PLAN B analog blog

Eric,

Hey - nice words, all.  Thanks, I appreciate it and very glad to see it's a
hit with you.  Couple of things:

1) You should be able to get more than four octaves - and although I use a
20 turn pot for the 1 volt/ oct trimmer, it still falls victim to Fedex
gorilla handling at times. But there's an easy solution and a very easy
adjustment you can make to fix this up - you should be seeing 7 if not 8
octaves out of them.  Go here:

http://www.buzzclick-music.com/track_adjust.jpg

My tracking is unlike some in that it's an attenuator - adjustments made to
the top end have very little effect on the bottom end.  Some, but not a lot
and it becomes intuitive quickly.  It's not like some tracking pots which
effect the low freq end as much as the top.

2) Regarding the sync.  Yeah, I struggled with this for some time on just
how sensitive to make this input.  Right now it's somewhere between what
many consider to be hard and soft sync.  Eric, if you want, you can add one
resistor to each VCO which will double it's intensity.  It's also an easy
one.  Get me off line and I'll give you the procedure.  Possibly a solution
is asking each how sensitive they would like this to be before I ship them
and then fitting the input with that average value on a  permanent basis on
future builds. 

Anyway, thanks for the kinds words.  I'm really glad you dig it and that you
'got' the thrust behind it's conventions.

- P






alt-mode wrote:

> Folks,
> 
> I received my two Plan B Model 15 VCOs today!  The unit I received for AHNE
> 2005 had some problems and had to go back to Peter but these two units work
> great and track very nicely!
> 
> I haven't spent a great deal of time with the VCOs so this set of
> observations is based on my first hour or so with the VCOs.
> 
> First, these are *very* full featured VCOs.  Variable wave shapes, PWM,
> sync, multiple waveform outputs, sine output, you get the idea.  They
> plugged into my Doepfer case just fine although Peter uses a power cable
> orientation that is opposite the Doepfer standard.  -12V is up on top
> instead of the bottom so you must be careful to plug the power in correctly!
> 
> The VCOs sound very good.  I was quickly able to get standard waveforms and
> track over the 4 octaves of my CV keyboard with no problems.  The tracking
> matched my existing Doepfer and ASys oscillators.
> 
> The fun begins with the FM inputs.  These seem to be more powerful and
> musical than other VCOs.  Putting a fast EG into the FM input gets the
> characteristic 'thunk' that Peter likes as well as lots of interesting, yet
> controllable, FM effects.
> 
> The waveshape morphing is very cool and voltage controllable.  There were
> some nice timbres I got just using this without much filtering.  The PWM is
> also quite good sounding.
> 
> My only disappointment so far has been with the sync input.  This just may
> require some more fiddling but I wasn't able to get that classic sync sweep
> sound.  I got some interesting sounds but not quite what I expected.  Again,
> this just may be my lack of time fiddling with it.
> 
> So, Plan B Model 15 VCOs are real, they sound great, and it sounds like
> Peter is getting past his shipping hurdles.
> 
> Eric
> 
>

Eric, 

I would be interested to hear your take on the M15's timbral similarities to
the Buchla 258 and Easel VCOs (excluding the wavefolding features on the
Easel, which the Plan B does not do).

Also, not sure what you mean about the power being opposite orientation.  Do
you mean in relation to the Doepfer PSU power buss - that a twist of the
cable is required?  Here's the correct method if anyone has questions about
this:

http://www.buzzclick-music.com/Mdl15_power_connection.jpg

- P

Peter,

I didn't mean to imply that the tracking was limited to 4 octaves!  That was
all I had available on my controller at the time.  I haven't had a chance to
test further.  I'm sure the range is much greater.

OK, now I understand where the sync is going.  It is OK for it to be
different, it just wasn't what I was expecting.  Actually, having something
that sounds a bit different is a nice change.  I have hard sync from the
Doepfer and ASys oscillators in my system.

Regarding the power connection, Doepfer has a convention that -12V is always
the lowest set of pins on the connector when you look at a module.  The "red
line" of the power cable is always oriented down.  The Plan B has the -12V
as the highest set of pins on the connector so the "red line" is on top but
the cable needs to be twisted to put the "red line" down when it connects to
the bus board.  Not a problem, just different.

I'll try to do some comparisons with the Buchla Music Easel VCOs.  I
actually have a bunch of Easel samples recorded that I need to put up for
folks to get a better idea of what it sounds like.

    Eric

Gents,

Please refer to the following diagram when connecting power to your Model
15: 

http://www.buzzclick-music.com/Mdl15_power_connection.jpg

It is absolutely essential that the red band on the cable connect to the -12
volt end of the M15 and the Doepfer or A. Sys RS10/15  power buss.  Do not
go by the orientation of the 'escape route' of the cable coming from the
connector as shown on the diagram (meaning the cable may exit the cable
connector from the other side) - GO BY THE ORIENTATION OF THE RED BAND ON
THE CABLE.

If power is connected backwards on the new Analogue Systems RS-10 or RS-15
rack all you will do is blow a fuse.  If connected backwards on a  Doepfer
power rails, there has been one instance where the M15 required repair
(there have been two other instances reported to me though where the Doepfer
fuse blew too and no damage occurred).

However, you can avoid all of this by following the simple directions on the
diagram in the link above.

- P