THE API 550 STORY
Paul Wolff
(AD) The first 550 series had 3 bands, with the top and bottom having
3 frequencies and shelf/peak. The middle band had 5 frequencies. The
filter design is a T type passive filter, with buffers and 2520 op-amps
(unity gain). The filters were either switched in the feedback path
(BOOST) or in series (CUT). They were basic, proportional Q designs,
not by desire, but by necessity to keep the frequencies centered while
the boost/cut switched changed the loading of the filter. Each filter
of the 550 was isolated and LO-Z buffered by a 2 transistor 0-gain
circuit. The in/out switch lifted all of the filters off ground. When
out, they still had about a 1/2 dB difference at full boost or cut! The
filter was and still is a 15KHz/50Hz hi/lo pass filter that was
passive. It was also grouped together with the others. In those days,
it was called a "broadcast filter" because of the bandwidth of FM. The
lamp was powered external by 24 volts on pins that were later not used
(until I came along). I was unbalanced in. By the way, all the eqs
required recapping as they would lose low end when the filter switch was
switched in. The panels were 5.25" tall and exactly 1.25" wide, then
they were painted. That's why they don't fit in racks sometimes. They
later trimmed off to 1.235" wide. They had long silver frequency knobs
with blue inserts and without pointers.
Then the 550A came along. It added 2 additional frequencies to the top
and bottom bands, one higher and one lower. The filter changed cap
values, and each filter had its own switch contact, which isolated them
when out. (no more 1/2 dB). They also went to a 3 transistor buffer.
This was better for offset. They early ones were unstable, so they had
to add 1Meg resistors around the 2520s and small caps (39pf-47pf). They
also replaced the lamp with an internal powered LED. The input was
still unbalanced. This EQ was the main EQ for API, with several minor
changes to improve stability. The caps varied from year to year and
depended on how good they were doing at the time...They also went to
blue small pointer knobs for the frequency knob with silver inserts.
That blue color is now illegal, as it is a polluter for anodizing
companies. That's why ours are darker.
Right before API went bust, they decided to come out with a cheaper
design of the 550A, to reduce costs. At the time, they did not realize
that the EQs were proportional Q, which was one very big reason we all
liked them, but didn't know it yet. They came out with the new 550A and
sold a few thousand, then went out of business. Just about the time
Datatronix took them over, everybody said at the same time "WHAT THE
HELL ARE THESE?" Datatronix also started making them, without realizing
that they sounded different. They got most of the blame, though. When
I worked there, I took a look at the 550A and the 550A-1 to find the
difference. Also at the same time, Sunset Sound in Hollywood was
building the first Sunset console totally designed in house. The had 3
Bushnell/Demiddio consoles and just about created the LA sound. The
consoles used 550As and 300 series cards. ( I ended up with the Studio
One console for my studio, then it went to Tom Silverman, then to
Micheal Block in PA, where it is now, with Shelly at the helm). Sunset
paid Datatronix to re-manufacture the 550A, exactly the same, but with
headers on the switches for repairing. They paid for the design, and in
return they got a limited exclusive agreement to sell them, seeing as
the got hosed with 250 of the 550A-1s which now were "exposed".
Datatronix had no choice but to keep selling the dash ones. I finally
discovered that the 550A-1 was a constant Q filter, and actually amount
to nothing more than a 3 band 560 circuit. Once that was out, the
gossup started flying. Do they have 2 op amps or 1. Bla Bla Bla.....
After the exclusive agreement expired, Datatronix started selling both
(Duh?) the A and the A-1. S T U P I D. When they ran it into the
ground, I picked it up and the first thing I did was to take the 550A-1
and shit canned it and started making the originals again.
I later introduced the 5502 dual four band version of the 550A, but with
77 frequencies on each band and an additional mid band. I didn't start
out with a 4 band 550A because of all the bad pres from the last
change. Everyone wanted another band, but didn't want me to change
anything! I introduced the 5502 and made them until I got the
confidence of everyone, then after being asked by O-Henry studios to
make them the first 70 units of what is now the 550B, we introduced the
B and dropped the 5502 (now a classic, less than 200 made). We have
never discontinued the 550A, but since we introduced the B, we have only
sold 7 550As and thousands of Bs. Many say that they don't sound the
same. Well 99% of them can't hear the difference, and are only
repeating what they hear. There is a slight difference, which we
attribute to newer parts and different ways steel is made, etc. Most of
the crap about it is because of the used equipment brokers wanting to
keep making money on the old ones and keep the "buy do they suck" rumors
flying. Take any of them in a blind test and let them pick out the A or
B. In fact, hook their balls up to 10,000 volts and then see if they
feel lucky today......(please let me hook them up---oh please...) The
Bs still sound better than most EQs around.
So there you have it, more shit from Paul about the LUV goo around API.
Like I said before, they give me shit about the difference between the A
and the B, then say "well, I'll probably buy an SSL..." Save it.
God, I love this business....
Next story, the 512 mic pre and Lunchbox...
SteveHigdn
API rocks.... Long Live API!
Steve Higdon
Rick Novak
Paul Wolff wrote:
> the first thing I did was to take the 550A-1 and shit canned it and
> started making the originals again.
Our hero!
> Right before API went bust, they decided to come out with a cheaper
> design of the 550A, to reduce costs. At the time, they did not realize
> that the EQs were proportional Q, which was one very big reason we all
> liked them, but didn't know it yet. They came out with the new 550A and
> sold a few thousand, then went out of business.
So there are a few thousand A-1's out there in 550A clothing? Yeow! Could
you tell us the serial numbers so we can watch out for those?
> I later introduced the 5502 dual four band version of the 550A, but with
> 77 frequencies on each band and an additional mid band.
These weren't the stereo EQs were they? I met someone who had a mastering
box containing what he described as 4 pairs of stereo 550's. Actually it
was 8 EQs, but with 4 sets of knobs. Each set mechanically controlled a
pair of EQs. It had a total of 16 x 2520's. Was this thing manufactured
by API or did someone post-API assemble it?
I could have bought it for the price of 4 x 550's and occasionally kick
myself for having passed on it.
Thanks as always for your expertise,
Ciao, Rick Novak.
Paul Wolff
> Our hero!
Mine too...
>
> So there are a few thousand A-1's out there in 550A clothing? Yeow! Could
> you tell us the serial numbers so we can watch out for those?
Look at the connector, inside and see if there are any ICs. It also has only
one 2520, in the same clothes...
Made by someone else, or an API one off. Good deal....
Lloyd206
That was a fantastic story about the API EQs. Thanks so much. Can't wait for
the next installment on the lunchbox etc. Did I miss any? Oh please, oh please
would ya send them to me? Much better than the book I'm reading.
Yours,
R.L,nyc.
Rick Novak
If you missed the 560 installment check DejaNews. It was a goodie, too. R.N.