D130F History

From hargers–(at)–irmail.net Sat Sep 7 09:17:25 CDT 1996
From: Harvey Gerst
Newsgroups: alt.guitar.amps
Subject: Re: How many watts can a JBL D-130 safely handle?
Date: Sat, 07 Sep 1996 01:41:09 -0700
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Harry Avant wrote:
>
> It’s amazing about the variation in answers you’ll get. Watts of what
> kind? RMS at 30 hertz? White noise? The question has almost no
> meaning without stating some parameters.
>
> If you look at the original spec sheet for the speakers in that series
> you’ll see that the D-130 is rated at 25 watts. Since this appears on
> the rear of the pamphlet that gives dimensions for recommended B/R
> enclosures, one should assume that it is 25 watts when mounted in the
> proper cabnet.
>
> You should find that about 20 to 30 watts into one of these in a
> proper sized enclsure will drive you out of the room. If you put it
> in an undersized and over damped box like a Benson then the speaker
> will take more power, but it will need it to get the volume.
>
> The D-130 was/is an effeceint speaker. It doesn’t need a lot of input
> to get a lot out.

On the other hand, I saw a lot of D130’s come through with fried voice
coils that were running off a 12 Watt Williamson amp during the 50’s and
60’s. Integrated music from HiFi systems caused one kind of problem –
using the D130 as a musical instrument speaker created other problems.

That’s why I suggested the D130F (which was a redesigned D130), made
expressly for musical instrument amps, as were the D110F (a totally new
design), the D120F (a redesign of the D131), and the D140F (a new design
using existing parts).

Power specifications for the F series were nominally 35 to about 60
Watts. How did I arrive at these figures? Pretty simple, I played guitar
and bass through them and kept increasing the power till they blew. Then
I downrated them from the power that fried them. Pretty hi-tech, huh? It
seemed to work pretty well (of course we didn’t have synth players back
then).

The major amp manufacturers back then were Fender, Sunn, Kustom, and
Ampeg. Rickenbacher and Mosrite also bought some, but nowhere near the
volume of the other amp makers. All had JBL speaker options.

And yes, the “F” stood for Fender, since they were the largest single
buyer, and also distributed the F series to music stores. They had no
part in the design or the idea for the new series, I am solely to blame
for that.


Harvey Gerst

Indian Trail Recording Studio
http://users.aol.com/harvgerst/records/studio.html
Indian Trail Records
http://users.aol.com/harvgerst/records/records.html

From hargers–(at)–irmail.net Wed Sep 11 15:43:48 CDT 1996
From: Harvey Gerst
Newsgroups: alt.guitar.amps
Subject: Re: How many watts can a JBL D-130 safely handle?
Date: Wed, 11 Sep 1996 13:54:45 -0700
Mime-Version: 1.0
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Teleologist wrote:
>
> Dick Dale seems to be the one claiming Fender went to JBL on behalf of him.
> In “Fender Sound Heard Around the World” he’s quoted as saying the “F was
> invented as a result of melting voice coils & destroying surrounds”. It’s
> also stated that “the aluminum dust cover was Leo’s idea”. In his 9/96 GP
> interview he talks of the ‘Dick Dale’ kit available from JBL which includes
> a larger magnet, larger voice coil, thicker wires, aluminum dust cover, &
> rubberized front rim which brings the speaker(presumably a D130) up to Dick
> Dale & Fender specs! I’ll be ‘kind’ and say that he comes off as ‘a bit
> arrogant’ in the interview!

I never had the honor of meeting or talking to Dick Dale, so I’d have to say
that perhaps his memory has been clouded by the passing years. It’s true that
the JBL F series was partly about improving the current 2 models being used by
Fender and others, namely the D130 and D131. It was my proposal to expand the
line of speakers and at the same time, make some refinements to those speakers
to make them more suitable to the guitar market. Here’s what I did and why:

Opened the voice coil gap slightly on the D130F to allow more tolerance in
mounting. Most people didn’t realize that even though 8 mounting holes were
available, only using four is the recomended mounting. And you don’t screw them
down tight to the board – that warps the frame. You use two fingers to do the
final tightening – the casket will them complete the seal. When you warp the
frame by overtightening, the voice coil can go out of round and eventually drag
and short out. I opened the gap slightly to allow for this problem with just a
very slight loss in efficiency – less than 1 dB.

Did the same thing on the D131 (and renamed as the D120F).

Using parts from the D130A and D150 woofers, I created a new woofer desinged for
bass guitar applications called the D140F. This had a copper voice coil and an
aluminum dome.

Using the magnet assembly from the D123 and the basket from an LE-10, I added
the D110F to complete the line of musical instrument speakers.

The surrounds were NOT “rubberized”. JBL had developed a high viscosity coating
to add to the existing hifi line of speakers that reduced ringing. I used it for
a different reason. The hifi speaker surrounds dried out when exposed to
excessive sunlight and heat, and I reasoned the viscose coating (we called it
“goop” back then) would help prevent that.

> The other reference to Fender going to JBL was in conjunction with the
> development of the 1959 Vibrasonic. In Morrish’s Fender amp book – Bill
> Carson recalls testing a protype JBL with a copper instead of aluminum
> voice coil & a thin paper cone? Can you shed some light on this obscure
> piece of JBL history?

Bill’s probably refering to the D130A which was simply a standard JBL woofer at
the time – all the woofers had copper voice coils. The 130A was basically a D130
with a copper voice coil and a paper dome and was used in the 001 system
primarily (D130A, N1200 xover, and 175DLH driver/horm assembly). I felt the cone
was too light for bass guitar and we wound up using the cone from the 150 woofer
– a heavier unit. The duraluminum dome was added to the D140F, instead of the
paper dome for cosmetic reasons at first, but later proved useful in adding a
little more top end to the bass (not much though).

> For the original poster – regarding power ratings, I checked my
> official(3/70) JBL spec sheet for the F models and the 110F, 120F, & 130F
> are all rated at 100W continuous, the 140F–(at)–150W continuous. JBL defines
> ‘continuous power’ in my 4311B spec sheet as 3dB greater than RMS which
> would put the RMS rating of a D130F at 50W. On the other hand, D120Fs &
> D130Fs ran reliably in Showman 12s, Showman 15s, and early Boogies at
> considerably more power, so Mr. Gerst’s & JBL’s ratings are not marketing
> hype! It also appears that the 120F & 130F use identical magnet structures
>–(at)–11 pounds, 12,000 gaus flux density, and 275,000 maxwells total flux.

The D120F and the D130F, like their close cousins, the D130 and D131, all shared
the same voice coil, dome, spider, and magnet assembies, except for the
slightly wider gap on the top plate. I think the flux density was really around
11,700 gauss or so on the 120F & 130F because of the slightly enlarged gap,
mentioned earlier.

Power handling was always a touchy subject and I just basically guessed at what
I thought it could handle, based on normal playing. It was a little tricky since
we were dealing with rock, country, jazz, and blues players and the power
handling figures were just suggestions, regardless of how official the spec
sheet looked.

We now return you to your regularly sheduled programing.


Harvey Gerst

Indian Trail Recording Studio
http://users.aol.com/harvgerst/records/studio.html
Indian Trail Records
http://users.aol.com/harvgerst/records/records.html

From hargers–(at)–irmail.net Thu Sep 12 10:30:38 CDT 1996
From: Harvey Gerst
Newsgroups: alt.guitar.amps
Subject: Re: How many watts can a JBL D-130 safely handle?
Date: Thu, 12 Sep 1996 06:54:53 -0700
Mime-Version: 1.0
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Harry Avant wrote:
>
> That is probably true but we’re mixing oranges and grapefruits here.
> Kroger’s original post asked about the power handling of a D-130. Not
> a D-130F. I’ll stick to my earlier post which listed the power rating
> well below the specs for the F series.
>
> I think Kroger did get a D-130 without any F, G , Q or what ever and
> that should make for the difference in power handling. And as we all
> know all to well the cabnet and so forth will make the “specs” moot
> anyhow.

Harry,

The D130 and the D130F were essentially the SAME speaker. Exactly the
same voice coil, cone, spider assembly, magnet, basket. The only things I
did to the F are listed in a previous post, along with my reasons for
doing them.

I revised the guitar ratings since those D130 ratings were for INTEGRATED
music, like a symphony or a full band playing from the radio, tape or a
record. The rating for a single live instrument like a guitar is much
different, since there is nothing below 80 Hz or above 5 or 6 KHz coming
out of a guitar (at least back then). A D130F (or a D130) could easily
live with a higher power rating and we/JBL/I adjusted the rating
accordingly. The new rating would also apply to a JBL D130 if used for
that purpose.

If you had called JBL back then, you would have been transfered to me and
that is what I would have told you. Since I was in charge of that
division, I was responsable for creating those ratings and that was
our/my official position on the subject. As far as power handling, there
was no difference – the rating was changed to more accurately reflect
what the D130 or D130F could handle if used with a guitar as the source.

The lower rating also still applied if either speaker was used for full
range music reproduction. For what Jim Kroger wants to do with the
speaker, my original comments and ratings still stand. These were my
“babies” and if you want to disagree with me, that’s fine. If you were at
JBL at the time I was designing these, we could have had some rousing
discussions about it. And besides, I think I also wrote those spec sheets
for the D130 as well.


Harvey Gerst

Indian Trail Recording Studio
http://users.aol.com/harvgerst/records/studio.html
Indian Trail Records
http://users.aol.com/harvgerst/records/records.html

From hargers–(at)–irmail.net Sat Sep 14 10:15:40 CDT 1996
From: Harvey Gerst
Newsgroups: alt.guitar.amps
Subject: Re: How many watts can a JBL D-130 safely handle?
Date: Sat, 14 Sep 1996 02:42:25 -0700
Mime-Version: 1.0
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Teleologist wrote:
>
> A couple more Q’s & I’ll leave you alone:) – Didn’t know the D140F has a copper
> voice coil – is it an edgewound ribbon like the aluminum coils? What were the
> reason(s) for using copper (vs. aluminum) in the D140F?

Yes, the D140F had an edgewound copper ribbon voice coil. Copper has better heat
conductivity than aluminum (think pots and pans) but it’s heavier and not as
responsive to high frequencies, due to it’s weight. For use in woofers, copper is
the wire of choice.

Actually, had I thought about it some more, I should have probably made the D140F
more of a full range speaker, but it was basically designed as a replacement for
people using D130A woofers for live music.


Harvey Gerst

Indian Trail Recording Studio
http://users.aol.com/harvgerst/records/studio.html
Indian Trail Records
http://users.aol.com/harvgerst/records/records.html

 

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