From eli@gs160.sp.cs.cmu.edu Fri Nov 22 13:27:18 1996 21 Nov 96 14:27 EST 21 Nov 96 14:27 EST id TAA170693; Thu, 21 Nov 1996 19:23:10 GMT id TAA156860; Thu, 21 Nov 1996 19:23:06 GMT From: ANALOGUEMAN@delphi.com id <01IC3ZYSR8N496ZS6V@delphi.com>; Thu, 21 Nov 1996 14:23:06 -0500 (EST) Date: Thu, 21 Nov 1996 14:23:06 -0500 (EST) Subject: Doepfer A-100 Review *** Part Three *** Cc: anodaleb@ix.netcom.com, James@jaidee.demon.co.uk, frans@CCIT.ARIZONA.EDU, 103053.2325@CompuServe.COM, tb@guido.zkm.de, synth-diy@horus.sara.nl Message-id: <01IC3ZYSR8N696ZS6V@delphi.com> X-VMS-Cc: @RFDCC.LIS MIME-version: 1.0 Content-type: TEXT/PLAIN; CHARSET=US-ASCII Content-transfer-encoding: 7BIT **************************************************************************** 21 Nov '96 ------------ Greetings Guys, Firstly, may I apologize for the delay in the appearance of this review. These modules were ordered some months ago, but disappeared in transit, due to the incompetency of a courier service, who had them sitting in one of their warehouses, about half a mile down the road, for about two months before discovering them again. I swear that if couriers had brains, and brains were gunpowder, they wouldn't have enough to blow their hats off! This is the third of an ongoing batch of modules in the A-100 range that I've received, and contains a number of sound shaping devices this time around. As always, I'll list not only what I think of them, but also the ics that they contain, for those interested in the component make up. Please note, that I'm in no way connected with Doepfer Musikelektronic GmbH, and that these are purely personal opinions. Doepfer can be contacted on the following (*new address and phone numbers*) : Geiger Str. 13 82166 Grafelfing Germany. Phone: 00 49 89 898 09510 Fax : 00 49 89 898 09511 As always, I would welcome any comments and corrections with regards to this review. A fourth batch of modules should be with me sometime in December, and will contain the new precision oscillators, and the first two vocoder modules. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - A-119 Ext. Input/Envelope Follower ----------------------------------- This module has two socket inputs- a mono 3.5mm and a stereo 1/4" socket. These are labeled Asym.In, and Symm.In respectively. Although you may be injecting a stereo signal into the 1/4" socket, the sound will be a sum of the left and right. There are two identical audio output sockets, with a gain pot for the overall volume control, along with an overload LED should the output signal become too hot. An envelope output socket with an LED indicator is provided along with gate out socket with an associated threshold pot, which also has an LED indicator. As I haven't really had the oportunity to use an envelope generator before (nothing I own has one), I tryed it out by injecting a simple boring sampled kick drum into it, and patched up a sine wave generated from one of the systems filters. I then took the envelope out from the 119 and patched it in to the cv input of the filter and a vca. The result was that I now had a sound of exactly the same duration and feel of the original sound, and when mixed together gave something ultimately more usable. I then used the same patch, but also took the gate output, and put that into an envelope generator, which then went into the filters cv input. This gave me a greater control over the filter's response, but with the final sound being triggered at exactly the same time as the external one. Internaly, the A-119 uses two TL064CNs. A-121 12dB/Oct Multimode Filter -------------------------------- This is the first of three VCFs which uses the 3320 chip from Curtis. Configured as a 12 dB/octave type filter, it has four different and simultanious outputs, each with it's own separate socket on the front. It gives notch, highpass, bandpass, and lowpass outputs and there is a single audio input with a level pot. Apart from a frequency control knob, there are two frequency control voltage input sockets, one of which has an associated attenuation pot. Resonance can be controlled manually, with a pot of it's own, or via an external control voltage, of which there are two socket inputs. One of these has a level pot. Functionally, all four filters give the expected results, but I have to say, that quality wise, this filter really does hit the spot. Whereas the A-120 was slightly disappointing, this one oozes quality. The sound that it passes is both smooth and large from the lowpass output, and does have a slightly familiar feel to it. If someone were to be putting together one of these systems, and were unsure as to which filter to go for first of all, then this would be the one that I would recommend, as the most usable. It uses two pcbs; a small one for the filter ouput sockets, and the main one which seats the single CEM3320 and a TL062CP. There is also three mini turn resistors for scale, offset, and feedthrough. All the pots are 50K, four of which are linear, and one log. A-122 24 dB/Oct Lowpass Filter ------------------------------- The second of the Curtis chipped filters, this is a straight forward 24 dB/oct configured lowpass type. The audio input socket is accompanied by a level pot, and there are the usual frequency and resonance knobs. There are two cv inputs to control the cutoff level, one of which has an attenuation pot. There is also a cv input for controlling the resonance, which is also attenuated via it's own knob. Sound wise, this filter is what I'd call 'typically Curtis'. Nothing unexpected, but solid and very usable, capable of both broad and narrow filtered type sounds. Apart from the 3320, the only other ic it uses is a TL062CN, with a couple of miniturns for offset and scale adjustments. A-123 24 dB/Oct Highpass Filter -------------------------------- The third of the Curtis chip filters available is a 24 dB/oct highpass. The socket and pot arrangement on the front of the panel is identical to the A-122 (see above). As always, it's always nice to see the implementation of resonance on the highpass filter, with a control volt input to boot. Internally, it is more or less the same as the A-122, with the exception of an additional miniturn, which isn't labelled. A-125 VC Phase Shifter ---------------------- This is an interesting sounding module, and great fun to use. It has an audio input socket with a level pot, as does the cv input socket, which controls the phase shift ammount. There is also a dedicated shift knob for manual control. The last two pots control the resonance and mix ammounts, along with an audio out socket. It's a great shame that Doepfer didn't include a cv input for the resonance, as there is room on the front panel for at least a couple of more sockets. The mix knob can be thought of as a wet/dry control, as the signal is uneffected at zero, and a set mix of 50/50 at ten. The resonance control really makes this module, as it's use emphesises certain frequencies within the phased signal that add that 'something extra' to it. The shift itself isn't too dramatic, but enough to enlarge the original signal, with out muddying it. Using the cv inputs to add subtle ammounts of phase shift to a sound, really gives it a polished feel. The pcb is a mass of resistors and capasitors. It uses six BF245 transistors, two TL064CNs, and a TL062CN, along with an offset miniturn. A-128 Fixed Filter Bank ------------------------ With only two sockets, an audio in and out, the rest of the panel is taken up with fifteen pots, each with an assigned frequency. The fixed frequencies that it effects are- 50, 75, 110, 150, 220, 350, 500, 750 Hz, 1.1, 1.6, 2.2, 3.6, 5.2, 7.5, 11.0 KHz. Whilst nothing more than a knobbly graphic equaliser, this is rather usefull for removing certain frequencies from a sound, from time to time. A resonant filter bank would have undoubtedly been much more usefull, but Doepfer may well have one planned for the future. The module has threee identical pcbs inside, each one for five of the pots, and each holding three TL064CNs, with differing value capasitors for the various frequency bands. A-148 Dual Sample & Hold ------------------------- This is a simple and basic sample and hold, with two per module. Each one has a trigger and a sample in, and a S&H outpot socket. There also are a couple of leds displaying +/- control for the output signal. Internally, each S&H uses a MC14053BCP, and a TL064CN. A-150 Dual VC Switches ----------------------- This is an amazingly simple but highly effective and usefull module to have. Each vc switch has four sockets: a control volt input, an input/output 1 & 2, and an output/input socket. The I/O 1 and I/IO 2 have an led indicator each. As the name suggests, by applying a control voltage of less than -3.6v, the input of I/O 1 is routed to the O/I socket, and when a cv of more than +3.6v is applied, then the input of I/O 2 is routed. As an example of it's use, by patching a square wave into the first input, and a sawtooth into the second, and using the square wave as the cv switching source aswell, you will have a waveform at the output that consists of a single cycle of each of the two inputed waveforms. Controlled switching between two different filter types is also great fun. Although I haven't yet tried it, I understand that the sockets are bidirectional, which in practice should mean that a signal put into the O/I socket can be switched to either of the other two. The pcb uses a BC549, and a MC14053BCP IC for each of the two switches. A-191 Midi-CV/Shepard Generator -------------------------------- I'm going to hang back on my opinions on this module for a while. You see, it was originally advertised as a straight forward Shepard Generator, which to put it simply, is a device which generates a number of modulating waveforms, triangle for example, each of which is slightly out of phase with the last, giving rise to the possibility of infinitely rising filters etc. But since ordering them, Doepfer have drastically changed the spec, adding a midi input, allowing such delights as the ability to sync the waveforms to midi, and enabelling the module to output midi controllers from the output sockets, such as #01 (mod. wheel), #05 (portmento), #10 (pan) etc. Unfortunately, as the module has a digital side of it, which requires operating via a push button system, and the only documentation currently supplied with it is in German, it's going to take me a little while to get my head fully around the damn thing. (If there are any German speaking friends out there who own one, and could email me a summery of the nineteen page manual, I would be most grateful). Externally, it has sixteen output sockets, five push buttons, three LEDs, and a midi input socket. Internally, it has an eprom, an Intel 8052 processor, two 5628CNs, a TLC272IP, a DM74LS573N, a H4C509, and a 9526, and is all contained on two pcbs. This module, as the forthcoming A-190 midi-cv module, requires a five volt supply, unlike the rest of the system, which uses plus/minus twelve. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - There are no new forthcoming modules to report on at present, with the exception of three utility type ones, which should be available at the end of this year. These are- A-176 CV Source - Provides 3 manally adjustable CVs, 2 of which have an additional fine control pot (for precise tuning of a VCOs frequency etc). A-177 ECM - An interface for the connection of external controllers such as a foot pedal etc A-179 BAC - The Bus Access Module provides access to the system-bus. It also will have 'signal refreshing' amplifiers for use when in connection to more than one rack frame. I should have another batch of modules with me sometime in December, which will include the new A-111 high end oscillators, and the first two vocoder modules. I'll hopefully post Part Four to the lists before Christmas, depending upon when they arrive. Until then, chow :) Sean. **************************** *** Sean Coppinger :] *** *** == == == ==== == == == *** ** analogueman@delphi.com ** ** == == == ==== == == == ** ** + 44 (0)181 992 3351 ** *** or *** ** + 44 (0)956 17 52 68 ** *-*-*-*-*-*-*--*-*-*-*-*-*-* *** control the voltage ;) *** ****************************** ****************************