2way speakers with E120?

[jcomba]

A guitarist friend of mine gave me a pair of E120 in good shape. Can I build hifi speakers with those? What kind of box and what kind of size would you advise? I guess an ennergic tweeter would mix up well, maybe a 075, or something like beyma cp22? thanks for your tips!

[Mr. Widget]

A guitarist friend of mine gave me a pair of E120 in good shape. Can I build hifi speakers with those? I built a pair of two ways decades ago with a pair of K120s for a buddy of mine. He loved them... I always thought they were a bit too lean on the bottom.


Widget

[Eaulive]

A guitarist friend of mine gave me a pair of E120 in good shape. Can I build hifi speakers with those? What kind of box and what kind of size would you advise? I guess an ennergic tweeter would mix up well, maybe a 075, or something like beyma cp22? thanks for your tips!

It's not really a bass producing speaker and like Widget said it will probably be kind of lean.
On top of it it's a high efficiency speaker with little linearity and limited excursion, I think it's more intended to be a midbass unit than a true woofer.

[jcomba]

Ok first, lean bass... I have a pair of jbl l112, bass is almost too much for my space, how lean would be the e120 if you compare those. No trick to fix that? Back horn? quater wave.... Does "high efficiency speaker with little linearity" means hard to filter?

[Mr. Widget]

I have a pair of jbl l112, bass is almost too much for my space, how lean would be the e120 if you compare those.Very lean.


No trick to fix that?Corner loading and filtering will help, but basically the speaker was not designed to produce much output below about 100Hz.


Does "high efficiency speaker with little linearity" means hard to filter?Well, it is easy to say that this speaker was designed to produce music not to reproduce music so that any non linearity would be considered a character rather than a flaw, but the fact is that this speaker is the direct descendant of the D120 which in fact was initially intended as a music reproducer. You certainly can work around it's flaws, but be aware that it will not be easy to make this speaker perform as a "hi-fi" speaker... the bass below 50-60Hz will be very difficult to get and there are numerous peaks in it's upper response.

All that aside, the friend I made the K120 two-ways for (with an EV-T35A crossed at~4.5K) was a professional jazz musician and he loved the sound. I did not.

Widget

[Harvey Gerst]

Very lean.

Well, it is easy to say that this speaker was designed to produce music, not to reproduce music so that any non linearity would be considered a character rather than a flaw, but the fact is that this speaker is the direct descendant of the D120 which in fact was initially intended as a music reproducer.
Widget
The E120 is a direct descendant of the D120 (a guitar speaker), and the D120 is a direct descendant of the D131, which in fact, was a music "reproducer".

I was never a big fan of the D131 or the D120/E120/K120 speakers, but they were popular with other guitar players. When I created the D120, I tried to change the tone as little as possible from the D131. I personally didn't like the sound of the D120 or the D131, but others did, so I left it alone.

[Ruediger]

A proper Thiele design for the E120 without any freuency-dividing network and with ideal cables and an ideal amplifier would lead to a very small box and a -3dB frequency of ca. 160 Hz (1st alignment in Thiele's tables).

With a real-life network, real-life cables and a real-life amplifier the total "generator resistance" as seen by the loudspeaker would be ca. 1.5 Ohms (this is "configurable"). That would lead to a small box with a -3dB frequency of ca. 140 Hz (2nd alignment in Thiele's tables).

So 140 Hz is what You can expect. You could make the box larger and tune it lower than for a "proper design" (maximally flat), but that would lead to what Mr. Widget calls a lean bass.

In the "Transducer Information Forum" there is a data sheet for the E120 and a frequency plot. The frequency plot shows that You cannot use the E120 for HiFi above 800 Hz - 1 kHz.

You could use it as a low mid in a four-way disco-speaker. Or You might sell it to a guitar player.

Ruediger

[jcomba]

Ok, so reading you all got me out of my "hey a loudspeaker, lets build something" state. However, it would be sad to just sell it or something, and I nust admit I want to try high efficiency jbl. I like my L112 pretty much, I love my le8t, so next step would be high efficiency isn't it? So I've been looking for several forums etc here localy and someone would like to exchange E120 with some reconed K110... Been looking for parameters, seems to be a window for bass reflex (and quater wave?), sansui even made some kind of monitor out of it... What do you think about that? Thanks to all for your kind help!

[Ruediger]

The E110 has the following TS parameters:

fs = 65 Hz, Vas = 1.6 cuft, Re = 6.0 Ohms, Qe = 0.4, Qm = 4.0, Qt = 0.36

The "generator resistance" is the sum of dc-resistance in the crossover series coil, cable resistance, and amplifier output impedance.

The total Q ("Qt") can be calculated as follows:

1/Qt = 1/Qa + 1/Qe [ Re / (Rg + Re) ]

Rg = 0.0 Ohms --> Qt = 0.36
Rg = 0.5 Ohms --> Qt = 0.39
Rg = 1.0 Ohms --> Qt = 0.42
Rg = 1.5 Ohms --> Qt = 0.44

Thiele's table, entry 5:

Qt = 0.383, f3 = fs * 1.00 = 65 Hz, Vab = Vas / 1.414 = 1.14 cuft


Thiele's table, entry 6:

Qt = 0.415, f3 = fs * 0.87 = 57 Hz, Vab = Vas / 1.055 = 1.5 cuft

Ruediger

[more10]

I have got a few E120-8. My plan is to build straight horns going from 56 Hz, but crossed over at 80 Hz. They will reach 800 Hz. With a phase plug they would go even higher. If the result is not to my liking, i have a few 2202 to use instead.

[Ruediger]

I have got a few E120-8. My plan is to build straight horns going from 56 Hz, but crossed over at 80 Hz. They will reach 800 Hz. With a phase plug they would go even higher. If the result is not to my liking, i have a few 2202 to use instead.

In the Technical References thread in the General Audio Discussions forum there is a paper from D.B. Keele about horn design using TS parammeters.

Ruediger

[Tim Rinkerman]

I have got a few E120-8. My plan is to build straight horns going from 56 Hz, but crossed over at 80 Hz. They will reach 800 Hz. With a phase plug they would go even higher. If the result is not to my liking, i have a few 2202 to use instead.
I set 2202's on fire using them as mid bass drivers. My JBL rep at the time in Buffalo said that using them above 100 hz. didn't allow them to pump enough air through the gap and voice coil to cool them properly....just my 2 cents....

[Fred Sanford]

A friend & I used them as mids in a large active-x-over 3-way PA system for years without issues (see pic). Also used them in passive 2-way monitors, and (as mentioned) they're efficient but lean on the bass (which works for vocal monitors).

je

[Eaulive]

I set 2202's on fire using them as mid bass drivers. My JBL rep at the time in Buffalo said that using them above 100 hz. didn't allow them to pump enough air through the gap and voice coil to cool them properly....just my 2 cents....

Makes sense...:hmm:

[Ruediger]

I set 2202's on fire using them as mid bass drivers. My JBL rep at the time in Buffalo said that using them above 100 hz. didn't allow them to pump enough air through the gap and voice coil to cool them properly....just my 2 cents....

The 2202 is recommended as a midrange driver, and in a properly designed ported cabinet or in a horn it will make only small excursions.

It is rated just 50 Watts RMS, that might be the reason. Also the back chamber may have functioned as a thermal barrier.

How big was the back chamber, and how efficient was the low bass?

Ruediger

[Eaulive]

The 2202 is recommended as a midrange driver, and in a properly designed ported cabinet or in a horn it will make only small excursions.

It is rated just 50 Watts RMS, that might be the reason. Also the back chamber may have functioned as a thermal barrier.

How big was the back chamber, and how efficient was the low bass?

Ruediger

The 2202 is rated 300W Program (AES) (there's no such think as a Watt "RMS")

I think is possible for a bass driver to have reduced power handling when the excusion is limited. It makes sense to me.

[Ruediger]

The 2202 is rated 300W Program (AES) (there's no such think as a Watt "RMS")

I think is possible for a bass driver to have reduced power handling when the excusion is limited. It makes sense to me.

The data sheet says 50 Watts RMS.

RMS does make sense here, as terms such as program power, square wave power, music power are in (marketing) use. You Yourself use the term "Program".

Ruediger

[Eaulive]

The data sheet says 50 Watts RMS.

RMS does make sense here, as terms such as program power, square wave power, music power are in (marketing) use. You Yourself use the term "Program".

Ruediger

The specs I have state 300W here, strange... http://www.jblproservice.com/pdf/Discrete%20Sales%20Models/2202HJ.pdf

There's no such thing as RMS power, it is a misnomer.

http://www.hifi-writer.com/he/misc/rmspower.htm

http://www.google.ca/url?sa=t&source=web&cd=7&ved=0CGcQFjAG&url=http%3A%2F%2Fwww.n4lcd.com%2FRMS.pdf&ei=sSaKTbbeEZGH0QHslrnzDQ&usg=AFQjCNH1uHG_Dxo4FVVOnsdpxUNkcNm_Fw

http://en.wikipedia.org/wiki/Audio_power

http://www.google.ca/search?q=rms+power&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

[jcomba]

Ok but what about the k110? And my purpose is to build home use speakers, so any thoughts most welcome! Some other guy want to exchange for 4 2115b?

[Eaulive]

The data sheet says 50 Watts RMS.

RMS does make sense here, as terms such as program power, square wave power, music power are in (marketing) use. You Yourself use the term "Program".

Ruediger

Ok, found it: http://cn.jblpro.com/pub/obsolete/2202.pdf

I guess there's a difference between the 2202A and the 2202H

It's rare to see JBL talk about "RMS power", they usually state "sine wave power"
Must have been directed to the audiophool crowd :D

[Ruediger]

The specs I have state 300W here, strange... http://www.jblproservice.com/pdf/Discrete%20Sales%20Models/2202HJ.pdf



My info is from the datasheet for the alnico version (www.jblpro.com -> vintage), Your info is valid for the ceramic version.

[Ruediger]

Ok but what about the k110? And my purpose is to build home use speakers, so any thoughts most welcome! Some other guy want to exchange for 4 2115b?

I told You two designs for the E110. That should have the same parameters as the K110. Can somebody confirm this?

Ruediger

PS: if You do not yet have the E110 (or K110) then there are better alternatives.

[Eaulive]

My info is from the datasheet for the alnico version (www.jblpro.com (http://www.jblpro.com) -> vintage), Your info is valid for the ceramic version.

Yup, I realized that afterwards :)

[jcomba]

What are you thinking about when you say better alternatives?

[Ruediger]

What are you thinking about when you say better alternatives?

Drivers which are more linear, and larger drivers. Is space an object? What are Your constraints?

ruediger

[jcomba]

Well, yes space could be a problem. Money also. Well for bass level... I have a pair of l112 used as main speakers, and wana build something for a small room this time, where l112 bass is too much. I would also like something more efficient, but witch doest need to be able to andle much power. listening maynly jazz, acoustical recordings. Maybe something LE8Tish but with a little more bass.

[Ruediger]

Well, yes space could be a problem. Money also. Well for bass level... I have a pair of l112 used as main speakers, and wana build something for a small room this time, where l112 bass is too much. I would also like something more efficient, but witch doest need to be able to andle much power. listening maynly jazz, acoustical recordings. Maybe something LE8Tish but with a little more bass.

LE8T requires a relatively large cabinet and will give a reasonable bass. In the Library there is a brochure of the LE8T together with a building plan. In the Transducer Information forum there is a datasheet for the LE8T. The response is non-linear, but I think that can be filtered.

ruediger

[jcomba]

I already have a pair of le8t. I've tried them in a lancer 44 size box but seems a bit lost in it, better to my taste with the pr8's and a 20something liter box. Anyway, my point was also to get more efficiency.

[Ruediger]

...
Anyway, my point was also to get more efficiency.
...

Thiele's paper, equation 76:

efficiency = (2 * pi * fs)**3 * Vas / 4 * pi * c**3 * Qe

fs ~ f3 --> fs = foo * f3, foo is some prop. constant
Vas ~ Vab --> Vas = bar * Vb, bar is some prop. constant

Lumping all constants together to some fudge factor ff:

efficiency = ff * f3**3 * Vab

with curt(X) := cube root(X) -->

efficiency = ff * [ f3 * curt(Vab) ]**3

For a given efficiency, the -3dB frequency is inversely proportional to the cube root of the box volume. Halve the -3dB frequency, and double the edge length of Your box. This means: make the box volume 8 times as large.

If You want more efficiency, raise f3 or make the box larger, or both.

ruediger

[jcomba]

How! I was absolutely unaware of that matter. But I can't make that big box, and I wouldn't know how to raise f3. Thats why I was asking about the k110 witch is efficient and seems to be ok for a 40 something litter box. I don't know how it does sound... And don't have the skill to make some complicated filters, so I've understood it was feasible, but I would also like to have a more subjective opinion.

[Ruediger]

...
But I can't make that big box, and I wouldn't know how to raise f3.
...

You missinterpreted the following sentences:

For a given efficiency, the -3dB frequency is inversely proportional to the cube root of the box volume. Halve the -3dB frequency, and double the edge length of Your box. This means: make the box volume 8 times as large.

If You want more efficiency, raise f3 or make the box larger, or both.

I did not mean that You could or should change the parameters at will. If a speaker designer decides to make one parameter "better" then another parameter will get worse.

If You have a working Thiele alignment, and another alignment is possible for Your driver, and if that alignment has a "better" f3, then it will have a worse (larger) Vab.

ruediger

[jcomba]

Thanks for clarification. Any subjective opinion on the k110?

[jcrobso]

The specs I have state 300W here, strange... http://www.jblproservice.com/pdf/Discrete%20Sales%20Models/2202HJ.pdf

There's no such thing as RMS power, it is a misnomer.

http://www.hifi-writer.com/he/misc/rmspower.htm

http://www.google.ca/url?sa=t&source=web&cd=7&ved=0CGcQFjAG&url=http%3A%2F%2Fwww.n4lcd.com%2FRMS.pdf&ei=sSaKTbbeEZGH0QHslrnzDQ&usg=AFQjCNH1uHG_Dxo4FVVOnsdpxUNkcNm_Fw

http://en.wikipedia.org/wiki/Audio_power

http://www.google.ca/search?q=rms+power&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

FYI: The term RMS applies to a pure sine way ONLY and nothing else. RMS voltage is derived by taking the positive swing of the sine wave and taking the peak voltage of the sine way and multiplying it times .707 and you have and RMS voltage.
For people in the US we have 120v RMS sine wave power. The voltage swings from 0 volts up 170V positive peak back to 0 and down to 170V negative peak. So we take the positive peak of 170V X .707=120.19V
There is an article that tries to discredit RMS by using a Square wave with a 5 second cycle.:banghead: Remember RMS=pure sine wave!

[Eaulive]

FYI: The term RMS applies to a pure sine way ONLY and nothing else. RMS voltage is derived by taking the positive swing of the sine wave and taking the peak voltage of the sine way and multiplying it times .707 and you have and RMS voltage.
For people in the US we have 120v RMS sine wave power. The voltage swings from 0 volts up 170V positive peak back to 0 and down to 170V negative peak. So we take the positive peak of 170V X .707=120.19V
There is an article that tries to discredit RMS by using a Square wave with a 5 second cycle.:banghead: Remember RMS=pure sine wave!

I think you didn't understand the article. It doesn't "discredit" RMS, it simply says that the RMS power, even if it could be calculated is meaningless and does not represent any useful value.
The "heating" or "working" or "usable" power created by computing the RMS voltage into a load is the "Average power", not the RMS power.

RMS power or Watts RMS is a useless measure, using "RMS power" instead of the correct "Average power" to rate amplifiers and speakers is a misnomer.

My last link didn't work, here is the right one http://www.eznec.com/Amateur/RMS_Power.pdf

[Eaulive]

Remember RMS=pure sine wave!

Yes and no.
You should say "the RMS value of a pure sine wave is always 0.707", but any waveform has an RMS value, depending on the waveform the RMS value will vary from 0 to 1

For a perfect square wave, the RMS value is 1. In the example we're talking about the square wave is not AC, it's simply a circuit DC and an on/off switch, it's an example to illustrate the average power.

RMS is a mathematical function, like average, that reduces a complex function to
a single value. And, like average, it has a precise definition. The definition is
revealed by the name – it’s the square Root of the Mean of the Square of the
function.