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josh
10-11-2006, 10:15 AM
I am sure this question as been asked before.
I am curious to know why the vintage speakers of the past are so much more efficient than todays speakers. For example, the Altec 515B is about a 30 watt speaker while almost any decent 15" speaker made today are 200 watt and up. Am I correct? So why don't manufacturers produce efficient speakers today. With all of the new technology out there I would think todays speakers would be more efficient than those of the past. Does anyone else agree with me?

Thanks
Josh

grumpy
10-11-2006, 10:24 AM
watts are cheap.

edgewound
10-11-2006, 10:40 AM
I am sure this question as been asked before.
I am curious to know why the vintage speakers of the past are so much more efficient than todays speakers. For example, the Altec 515B is about a 30 watt speaker while almost any decent 15" speaker made today are 200 watt and up. Am I correct? So why don't manufacturers produce efficient speakers today. With all of the new technology out there I would think todays speakers would be more efficient than those of the past. Does anyone else agree with me?

Thanks
Josh

Well Josh,

Efficiency and power handling are mutually exclusive....and power ratings are a little different today than say 30 years ago.

There are still speakers that have both high efficiency and high power handling. Unfortunatley with JBL, the Musical Instrument series that had the highest sensitivities...D/K/E Series... have been discontinued, but are still supported with replacement parts.

The JBL 2227H is a 15" VGC driver that handles 600 watts with a 100dB sensitivity, 50Hz-3000Hz....very impressive.

The materials used in the voice coil construction today can take alot more heat, so in effect the power handling goes up. A Vintage speaker reconed with a new factory recone kit will handle more power while theoretically having the same efficiency...all other things being equal anyway.

The weight of the moving mass...cone, spider, voice coil... will have an effect on it's sensitivity. Lighter weight means greater sensitivity.

Power ratings. Using AES standards to make things somewhat understandable, a 30 watt speaker was rated using the most conservative sinewave test. Sinewave is the most stringent power rating method. 30 watts sinewave equals 60 watts pink noise equals 120 watts program equals 240 watts peak transient. The doubling of power equals an additional 3dB of output SPL...not taking into consideration, power compression, which is a speakers inability to make more sound when it's thermal power limits are reached, short of burning up the voice coil.

As the years passed in practical use it was discovered that amp clipping from not enough headroom...or too small an amp for a desired playback level....causes more voice coil burnouts than over powering. Speakers like clean power. That's when AES Standard RS426A was developed. A speaker's power rating is determined by playing frequency limited pink noise for eight hours with a 6dB crest factor. This means that a speaker's pink noise rating must withstand peaks of four times the RMS power.

JBL's VGC drivers rated at 600 watts pink noise can withstand peaks of 2400 watts. Doug Button, whom designed the patented 'Vented Gap Cooling drivers at JBL, told me that the drivers are tested with 3000 watt amps in the lab.

BTW...those 600 watt VGC drivers are rated at 300 watts sine wave...see the difference?

Of course the speaker has to meet the mechanical requirements of the power rating within a specified frequency range, due to cone/voice coil
excursion limits.


Hope this helps.

Hoerninger
10-11-2006, 11:19 AM
I'm talking here about bass, not treble:
Simply said a high efficiency loudspeaker has a strong magnet, which results in a low QTS factor. Such a speaker in a closed box or mostly in a bass reflex enclosure will not have sufficient bass.
Besides that In former times there was not such a need for deep bass, a high efficiency speaker is best suited for a horn , it is only limited by size.
Each speaker is a compromise of specs. Today there is less efficiency but more deep bass and more power by the amps.
- The power rating has been dicussed above.
____________
Peter

spkrman57
10-11-2006, 11:35 AM
Tighter tolerences and better materials.

To some it is worth the cost. I had E-140's reconed to E-130's with paper dustcap. Sweet driver at 105db/watt and approx response is 120hz to 3.6khz. I use a sub for under 120hz and a tweeter for the top end. This system is smooth and sweet to listen to.

By the time I bought the E-140s, and reconed them, I have a healthy investment in them, but worth the cost to me as I like the vintage sound!

Ron

SEAWOLF97
10-11-2006, 03:52 PM
My old AR3's barely even function with less than 25 watts pushing them.

josh
10-12-2006, 01:01 PM
I appreciate everyone's input.
Thanks for clearing this up for me.

Thanks
Josh

louped garouv
04-16-2007, 10:16 AM
Well Josh,

...and power ratings are a little different today than say 30 years ago.

...
Vintage speaker reconed with a new factory recone kit will handle more power while theoretically having the same efficiency...all other things being equal anyway.

The weight of the moving mass...cone, spider, voice coil... will have an effect on it's sensitivity. Lighter weight means greater sensitivity.

Power ratings. Using AES standards to make things somewhat understandable, a 30 watt speaker was rated using the most conservative sinewave test. Sinewave is the most stringent power rating method. 30 watts sinewave equals 60 watts pink noise equals 120 watts program equals 240 watts peak transient. The doubling of power equals an additional 3dB of output SPL...not taking into consideration, power compression, which is a speakers inability to make more sound when it's thermal power limits are reached, short of burning up the voice coil.

...

BTW...those 600 watt VGC drivers are rated at 300 watts sine wave...see the difference?

Of course the speaker has to meet the mechanical requirements of the power rating within a specified frequency range, due to cone/voice coil
excursion limits.


Hope this helps.

Is this true, can I feed my Altec 515Bs much more power than I had previously thought? IE differences b/t (& conversion between) power rating methods over the years.....

that would be sweet.....

Baron030
04-16-2007, 04:43 PM
Quoted by: louped garouv


Is this true, can I feed my Altec 515Bs much more power than I had previously thought? IE differences b/t power rating methods over the
years.....
that would be sweet.....


Yes, you can feed your Altec 515Bs lots more power.

But, it might require some CAREFULL MONITORING!!! What this means is that you need to be keenly aware of how your speakers sound. With a really high powered amplifier, there is never going to be any clipping or distortion. So, if you hear any distortion at all, then you are most likely over-driving your speakers and you need to back off on the volume, FAST!

Another indicator that you are pushing the very upper limit of your speaker system's power capacity is the effect of power compression. When you first start playing your system, the voice coils are going to be at room temperature and the dynamic range and transient response of your drivers are going to be at their best. But, if you notice that within a few minutes of loud playing, that the volume drops slightly and transients have lost a bit of their punch and intensity. Then you should be aware that the voice coils are getting hot. And it would be a good idea back off a bit on the volume.

As you read from above, most drivers can handle extremely large power peaks without any risk of damage, provided that these peaks are short lived and that they don't cause excessive cone excursion or voice coil heating. For example, over a period of 5 years, I ran my old 030 system with a Crown K1, without any damage to the drivers. The D-130s are only rated about 60 watts and the Crown K1 is very capable of putting out 350 watts per channel. So, the Crown K1 could have done a lot of damage, if I ever got stupid, hence, the need for careful monitoring.

Actually, the best defense that the 030 system ever had over the Crown K1 was a really strong offense.
As in, "Oh My God, that's offensively loud". Gee, I better turn it down to save my hearing.

So, as long as your Altec's sound nice and clean, a really high powered amplifier is only going to put a great big smile on your face. :D

Baron030

scott fitlin
04-16-2007, 05:15 PM
I agree, Baron, but there are some other tell tale signs of overpowering as well.

With Altec 515,s or any other older high sensitivity driver, a bigger amp will make them play considerably louder, youll hear alot more midrange, as that is where much of the sensitivity is. A bigger amp can play clean, but the speakers may become somewhat harsh sounding if pushed harder.

Another thing to watch out for is over excursion. The old high efficiency drivers had high compliance suspensions. A nice bass transient from a bigger amp can make those Altecs travel too far, you'll hear this as a very noticeable popping sound. Even at moderate levels, a big bass drum whack will cause this to happen. When I still had my Altec 421,s in my system, I upgraded to Bryston 4B,s, and the Altecs could not handle the transients when powered with these amps.

And, of course, your 100% correct about thermal compression.

Since Louped Garouv is using his system configured like a dance music system, where we DO like the sound of the woofers pumping, and his system is a crossover driven system, he may actually be safer with the amp he has, upgrading will change things. Yes, it will play cleaner without clipping, but, he will not be able to pump his system the same way. He will have to be much more careful.

However, as always, try some different amps, see what results you can achieve, and let your ears be the judge.

:)

louped garouv
04-17-2007, 01:54 AM
Since Louped Garouv is using his system configured like a dance music system, where we DO like the sound of the woofers pumping, and his system is a crossover driven system, he may actually be safer with the amp he has, upgrading will change things. Yes, it will play cleaner without clipping, but, he will not be able to pump his system the same way. He will have to be much more careful.

However, as always, try some different amps, see what results you can achieve, and let your ears be the judge.

:)

i currently have them on a Crest Audio V500.... rated @ 150WPC @ 8 Ohms...

so i figure i'm @ ~ 70/80 WPC @ 16 Ohms.....

probably going to try an old crown DC150 or DC300.....

should be fun if i am careful until i get a feel for the "new" amps



thanks all..... food for thought, that's certain

scott fitlin
04-17-2007, 11:27 AM
i currently have them on a Crest Audio V500.... rated @ 150WPC @ 8 Ohms...

so i figure i'm @ ~ 70/80 WPC @ 16 Ohms.....

probably going to try an old crown DC150 or DC300.....

should be fun if i am careful until i get a feel for the "new" amps



thanks all..... food for thought, that's certainActually, the DC-300A and your Crest V500 are pretty much the same power rating. The DC0300A will sound different though, direct coupled amps have a certain sound in the bass. I think you might like your 515,s powered by a Crown DC-300A.

So, you have 75 watt 515,s, you are pretty well matched.

louped garouv
04-17-2007, 11:35 AM
Actually, the DC-300A and your Crest V500 are pretty much the same power rating. The DC0300A will sound different though, direct coupled amps have a certain sound in the bass. I think you might like your 515,s powered by a Crown DC-300A.

So, you have 75 watt 515,s, you are pretty well matched.

from listening for a few months now, it seemed like about 75W was a good match for the 515Bs.... double what I thought was the rated power....

it sure sounds pretty good.... at least to me and my buddies

(had an older friend, he's in his mid 60s, over a few weeks ago, he said it was the best sounding system he had heard since the late 70's or so, when he had some friends that were nuts for audio :) )

I thought the two amps were pretty close....

saw a local DC300A the other day that has been modified with some really large heatsinks on the back.... I may go pick it up for a demo.....

scott fitlin
04-17-2007, 11:54 AM
from listening for a few months now, it seemed like about 75W was a good match for the 515Bs.... double what I thought was the rated power....

it sure sounds pretty good.... at least to me and my buddies

(had an older friend, he's in his mid 60s, over a few weeks ago, he said it was the best sounding system he had heard since the late 70's or so, when he had some friends that were nuts for audio :) )

I thought the two amps were pretty close....

saw a local DC300A the other day that has been modified with some really large heatsinks on the back.... I may go pick it up for a demo.....In rated watts the Crest and crown are equal, but, in the real world, that old Crown will produce house shaking bass you'll never get from that economy Crest. One thing to pay attention to, however, is the Crown DC-300A has a different input sensitivity than your Crest. The Crown has a higher input sensitivity of 1.75v so will be harder to drive, youll have to readjust your system to satisfactorily drive the Crown. Should be worth the effort, though!

Look at the massive transformer on the back of the DC-300A, thats one reason right there.

Try the Crown, you might be surprised at the outcome.

louped garouv
04-17-2007, 02:40 PM
just picked up the DC300A...

tech fresh (well he finished checkiing everything out two months ago), and got a "deal" b/c it had been sitting too long.....

will report back in a few days...

:bouncy:

readswift
03-22-2008, 04:16 PM
Hello, can someone help me! I know there is a JBL PDF paper where they show the power compression ratios of different 15" woofers including TAD , SFG and VGC !! Their website is down ...
:)

allen mueller
03-22-2008, 06:56 PM
just picked up the DC300A...

tech fresh (well he finished checkiing everything out two months ago), and got a "deal" b/c it had been sitting too long.....

will report back in a few days...

:bouncy:

Another good amp to look out for is the crown PS seireis, 200 or 400. Both great amps and can be had for around $100 f you keep an eye out.

readswift
03-22-2008, 07:41 PM
whats happening with the jbl site??
http://www.jblpro.com/pub/technote/tn_v1n22.pdf

I want this one ...

hjames
03-22-2008, 07:45 PM
whats happening with the jbl site??
http://www.jblpro.com/pub/technote/tn_v1n22.pdf

I want this one ...

Maybe down for the weekend, some easter maintenance ... or perhaps a crash over a holiday weekend.

Seems like the whole site is offline right now - http://www.jblpro.com/ (http://www.jblpro.com/pub/technote/tn_v1n22.pdf)
- I'd check back next week.

readswift
03-22-2008, 07:58 PM
well tomorrow i might buy some 2225's for PA usage and some info would be necessary. But I think I buy thm anyway, hehe .

Question , is the 2344 horn too big for MTM type mounting , right ? Planning to use waveguide instead of it actually.