Doepfer

In a message dated 4/24/2006 2:21:26 AM Pacific Standard Time,  
hardware@doepfer.de writes:



you are right. It's the same matter. The rectangle output of  the A-111 is AC
coupled (capacitor between the rectangle output of the  CEM3340 and the
socket). This leads to problems with npn transistor input  stages like the
A-117 or the A-113 clock input. There is a simple solution:  the capacitor
C10 has to be shorted e.g. with a short wire or a solder  blob. C10 is
located on the small adapter board that holds the 4 output  sockets near the
10 pin connector. We think about replacing the AC coupling  capacitors of the
A-111 by wires but have to check first if this may cause  problems in other
applications.

Best wishes
Dieter  Doepfer





thanks for the confirmation about the problem !
best,
dave
 
 


[Non-text portions of this message have been removed]

--- In Doepfer_a100@yahoogroups.com, davevosh@... wrote:
>
>  
> In a message dated 4/24/2006 2:21:26 AM Pacific Standard Time,  
> hardware@... writes:
> 
> 
> 
> you are right. It's the same matter. The rectangle output of  the
A-111 is AC
> coupled (capacitor between the rectangle output of the  CEM3340 and the
> socket). This leads to problems with npn transistor input  stages
like the
> A-117 or the A-113 clock input. There is a simple solution:  the
capacitor
> C10 has to be shorted e.g. with a short wire or a solder  blob. C10 is
> located on the small adapter board that holds the 4 output  sockets
near the
> 10 pin connector. We think about replacing the AC coupling 
capacitors of the
> A-111 by wires but have to check first if this may cause  problems
in other
> applications.
> 
> Best wishes
> Dieter  Doepfer
> 
> 
Hello Dieter,

I've just shorted C10 on my A-111.

But the A-113 still has problems with tracking frequency's below 90Hz.

Greetings,

Dirk.

--- In Doepfer_a100@yahoogroups.com, "vliesgaard" <vliesgaard@...> 
wrote:
>
> --- In Doepfer_a100@yahoogroups.com, davevosh@ wrote:
> >
> >  
> > In a message dated 4/24/2006 2:21:26 AM Pacific Standard Time,  
> > hardware@ writes:
> > 
> > 
> > 
> > you are right. It's the same matter. The rectangle output of  the
> A-111 is AC
> > coupled (capacitor between the rectangle output of the  CEM3340 
and the
> > socket). This leads to problems with npn transistor input  stages
> like the
> > A-117 or the A-113 clock input. There is a simple solution:  the
> capacitor
> > C10 has to be shorted e.g. with a short wire or a solder  blob. 
C10 is
> > located on the small adapter board that holds the 4 output  
sockets
> near the
> > 10 pin connector. We think about replacing the AC coupling 
> capacitors of the
> > A-111 by wires but have to check first if this may cause  problems
> in other
> > applications.
> > 
> > Best wishes
> > Dieter  Doepfer
> > 
> > 
> Hello Dieter,
> 
> I've just shorted C10 on my A-111.
> 
> But the A-113 still has problems with tracking frequency's below 
90Hz.
> 
> Greetings,
> 
> Dirk.


hello dirk,

90 hz is pretty low, i'm not sure if frequency division
makes sense with such low frequencies. afaik the a113
can only output audio frequencies (please correct me
if i'm wrong, dieter), so if you divide a 90 hz signal
you get out of the audio range quickly.
just an idea.

best wishes

ingo

Dirk,

does this problem occur with the A-111 only or even with A-110? And are you
sure that you shortened C10 (not C9, C9 is responsible for AC coupling of
the sawtooth) ?

Best wishes
Dieter Doepfer

> Hello Dieter,
>
> I've just shorted C10 on my A-111.
>
> But the A-113 still has problems with tracking frequency's below 90Hz.
>
> Greetings,
>
> Dirk

--- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...>
wrote:
>
> Dirk,
> 
> does this problem occur with the A-111 only or even with A-110? And
are you
> sure that you shortened C10 (not C9, C9 is responsible for AC
coupling of
> the sawtooth) ?
> 
> Best wishes
> Dieter Doepfer
> 

Hi,

It only occurs with the A-111 pulse output. 
I don't have a A-110, but the A-113 works as expected with Roland
System 100 vco's, Analoge Systems vco's/lfo's and the pulse output of
the A-154 sequenser controler.

I shorted both C's, just to make sure, and it helps a lot. 
But the A-113 still has problems tracking low frequenty's.

Greetings Dirk.

hello all,

it seems that dieter's message had a little typo in 
the first part. modifications on the first and second series of
bbd-modules are only necessary for 128 and 4096 stages ic's.
256 stages modules do not need any modification.

best wishes

ingo



--- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...> 
wrote:
>
> Because we had some inquiries I have to point out that it is not 
possible to
> order a modified module of the first two series and exchange it 
later for a
> non-modified module from the third series (~June 2006). If you want 
to have
> an A-188-1 with  128, 256 or 4096 stages without the "DIY 
modification" I
> ask you to wait until June. Please refer to my message from April 
11, 2006.
> Same as for the A-188-1 with 4096 stages (MN3005) applies to the A-
188-1
> with 128 stages (MN3006)! Only the modules with 256, 512, 1024 and 
2048
> stages can be manufactured without that ugly DIY mods.
> 
> Best wishes
> Dieter Doepfer
> 
> > -----Ursprüngliche Nachricht-----
> > Von: Doepfer_a100@yahoogroups.com
> > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> > Gesendet: Mittwoch, 26. April 2006 07:37
> > An: Doepfer_a100@yahoogroups.com
> > Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking 
problems
> >
> >
> > --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@>
> > wrote:
> > >
> > > Dirk,
> > >
> > > does this problem occur with the A-111 only or even with A-110? 
And
> > are you
> > > sure that you shortened C10 (not C9, C9 is responsible for AC
> > coupling of
> > > the sawtooth) ?
> > >
> > > Best wishes
> > > Dieter Doepfer
> > >
> >
> > Hi,
> >
> > It only occurs with the A-111 pulse output.
> > I don't have a A-110, but the A-113 works as expected with Roland
> > System 100 vco's, Analoge Systems vco's/lfo's and the pulse 
output of

> > the A-154 sequenser controler.
> >
> > I shorted both C's, just to make sure, and it helps a lot.
> > But the A-113 still has problems tracking low frequenty's.
> >
> > Greetings Dirk.
> >
> >
> >
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
>

OK, I'll check this with an A-111 and A-113. But it may take a few days as
we are very busy with testing and modifying the BBD modules as the customers
are waiting anxiously for their modules.

Best wishes
Dieter Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> Gesendet: Mittwoch, 26. April 2006 07:37
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking problems
>
>
> --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...>
> wrote:
> >
> > Dirk,
> >
> > does this problem occur with the A-111 only or even with A-110? And
> are you
> > sure that you shortened C10 (not C9, C9 is responsible for AC
> coupling of
> > the sawtooth) ?
> >
> > Best wishes
> > Dieter Doepfer
> >
>
> Hi,
>
> It only occurs with the A-111 pulse output.
> I don't have a A-110, but the A-113 works as expected with Roland
> System 100 vco's, Analoge Systems vco's/lfo's and the pulse output of
> the A-154 sequenser controler.
>
> I shorted both C's, just to make sure, and it helps a lot.
> But the A-113 still has problems tracking low frequenty's.
>
> Greetings Dirk.
>
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>

Because we had some inquiries I have to point out that it is not possible to
order a modified module of the first two series and exchange it later for a
non-modified module from the third series (~June 2006). If you want to have
an A-188-1 with  128, 256 or 4096 stages without the "DIY modification" I
ask you to wait until June. Please refer to my message from April 11, 2006.
Same as for the A-188-1 with 4096 stages (MN3005) applies to the A-188-1
with 128 stages (MN3006)! Only the modules with 256, 512, 1024 and 2048
stages can be manufactured without that ugly DIY mods.

Best wishes
Dieter Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> Gesendet: Mittwoch, 26. April 2006 07:37
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking problems
>
>
> --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...>
> wrote:
> >
> > Dirk,
> >
> > does this problem occur with the A-111 only or even with A-110? And
> are you
> > sure that you shortened C10 (not C9, C9 is responsible for AC
> coupling of
> > the sawtooth) ?
> >
> > Best wishes
> > Dieter Doepfer
> >
>
> Hi,
>
> It only occurs with the A-111 pulse output.
> I don't have a A-110, but the A-113 works as expected with Roland
> System 100 vco's, Analoge Systems vco's/lfo's and the pulse output of
> the A-154 sequenser controler.
>
> I shorted both C's, just to make sure, and it helps a lot.
> But the A-113 still has problems tracking low frequenty's.
>
> Greetings Dirk.
>
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>

Ingo,

thank you. You are right. Only 128 and 4096 stages are affected.

Dieter

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von selfoscillate
> Gesendet: Mittwoch, 26. April 2006 12:40
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] Re: A-188-1 with 128 and 4096 stages
>
>
>
> hello all,
>
> it seems that dieter's message had a little typo in
> the first part. modifications on the first and second series of
> bbd-modules are only necessary for 128 and 4096 stages ic's.
> 256 stages modules do not need any modification.
>
> best wishes
>
> ingo
>
>
>
> --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...>
> wrote:
> >
> > Because we had some inquiries I have to point out that it is not
> possible to
> > order a modified module of the first two series and exchange it
> later for a
> > non-modified module from the third series (~June 2006). If you want
> to have
> > an A-188-1 with  128, 256 or 4096 stages without the "DIY
> modification" I
> > ask you to wait until June. Please refer to my message from April
> 11, 2006.
> > Same as for the A-188-1 with 4096 stages (MN3005) applies to the A-
> 188-1
> > with 128 stages (MN3006)! Only the modules with 256, 512, 1024 and
> 2048
> > stages can be manufactured without that ugly DIY mods.
> >
> > Best wishes
> > Dieter Doepfer
> >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Doepfer_a100@yahoogroups.com
> > > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> > > Gesendet: Mittwoch, 26. April 2006 07:37
> > > An: Doepfer_a100@yahoogroups.com
> > > Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking
> problems
> > >
> > >
> > > --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@>
> > > wrote:
> > > >
> > > > Dirk,
> > > >
> > > > does this problem occur with the A-111 only or even with A-110?
> And
> > > are you
> > > > sure that you shortened C10 (not C9, C9 is responsible for AC
> > > coupling of
> > > > the sawtooth) ?
> > > >
> > > > Best wishes
> > > > Dieter Doepfer
> > > >
> > >
> > > Hi,
> > >
> > > It only occurs with the A-111 pulse output.
> > > I don't have a A-110, but the A-113 works as expected with Roland
> > > System 100 vco's, Analoge Systems vco's/lfo's and the pulse
> output of
> > > the A-154 sequenser controler.
> > >
> > > I shorted both C's, just to make sure, and it helps a lot.
> > > But the A-113 still has problems tracking low frequenty's.
> > >
> > > Greetings Dirk.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> >
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

--- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...>
wrote:
>
> OK, I'll check this with an A-111 and A-113. But it may take a few
days as
> we are very busy with testing and modifying the BBD modules as the
customers
> are waiting anxiously for their modules.
> 
> Best wishes
> Dieter Doepfer
> 

Don't worry, you get the full 100 points for customer service. If only
other company's were that good.


One use the A-113 is creating interesting rhythms. 
E.g. if you divide the 16th notes of the sequenser, with the A-113, by
2 3 5 and 7 you get a very complex rhythm patern.
Thats why it should track low frequenty's.

Greetings Dirk.

Dirk,

it took a while but now we found the reason and a solution ...

We had problems to understand why the combination of A-110 (rectangle)/A-113
is working perfect but not A-111(rectangle)/A-113 at low frequencies.
Strangely enough the combination A-111(sawtooth)/A-113 causes no problems.

The reason is the negative slope of the A-111 rectangle ! Our oscilloscope
showed in high res mode (1us/div) that the negative slope is not a single
slope but has some ups and downs (a bit like a down-going triangle).
Obviously the waveform converter inside the CEM3340 has this behaviour as
the rectangle output of the A-111 is nothing but the rectangle output of the
CEM3340 (only via 1k protection resistor and AC coupling capacitor). In
normal applications this causes no problems and cannot be heard (each VCA or
VCF or mixer behind the A-111 smoothes this multiple slopes which are in the
microsecond range). But the A-113 is very fast and detects these multiple
slopes at low frequencies. This causes the problems of the A-111/A-113
combination you described.

There are several solutions for this problem:

1. Do not use the rectangle but e.g. the sawtooth output of the A-111 to
trigger the A-113 (the sawtooth has no multiple slopes)
2. Process the rectangle output by any other module (VCA, VCF, mixer) before
it is used to trigger the A-113.
3. Add a capacitor to the A-113 (in parallel to diode D3). We tried 2n2 and
then the A-113 tracks perfect from about 10Hz. If you contact me directly
(hardware@doepfer.de) I can send you a picture that shows the position of D3
on the A-113 board. In this case even the rectangle output of the A-111 can
be used to trigger the A-113.

Best wishes
Dieter Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> Gesendet: Donnerstag, 27. April 2006 12:35
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking problems
>
>
> --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...>
> wrote:
> >
> > OK, I'll check this with an A-111 and A-113. But it may take a few days
as
> > we are very busy with testing and modifying the BBD modules as the
customers

> > are waiting anxiously for their modules.
> >
> > Best wishes
> > Dieter Doepfer
> >
>
> Don't worry, you get the full 100 points for customer service. If only
> other company's were that good.
>
>
> One use the A-113 is creating interesting rhythms.
> E.g. if you divide the 16th notes of the sequenser, with the A-113, by
> 2 3 5 and 7 you get a very complex rhythm patern.
> Thats why it should track low frequenty's.
>
> Greetings Dirk

Thanks for the exelent service.

--- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...> wrote:

>
> Dirk,
> 
> it took a while but now we found the reason and a solution ...
> 
> We had problems to understand why the combination of A-110 (rectangle)/A-113
> is working perfect but not A-111(rectangle)/A-113 at low frequencies.
> Strangely enough the combination A-111(sawtooth)/A-113 causes no problems.
> 
> The reason is the negative slope of the A-111 rectangle ! Our oscilloscope
> showed in high res mode (1us/div) that the negative slope is not a single
> slope but has some ups and downs (a bit like a down-going triangle).
> Obviously the waveform converter inside the CEM3340 has this behaviour as
> the rectangle output of the A-111 is nothing but the rectangle output of the
> CEM3340 (only via 1k protection resistor and AC coupling capacitor). In
> normal applications this causes no problems and cannot be heard (each VCA or
> VCF or mixer behind the A-111 smoothes this multiple slopes which are in the
> microsecond range). But the A-113 is very fast and detects these multiple
> slopes at low frequencies. This causes the problems of the A-111/A-113
> combination you described.
> 
> There are several solutions for this problem:
> 
> 1. Do not use the rectangle but e.g. the sawtooth output of the A-111 to
> trigger the A-113 (the sawtooth has no multiple slopes)
> 2. Process the rectangle output by any other module (VCA, VCF, mixer) before
> it is used to trigger the A-113.
> 3. Add a capacitor to the A-113 (in parallel to diode D3). We tried 2n2 and
> then the A-113 tracks perfect from about 10Hz. If you contact me directly
> (hardware@...) I can send you a picture that shows the position of D3
> on the A-113 board. In this case even the rectangle output of the A-111 can
> be used to trigger the A-113.
> 
> Best wishes
> Dieter Doepfer
> 
> > -----Ursprüngliche Nachricht-----
> > Von: Doepfer_a100@yahoogroups.com
> > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> > Gesendet: Donnerstag, 27. April 2006 12:35
> > An: Doepfer_a100@yahoogroups.com
> > Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking problems
> >
> >
> > --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@>
> > wrote:
> > >
> > > OK, I'll check this with an A-111 and A-113. But it may take a few days
> as
> > > we are very busy with testing and modifying the BBD modules as the
> customers
> > > are waiting anxiously for their modules.
> > >
> > > Best wishes
> > > Dieter Doepfer
> > >
> >
> > Don't worry, you get the full 100 points for customer service. If only
> > other company's were that good.
> >
> >
> > One use the A-113 is creating interesting rhythms.
> > E.g. if you divide the 16th notes of the sequenser, with the A-113, by
> > 2 3 5 and 7 you get a very complex rhythm patern.
> > Thats why it should track low frequenty's.
> >
> > Greetings Dirk
>

Hi Dieter & Dirk,

I don't own an A-113, so I cannot see the exact problem first-hand, 
but I did observe the nasty 'mush' on the falling edge of the A-111 
square wave output (when it is below about 300Hz).

I notice that the CEM3340 datasheet says that the falling edge is 
more rounded than the rising one, and that this can be improved by 
placing a 1meg resistor between pins 4 and 5 (pulse out and PWM 
input). This adds some hysteresis to the internal comparator, and 
should 'square up' the output. So I tried it and indeed it _did_ 
square up the signal, and also removed all the nasty 'noise' that 
Dieter reported. 

Thus this _may_ offer another possible solution, but the datasheet 
warns that adding the resistor might cause the internal comparator to 
oscillate, depending on the board layout etc. It certainly seemed 
well-behaved for the very simply check I made - perhaps Dieter can 
offer a more informed view on how good this might be as a solution 
(e.g. if the VCO is being rapidly switched between different 
frequencies, could this cause any problems?).

Tim

[*Fourth* attempt at posting this, so I really hope multiple copies 
don't suddenly arrive...]


--- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...> 
wrote:
>
> Dirk,
> 
> it took a while but now we found the reason and a solution ...
> 
> We had problems to understand why the combination of A-110 
(rectangle)/A-113
> is working perfect but not A-111(rectangle)/A-113 at low 
frequencies.
> Strangely enough the combination A-111(sawtooth)/A-113 causes no 
problems.
> 
> The reason is the negative slope of the A-111 rectangle ! Our 
oscilloscope
> showed in high res mode (1us/div) that the negative slope is not a 
single
> slope but has some ups and downs (a bit like a down-going triangle).
> Obviously the waveform converter inside the CEM3340 has this 
behaviour as
> the rectangle output of the A-111 is nothing but the rectangle 
output of the
> CEM3340 (only via 1k protection resistor and AC coupling 
capacitor). In
> normal applications this causes no problems and cannot be heard 
(each VCA or
> VCF or mixer behind the A-111 smoothes this multiple slopes which 
are in the
> microsecond range). But the A-113 is very fast and detects these 
multiple
> slopes at low frequencies. This causes the problems of the A-111/A-
113
> combination you described.
> 
> There are several solutions for this problem:
> 
> 1. Do not use the rectangle but e.g. the sawtooth output of the A-
111 to
> trigger the A-113 (the sawtooth has no multiple slopes)
> 2. Process the rectangle output by any other module (VCA, VCF, 
mixer) before
> it is used to trigger the A-113.
> 3. Add a capacitor to the A-113 (in parallel to diode D3). We tried 
2n2 and
> then the A-113 tracks perfect from about 10Hz. If you contact me 
directly
> (hardware@...) I can send you a picture that shows the position of 
D3
> on the A-113 board. In this case even the rectangle output of the A-
111 can
> be used to trigger the A-113.
> 
> Best wishes
> Dieter Doepfer
> 
> > -----Ursprüngliche Nachricht-----
> > Von: Doepfer_a100@yahoogroups.com
> > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> > Gesendet: Donnerstag, 27. April 2006 12:35
> > An: Doepfer_a100@yahoogroups.com
> > Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking 
problems
> >
> >
> > --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@>
> > wrote:
> > >
> > > OK, I'll check this with an A-111 and A-113. But it may take a 
few days
> as
> > > we are very busy with testing and modifying the BBD modules as 
the
> customers
> > > are waiting anxiously for their modules.
> > >
> > > Best wishes
> > > Dieter Doepfer
> > >
> >
> > Don't worry, you get the full 100 points for customer service. If 
only
> > other company's were that good.
> >
> >
> > One use the A-113 is creating interesting rhythms.
> > E.g. if you divide the 16th notes of the sequenser, with the A-
113, by

> > 2 3 5 and 7 you get a very complex rhythm patern.
> > Thats why it should track low frequenty's.
> >
> > Greetings Dirk
>

Tim,

thank you for this information. I will try if the additional 1M resistor
will work for the A-111. If this is true we will the resistor for new A-111
and prepare a document how to add this resistor for existing A-111.

Best wishes
Dieter Doepfer

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com
> [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von Tim Stinchcombe
> Gesendet: Sonntag, 7. Mai 2006 10:32
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking problems
>
>
> Hi Dieter & Dirk,
>
> I don't own an A-113, so I cannot see the exact problem first-hand,
> but I did observe the nasty 'mush' on the falling edge of the A-111
> square wave output (when it is below about 300Hz).
>
> I notice that the CEM3340 datasheet says that the falling edge is
> more rounded than the rising one, and that this can be improved by
> placing a 1meg resistor between pins 4 and 5 (pulse out and PWM
> input). This adds some hysteresis to the internal comparator, and
> should 'square up' the output. So I tried it and indeed it _did_
> square up the signal, and also removed all the nasty 'noise' that
> Dieter reported.
>
> Thus this _may_ offer another possible solution, but the datasheet
> warns that adding the resistor might cause the internal comparator to
> oscillate, depending on the board layout etc. It certainly seemed
> well-behaved for the very simply check I made - perhaps Dieter can
> offer a more informed view on how good this might be as a solution
> (e.g. if the VCO is being rapidly switched between different
> frequencies, could this cause any problems?).
>
> Tim
>
> [*Fourth* attempt at posting this, so I really hope multiple copies
> don't suddenly arrive...]
>
>
> --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...>
> wrote:
> >
> > Dirk,
> >
> > it took a while but now we found the reason and a solution ...
> >
> > We had problems to understand why the combination of A-110
> (rectangle)/A-113
> > is working perfect but not A-111(rectangle)/A-113 at low
> frequencies.
> > Strangely enough the combination A-111(sawtooth)/A-113 causes no
> problems.
> >
> > The reason is the negative slope of the A-111 rectangle ! Our
> oscilloscope
> > showed in high res mode (1us/div) that the negative slope is not a
> single
> > slope but has some ups and downs (a bit like a down-going triangle).
> > Obviously the waveform converter inside the CEM3340 has this
> behaviour as
> > the rectangle output of the A-111 is nothing but the rectangle
> output of the
> > CEM3340 (only via 1k protection resistor and AC coupling
> capacitor). In
> > normal applications this causes no problems and cannot be heard
> (each VCA or
> > VCF or mixer behind the A-111 smoothes this multiple slopes which
> are in the
> > microsecond range). But the A-113 is very fast and detects these
> multiple
> > slopes at low frequencies. This causes the problems of the A-111/A-
> 113
> > combination you described.
> >
> > There are several solutions for this problem:
> >
> > 1. Do not use the rectangle but e.g. the sawtooth output of the A-
> 111 to
> > trigger the A-113 (the sawtooth has no multiple slopes)
> > 2. Process the rectangle output by any other module (VCA, VCF,
> mixer) before
> > it is used to trigger the A-113.
> > 3. Add a capacitor to the A-113 (in parallel to diode D3). We tried
> 2n2 and
> > then the A-113 tracks perfect from about 10Hz. If you contact me
> directly
> > (hardware@...) I can send you a picture that shows the position of
> D3
> > on the A-113 board. In this case even the rectangle output of the A-
> 111 can
> > be used to trigger the A-113.
> >
> > Best wishes
> > Dieter Doepfer
> >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Doepfer_a100@yahoogroups.com
> > > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> > > Gesendet: Donnerstag, 27. April 2006 12:35
> > > An: Doepfer_a100@yahoogroups.com
> > > Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking
> problems
> > >
> > >
> > > --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@>
> > > wrote:
> > > >
> > > > OK, I'll check this with an A-111 and A-113. But it may take a
> few days
> > as
> > > > we are very busy with testing and modifying the BBD modules as
> the
> > customers
> > > > are waiting anxiously for their modules.
> > > >
> > > > Best wishes
> > > > Dieter Doepfer
> > > >
> > >
> > > Don't worry, you get the full 100 points for customer service. If
> only
> > > other company's were that good.
> > >
> > >
> > > One use the A-113 is creating interesting rhythms.
> > > E.g. if you divide the 16th notes of the sequenser, with the A-
> 113, by
> > > 2 3 5 and 7 you get a very complex rhythm patern.
> > > Thats why it should track low frequenty's.
> > >
> > > Greetings Dirk
> >
>
>
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