Doepfer

Hello

It seems that the highest frequency of the A-110 lies around 
1200 Hertz, while the A-121 set to self-oscillation can produce 
frequencies up to 14000 Hertz. 
Is this correct?

Is it possible to produce sine waves of approximately 18000 
Hertz with the A-100?
I've tried patching the same signal (from A-121) into both Ring 
Mod inputs, hoping I could simply double the frequency that way, 
but this doesn't seem to work.

And does anybody know where I could get one of those separate 
Belton reverb units used for the A-199?

Many thanks for help.

MD

hello MD,
welcome to the list!!sorry but,i can't help you in
your questions...i hope  other members may be able to
help...by the way,as you seem to have the a199 spring
reverb,can you tell me some things about the sound of
this reverb unit??i am thinking about buing one in the
near future...
your idea about doubling the freq. of an osc by using
the ring modulator seems nice,but i don't know why it
didn't work,though...
synthfreak
[doepfer_a100] group moderator


--- mdimmm <mdimmm@yahoo.com> wrote:
> Hello
> 
> It seems that the highest frequency of the A-110
> lies around 
> 1200 Hertz, while the A-121 set to self-oscillation
> can produce 
> frequencies up to 14000 Hertz. 
> Is this correct?
> 
> Is it possible to produce sine waves of
> approximately 18000 
> Hertz with the A-100?
> I've tried patching the same signal (from A-121)
> into both Ring 
> Mod inputs, hoping I could simply double the
> frequency that way, 
> but this doesn't seem to work.
> 
> And does anybody know where I could get one of those
> separate 
> Belton reverb units used for the A-199?
> 
> Many thanks for help.
> 
> MD
> 
> 


=====
synthfreak(parallel worlds)
athens-greece
[Doepfer_a100] group owner-moderator

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Hi MD (or what your name ever may be...)

> It seems that the highest frequency of the A-110 lies around
> 1200 Hertz, 

No, that is surely not the upper limit.

As far as I remember the multimode filter has a capacitor which damps the
self-oscillation in higher regions, because the filter would hang in
self-oscillation at high frequencies, though resonance was turned down
again. This limits the maximum frequency for selfoscillation. (This trick
is not Doepfers idea but is taken over from the application notes for the
CEM3320 chip).


I think the A120 should be able to do self oscillation in ranges up to
50.000 Hz

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

Hi MD,

> It seems that the highest frequency of the A-110 lies around 
> 1200 Hertz

supply the A-110 (CV 1) with a high voltage.

The Tambourine-Patch on the Modular-Planet.de requires a high voltage 
source. The measurement shows 21000 Hz at A-110-Triangle (only 10500 
Hz at Sine, but I don`t know the cause!).

In this manner the A-111 produces a frequency of 80000 Hz!

Greetings

Josef

Hi Josef

> source. The measurement shows 21000 Hz at A-110-Triangle (only 10500
> Hz at Sine, but I don`t know the cause!).
A look at the schematic 
http://www.doepfer.de/a110_tec.htm
shows a lowpass functionality by R52 and C9; I am to lazy to get the
frequency, that is determined by those two values, but I think the
dimension of those two parts is the limitation. If you need higher "sine"
you need to decrease the value of C9, but this again results in a worse
pseudo sine.

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

hi josef,
sorry for asking a rather stupid question...but what equipment do you 
need in order to measure the frequency of an osc.??
synthfreak




-- In Doepfer_a100@y..., "modularplanet" <webmaster@m...> wrote:
> Hi MD,
> 
> > It seems that the highest frequency of the A-110 lies around 
> > 1200 Hertz
> 
> supply the A-110 (CV 1) with a high voltage.
> 
> The Tambourine-Patch on the Modular-Planet.de requires a high 
voltage 
> source. The measurement shows 21000 Hz at A-110-Triangle (only 
10500 

> Hz at Sine, but I don`t know the cause!).
> 
> In this manner the A-111 produces a frequency of 80000 Hz!
> 
> Greetings
> 
> Josef

Hi 

> sorry for asking a rather stupid question...but what equipment do you
> need in order to measure the frequency of an osc.??
Three porssibilities:
- use a frequency counter (the coolest looking are with with 
  nixie tubes ;) )
- use an oszilloscope: you can calculate the 
  frequency from the width of the waveform
- use a sound with known frequency, e.g. a tunable digital synth. Take 
  the signal with the asked frequency and divide it down until it is close 
  to the known frequency. Tune the known frequency until the beating stops.

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

Hi everyone,
I can offer some comments on the above:

1. The sine wave from the A-110 is generated from the triangle wave
(through a voltage divider, then taken across a diode, and the
exponential type curve produced is then scaled up, which is why the
sine wave is not very sine-like!). Thus there is no way they should
have different frequencies! Resistor R52/capacitor C9 used in this
process don't affect the signals frequency. (Same method is used for
the sine wave in A-111, A-145 and A-147.)

2. The main capacitor in A-110 controlling the frequency ranges is C3
- in theory halving this will double all frequency ranges; in
practice, if you were to do this, I don't know what the 'quality' of
the waveforms would be though!

3. The max freq I can get from both my A-110's is about 10500Hz: top
range, with about 8V input. Max from A-121 is 13500Hz (A-122 similar).
I haven't spent much time looking at the filters (yet!), so I don't
know what the limiting factor is.

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

> have different frequencies! Resistor R52/capacitor C9 used in this
> process don't affect the signals frequency. 
They don't affect the frequency, but the waveform converter might get too
slow to follow the feeded triangle wave.

> I haven't spent much time looking at the filters (yet!), so I don't
> know what the limiting factor is.
I don't have the schemoe  of the CEM-Filter-Modules here, but at
http://www.synthtech.com/cem/cemdata.html you might find the Datasheet of
the CEM 3320. There you see four caps with 300pF called Cp; decreasing
their value will affect the tuning.

There are no data regarding max frequency, but to me it looks like only the
first two pages of the datasheet - I remember them longer.

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

Hi Florian,
Thanks for that:

> I don't have the schemoe  of the CEM-Filter-Modules here, but at
> http://www.synthtech.com/cem/cemdata.html you might find the
Datasheet of
> the CEM 3320. There you see four caps with 300pF called Cp; decreasing
> their value will affect the tuning.
> 
> There are no data regarding max frequency, but to me it looks like
only the
> first two pages of the datasheet - I remember them longer.

Yeah, I found this site a while back - when I did I was pleased to
find some info on the CEM chips, and then was disappointed by the
amount, they do seem a bit skimpy! When I get more time (and when I
understand filters better!) I'll see if I can work out the transfer
functions of the filters as implemented in A-121, 122, which should
help to provide more insight.

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 Bakis,

I use the 
   ‚Sweep Function Generator with Frequency Counter`
from www.conrad.com (a cheap mail-order house!).

The Frequency Counter measures from 2 to 100000 Hz.
For more informations go to the International-Site at Conrad and 
search for the Item-No.:
    123110-92

For tuning-informations (notes, octave range, cent-detuning) I use a 
chromatic tuner (Korg AT-12).

Another possibility is measurement with software: record a tone and 
measure them (for example) with WaveLab. 

By the way: In WaveLab there is an oscilloscope (the scopion-PlugIn). 
A big oscilloscope is in samplitude (www.sekd.de). You can use this 
oscilloscope with the demo-software!

Josef