Sonic Six Filter Change...

[noddyspuncture]

Hi, I am buying a Sonic Six.

I downloaded a service manual and it states that it is for serial numbers 1300 and above.
A 'Sound On Sound' article states that the Diode filter was dropped and the Moog Transistor Ladder filter was used from serial number 1264.

This seems odd to me. There is a discrepancy here..!?
Does anyone know exactly which serial number was the filter cross-over point please?

Cheers,
Tom

[CZ Rider]

According to the Norlin issued Sonic V/VI service manual, serials of 1264 and below used the original filter design with the diode ladder. And the schematics with the revised Moog style transistor ladder were serial 1265 and above.
I have never seen the Sonic V/VI service manual online?


Or the schematic to the original diode ladder filter online? That would make a cool clone project.


There are a few ways to spot an early version. The early ones had only two rockers on the left where the power and speaker switches are. The later ones had three switches. And the logo on the top right reads "Sonic Six" on the early ones, while later ones read "Sonic Six Synthesizer".

Early model with two switches:


Later model with three switches:

[noddyspuncture]

Thanks Terry,

So the one I'm getting looks like the later one - but I am still confused...

Looking here, on Kevin's site: http://www.synthfool.com/docs/Moog/Moog ... Manual.pdf
... on page 2 it states: for serial numbers 1300 and above.

I assume the early ones with the diode filter - serial numbers below 1264, had a different service manual.

So then what happens between 1264 & 1300 service manual-wise...?
Is there a 3rd manual for those...?

Cheers,
Tom

[CZ Rider]

In the Modifications section of the manual you downloaded, page 48. (Next to last page) The manual describes the differences and changes to be made.
The changes listed are the external input resistors to change the serial 1265 to 1300 units to respond to 1 volt per octave. Indicating the 1265 to 1300 units were set up to 5 volt per octave sensitivity. So the filters and oscillators were the same but input resistor different. Easy upgrade for both the oscillators and filter CV inputs. The other upgrade was a diode across a cap to avoid the power supply from not powering up. And a pitch bend ammount change. So even though the manual reads 1300 and above, in the back of the manual addresses those 1265 to 1300 units.
That 1973 manual is incomplete because it does not cover the Sonic V or early Sonic VI up to 1264 with the diode filter. It does cover the serial 1265 on up and lists the upgrade needed for those 36 units with serials between 1265 and 1300. I have seen Sonic VI's that were made after that manual print date, so again it may be incomplete with the latest upgrades or revisions.
The 1978 Norlin manual covers all the models made and has seperate schematics for both revisions.

[noddyspuncture]

Thanks Terry,
I missed all that.
I need to pay more attention...

[trionide]

Hi, I don't know if this old discussion is still active...
I have a Sonic Six; its serial is 1263, very close to the 1265 border!
I made the resistors modifications in order to make it respond to 1 volt per octave. So I believe mine is like the ones between 1265 and 1300 because now it works perfectly driven by 1 v/oct sequencers.

My doubt is: what are the differences between the 1-1264 and the 1265-1300 units?

I cannot find the Sonic V/VI manual by Norlin; does anyone have it? I'm willing to buy also a copy of it.

Thank everyone in advance