Doepfer

Hi, I'm new to the group and have set my A100 to operation for the first time a few days ago. I have one question concerning the high end VCO A-111. When I modulate the PCV-Input with an LFO and turn the PCV knob clockwise, there is also a weak FM in all signal outputs, bad enough not to use PWM.

Is this a fault in my VCO, and is there any solution for it?

Best regards, Markus

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

hello,
i had the same problem with a few of my a111's.
just plug a minijack cable into the hard sync input.
leave it there and then i think the problem will
dissapear. it is a problem with the hard sync input
minijack socket... you can permanently correct this
problem (so you don't have to leave plugged a cable to
the hardsync socket all the time...), i guess, with
the instructions that are present in the doepfer
website in the faq page. there is some touching of the
metal plates going on inside the minijack socket. i do
not exactly remember how i corrected this, but i think
that was the procedure described in the doepfer faq
page.
tell me if pluggin a cable into the hard sync input
corrected your problem first, though.
best regards,
Bakis.




--- Markus Grieß <markus.griess@gmx.net> wrote:

> Hi, I'm new to the group and have set my A100 to
> operation for the first time a few days ago. I have
> one question concerning the high end VCO A-111. When
> I modulate the PCV-Input with an LFO and turn the
> PCV knob clockwise, there is also a weak FM in all
> signal outputs, bad enough not to use PWM.
> 
> Is this a fault in my VCO, and is there any solution
> for it?
> 
> Best regards, Markus
> 
> [Non-text portions of this message have been
> removed]
> 
> 


Bakis Sirros - Parallel Worlds
[Doepfer_a100] group owner
http://www.parallel-worlds-music.com
http://www.myspace.com/parallelworldsmusic
http://www.shimarecords.co.uk
http://www.rubber.gr
Athens-Greece

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Hello Bakis,

 

thanks for your response. Plugging a cable into the hard sync input (or any
other jack) did not fix the problem. I also tried a shorted plug in the CV1
input as I supposed crosstalk, without success (I’m not sure whether the
sensitive CV1 input is shorted to 0V when no plug is inserted and I do not
have schematics of the A111).

 

I didn’t find any hint at the Doepfer page. Any other idea?

 

Best regards,

Markus

 

  _____  

Von: Doepfer_a100@yahoogroups.com [mailto:Doepfer_a100@yahoogroups.com] Im
Auftrag von Bakis Sirros
Gesendet: Freitag, 29. Dezember 2006 23:50
An: Doepfer_a100@yahoogroups.com
Betreff: Re: [Doepfer_a100] PWM with A-111

 

hello,
i had the same problem with a few of my a111's.
just plug a minijack cable into the hard sync input.
leave it there and then i think the problem will
dissapear. it is a problem with the hard sync input
minijack socket... you can permanently correct this
problem (so you don't have to leave plugged a cable to
the hardsync socket all the time...), i guess, with
the instructions that are present in the doepfer
website in the faq page. there is some touching of the
metal plates going on inside the minijack socket. i do
not exactly remember how i corrected this, but i think
that was the procedure described in the doepfer faq
page.
tell me if pluggin a cable into the hard sync input
corrected your problem first, though.
best regards,
Bakis.

--- Markus Grieß <markus.griess@ <mailto:markus.griess%40gmx.net> gmx.net>
wrote:

> Hi, I'm new to the group and have set my A100 to
> operation for the first time a few days ago. I have
> one question concerning the high end VCO A-111. When
> I modulate the PCV-Input with an LFO and turn the
> PCV knob clockwise, there is also a weak FM in all
> signal outputs, bad enough not to use PWM.
> 
> Is this a fault in my VCO, and is there any solution
> for it?
> 
> Best regards, Markus
> 
> [Non-text portions of this message have been
> removed]
> 
> 

Bakis Sirros - Parallel Worlds
[Doepfer_a100] group owner
http://www.parallel <http://www.parallel-worlds-music.com> -worlds-music.com
http://www.myspace. <http://www.myspace.com/parallelworldsmusic>
com/parallelworldsmusic
http://www.shimarec <http://www.shimarecords.co.uk> ords.co.uk
http://www.rubber. <http://www.rubber.gr> gr
Athens-Greece

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

hi Markus

> Hi, I'm new to the group and have set my A100 to operation for the first 
> time a few days ago. I have one question concerning the high end 
> VCO A-111. When I modulate the PCV-Input with an LFO and turn the 
> PCV knob clockwise, there is also a weak FM in all signal outputs, 
> bad enough not to use PWM.
Pay attention: the faster the PWM, the more it will sound like pitch 
modulation. For our ear a width modulated pulsewave is not one up and 
one down movement but two peaks, where one is frequency modulated[*]. If 
the FM seems to get weaker with slower LFO frequencies, then your A-111 
is not buggy but you discovered a nice psychoacoustical phenomenon.

As rule of thumb you can say: the faster the modulating frequency is, 
the smaller the modulation amount should be


Florian

[*] you can test this by sending a pulswave through a unmodulatied 
phaseshifter and listening only to the effectsignal and then listen only 
to the original signal (no mix) you won't hear a difference.
If you have a look at an oscilloscope (or wave edit window of a digitla 
recording tool), you will see that the waveforms look completely different.

hi Markus

> Hi, I'm new to the group and have set my A100 to operation for the first 
> time a few days ago. I have one question concerning the high end 
> VCO A-111. When I modulate the PCV-Input with an LFO and turn the 
> PCV knob clockwise, there is also a weak FM in all signal outputs, 
> bad enough not to use PWM.
Pay attention: the faster the PWM, the more it will sound like pitch 
modulation. For our ear a width modulated pulsewave is not one up and 
one down movement but two peaks, where one is frequency modulated[*]. If 
the FM seems to get weaker with slower LFO frequencies, then your A-111 
is not buggy but you discovered a nice psychoacoustical phenomenon.

As rule of thumb you can say: the faster the modulating frequency is, 
the smaller the modulation amount should be


Florian

[*] you can test this by sending a pulswave through a unmodulatied 
phaseshifter and listening only to the effectsignal and then listen only 
to the original signal (no mix) you won't hear a difference.
If you have a look at an oscilloscope (or wave edit window of a digitla 
recording tool), you will see that the waveforms look completely different.

Hi Markus,

> I didn't find any hint at the Doepfer page. Any other idea?

After checking some of the history on this problem, I realised I too 
had this problem when I first got my A-111 (over 4 years ago), and 
the solution then, by EMIS the UK distributor, was to replace the 
CEM3340 chip. In an old email I had written to Dieter at the time, I 
mentioned that specifically grounding the hard sync input did *not* 
cure the problem!

However, checking past messages, the last time this appeared seems to 
have been post #9193, about a year ago: one of the follow-up posts, 
#9203, contained the suggestion from Dieter about grounding the hard-
sync input, but checking my module against what he says doesn't make 
sense, as the switched contact on mine is *not* grounded (but I'm 
guessing on new modules they solder across the gap). Hence I suggest 
the following:

Insert a patch lead into the hard sync socket, and *deliberately 
ground the tip at the other end*.

If this cures it, have a look at the switched contacts on the hard 
sync socket - these are the two on the very end of the board. I 
suspect that they are bridged with solder: if they are, then probably 
a new socket is needed; if they are not, then bridging them with 
solder will have the effect of always grounding the hard sync line 
when no plug is inserted, which hopefully should then give a 
permanent solution.

If inserting and grounding the lead doesn't totally remove the 
problem, then I suspect you'll need a new chip as I did!

Tim

Hi Tim,

> If inserting and grounding the lead doesn't totally remove the 
> problem, then I suspect you'll need a new chip as I did!

thanks for your help. I found out that the connections an the
sockets/switches are ok; so the CEM3340 seems to be faulty. Since the
rest seems to be working well, I will not replace the CEM but add a
comparator for the PW/PWM instead, like in the A-110.

Best regards,
Markus

hello,
the problem thast mark describes is that he hears a
bit of FM when listening to other wevforms of the a111
while an lfo modulates the PW of the PWM input.
i suspect maybe the cem3340 is defective...?
is that a new a111 module?
best regards,     :-)
Bakis.



--- Florian Anwander <Florian.Anwander@consol.de>
wrote:

> hi Markus
> 
> > Hi, I'm new to the group and have set my A100 to
> operation for the first 
> > time a few days ago. I have one question
> concerning the high end 
> > VCO A-111. When I modulate the PCV-Input with an
> LFO and turn the 
> > PCV knob clockwise, there is also a weak FM in all
> signal outputs, 
> > bad enough not to use PWM.
> Pay attention: the faster the PWM, the more it will
> sound like pitch 
> modulation. For our ear a width modulated pulsewave
> is not one up and 
> one down movement but two peaks, where one is
> frequency modulated[*]. If 
> the FM seems to get weaker with slower LFO
> frequencies, then your A-111 
> is not buggy but you discovered a nice
> psychoacoustical phenomenon.
> 
> As rule of thumb you can say: the faster the
> modulating frequency is, 
> the smaller the modulation amount should be
> 
> 
> Florian
> 
> [*] you can test this by sending a pulswave through
> a unmodulatied 
> phaseshifter and listening only to the effectsignal
> and then listen only 
> to the original signal (no mix) you won't hear a
> difference.
> If you have a look at an oscilloscope (or wave edit
> window of a digitla 
> recording tool), you will see that the waveforms
> look completely different.
> 


Bakis Sirros - Parallel Worlds
[Doepfer_a100] group owner
http://www.parallel-worlds-music.com
http://www.myspace.com/parallelworldsmusic
http://www.shimarecords.co.uk
http://www.rubber.gr
Athens-Greece

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hello again,
if i remember right:
out of the 8 a111's i have,
one of my a111's had the exact same problem with the
PWM input and it turned out that its CEM3340 needed a
replacement(wich doepfer replaced and the module
worked fine afterwards).
then, after some months, two of my other a111's had
the exact same PWM problem and, by just plugging a
cable into the hard sync input and then adjusting the
metal plates of the hardsync input socket, fixed the
problem entirely!
so, it seeems that this PWM symptom has two different
causes...
at least that is my experience so far.
best regards,    :-)
Bakis.


--- Tim Stinchcombe
<timothy@tstinchcombe.freeserve.co.uk> wrote:

> Hi Markus,
> 
> > I didn't find any hint at the Doepfer page. Any
> other idea?
> 
> After checking some of the history on this problem,
> I realised I too 
> had this problem when I first got my A-111 (over 4
> years ago), and 
> the solution then, by EMIS the UK distributor, was
> to replace the 
> CEM3340 chip. In an old email I had written to
> Dieter at the time, I 
> mentioned that specifically grounding the hard sync
> input did *not* 
> cure the problem!
> 
> However, checking past messages, the last time this
> appeared seems to 
> have been post #9193, about a year ago: one of the
> follow-up posts, 
> #9203, contained the suggestion from Dieter about
> grounding the hard-
> sync input, but checking my module against what he
> says doesn't make 
> sense, as the switched contact on mine is *not*
> grounded (but I'm 
> guessing on new modules they solder across the gap).
> Hence I suggest 
> the following:
> 
> Insert a patch lead into the hard sync socket, and
> *deliberately 
> ground the tip at the other end*.
> 
> If this cures it, have a look at the switched
> contacts on the hard 
> sync socket - these are the two on the very end of
> the board. I 
> suspect that they are bridged with solder: if they
> are, then probably 
> a new socket is needed; if they are not, then
> bridging them with 
> solder will have the effect of always grounding the
> hard sync line 
> when no plug is inserted, which hopefully should
> then give a 
> permanent solution.
> 
> If inserting and grounding the lead doesn't totally
> remove the 
> problem, then I suspect you'll need a new chip as I
> did!
> 
> Tim
> 
> 
> 
> 
> 
> 


Bakis Sirros - Parallel Worlds
[Doepfer_a100] group owner
http://www.parallel-worlds-music.com
http://www.myspace.com/parallelworldsmusic
http://www.shimarecords.co.uk
http://www.rubber.gr
Athens-Greece

__________________________________________________
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hello again,
well, IIRC, this problem's differential diagnosis is:
if the specific PWM problem appears alone, chances are
that the cause is a defective CEM3340 chip.
if this specific PWM problem appears together with
another problem-that being the vco not sounding
correctly in the higher registers, then chances are
that the cause is the hardsync input socket.
best regards,
Bakis.



--- Bakis Sirros <synth_freak_2000@yahoo.com> wrote:

> hello again,
> if i remember right:
> out of the 8 a111's i have,
> one of my a111's had the exact same problem with the
> PWM input and it turned out that its CEM3340 needed
> a
> replacement(wich doepfer replaced and the module
> worked fine afterwards).
> then, after some months, two of my other a111's had
> the exact same PWM problem and, by just plugging a
> cable into the hard sync input and then adjusting
> the
> metal plates of the hardsync input socket, fixed the
> problem entirely!
> so, it seeems that this PWM symptom has two
> different
> causes...
> at least that is my experience so far.
> best regards,    :-)
> Bakis.
> 
> 
> --- Tim Stinchcombe
> <timothy@tstinchcombe.freeserve.co.uk> wrote:
> 
> > Hi Markus,
> > 
> > > I didn't find any hint at the Doepfer page. Any
> > other idea?
> > 
> > After checking some of the history on this
> problem,
> > I realised I too 
> > had this problem when I first got my A-111 (over 4
> > years ago), and 
> > the solution then, by EMIS the UK distributor, was
> > to replace the 
> > CEM3340 chip. In an old email I had written to
> > Dieter at the time, I 
> > mentioned that specifically grounding the hard
> sync
> > input did *not* 
> > cure the problem!
> > 
> > However, checking past messages, the last time
> this
> > appeared seems to 
> > have been post #9193, about a year ago: one of the
> > follow-up posts, 
> > #9203, contained the suggestion from Dieter about
> > grounding the hard-
> > sync input, but checking my module against what he
> > says doesn't make 
> > sense, as the switched contact on mine is *not*
> > grounded (but I'm 
> > guessing on new modules they solder across the
> gap).
> > Hence I suggest 
> > the following:
> > 
> > Insert a patch lead into the hard sync socket, and
> > *deliberately 
> > ground the tip at the other end*.
> > 
> > If this cures it, have a look at the switched
> > contacts on the hard 
> > sync socket - these are the two on the very end of
> > the board. I 
> > suspect that they are bridged with solder: if they
> > are, then probably 
> > a new socket is needed; if they are not, then
> > bridging them with 
> > solder will have the effect of always grounding
> the
> > hard sync line 
> > when no plug is inserted, which hopefully should
> > then give a 
> > permanent solution.
> > 
> > If inserting and grounding the lead doesn't
> totally
> > remove the 
> > problem, then I suspect you'll need a new chip as
> I
> > did!
> > 
> > Tim
> > 
> > 
> > 
> > 
> > 
> > 
> 
> 
> Bakis Sirros - Parallel Worlds
> [Doepfer_a100] group owner
> http://www.parallel-worlds-music.com
> http://www.myspace.com/parallelworldsmusic
> http://www.shimarecords.co.uk
> http://www.rubber.gr
> Athens-Greece
> 
> __________________________________________________
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam
> protection around 
> http://mail.yahoo.com 
> 


Bakis Sirros - Parallel Worlds
[Doepfer_a100] group owner
http://www.parallel-worlds-music.com
http://www.myspace.com/parallelworldsmusic
http://www.shimarecords.co.uk
http://www.rubber.gr
Athens-Greece

__________________________________________________
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Tired of spam?  Yahoo! Mail has the best spam protection around 
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