noob question about sensitivity

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I just found this site here, and am reading stuff like crazy -- I am new to tube amps and high efficiency audio -- I have come across the issue of speaker sensitivity -- and have found a pair of JBL speakers, the sensitivity in the specs show that they are 96db/1w/1m -- but they are 15" woofer and a horn. It also says recommended 250 watts minimum -- I am reading in places that the higher the sensitivity, the less power you need to drive them, and have found really expensive speakers that are 96 db sensitive but are made for 10 watt or less systems -- could these possibly be that good??? and would they work well for a 10 watt or less tube amp even though they say they need 250 watts? Would they be good for home speakers or just DJ/ PA systems? -- Can anyone please shed some light on these for me? I'm not sure about most of this stuff, I understand very little of all the terms and do not have an electronics degree or background (unless you're talking cars, done 30 years of that...) here are the specs:

Frequency Range (-10 dB) 38 Hz - 16 kHz
Frequency Response (±3 dB) 50 Hz - 12.5 kHz
Sensitivity (1w/1m) 98 dB SPL
Nominal Impedance 8 ohms
* Power Capacity 250 watts
* Peak Power Capacity 1000 watts
Recommended Amplifier Power 250 watts to 500 watts into 8 ohms
Maximum SPL 128 dB
Nominal Dispersion 90º x 50º
Crossover Frequency 1.6 kHz

* "Power Capacity" and "Peak Power Capacity" ratings are based on the average and peak power capacity of product samples subjected to a 100 hour power test using random noise with a 6 dB crest factor, in accordance with IEC standards.
 
A sensitivity of 98 dB 1W/1M means that at 1 meter distant from the speaker and the speaker is receiving 1 electrical watt, then the sound level at your ears produced by the speaker is 98 dB. 98 dB is quite loud. Increase the distance to 2 meters and the sound level is reduced by 6 dB to 92 dB which is still loud. Assuming a nominal impedance of 8 Ohm, then 1 watt electrical power is equal to 2.83V across the input terminals of the speaker.

Sensitivity is sensitivity irregardless of the power capacity rating. So you would be able to derive adequate loudness for home listening using an amplifier rated at 10W driving a speaker with a capacity of 250W.

The drawback would presumably be paying extra for unused power handling.
 
High Efficiency Speakers - HES

Yes greggbruce,
They should work fine. The problem here (and you don't show any link or info on models, you should make our work easier... if, if, if!) is that a PA speaker is not so accurate, with nothing for LF extension and a short range/frequency response in this case that you mention certainly not to ~20KHz. As you will find they also have many acoustic peaks and dips, some more musical than others. A studio speaker is very flat and might have also high sensitivity, and a home speaker, I presume (insert here your choices... home/car/picnic, all) if what you want/need is more accurate and relaxed. The 3 models types should work with the type amp you mentioned. It's an interesting subject. Go peep at the full range forum and look at some of the very high sensitivity model drivers for ideas.

Links various:
http://www.diyaudio.com/forums/full-range/234822-what-do-these-fe207es.html#post3468073
http://www.diyaudio.com/forums/mult...ed-bass-midrange-home-audio-applications.html
Fostex FE206En in Double Bass-Reflex Speaker Enclosure
JA8008 + TW034, 95 dB high-efficiency speaker by Troels TQWT-
Good interesting info/read on monitors L format Mystery Large Format Monitors
Pi Speaker Kits, one Pi kit
 
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Yes greggbruce,
They should work fine. The problem here (and you don't show any link or info on models, you should make our work easier... if, if, if!) is that a PA speaker is not so accurate, with nothing for LF extension and a short range/frequency response in this case that you mention certainly not to ~20KHz. As you will find they also have many acoustic peaks and dips, some more musical than others. A studio speaker is very flat and might have also high sensitivity, and a home speaker, I presume (insert here your choices... home/car/picnic, all) if what you want/need is more accurate and relaxed. The 3 models types should work with the type amp you mentioned. It's an interesting subject. Go peep at the full range forum and look at some of the very high sensitivity model drivers for ideas.

sorry, didn't have anymore time to paste link, here it is -- looks like 350 bucks a pair is what they can be had for -- free shipping...
JBL :: Product
 
In reality, if not building diy (JBL drivers), you can't beat the price for all the materials.
What I would do, buying the small JBL PA speaker and building a bigger enclosure that those drivers where made for. That would make for a good exercise. Certainly not for such a 10W amp, but who said it doesn't work fine?
JBL JRX115 Product
JBL JRX115 Spec Sheet
JBL JRX115 Technical Manual
JBL M115-8A Woofer THIELE SMALL

You get for that price,
15" Woofer: JBL M115-8A
1" CD Tweeter: JBL 2412,
Waveguide/Horn: JBL JRX Series 12 inches wide by 6.5 inches. The mythical Zilch :RIP::knight: Econowave PT-F95HF waveguide (90° x 50°, 6.5 x 12.
inch) with the "JBL 338800-001" reference.
Filter for 2426H on (PF-F64HF) 338800-001 waveguide

Now I bet you can not have in such a small speaker the F3 that is announced, usually in PA speakers, many times, that is close to 90Hz.
So building a home-box/new HiFi enclosure would be a priority for that LF extension, saving or selling the originals.

Let's check them:
Box dimensions ~35 centimeters by 43 centimeters by 68.6 centimeters has a volume of 103.24 liters (Enclosure Construction: 19 mm (¾ in) MDF). Net: 79L less all the drivers, ports and internals with a final net of ~72L. When you model this it gives F3 close to 65Hz, no low frequencies, that is about the same showing in the Tech Spec below.
For that, a respectable loudspeaker in the home, count here with same room-gain, having some low frequency extension with this driver (JBL woofer), you need the biggest box you can build i.e., >200L to have F3 close to 40/45Hz (ff) or about 34 Hz, what is the same. :cool:

On another note for the sake of comparing to other speakers references or kits,
you have the Pi Speaker Kits, four Pi kit, with JBL2226 (+$250.00) for $650.00 and maybe a better waveguide combo and high frequency compensation, with the best high frequency reproduction/quality/price relation in the market. :D
 

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Hi,

38 Hz to 16khz -10dB is not hifi.

+/- 3dB 50Hz to 12.5KHz is not really hifi.

You can be sure those numbers are nearfield
and even worse typical farfield for home hifi.

Great for parties, useless otherwise.

rgds, sreten.

Good value hifi speakers don't do parties.
 
Sensitivity is sensitivity irregardless of the power capacity rating.

What I said before is true. But after giving it some thought and rereading, sensitivity and power rating are interrelated. With a target sound intensity level in mind, that sound intensity can be achieved in two ways: with a relatively insensitive driver at some level of power consumption or with a relatively more sensitive driver consuming much less power.

For example, you might decide that a driver should be able to produce 100 dB at 1 meter.

If the driver that you've got is a relatively very insensitive one, say 76 dB 1W/ 1M, then that driver would require 256W to produce 100 dB at 1 meter.

On the other hand if the driver that you've got is moderately sensitive, say 85 dB 1W/ 1M, then that driver requires only 32W to produce 100 dB at 1 meter, or 1/8th the wattage required by the very insensitive one.

If the target sound pressure level is substantially greater than what the driver produces given 1W, and the driver is relatively insensitive, then the wattage required to achieve the target can become very substantial.

(For each 3 dB increase of sound pressure level, wattage must double.)

-cT
 
Hi,

38 Hz to 16khz -10dB is not hifi.

+/- 3dB 50Hz to 12.5KHz is not really hifi.

You can be sure those numbers are nearfield
and even worse typical farfield for home hifi.

Great for parties, useless otherwise.

rgds, sreten.

Good value hifi speakers don't do parties.


this is the type of opinions I've been looking for, good or bad -- after looking, I really didn't pay any attention to the freq response -- what is human hearing again?? up to 20k ?
current room size I have to fill is approx 20'x20' with a 14' ceiling ....

anyone have any suggestions?

I am leaning towards something like the decware amps to start with, (so I need speakers to match) just entry level, maybe the small one

"This 2 watt per channel Single Ended Triode amplifier is capable of driving almost a dead short - rare in the world of SET amplifiers! It can be driven directly from any source (such as your CD player or DAC) without a preamp. It will drive typical hi-fi speakers to conversation listening levels and hi-efficiency speakers (94dB 1w1/m) to a satisfyingly loud level. The amplifier operates in pure class A and has zero negative feedback.

The bass surprises everyone, and the amp features two inputs and a selector switch so you can have two sources. The volume control is mounted on the front. Tubes for it are more than affordable, the amp is self biasing making it a completely hassle free experience to own and enjoy one. It comes with a lifetime warranty because it's actually built that well."


... working with a limited budget here, and am anxious to start hearing the stuff I've been missing since the reel to reel tube sound from my childhood in the late 60's...
 
I just found this site here, and am reading stuff like crazy -- I am new to tube amps and high efficiency audio -- I have come across the issue of speaker sensitivity -- and have found a pair of JBL speakers, the sensitivity in the specs show that they are 96db/1w/1m -- but they are 15" woofer and a horn. It also says recommended 250 watts minimum -- I am reading in places that the higher the sensitivity, the less power you need to drive them, and have found really expensive speakers that are 96 db sensitive but are made for 10 watt or less systems -- could these possibly be that good??? and would they work well for a 10 watt or less tube amp even though they say they need 250 watts? Would they be good for home speakers or just DJ/ PA systems? -- Can anyone please shed some light on these for me? I'm not sure about most of this stuff, I understand very little of all the terms and do not have an electronics degree or background (unless you're talking cars, done 30 years of that...) here are the specs:

Frequency Range (-10 dB) 38 Hz - 16 kHz
Frequency Response (±3 dB) 50 Hz - 12.5 kHz
Sensitivity (1w/1m) 98 dB SPL
Nominal Impedance 8 ohms
* Power Capacity 250 watts
* Peak Power Capacity 1000 watts
Recommended Amplifier Power 250 watts to 500 watts into 8 ohms
Maximum SPL 128 dB
Nominal Dispersion 90º x 50º
Crossover Frequency 1.6 kHz

* "Power Capacity" and "Peak Power Capacity" ratings are based on the average and peak power capacity of product samples subjected to a 100 hour power test using random noise with a 6 dB crest factor, in accordance with IEC standards.


Back to your original question, the recommended power amplifier output power (in this case 250W to 500W) is the amplifier MAXIMUM output power you can safely use along this speaker set, and it would make sense.

Of course you can use less than 250W amplifiers but JBL thinks it's a waste of money buying this speakers and you may want to go for a less rated power set.
But you might connect them to a small AM transistor radio working on AAA batteries if you'd like :)
 
I really didn't pay any attention to the freq response -- what is human hearing again?? up to 20k ?

anyone have any suggestions?

... working with a limited budget here, and am anxious to start hearing the stuff I've been missing since the reel to reel tube sound from my childhood in the late 60's...
There are some males over the age of puberty that can hear to 20 kHz, but 16- 18 kHz would be more typical. Most males over the age of 40 don't hear much past 15 kHz.

I'd suggest that much of the reel to reel tube sound from your childhood in the late 60's was due to the way things were recorded, tubes and tape saturation have a distortion quality that is distinctive and generally euphonic.

The sound of a tube microphone through a tube console recorded with a tube tape recorder, the recorded output used for cutting a master with a tube lathe, then played back with a needle and cartridge through a tube RAII pre-amp and re-recorded on another tube reel to reel ends up with a different sound than achieved with most current recording processes.

Unfortunately, simply using tube power won't change the basic recording process, if you miss the sound of the old recordings, I'd suggest the best way to hear that sound is to listen to old recordings.
 
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There are some males over the age of puberty that can hear to 20 kHz, but 16- 18 kHz would be more typical. Most males over the age of 40 don't hear much past 15 kHz.

I'd suggest that much of the reel to reel tube sound from your childhood in the late 60's was due to the way things were recorded, tubes and tape saturation have a distortion quality that is distinctive and generally euphonic.

The sound of a tube microphone through a tube console recorded with a tube tape recorder, the recorded output used for cutting a master with a tube lathe, then played back with a needle and cartridge through a tube RAII pre-amp and re-recorded on another tube reel to reel ends up with a different sound than achieved with most current recording processes.

Unfortunately, simply using tube power won't change the basic recording process, if you miss the sound of the old recordings, I'd suggest the best way to hear that sound is to listen to old recordings.

yes, I am acquiring old recordings, reel to reel tapes and some records...
the little voice of music reel to reel I have makes the music sound so REAL and present and ALIVE (as I remember it) instead of sterile like it all seems to sound today --- I would like to bring it to more than just one speaker out of a tape player.... I have even seen some reel to reel tapes from artists I liked in 80's..... before it all went digital and to cd's.
I am leaning more so to the big band stuff, tho, lenny herman, sam donohue, ella fitzgerald, sinatra, and the like. I have even found some reel to reels that were never made into records or cd, and there are still some I am searching for...
 
Hi,

I'm no fan of Decwares misleading and outlandish claims.

Transformer coupled valve amplifiers don't like low
impedance, they never have and they never will.

rgds, sreten.

http://lundahl.se/wp-content/uploads/2013/06/cb-amplifier_8wse.pdf

Checkout Pi Speakers and the Econowave.

yes, yes, now I'm getting somewhere....

what do you mean my low impedance -- 2 or 4 or 8 ohm? or is even 16 considered low?

thx for the link, going to read it now.
and I will be checking out pi and econowave, thx.
 
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The load the valve sees is set by the designer, by way of the transformer. There is usually a selection of speaker windings eg: 4, 8 and 16 ohms, and since they work this way it is desirable to keep the impedance close to this. There are benefits and drawbacks to going both higher and lower.
 
Try visiting some music stores and PA dealers (and pawn shops) and listening to speakers like the JBLs. If something sounds promising, maybe you can rent a pair for a day or two and try them at home. It's also worth asking any sound rental and installation places if they have gear to sell. Also, check notice boards in music stores and online ads for used speakers.

Consider bringing something like a battery operated T-amp rather than depending on whatever amp the vendor has available. Bring a music source that includes a sinewave sweep from 20 to 20k; that will reveal rattles and buzzes and possibly voice coils with loose windings.
 
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