As partners we are not conservators, but we have been around the block a few times.
A craze began about 1960 in consumer sound systems
to find economical sound.
Today consumers prefer vintage
than settle for less passionately made afterthoughts.
It's not just that the previous age of creation ended in a
flurry of failure & returns,
but it did so while jobs shifted from United States electronics wholesalers to Chinese
supplied big box retail outlets: no-return, no credit retailing.
Few seemed to notice the
previous age of affordable VERY high quality as well as audio durables was
other direction. Perhaps they equated post-war Japanese
manufactured goods quality
with the same outcomes and low costs availed by labor and mineral wealth of China.
De-Evolution is reversing this
as expectations rebound from inflated low price appeal.
Some Audio Background Information
Years ago when all amplifiers were high voltage tube driven, you didn't need to have a rating.
That's because voltage was controlled and steady by transformers, and current changed both
during the change of signal that makes the sound as well as any change in volume control or levels.
Transformer coupling or pickups of guitar or phono needles came
to be know as 'high impedance'.
This could be 10K to 30K for
dynamic magnet centered microphone diaphragms but is largely
irrelevant for other devices except for the fact that adding more resitance MAY increase efficiency.
Stability/response at low ohms became an issue when non-transformer driven circuits appeared.
Thus the formula: Amplifier Watts x ( Rated at Ohms / Speaker Chain Ohms) must be defined
so that the question- how many watts a speaker handles can be answered. Old watt ≠ NEW watt
A 6L6 push pull might use 450 volts and max out at 100ma for 45 watts at wire output terminals.
Today's 1000 watt/channel into best sounding 4ohm 'minimal' resistance assumes these standards:
8 ohm standard and that being aluminum voice coil (the older standard being 8 ohms)
which requires 1.6X amperage to drive it to the same deciBels as copper alloy material voice coil.
Thus 500/8 = 62.5 and 62.5/1.6 is approximately the same as an older 40 watt RMS output rating.
To let out a little trade secret, most copper coils are only 92 percent copper at the very most.
Pure #23 wire averages 0.6 ohms and destabilize the amplifier control, especially with
4 ohm speakers. The better the amplifier design, the lower ohms it tolerates and still sounds good.
Here at djumble, we plan introduce speakers that have any desired type of coil and gap.
We make available all thicknesses of formers in Kapton, Fiberglass and Polysulfone as well.
A kind of parallel to the genius of the Mayan pre-classic buildings happend when JBL in the late
classic period used 30-60 feet 100% copper coil in E series 8/16 ohm drivers. Massive IR design
thinking moved in other ways in the post-classic designs to get more reliable full range operation.
Ductile oxygen free copper / OFHC trades strength to brittleness versus oxygen added ETP.
Specs: E-120-8 X/O 6000hz 0.4mH 103dB 150W 3.05" Xmax. Most 12 inch JBL had 4in V.C.
Specs: E-140 X/O 2500hz 1.1mH 100dB 99% pure Copper 15 inch speaker.
Specs: E-145 1.5mH 98dB Copper 15 inch speaker for organs. (130 4" 400W, 140 bass 300W)
2003: E Series changes to Kapton former Aluminum wire. E-120-8 now 300W 1.5" Xmax.
It seems possible that the sensitivity was reduced but advertising was unchanged.
The older E-120 (no -8 or -16) with half the power handling and 1/2" more xmax was retired.
Above - A Waldom built E-120 coil 30 gage (.010") pure copper round wire 0.300 winding length.
Note it had a paper dust cap and aluminum former, both have tone effects. Overhung .025"
Some reconers do this much differently today. Integrity is an ever-present challenge.
A 103-dB 1W-@1M bobbin stretched wire by expansion. It bulged when cool and rubbed.
Franchise design goal: Pure 'C' or 'BC' Beryllium Copper proprietary wound.
The pre-classic period our franchise defines as the designs made when magnetic coupling of guitar
pickups and phonograph transformers dominated with pseudo-infinite impedances.
We feel bad today whenever we read online attempts to properly cover this subject.
The science models suggest that it takes one piece of good hardware. It's not that simple really.
To simplify, think of 'Classic Period' as when amplifier classes ('A', 'A/B', 'D') got media attention.
Selling to car audio and music playback, ceiling and wall markets.
If you're considering speaker franchises, then you are engineering savy enough
to know that the lowest sensitivity (86 to 90 dB at 1 watt measured at 1 meter) are also
the highest Sound Pressure Level (SPL) rated speakers, about 160 dB.
If large amounts of power, volts or amperes, tries to drive a sensitive PA speaker up to
very high sound volumes, it responds with 8 times the travel; it just does not work out.
The forces on edges of edgewound wire can be enough to cause sparks.
The forces make risk a factor. Larger gaps reduce risk and allow 160dB temporarily only.
For music playback, long uncompressed bass is not very common. Therefore technology
that is less efficient, less logical, has found a place. Like underhung voice coils.
Because JBL's thickest gap plate is 3/8 inch in their more focused full range designs,
the coil winding limits linear excursion at just over xMax=.25".
It would be one thing to talk linearlity, but mechanical travel is equally limited.
Adding more watts input gives zero incremental undistorted output, yet higher pressure.
Customers don't buy 500 watt rated light bulbs that produce 100 watts output either.
I can claim a boat with a 500 horse motor limited at 50 horsepower just as honestly.
Cars with 500 horse motors limited at 65 MPH can claim zero to 65 MPH in 5 seconds.
Acceleration and claims of linearity are similar departures from useful responses.
The incremental pulse comes at a high thermal cost as gaps in car 'woofers'
are 3.75 times the usual full range speaker gaps to allow large wire with heavy adhesives.
So continuous SPL is not what the ratings refer to even though SPL IEEE standard
four foot distances make it possible to claim with small underhung windings
or converesly, with large gaps and heavy large coils drawing power inefficiently.
We need to note here that edge wound voice coils in large power woofer gaps have no justification.
The reason is that the advantages of extra glue surface area but more importantly the
focusing effects of the small tips of edge windings working thinner focusing top plates
does not work on large currents with much less skin effect and proximity effects to drive electrons to the edges.
The K series advertised that edge winding put 'more wire' in the focus zone giving additional drive force.
In theory, a top plate could be machined to look like edgewound ribbon wire.
Such an underhung voice coild could then be as efficient as large windings.
JBL did make a 2220 15 inch in an underhung design, but the move toward
inline dual voice coils to compensate for less risky gaps has no scientific justification.
We don' handle those, but we can approximate special underhung car speakers.
Now Let's talk about the engineered life of speaker coils. The main wire physical property
is inductive reactance or IR. Without IR, coils would draw so much current in coulombs
of electron flow that it would glow like a light and burn up, perhaps slowly, but surely.
IR is more usefull than 'Watts' when talking high impedance, 'voltage drive' tube amplifiers.
We sell service as opposed to parts. We're not avoiding parts but considering application needs.
The IR effect produces counterbalancing magnetic fields to stop and slow the flow.
That impedance or braking action is proportional to the magnetic field exiting the wire.
But the greater percent of the field that has to flow at a high angularity to the surface
out of the wire, the greater damage caused to the wire's main conduting membrane too.
Coils are in the process of being worn out, while paper cones sluff off microfibers.
It is the exit area effect that edgewound voice coils are engineered to minimize
the concentrated force cross section, thus preserving the insulation sidewall
integrity while simultaneously focusing the process of magnetic field motor dynamics.
A specialized services chain like our franchises, while a big investment, can also
provide to new users a more expensive but vastly improved market entry point.
Car 'woofers' are large gap short coil windings underhung with small magnets.
While sensitivity has been low, the users of off shore made speakers had to endure
frequent failures & replacement or rebuilding kit expenses.
Speakers with thin wires
which work in tube amplifer instrument amplifiers do not
tolerate high current.
This created a market to refurbish JBL speakers.. (djumble
sets sold on eBay.).
For the past 5 years djumble has
been supplying kits for speakers on the internet.
Our expertise lead to international markets
that need our services: djumble.COM
Simple low component count assemblies handle 1200 real watts. We don't have to lie.
Established reputation of refab on established industry leading speaker product line.
Tens of millions of existing speakers in need of our product..