Newsgroups: rec.music.makers.synth
From: cassiel@cassiel.demon.co.uk (Nick Rothwell)
Subject: By public demand etc, Impressions of Peavey DPM-{SX,SP}
Date: Sat, 2 Jan 1993 22:34:00 +0000

I must stop this habit of mentioning whenever I come across a new piece of
gear; people keep mailing me asking for reviews of it. If only the
magazines would do likewise.... Anyway, some off-the-top-of-my-head
comments on the Peavey SX sampling front-end and SP sample player. This is
just stream-of-consciousness stuff rather than exhaustive and structured,
and I can't be bothered to go across the room and actually check things on
the units, so I'm just going to blather instead. Note also that I've only
been using it in earnest for a week or so, so I'm probably not fully
up-to-speed yet.

Why did I go for the Peavey? A number of reasons, such as clarity and
transparency of function (which roughly corresponds with ease-of-use, btw),
lack of creeping featurism and other chrome, small footprint (for a
rackmount, perhaps that should be palm-print?) and reasonable price.
Actually, perhaps I should mention the more fundamental reasons. I've been
looking at samplers ever since the Ensoniq Mirage, waiting for a machine to
come along which satisfied my requirements (sensible mass-storage, decent
file system, respectable sample transfer facilities, easily expandable
memory, flexible performance architecture). The Peavey is the first:
generic SCSI disks, standard SIMM's, decent firmware and SMDI. I can't
think of any previous products that satisfy these requirements.

Why did I *not* go for the K2000R? Well, the K2000R isn't (yet) a sampler,
it's overpriced in the UK ($3500 or so) and I refuse to let my finances and
artistic projects and plans be held to ransom by some wonder-machine which
can unleash my creativity and so on and so on. If the K2000 is that good,
I'll buy one in a year from the US. Right now, I have a deadline for a
performance project (more contemporary dancers, yummy) and need(*) a
sampler.

Basic overview: the SX is a 1U sampling front-end. It can sample in mono
via line or balanced XLR, and offload the sample via MIDI SDS or SMDI. The
front-panel functionality is sparse but adequate, and the unit can be
pretty much completely controlled by SysEx. The SP is a sampler without the
ability to sample; it can read sample files from floppy or SCSI disk, or
accept MIDI SDS and SMDI data. The idea is that the two units are
connected, ideally by SCSI for decent speed. Two drawbacks of this: the
combined system uses up *two* SCSI id's out of eight (not counting disks of
course), and secondly the SX always powers up with SCSI id 0 unless you
hold down a magic combination of buttons - this latter is a true pain in
the backside since all Mac internal disks have id 0 as well. The SP can
have id changed by internal jumpers. (Termination is also removable
easily.)

One benefit of having two separate units is that (analogue) resampling is
easy; just play the SP (through effects boxes or whatever) into the SX. Not
many samplers allow this - yet.

The SP controls the SX via SCSI as well as getting samples from it, and one
cute feature allows the SP's 2x20 LCD display to act as a level meter for
the SX - an interesting use of SCSI, I have to admit.

The SP can drive any half-sensible SCSI disk; I've driven Rodimes and
Quantums with it. It can install its own file system on the disk, but
doesn't have low-level formatting facilities, so you'd have to use
something else if you wanted to change interleave for example.

Not much more to say about the SCSI aspect of things, despite it being
crucial to the system. I have the SP, SX, two rackmounted Quantum disks,
and the SE/30 connected up on the same bus so that I can transfer samples
to/from the Mac via SCSI. One of the Quantums is for the SP, the other is
formatted for the Mac. The only real problem is that the Mac SCSI firmware
assumes it can grab the SCSI bus whenever it feels like it, so you have to
stop it doing so whenever doing SCSI on the SP (latching down a menu is my
preferred method, since menu tracking is a tight loop in the ToolBox ROM).
There's also all the hassle of getting SCSI termination right, but that's
no problem for anyone who's got a degree or two in computer science. Oh:
the SX only has one SCSI connector, which is a bit stupid - it has to go at
one end of the chain. So much for my plans for sampling in stereo with two
SX's...

On to the SP's performance architecture. 16 voice, two stereo output pairs,
no onboard effects. The *voice* architecture isn't much to write home
about, mainly because you've got (i) low-pass non-resonant filters and (ii)
that's about it. Given that, the *performance* architecture is quite
impressive, with good modulation options, bipolar and sideband modulation
rather like the MicroWave. Various LFO shapes and polarities, including
"grunge." Assignable external MIDI controller sources, and random
generators. Mod destinations include filter cutoff, LFO speed and depth,
pan position, amplitude. One LFO and two envelopes per tone (the voice
component). I'm not going to dwell on the modulation options mainly because
I can't be bothered, but they are quite impressive, and remind me very much
of what I remember about the E-MU Proteus boxes. The problem, of course, is
that there's only so much you can modulate, and without multimode or
resonant filtering you're limited. Actually, the lowpass filters do seem to
have a nice character to them. Before I forget, one interesting quirk: the
envelope generators have times but NOT levels: an envelope can either be in
gate mode (attack/decay/release) or trigger mode (attack/sustain
*time*/release). It seems a bit naive at first, but I rather like this
scheme, especially the trigger mode for shaping one-shot samples.

The performance architecture is in a number of layers: waves, tones, maps,
presets, multiset(s), bank. The SP follows the current fashion in not
having edit buffers: you edit the objects directly, creating new ones as
required, and playback reflects the current configuration of the system.
Note also that *all* the objects can be named individually, and names can
be copied between objects, which is rather nice. Waves are just sample data
plus loop information (single point, single direction (I think), no
crossfade), notional sample pitch. The SP knows about mono samples (such as
those from the SX), and via a procedure involving dancer sacrifices and
chicken entrails it can form stereo samples from pairs of mono ones.
(Panning a stereo sample seems to involve left/right attenuation, by the
way.) Tones are the things played by the voices: a tone is a wave plus DCF,
DCA, LFO, two ENV's, modulation options. I think pan settings and
modulation are the next level up (hang on, I'll check, since I have to
change the CD anyway... Cyrano de Bergerac soundtrack, recommended...) Ah.
Pan modulation options are in the tone, base pan position is in the map.
Note that the tone references any wave in the store; different tones could
use the same wave (different maps the same tone, and so on...).

Somewhere along here is the voice allocation machinery; tones (I think it's
tones) can be allocated to one of eight nominal voice busses; each bus has
a priority, a maximum polyphony, and a stealing/replacement algorithm
allowing various kinds of note muting. I forget the details, but it's a
very versatile scheme.

Next level up is the map; a map is named and numbered (of course), and
basically lays out a selection of tones across a nominal keyboard. The
number of zones is variable (maps are variable-size). For each zone,
there's a low and high point, and the tone is given a pan position and sent
to either the main or sub output jacks. Each zone either plays the tone at
a fixed pitch or keyboard-tracked with a specified transposition, and
specified volume level. Zones may not overlap.

Next up is the preset. A preset is the (named, numbered) thing responding
to a keyboard or to a single MIDI channel. This is where things get rather
bizarre. A preset plays a number of maps, but according to some rather
strange rules. A preset plays one or two layers at once (layer A and layer
B). These can be cross-faded by velocity, keyboard position, MIDI
controller, and so on. (I forget how many can take effect at once.) Layers
aren't first-class objects; a preset contains the two layers. You'd expect
a layer to refer to a map; in fact, it refers to four of them, switched by
velocity, MIDI controller, whatever (I think it can also be a random
pseudo-source) with assignable crossover points. But, only one map can take
effect for each voice, and even if selected by MIDI controller, once the
voice has chosen the map it lasts for the lifetime of the voice. I find
this bizarre but OK now I know how it works. The upshot of all this is that
any played note can fire from a selection of eight maps, but it can only
play two maps (i.e. two voices) at any time, one chosen from each preset
layer. The layer A map and layer B map voices can be dynamically mixed and
layered. The voice limit per note doesn't actually bother me since I use my
own performance software and can layer MIDI channels in all sorts of ways
anyway. Hmm, I don't recall the SP having any control over sustain pedal; I
think it's always on (hassle). Oh: there are other options at the preset
level: pan, output jack and various tone parameters can be overridden or
delta-incremented or decremented (U-50 style), and the layers can be
detuned with detuning available for modulation. I think the MIDI
controllers (aux1 to aux3) are assigned at preset level as well.

Next level up: multiset. 16 channels, each one either enabled or disabled,
each one with a preset and volume level. You can have sixteen multisets
(plus the current "edit" multiset) but presets and volumes are controllable
via MIDI so there isn't much point. I only have one multiset, permanently
configured for the (five) MIDI channels I'm using for the SP.

That's about it. A bank contains the entire state of the machine, from
waves all the way up to multisets. A floppy (or set of floppies) holds one
bank; a SCSI disk can hold several. You load a bank into the machine
manually (no MIDI-controlled loading). You can also pull waves, tones,
maps, presets across from other banks on disk in a scheme which almost but
doesn't quite work in all the ways you need. An obvious point: a bank
cannot be larger than the amount of RAM in the SP. Some of my banks are
current states for pieces of music, some are collections of raw waves, some
are sets of map templates.

Haven't mentioned the user interface yet. The usual sort, 2x20 LCD (better
than 2x16) with a generous number of dedicated buttons. Given this, the
user interface is pretty good, but there's only so much you can do with a
periscope, and setting up complex modulation routings is a bit of a hassle.
Nota bene: the SP has *no* SysEx implementation at all at the time of this
writing, so no librarians/editors are possible (librarians are rather
superfluous, but an editor would be welcome). The SysEx implementation is a
possible announcement at NAMM.

Can't think of anything else to mention. I have one or two minor gripes:
more sophisticated filtering would make a great difference, lack of remote
editing is a drawback, and the SX only samples in mono. (I'm still thinking
of the best way to rig two SX's to sample in stereo.) Otherwise, I'm pretty
impressed with the machine. For what it does, it does it very well, and the
modulation and performance options are quite impressive. It also seems
rock-solid and reliable, which is of course the most important thing.
Peavey UK's technical support is pretty good - I've chatted to them on the
phone at length - which makes a change. (Honorary mention here for Fostex
UK as well, who are very good.)

This review is shareware; if you decide to keep it, you are required to
send me a Lexicon LXP-1 via 2nd-day air. Failure to do so will result in
your receiving a copy of the Roland Guide to MIDI every week until you
comply.

And yes, I have more than enough of them to go round.

(*) Yeah, yeah...

                      Nick Rothwell  |  cassiel@cassiel.demon.co.uk
   CASSIEL Contemporary Music/Dance  |  cassiel@cix.compulink.co.uk

Newsgroups: rec.music.makers.synth