JBL speakers

[Teleguy61]

This is where you will find answers about JBLs.
http://audioheritage.org/

The D series speakers were a design that had a larger voice coil gap, so they would handle more power without overheating.

 

[Ten Over]

What?

Huh?

Oh. I see you edited the word to "starch".

I've long suspected that some people don't like JBL's because they will actually play what their amp is putting out whereas cheaply constructed speakers round everything off.

 

[strat a various]

I have a handful of K120's. I like them a lot. One of my main cabs is an oversized closed back bluesbreaker style cab with a K120 and an Eminence Man O' War. The closed back seems to make both speakers respond more similarly to one another, so I think it takes some of the edge off the K120. I have one E120, which is the ceramic version of the K120, and I've never been all that fond of it.

The K120 is, if I understand correctly, identical sounding to a D120. I have a couple of D120's, but one has been reconed, and the other is just really old, and I've never closely A/B'd them with a K120, so I can't say anything more than that they're clearly the same family.

I've been an EVM 12L man for decades. I own a pile of speakers, and I tend to gravitate back to the 12L's. One speaker that's really giving the EVM 12L a run for it's money is the Eminence Commonwealth. It's a monster cast frame speaker with an aluminum dust cone. It was supposed to be Eminence's take on the D120F, but I find it sits exactly in the space between the JBL's and the EVM. A phenomenal speaker, for those wanting to get into K120 territory, but thinking the K120 is too shrill. They don't make the Commonwealth anymore, but the Paul Franlin PF-350 is the same speaker with a paper cone. I'd love a 4x12 of PF-350's, but they weigh 22lbs, so I'll probably just have to stick with my 2x12 with the Commonwealths.

In the 90s, I blew two D130s, an EVM 12L, and a Peavey Black Widow, all cooked by solid state amps distorting ... square waves. None of the amps approached the RMS volume rating of the speakers. Square waves just generated too much heat in the voice coils.

 

[chezdeluxe]

In the 90s, I blew two D130s, an EVM 12L, and a Peavey Black Widow, all cooked by solid state amps distorting ... square waves. None of the amps approached the RMS volume rating of the speakers. Square waves just generated too much heat in the voice coils.

You might like this tech note from JBL discussing the problem of an amplifier with a lower notional power rating than the speaker causing the exact problem you describe. JBL's advice was to use an amplifier with more power than the speaker rating so that only undistorted signal for a certain desired volume level was applied to the speaker.

(link removed)

 

[Musekatcher]

You might like this tech note from JBL discussing the problem of an amplifier with a lower notional power rating than the speaker causing the exact problem you describe. JBL's advice was to use an amplifier with more power than the speaker rating so that only undistorted signal for a certain desired volume level was applied to the speaker.

(link removed)

That was considered a general rule for all high fidelity equipment 30+ yrs ago. If you look at the two graphs, you see there is more dwell at peak with a square wave, and there is less motion - motion equals cooling. So the VC heats up more with a square wave. I think instrument speakers are rated so they can take the full power under these conditions with margin, while PA and others are rated less conservatively?

 

[11 Gauge]

One speaker that's really giving the EVM 12L a run for it's money is the Eminence Commonwealth. It's a monster cast frame speaker with an aluminum dust cone. It was supposed to be Eminence's take on the D120F, but I find it sits exactly in the space between the JBL's and the EVM. A phenomenal speaker, for those wanting to get into K120 territory, but thinking the K120 is too shrill. They don't make the Commonwealth anymore, but the Paul Franlin PF-350 is the same speaker with a paper cone. I'd love a 4x12 of PF-350's, but they weigh 22lbs, so I'll probably just have to stick with my 2x12 with the Commonwealths.

Aw crap. I had intentions of getting a Commonwealth. At least it's good to know that the PF-350 is mostly similar. I don't seem to recall the Commonwealth costing north of $200, though (another thing that made it potentially a good deal).

 

[kafka]

Aw crap. I had intentions of getting a Commonwealth. At least it's good to know that the PF-350 is mostly similar. I don't seem to recall the Commonwealth costing north of $200, though (another thing that made it potentially a good deal).

Look for a used one. It took me a while to get a pair, but I found them.

My Jim Kelley FACS has the E120 in it, which is stock. I think I'm finally going to bit the bullet and replace it with either a K120 or a PF-350. The reissues were very successful with the EVM12L's, so I imagine the PF-350 would be a great match.

 

[strat a various]

You might like this tech note from JBL discussing the problem of an amplifier with a lower notional power rating than the speaker causing the exact problem you describe. JBL's advice was to use an amplifier with more power than the speaker rating so that only undistorted signal for a certain desired volume level was applied to the speaker.

(link removed)

Cool

 

[slider313]

Poo on specs...

My ears always liked Jensen's.

JBL' s remind me of starch.

Thin, tinny, pop with bass overdrive, you can hear the difference in the cone material, and that's a fact. The suspension recoils with a audible noise at near max power from a twin Reverb, Jensen's just distort much sooner and get mushier as you push more power to them.

JBL's sound thin, tinny and pop with bass overdrive?

I believe Dickey Betts would disagree. His tone on Live At Fillmore East is a 100 watt Marshall into four D120F's. Listen to his tone on "One Way Out" from Eat A Peach. That was recorded at the Fillmore during the same time. Nothing thin and tinny there.

Maybe the JBL's you've heard were in need of a recone. A healthy JBL should sound clean, yet have a fat midrange when pushed.

 

[strat a various]

JBL's sound thin, tinny and pop with bass overdrive?

I believe Dickey Betts would disagree. His tone on Live At Fillmore East is a 100 watt Marshall into four D120F's. Listen to his tone on "One Way Out" from Eat A Peach. That was recorded at the Fillmore during the same time. Nothing thin and tinny there.

Maybe the JBL's you've heard were in need of a recone. A healthy JBL should sound clean, yet have a fat midrange when pushed.

I've noticed players complaining of the sound of certain brands or models of speaker, and I can see that they haven't EQ'd their amp properly to achieve the tone they claim to seek. If I twist the knobs a little, and get a good sound, they will often say. "How did you do that?" Lol. I EQ'd the amp to the room, duh. Then about half of them will say, "Well, that's nice and all, but I never run my Bass knob that high, or my Treble knob that low." Then they put the EQ back to a craptacular tone and go on complaining about the speaker.

 

[Paul in Colorado]

"In the early sixties, performers using amplified musical instruments had very special ideas about the kind of sound they wanted - sound they couldn’t get from standard loudspeakers. To satisfy their unique requirements, major guitar manufacturers and musicians - from professional to beginner - turned to JBL.. The F Series provided the answer -with sound quality, efficiency and reliability only JBL could offer. That was the sixties. Today, amplifier power is much greater, listening tastes have grown increasingly sophisticated and the demands placed on musical instrument loudspeakers are more critical than ever before - precisely the reasons why JBL developed the K Series."

A direct quote from the JBL marketing material of the day.

Just because a K110,120 or 130 could be used for vocals doesn't take away from the prime motivation for their development which was for musical instruments.

The others in the musical instrument line were the K140,145 and 151 which were bass and electric organ speakers.

JBL had a last throw of the dice in the electric instrument field with the MI series which they advertised as suitable for "your guitar, keyboard or PA system"

I had two MI-12 speakers in an open back cab. They weren't a patch on the glorious K120.

(link removed)

I had a Music Man 130 with a single 15" JBL M-Series speaker. I think that they built it for pedal steel players. I sold it to a friend who played a Gretsch Country Gent. That combination sounded glorious. Sadly, he sold them both.

 

[Paul G.]

The K series were very similar to the Ds. I have read that JBL brought out the new model to bypass price controls set in place to control inflation.

 

[Ten Over]

The K series were very similar to the Ds. I have read that JBL brought out the new model to bypass price controls set in place to control inflation.

Nope.

 

[Janzach]

I'm planning on rebuilding the K120's
Thank you for all the advice it was invaluable !

 

[avspecialist]

I have 4 original JBL K 120’s. They are totally different sound from the D120’s. they come of much brighter and cleaner and a little more sterile. I got them to sound decent in a 1968 drip edge Bandmaster cabinet. I’m using a 1995 Twin amp as a head with it and they seem to match up well. Compared to my very early, possibly late 1967 Tone ring cabinet with a grey frame JBL D 140, the D140 is much warmer and harmonic sounding and slightly less efficient .

 

[oooogie]

What?

It seems to me that going off of your profile name Skydog that you are a fan of Duane Allman. Funny because he was a JBL disciple. As was Dickie for that matter.

 

[oooogie]

This is where you will find answers about JBLs.
http://audioheritage.org/

The D series speakers were a design that had a larger voice coil gap, so they would handle more power without overheating.

In fact the D120F was made slightly larger yet to diapate mare heat per fender's request. And each version that followed.

 

[elpico]

The d120f wasn't changed to handle more power than regular d120. Two changes were made to make it a little more rugged for musicians: 1. some goop was put on the surround to make it less likely to dry out and crack when baking in the sun at outdoor gigs. 2. The voice coil gap was increased a small amount. The original speaker had such close tolerances here that even with the big cast frame it was possible to make the voice coil rub by over-tightening the mounting screws. This would flex the frame ever so slightly and cause a voice coil rub. Guess they figured that was a bit finicky for ham fisted musicians and guitar techs.

The power rating for the d120f was simply the level they found you could play *guitar* through them without blowing them. They deliberately blew up a few with a beastly Macintosh amp to find out.

 

[CoolBlueGlow]

In the 90s, I blew two D130s, an EVM 12L, and a Peavey Black Widow, all cooked by solid state amps distorting ... square waves. None of the amps approached the RMS volume rating of the speakers. Square waves just generated too much heat in the voice coils.

Well, not to be a nay-sayer, but it could have been your solid state amp was simply DC'ing the speakers, and not from "square wave distortion" either.

BJT powered transistor amps of that era were famous for getting unstable when driven hard. To be specific, "unstable" in a direct coupled bipolar junction equipped transistor amp equals substantial DC current across the voice coil.

No, you would never hear or know it unless you had the amp on the bench, until the magic smoke came out of the speaker cabinet. The DC current is in the background, at the same time as your amp is trying to make the AC current you call "music".

Not promising you that was it, just saying that it is possible. The essential voice coil design, size, and venting of the speakers you mention is all far superior to typical 1", 1.25" or 1.5" non-vented style speakers. There is nothing about their design or functionality that would cause them to fail more quickly than so-called "guitar specific" speakers like Celestion, Jensen, Utah, CTS, etc.

 

[abcdefghijklmnop]

I love my 67 Twin with factory JBLs. 76 pounds of tone. They have a very unique little "chirp" at the top of the note that I have not heard another speaker do. In a Twin Reverb, the reverb detail and decay though a JBL is unbelievable.