Have you ever been bitten by a loud little dog? In the back of your knee, or maybe in your hand? That does sometimes happen, even though the critters in question “never bite”, as their owners assert.
Now, to be fair, there are different types of dogs …
Let’s take the big ones. They can give you a deep growl and a loud snarl and still be basically nice critters, more playful than vicious. Gentle giants … Then there are the mean little ones! Tugging at their leashes, they bark at anything that moves. They are really aggressive, despite their tinyness. Really mean, the opposite of those big members of their species.
Panning over to GRP, we find astonishing parallels to this animal world.
The A8, for example, is a big dog. It has a mighty growl (bi-timbral, if you need it), but in the end it’s good-natured, usually well-behaved and seldom brash. Just the opposite of its little brother, the A4. This one tugs like mad at its leash, yaps uncontrollably and can be freakish. Bundled fury, the tonal reincarnation of that mean little dog that tries to take a bite out of you now and then …
Half of an A8? You’re kidding …
Those who might not know the „big one” should look at the test report on the GRP A8. A feast for the eyes, that synthesizer, and tonally state of the art, there’s no doubt about it. Essentially the GRP A4 can do what half of an A8 can do, excepting the fixed filter bank sounds, of course (this module is missing). In the last months, I confess, I was a bit sceptical as to whether an A4 really had something “new” to offer. Being just “half an A8” - which is what it looks like on paper and at a glance, and which is what all the online information and forums and discussions, etc. would seem to insinuate.
Let’s be honest, it just isn’t that way. The A4 has many (sometimes unexpected) special features that neither the big A8 nor any other instrument offers. It’s a completely independent synthesizer – not just within the GRP group. Fundamentally independent.
Concept and layout
The GRP A4 offers:
- 3 VCOs
- 2 sub-oscillators
- white / pink noise
- ring- and cross-modulation
- VC low frequency oscillator 1
- low frequency oscillator 2
- sample & hold
- VCF 1: 6/12/18/24dB low pass
- VCF 2: HP/BP/LP/Notch multi mode
- 2 envelopes with auto-repeat function (!)
- portamento, bend amount, hold, A = 440 Hz test tone
- 2×8 / 1×16 step CV and GATE sequencer
- Audio-in, ext. env. follower
- MIDI (vel, aftertouch, bender, clock, …)
- CV/Gate (VCO, VCF, VCA, …)
Where to begin? Perhaps indeed with the A8. Again, I recommend taking a glance at that earlier report and listening to some of those soundfiles. This inadvertently also says a lot about the A4. And we gain the freedom to dedicate this report exclusively to the new GRP A4 – that aggressive critter tugging on its leash.
From here it’ll be slow going. We don’t want to miss any of the subtle innovations. Here a reduction (now “only” 3 modulations sources for PWM – LFO 1/2, sequencer – in opposite to the 12 to be found on the A8 – 11 + sequencer), there an enhancement (improved FM options: 11 powerful modulation sources, now including velocity, aftertouch and modwheel). Increased beating according to finger pressure …! A wonderful feature, demonstrated in the soundfile „3VCOvelocityFMsolo“.
The mixer regulates the volume of VCO 1/2/3, sub-oscillator 1/2, ring-modulator, noise and the external audio signal.
Voltage Controlled Filter
We’re going to spend a little time here. The extensive filter department of the A4 is in many respects, hmmmmm ….. spectacular. The basic outfit – two VCFs useable individually as well as in series or parallel – hasn’t changed a bit since the A8. However, the following innovations have turned the A4 filter setup into the mightiest sound weapon on the analog synthesizer market.
- independent volume control on both filters. Admittedly, a must …
- independent distortion control on both filters, with superior results
- Direct Out. Unique! The 24dB filter is relegated to the left audio output, the 12dB filter to the right audio output. Result: a fabulous stereo audio image, emerging from the shadows of the GRP A8 and in fact outdoing its predecessor because of the improved modulation possibilities of the VCFs.
- switchable 6/12/18/24dB low pass filter. The slender 6dB I find to be especially attractive – a refreshing alternative to the tried and true 24dB filter sound.
- 6 (!) FM-paths per filter:
- FM1: 11 modulation sources
- FM2: VC LFO 1
- FM3: sequencer-CV or keyboard tracking
- velocity control of the filter envelope
- analog CV-IN (patch panel area)
- LFO 2: global modulation of both filters (adjustable in the LFO 2 section)
Well, to be honest – the filter sounds are beyond description. A major feature is, of course, the new distortion function, along with sound enhancement thanks to the (filter) direct-out mode.
Need convincing? Listen to “3VCOliveSequTrigFMVCF_2″ attached to this review. No auto-pan is used, even if you think you hear it. Instead, both filters are sent separately to left and right output, independently controlled by VC LFO 1 … which, in effect, results in an auto-pan image, with increased flexibility.
By the way: this function DIR OUT (practically invisible – there is just this little silver switch), is a by-product of the huge A8. From the very beginning it was clear that the biggest deficit of the A4 (in comparison with the A8) would be the missing stereo sound. The only possibility to counteract this was to split the A4 signal path at a certain point. This probably caused some headaches among the technicians. Which is why Paolo Groppioni handed the A4 prototype over with a shoulder buff and a wink and the comment: „THIS was a lot of work“.
Envelopes with LOOP-function
The two envelopes are for the VCFs and the VCA respectively. The envelope amount can be adjusted separately for the 24dB- and 12dB-VCF (again, with positive and negative intensity).
The LOOP function is new. Once activated, it auto-triggers each envelope, whereby the trigger-speed is in direct relation to the envelope settings. EMS VCS3 / AKS synthesizers have this function, but also the EDP Wasp and the OSCar.
Viewed in this light, we have two „additional LFOs“, because in effect, the cyclical sequence of the envelopes comes very close to the result of an LFO modulation. Whereby all modules – LFOs and also the loop-EGs – go far up the audio range, thus providing the basis for sublime experimental tonal results (this includes premium vocal sounds).
If the loop function is set to GATE, it will only be enabled if you hit a new key. This can be of special importance when playing legato (when only single notes within a melody are effected by the loop EG while all others stay unchanged).
Players with only basic piano skills can also profit from this feature. Legato can be programmed step by step via MIDI (and a software sequencer). This has the advantage that gate times and velocity values can be precisely programmed, and that the A4 sequencer may be clocked to MIDI (as well as LFO 1 … and auto-pan). This is just one example of how flexible the A4 is when controlled by MIDI.
There are 16 (!) VCAs in the GRP A4. The most important ones are:
- 2 VCAs for the AUDIO signals (L – R)
- 2 VCAs for AUTO-PAN (L – R)
- 2 VCAs for the LFOs (VC LFO 1 – LFO 2)
- 2 VCAs for processing velocity on both filter frequencies
The „main“ VCA section contains an ADSR envelope. This VCA may also be controlled by VC LFO 1 and – adjustable in the LFO 2 section on the opposite side of the instrument – by LFO 2. And there’s even an external CV input for the VCA.
This is especially interesting in combination with the internal step sequencer. With the help of a short patch cable you’re able to route any of the two sequencer rows to the VCA. A nice little feature.
But however you look at it, this doesn’t play a significant role with the GRP A4. Simply because the user can create his own personal auto-pan in the filter department. We mentioned this briefly: the stereo-modulation of the two filters in DIR OUT mode … which results in an auto-pan image, with increased flexibility.
But let me describe how to program a “perfect” auto-pan sound …
Switch the filter routing to DIR(ect) OUT. Set both filters (left and right) to 12dB low pass. Now turn up frequency modulation by LFO 1 (FM path 2), set the left intensity to positive, the right to negative. Voilà … you’ve got a perfect auto-pan sound. Now, let’s go a few steps further. Switch the left VCF to 6dB and the right to NOTCH. Keep LFO 1 for the left filter modulation and choose LFO 2 for the other … we’re already far beyond the usual simple, boring auto-pan settings. And yes, I told you there are 6 (!) FM-paths with each filter – so you can imagine how flexible the „stereo modulations“ on both VCFs can be. A few more steps: use the internal sequencer, experiment with sample & hold, raise LFO 1 speed to 1 kHz, etc. The creative possibilities by just fiddling around seem endless. And we haven’t usedMIDIyet … add some velocity- and modwheel-control. It’s great fun!
An independent auto-pan module still has great advantages. Once enabled, the sound moves automatically from one side to the other (of course …) and auto-pan can be synchronized to LFO 1 (and thus toMIDI).
VC LFO 1
By the way, the aftertouch signal may be replaced by an analog CV. Use any external control voltage for dynamic modulation purposes. Once again, applying the internal step sequencer would be a quick solution. Patch Row B to CV AFT T and off you go …
Ah yes, this socket functions for both VCA and AFT T control. Tip = VCA, ring = AFT T. It’s the only stereo socket on the GRP A4 patch panel.
It should be clear by now that the potential inherent in the LFO 2 is dramatic.
Sample & Hold
Finally, we’re here! The sequencer is indisputably a GRP gem. It provides:
- 2 CV-rows à 8 steps
- 2 Gate-rows à 8 steps
- end step / skip function with each step
- 2 x glide: row A / row B
- 2 x range: x2 / x4 / x8 (= 2 / 4 / 8 octaves)
- 2 x quantizer: row A / row B (on/off)
- several step repeat options
- several clock divider options
- several sequencer modes (forward, backward, alternatively, random, …)
Detailed information of these individual functions can be found in the GRP A8 report. But there are some additional GRP A4 novelties …
CV SEQ CLOCK: row A or B can now be used for speed control (as with the old but wonderful Korg SQ-10 sequencer). This allows for syncopation and other rhythmical niceties. The downside of course, is that you loose one of the two sequencer rows. But we have the solution at hand … (please continue reading :o).
CV IN CLK MOD: it’s also possible to use an external control signal for speed control. There’s a CV IN jack in the patch area. Excellent.
ROW A / A+B TRNP: this allows merging sequencer and MIDI data for external CV/Gate use. Patch MIDI CV OUT with (e.g.) ROW A+B TRNP for real-time sequencer transposing (via MIDI) of any CV/Gate synthesizer connected to the A4. This is not necessary when running the A4 itself (here, MIDI- and sequencer-data is merged internally and automatically in the VCO section). But it’s necessary when controlling other analog synthesizers (such as Roland SH-09, ARP Odyssey, etc.) with the A4 sequencer. Logically, you want the outputted sequences to follow your MIDI-masterkeyboard transpose commands, of course! And there you have it, the solution we promised you.
In addition, the GRP A4 now also offers a full MIDI-CV/Gate interface. Another welcome aspect …
VCO 1 OFF
I’m sure you have those legendary sync sounds of the 70s and early 80s in your ear. Screaming like an electric guitar was one of the most characteristic sounds of analog synthesizers.
There are many ways to obtain this typical sync-effect. LFO modulation of the slave-oscillator is probably the simplest one. Those who want to play more expressively will try to control the sync-effect with their fingers, instead. Via pitch-bender, for example.
And this is why you need the VCO 1 OFF switch. Since bending all VCOs would result in no sync-effect at all, the master-oscillator (VCO 1) must be disabled. It’s a simple, but absolutely necessary detail. And it’s one of the important features that the large A8 is missing (although this instrument offers other advantages, I have to admit).
Paolo Groppioni even went a step further: VCO 1 OFF is also available for portamento. So, while the 1st oscillator immediately plays the correct pitch, VCO 2 and 3 get there slowly, depending on the portamento time you set. A great source of subtle (or drastic) sound effects.
EXT In / ENV Follower
This is probably one of the most intriguing modules of the A4. An external signal can be fed into the synthesizer. What you do after that depends on your final sound goal. The external signal can …
- be used for regular signal processing (through VCF and VCA)
- become part of the ringmodulation sound
- become part of sample&hold
- trigger the envelopes
- control speed (!) of VC LFO 1
- control both filter frequencies
That sounds exciting, right? Since I never use a microphone in my studio (I don’t even own one!), I have to refer to Enrico Cosimi for sound examples. He demonstrates the EXT In / ENV Follower module very well in his third GRP A4 Youtube Video for Audio Central Magazine. You can also learn a little Italian in the video, which is always handy!
However, there’s one sound sample at GreatSynthesizers, where the Jomox XBase 09 drum machine was fed through the filters of the GRP A4. Worth listening to …
The CV/Gate panel gives us clear information as to which possibilites there are for control voltage. Many of these have already been discussed. On the back of the A4 there’sMIDIIN / THRU and USB. This last interface is no substitute for MIDI. It enables eventual firmware updates (sequencer & MIDI program).
And, is the GRP A4 good?
You’ll find 50 minutes of sound files attached to this review. Do take the time to “give them a listen” and make your own picture of what this instrument can do. Or of “some” of what this instrument can do …
Almost. Even the GRP A4 has some things missing, and some solutions aren’t ideal … Exactly two things come to mind.
First, filter frequency modulation is not possible via pitchbender. I was really surprised that, with all the sophisticated technology of the A4, this simple and very important aspect was not taken into account. Sure, there are tons of modulation sources for both filters: modwheel, velocity, aftertouch, all 3 (!) VCOs … however, the pitchbender can not communicate with the filters. This might be no “really big” problem for most musicians, since the modwheel is also there for modulation purposes. But what if you use a Roland MIDI keyboard? It usually has a stupid pitchbend-modwheel combination, offering only very limited modulation performance control by shifting the whole thing a few millimeters (!) away. This is no substitute for a real modulation wheel, not at all.
Certainly, there are other companies whose keyboards feature two proper wheels, one for pitch bending, one for modulation: Yamaha synthesizers, Kurzweil keyboards, the Alesis Andromeda, the John Bowen Solaris, etc. Better to use one of those keyboards to control the A4!
GRP A8 and GRP A4
It remains to be said, that the A4 has a limited production. GRP has extended the production plan somewhat and is going to build a total of 50 units. At the moment, 37 of these have been prepaid and thus ordered. True, there is a realistic chance that a second edition of the A4 will be produced. Production of this little critter is simple easier than that of the “big dog” A8.
Update March 2013: Due to large demand, GRP will build a second series of the A4 synthesizers in summer 2013. Contact for info and reservation.
GRP A4 (second series, 2013)
Production: 50 units
Delivery: summer / autumn 2013
Price: € 3,667.– plus taxes and shipping
(approx. 4,400 Euros + shipping)
Website GRP: www.grpsynthesizer.it