Their very, very first units were self-oscillators, in reality there was no
PWM chips yet made or were cost prohibitive. Can't remember when the
decision was made to go regulated with a controller. You are right though,
the really small amps (below 100 Watts) were "loosely regulated" (hate the
phrasology). Mostly due to PCB real estate for the secondary storage
device (large Inductor). PPI even produced a unit called internally as the
"Peanut". Might have been 10-12 Watts/ channel whose heatsink was only
about 3-4" long. But very early on, there was a push internally for for
PWM P/S as there was the issue of excessive heat caused by high idle
currents on the larger amplifiers when using fixed duty cycle Pulse width
power supplies. There was also the issue of the protection afforded a
regulated design.

In general, I try not to use the term "loosely regulated" when describing a
power supply as there can be loosely regulated PWM supplies and there can
be tightly regulated fixed duty cycle power supplies. A better way is to
always describe the topology. PWM Fixed frequency forward converter,
Flyback converter, etc. PPI PWM power supplies are mostly of the Fixed
frequency forward converter type. The PPI2350 is the exception as it is a
PWM full H-bridge converter. This spreads the "electrical stress" on the
MOSFET devices but also can fail spectacularly when cross conduction
occurs.

JA


John Durbin wrote:

Thanks! I have met a few of the characters that were part of that
hsitory, and had heard some pieces of those details over the years, but
not in a cohesive way. Only thing I saw there that I am still curious
about is the full PWM going that far back with PPI - seems to me they
made loosely regulated amps early on, and on other occasions throughout
the history of the brand. For example, when I was an Orion dealer back
in 87/88, we also dabbled in PPI amps and processors, around the period
when they had models like the 2075, and I seem to recall an asymmetric 4
channel model called the 4030 or something like that. I don't recall
those pieces having the extra transformer you'd expect from a fully
regulated design. In the PCX family, only the larger models are fully
regulated - the smaller ones are loosely regulated, i.e. "adaptive PWM
power supply" as Marketing calls it :-)

JD

John Andreen wrote:

John Durbin wrote:



I never said ay of those guys were engineers, but they damn sure know
they don't have to hide from dealers that want to return entire
shipments of defective amplifiers any more ... I think perhaps you are
extrapolating a little further than my remarks actually warranted. You
clearly know the inside story from the pre-ADST days far better than I
do, but if you go back and read what I wrote it was clearly referencing
the conditions at ADST when we acquired them.

As to the heat sink commonality, you tell me: did one of the companies
produce for the other or not? Did one of the two steal an extrusion
design from the other? The two examples Captain Howdy was harping about
were clearly not what he claimed. Feel free to provide more specifics if
you ware arguing in his favor on that point.

JD




Mr Durbin,

I have gone back as far as I can remember and things kind of go like this.
A company called OHM TECH used to do contract board manufacturing for
Rockford Fosgate. After a period of time, these individuals at OHM TECH
saw an opportunity to make money by building their own product. This
handful of people started ORION. Time went by and several of the original
people had a falling out. They left and started Precision Power Inc. The
biggest differences were over topologies. Orion preferred fixed duty
cycle
quasi-regulated power supplies. PPI preferred fully regulated PWM
regulation schemes, hence the name Precision Power. At this juncture, I
am
pretty sure that only a handful of companies were using PWM. There was a
gigantic rift between ORION and PPI that only ended when PPI and ORION
were
both under ADST roof. A little known factoid is that all ORION amplifiers
made up until the "Spock's Coffin" line had vestigial elements left over
in the Power supply section that are of little or no use in a MOSFET power
supply. In fact, these elements often have a substantial deleterious
effect on the amplifier. In short they can blow up just "because".

PPI was not without its share of internal strife either. An inside power
play between the 2 top shareholders resulted in a split that created
EXTANT
amplifiers. EXTANT even used PPI's first building as their base of
operations. This was largely due in fact to Mr Scoon still owning the
building.

PPI produced amplifiers for Crutchfield, Jensen, Sansui, MTX and your
speaker guy's (Doctor Dave) ex-employer. Not once did they produce
products for ORION. Nor did they ever conspire with them and use their
heatsinks. PPI extrusions have always been "their own" and the extrusion
dies were always purchased outright.

Does this help?

John Andreen