Doepfer

We added some features to the A-111-1 and renamed it to A-111-2:

- the nearly perfect triangle-to-sine converter suggested by Tim Stinchcombe in this group
- manual linear frequency control (for low frequencies close to 0 Hz)
- LFO mode
- LED display
- separate output buffer/amplifier for each waveform
- same levels for all waveforms (10Vpp)

The A-111-2 is based on the CEM3340 Rev G. There was a close cooperation with OnChip since 2015 regarding to the new CEM3340 and we
received the first samples in January during NAMM for our development. The first production batch of the CEM3340 Rev G arrived 2
weeks ago and the production of the A-111-2 during the next few days (we are still waiting for the latest front panel and pcb
samples). I'd expect the first modules about end of July/August. The A-111-3 is also based on the CEM3340 Rev G and we are working
on a Thru-Zero VCO based on the CEM3340 Rev G (module A-111-4).

Best wishes
Dieter Doepfer



> Actually a question for the man himself, will there be an re-issue of the High End VCO with the new CEM 3340 Rev G VCO chip?

> So today i was lucky enough to write in on an order for both
> A-111-2, A-111-3 modules and the A-184-2 [ yeeeej :)] Following
> question comes to mind regarding the latest discussion abouth new
> vco module thru-zero capablities and the mentioning of the JH3
> dual cem 3340 vco module. The old JH3 dual vco schematic [
> http://jhaible.com/legacy/tonline_stuff/hj2vco.gif ] shows 7
> different sync capabilities between vco a/b. Could these sync
> functionalities be duplicated in a supposed patch with the
> A-111-2+A-111-3 and some logic/inverter modules?

Adding the corresponding circuits should be possible. Let me know your
results as the thru zero circuit we tried so far (based on an internal
Curtis information) does not meet our expectations. The toggling during the
zero transition does not work as it should under all conditions. Sometimes
the oscillation totally stops and comes back to live only by turning the
supply off/on. Maybe it has to do with Rev.G of the CEM3340. We discovered
that the CEM3340 stops working as soon as the linear reference current at
pin 13 becomes zero for a longer time (but that's essential for the thru
zero transition). If the transition is fast enough (i.e. modulating with a
higher frequency) and the linear current becomes zero for a short time only
it works. But as the modulation frequency becomes lower or one tries a
manual thru zero transition the oscillation stops sometimes. Maybe we still
have a mistake in the circuit but I don't think so. We just took an old
A-111-1 and modified it a bit so that the DC current voltage at pin 13 can
be manually adjusted (not a fixed value as in the standard application of
the CEM3340 by means of a resistor connected to +U). When the current
becomes zero the oscillations stops (as expected) but sometimes the VCO
comes not back to life when the linear current is increased again. Turning
off/on the supply is the only way to re-start the oscillation. We will have
to check out if this is valid for the original CEM3340 too or a drawback of
rev.G only. If Juergen Haibles circuit does not have this drawback we may
use his circuit and pay tribute to him posthumously.

Best wishes
Dieter Doepfer

P.S. The first batches of A-111-2, A-111-3, A-138o/p and A-184-2 have been
shipped to Alex4 and should be available from dealers soon.

We are still working on an CEM3340 based VCO with thru zero FM. But so far
the circuit does not yet work as it should. We will continue our research
and release the TZ3340 if the results are satisfying.

Best wishes
Dieter Doepfer

> By the way i havent been succesful yet on doing some tests on a
> thru-zero circuit with the new Rev.G 3340 based A-111-2+A-111-3
> modules. To be honest more a lack of time then effort on my side.
> Has there been developement at Doepfer residence regarding the
> thru-zero circuit testing for a possible A-111-4 module follow up?

There should be no difference in this regard between the old CEM3340 and
rev.G. Let me know if you can confirm that Juergen Haibles TZ circuit does
work. Our TZ circuit is a bit different and would offer more possibilities
(e.g. an additional control for the TZ "smoothness", i.e. if there is a soft
transition at f=0 as usual or a voltage jump before the wave continues which
generates additional overtones). But as already mentioned it does not yet
work as it should.

Best regards
Dieter Doepfer

> Good to hear that this developement is still in the pipeline! One
> of the things that im curious of is if the old JH3 dual vco
> schematic works with Rev.G, i also posess 2 A-111(-1) for doing
> test but i dont want to mess up an older type 3340 by poking
> around finding the right pin to insert a sync signal from
> another. Whenever i do have (safely) done some tests with results
> ill post it here.
>
> Posted by: ninonine@xs4all.nl