer this:

Thanks for the reply. The questions I still have remaining are what is the +,- db rating on the frequency response numbers and on the efficiency ratings, how was that measured i.e. 1w/1meter, 2.83v/1m, was it in a car or single plane environment. Without this info it's like telling someone it's 38 degrees outside and not saying whether it is in fairenheight or Celsius.

He answers with this:

Regardless of the manufacturer, ALL Thiele/Small parameters for any speaker are done in very controlled environments. All of our subs are tested with the 1w/1m method. As I said, All speakers are measured in the same manner and environment.

Talk about avoiding the question. This guy should run for a political office!!!!!

The specs on these woofers allege a 95 db efficiency and a 22-500 hz response. Well where hell is the rest of the information?

It's like he is saying you get what you get, just shut-up and buy them. Oh the contempt!!!

Is there an industry standard they have to follow? I've seen retailers advertise woofers with a power rating of 450 watts. When I read the small print it was only measured for a millisecond or something and the rms rating was 135 watts. Talk about misleading.

I sure have enjoyed working with JBL over the years in the pro-audio arena. When you get a spec sheet from them it's two pages long and they explain every last detail about their measurement procedures. Nice to know what you are getting.

 

[rschleicher]

Yeah, speaker frequency response specs are very suspect, especially for bass response. Sometimes they'll say "usable response down to xx Hz.", but how many dB down is "usable"? It would be nice if they always had a +/- dB number alongside the frequency range, but individual manufacturers are loath to do this when their competitors will quote a lower frequency (without qualifying it with a +/- dB figure).

 

[peplepew]

you can make the speakers do just about anything if you don't post the +or- tolerance.

I just wrote that tech back with a bit more aggressive request. I think I was insinuating he was being disingenuous. oh boy. I shouldn't hit send on my email til I cool down and have a chance to monitor myself in situations like that. lol! If he just would have answered the question.......

 

[WmAx]

What is with some of these speaker manufacturers??????? They just aren't transparent with their specs and trying to get the info from them is like pulling teeth. I asked the tech department at a manufacturer this:

Thanks for the reply. The questions I still have remaining are what is the +,- db rating on the frequency response numbers and on the efficiency ratings, how was that measured i.e. 1w/1meter, 2.83v/1m, was it in a car or single plane environment. Without this info it's like telling someone it's 38 degrees outside and not saying whether it is in fairenheight or Celsius.

He answers with this:

Regardless of the manufacturer, ALL Thiele/Small parameters for any speaker are done in very controlled environments. All of our subs are tested with the 1w/1m method. As I said, All speakers are measured in the same manner and environment.

Talk about avoiding the question. This guy should run for a political office!!!!!

The specs on these woofers allege a 95 db efficiency and a 22-500 hz response. Well where hell is the rest of the information?

It's like he is saying you get what you get, just shut-up and buy them. Oh the contempt!!!

Is there an industry standard they have to follow? I've seen retailers advertise woofers with a power rating of 450 watts. When I read the small print it was only measured for a millisecond or something and the rms rating was 135 watts. Talk about misleading.

I sure have enjoyed working with JBL over the years in the pro-audio arena. When you get a spec sheet from them it's two pages long and they explain every last detail about their measurement procedures. Nice to know what you are getting.

The Theile-Small parameters are all that is needed to calculate the frequency response of a subwoofer. You can add a transfer function accounting for your car interior sub placment/application to estimate a very accurate prediction. However, the response will change at high power use -- the electrical and mechanical parmaters change when most driver are used near their limits. Most Theile/Small parameters are given for small-signal(linear range of the speaker) input. Pro speakers will usually give hi level signal T&S parameters -- because these are usually used at or near their physical/electrical limits in practical use. A car speaker(in non competition applications) or home speaker are mostly used in small signal situations, where the speakers remain within their linear range that is very well represented by the T&S parameter aquisition method used commonly.

-Chris

 

[peplepew]

Chris,

I understand what you are saying. Power compression characteristics of drivers was an important issue when I dealt with pro-audio. Getting the most out of every enclosure was not only a financial issue but a truck pack and venue space issue as well.

I appreciate you having patience with me as I am just learning the ropes as to what to expect with hi-fi components. This particular manufacturer had very promising stats for 10" drivers to load in my imperial-9's. I need 4ohm drivers and have been entertaining the idea of car audio subs since they have a huge variety of 4ohm drivers. They advertised an efficiency rating of 95db. When I loaded the numbers into my program the calculated efficiency was only 84db. I am trying to determine whether there is a prolem with my number or theirs, in order to do that I need more information such as under what conditions they achieved their numbers. They aren't willing to devulge that information aparently. As I am learning, some manufacturers calculate their numbers as if they are in a car which adds about twelve db. A huge discrepancy that needs to be dealt with.

As a consumer I am trying to obtain the best value/dollar of low frequency drivers that will work in my application. This project is more for fun than anything and I'm obviously not going to dump 1K per driver on it. I would also like to know how much flexability I have with the drivers.

 

[plhart]

Ah, my Imperial 9 rebuilder. The 10" 3.5 ohm DCR subs I used in the originals would yield a 95dB sensitivity when two were wired in series and driven in the I-9 cabinet at 2.83V with the microphone 1 meter away.

Re; replacement woofers. These shouldn't be too hard to to find. What you want is to be able to do is find some woofers which, as a system, will overdamp the bass response. If you can achieve this then you can get a better bass balance back by either cutting the lengths of both ports or just adding a bit of bass boost on your pre-amp.

Try for this as a basic raw driver spec. It'll get you in the ballpark>>
10" with 4-layer voice coil, 1.5" but preferably 2"VC. ~28 to 32 ounce magnet. Minimum Xmax of 8mm (if that info is available). Qts less than 0.4, more like 0.3 to 0.35. FAR >25Hz. 30Hz is okay. Foam or rubber edge okay. Today's foams don't rot like the old stuff.

Try call my buddies at Speaker City USA, Burbank, CA. They should be able to hook you up easily.