02 April 2016

hot rodding Klipsch speakers

Here's a story of how to build a shop system
on the cheap.
Late last year I'd seen this ad for these PA speakers.
They are basically a Klipsch Cornwall,
in a smaller commercial cabinet,
called KP-301's.
Big 15" woofer and mid + tweeter horns.
Seemed like a steal!
The Cornwalls in our house rock out,
I'd only imagine what they'd sound like with some space.
The seller found out that they weren't complete,
so not in the great working condition he stated.
During his move,
he'd search for the missing components,
and get back to me.
Oh man what a tease!
Klipsch KP-301
My patience was tested.
I'd text every week or two to remind him.
Borderline hounding...
Over 2 months later we sealed the deal,
at an almost giveaway price,
lowered because one of the crossovers was MIA.
The excitement of the hunt was over.
The speakers sat...
got kicked around...
while a plan was formed.
Klipsch Type KP-3.0B Crossover
Here's the Klipsch kp-301 crossover - the type kp-3.0b.
An intricate dividing network,
made more confusing 
cause of the bi-amp plug system.
I remembered in our house speakers,
the similar Klipsch Cornwalls,
the crossover was much more simple.
Klipsch Type B Crossover schematic
How easy could that be in comparison?
I could build that no problem!
Well the parts all separate get pricey,
there had to be an easier way.
Klipsch Type E Crossover Schematic
After researching,
I realized it was possible 
to modify a Klipsch Heresy crossover.
The type E handles a 12" woofer,
the type B handles a 15" woofer,
along with different horn cutoff points.
It was worth experimenting.
Transforming Klipsch Type E to Type B (before phase change)
People love upgrading or parting out Klipsch speakers,
and a pair were sourced on eBay for cheap.
The changes were simple,
swapping a 2uf cap for a 4uf,
and moving wires on the autotransformer.
The cheapy Dayton poly caps are way smaller 
than the metal Aerovox oil filled caps,
but should work the same.
The basic crossover concept is easy.
The box on the left filters out highs to the woofer,
the silver can cap filters out lows for the tweeter,
the black cap filters out lows for the midrange,
and the autoformer on the right
levels the output to even things out.
Modified Type B Klipsch Cornwall Balancing Network - Crossover
At the last minute,
I remembered the type E had a phase shift,
and the +\- are swapped on the high and mid horns.
A rough plate covered the old plug hole,
and the crossovers screwed and wired in.
Please work!
Hey these are hot rodded shop speakers!
Form over function here...
Modified Klipsch KP-301 to Cornwall 
Thankfully the gamble paid off.
These sounded great for a $200 investment!
At lower volumes they had a big full sound,
however at louder volumes they could get a little honky,
the pitfalls of a horn system.
JBL made those angles shields to compensate.
I tried the ghetto trick,
and stuffed insulation into the slots.
Way better!
I've since cleared out the small tweeter.
Along with the VMPS speakers,
we've got an impressively loud shop system.


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