Sphere/Api 10 channel Sidecar .. New 900 EQs... New AUX Penthouse

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Here some fresh pic for now... ;)
Will do the update later

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PSUs in a roll-around.

GARY
 
Wow.... soooo impressive... this is a project beyond my wildest dreams... maybe someday.  You've created something beautiful.
 
A comparison between the original 900 and my 900-500 series will be coming in a future post.
Meanwhile here is a paper I wrote comparing Sphere Discrete op-amp EQs...


A BRIEF PRIMER ON SPHERE GRAPHIC EQ’s

There are three models that use discreet op-amps, the 900, 910 & 920. All are basically the same except
for extra features/options. All three sound the same and use the same inductor/capacitors values.

All three are swinging LCR topography with a separate non-tapped inductors on each band. The inductors
are all non-standard NOT off the shelf values. All three EQ models have two different independent
UN-balanced DOA sections that are pinned out separately.

The first section is the Swinging EQ DOA and the other section is called a BST or a “booster amp” DOA.
This section in a Sphere desk is actually the post fader amp with a fixed gain of 15db allowing the channel fader
to have 15db of boost. Note that the channel will not pass signal with the EQ module removed.

In common, all three models have nine bell octave bands. 50Hz, 100Hz, 200Hz, 400Hz, 800Hz 1.6kHz, 3.2kHz,
6.4kHz and 12.8kHz. The 6.4kHz band on all three models is switch-able between 6.4kHz, 5kHz and 8kHz.

The 900 is the most basic of the three. It has an 18 pin single sided card-edge connector that is often
referred to as the “long connector”. All the extra pins are for optional Mic/Line and Mute relays. In most 900s,
these options are not stuffed on the pcb. No Hi-Pass, shelf or phase/polarity switching are included.
The 900 front panel dimensions are 1.5” x 6.5”

The 910 and 920 are both built on the same pcb. The card-edge connector is 2-sided 10-pin and referred
to as the “short connector”. The 920 has a passive switch-able 5 frequency 2 pole Hi-Pass Filter that use
a non-tapped inductor and a multi-tapped inductor. Hi-Pass Freqs are 50Hz, 70Hz, 120Hz, 160Hz and 240Hz.
On the 910, this section is not stuffed and may or may not have shelf switches.

Besides The 5k and 8k switches, shelf switches a phase/polarity reverse switch is also included.
This switches the phase on the input of the BST DOA section. Sphere desks don’t have phase reverse switches
on the mic-pre card so its included on the BST section of the EQ module.
The 910/920 front panel dimensions are 1.5” x 7”

Because of the card-edge and front panel length differences, the 900 and the 910/920 are NOT mechanically interchangeable.

DOAs: The SPA-60 and SPA-62 are basically the same animal just a few R-values and a slight difference in
the Diode Biasing arrangement. (Of coarse the stand-alone SPA-62 has the series rail 313 bulbs.)
The 900’s DOAs resemble the SPA-60 and the 910/920 resembles the SPA-62 (no bulbs). In all cases,
these are not plug-in “SPA” DOAs but are part of the pcb.

The LCR swinging topology of Sphere EQs are almost identical to the API-553 EQ. Besides 9 vs. 3 Freq.Bands,
the Boost/Cut control on the API is a linear taper pot. The Sphere uses a 12-position Digitran lever switch for
each band connected to a fixed resistor ladder. Besides flat, (0db) the Digitran switches Boost +2db,+4db, +6db, +9db
and +12db and Cut -2db, -4db, -6db, -9db,-12db and -15db.
 
AUX PENTHOUSE ADDED.

When it comers to Aux sends on the eclipse A or B, it's very limited.
1 Stereo Echo send and a Cue send that can either be mono, dual mono
or stereo depending on how the MM102/22193 pcb is stuffed.

A good friend of mine that owns a beautiful 32 X 16 Eclipse A wanted
me to design a way to add 4 mono and 1 Stereo Aux sends to his desk.

Time to hit design desk. What better way to R & D this by adding these to my
little 10 x 8 desk using all Sphere circuits.

More about my build coming soon. Meanwhile here are a few pics.
Note these are not 500 series buckets. Front panels are 4.75".

Gary
 

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