Doepfer

Hi all,
	As promised, here is my modest list of mistakes that I have spotted in
the manual. My major gripes seem to have been covered elsewhere, i.e.
A-136 knobs all wrong; A-118 noise colour knobs affecting random
output; and A-141 not gated from bus.
	
A-131:
p4, IN2 is actually more sensitive than IN1, and so may distort sooner
(my module is the re-designed version of 2001, so may not apply to
earlier ones)
	
A-145/147:
p4 of 147 manual entry it says that sawtooth frequency is the same as
that of the other waveshapes, unlike the 145 where it is double the
other waveshapes - this should be in the 145 manual entry too!!!

A-145:
all amplitudes on pages 3 & 4 are roughly double those quoted (i.e.
are about +/- 5V)

A-146:
again, p3 & 4 amplitudes: para 1, +/- 4.5V; para 2, 0-8V; para 3, +/- 4.5V

A-150:
p3 - the switching threshold is about 0.6V, and not the 3.6V stated!
(Its basically the standard 'diode drop' over the base-emitter of the
transistor concerned.)

A-163:
p1, mine will divide from 1 up to 32 (and not 'about 20' as stated).

A-190:
p19 & table p23 - retrigger: I get 0-63 ON, 64-127 OFF, i.e. opposite
to what it says.
p21 table & p23 table as default after a full system reset, I get
assign mode = LAST and not highest.
(At power on, 'gate' flashes a half flash, and a full flash, i.e.
version '1.5' I assume.) (The biggest problem I had with this module
is that my keyboard - Evolution MK149 - is sending 0-127 for program
changes, whereas the 190 actually expects 1-128, the 190 following the
MIDI spec more strictly, as far as I know - I've suggested to Doepfer
that it would be nice to put a warning about this in 
future editions!)

Tim

[The views expressed above are entirely those of the writer and do not
represent the views, policy or understanding of any other person or
official body.]

Addition:
If you use the A-140 to "pitch shift" the oscillators there will be a 
drop when the sustain level is reached. you won´t notice if you use 
the eg for other things but it is rather dominant when used with 
pitch. (The 141 doesn´t do this -Dieter says). The work-around is to 
use the slew limiter as an Eg - if you do not have the 141

Keld

Hi 

> If you use the A-140 to "pitch shift" the oscillators there will be a
> drop when the sustain level is reached. you won´t notice if you use
> the eg for other things but it is rather dominant when used with
> pitch. (The 141 doesn´t do this -Dieter says). The work-around is to
> use the slew limiter as an Eg - if you do not have the 141
Another workaround would be to insert any module between the 140 and the
VCO, that does buffering. A simpe Buffer module might solve this.

Florian
-- 
Florian Anwander                  |ConSol*  HP-Support
Tel.   +49.89.45841-133           |Consulting&Solutions Software GmbH
Fax    +49.89.45841-139           |Franziskanerstr. 38, D-81669 München
email: florian.anwander@consol.de |http://www.consol.de

> Another workaround would be to insert any module between the 140 and the
> VCO, that does buffering. A simpe Buffer module might solve this.

Unfortunately there is no workaround solution by using another module
to buffer the ADSR output - I tried (in turn) through a 138, 175 (i.e.
invert twice), and a 129/3, and the problem is clearly still there. It
is caused by the transistor (Q5) which is used to 'switch' between the
decay and sustain phases: basically it doesn't switch off completely,
allowing a very small current to pass through, thus causing the
sustain level to drift downwards over time (I measured about a 0.2V
drop in about 35 secs). If you want a stable sustain level over time,
you cannot do it with an A-140!

Tim

[The views expressed above are entirely those of the writer and do not
represent the views, policy or understanding of any other person or
official body.]

I have had a look back through some of Joe's posts on the A-136
(#307), and can add a little more detail: in order to prevent *any*
hard clipping, the input signal needs to be less than about +/- 2V.
The level knobs 'L+' and 'L-' don't quite tie in with what is
suggested by the manual fig 1 p3: to get the highest (positive)
clipping level you need to set L+ at 0 (fully counter-clockwise), and
lowest (negative) clipping level is with L- at 10 (fully clockwise).
Thus as you increase L+ and decrease L-, more and more 'clipping'
takes place (according to how A+ and A- set!), as you progressively
'squeeze' the signal between the two 
values of L+ and L-.

Tim

[The views expressed above are entirely those of the writer and do not
represent the views, policy or understanding of any other person or
official body.]

Hi Tim

> It
> is caused by the transistor (Q5) which is used to 'switch' between the
> decay and sustain phases: basically it doesn't switch off completely,
> allowing a very small current to pass through, thus causing the
> sustain level to drift downwards over time (I measured about a 0.2V
> drop in about 35 secs). 
Ok, now I remember; this is known from many similar circuits.


> If you want a stable sustain level over time,
> you cannot do it with an A-140!
Assumingly true.


Florian
-- 
Florian Anwander                  |ConSol*  HP-Support
Tel.   +49.89.45841-133           |Consulting&Solutions Software GmbH
Fax    +49.89.45841-139           |Franziskanerstr. 38, D-81669 München
email: florian.anwander@consol.de |http://www.consol.de