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Re: Multiple loops on the EDP



You're missing a bunch of things, actually. The interface would certianly 
be
a nightmare, but that's not it. The main reason it's impossible in the
echoplex is because of the multiplies done for feedback. The echoplex is
several years old now, and therefore uses a somewhat dated processor, and
doing a 16x8 multiply on each sample takes up quite a few cycles. (It
doesn't have any additional DSP part because that was much too expensive at
the time, and wasn't considered necessary.) In addition to that, it's a 
very
control intensive device, with a lot of different control inputs from the
user interface. In order to guarantee very low latencies for all possible
inputs and midi, it has to devote quite a bit of it's processor to a real
time OS for handling everything for fast real-time operation. That
guarantees rhythmic precision from the controls and accuracy for syncs,
while making sure audio always goes to the right place in time. Also, the
echoplex and other loopers do both recording and playback simultaneously, 
so
it's full duplex, meaning there are really two audio streams that must be
supported per loop. There's not enough power there in the echoplex to 
handle
the interface, realtime OS, audio bandwidth, and more than one feedback
multiply for each sample. Having that power would have meant making it much
more expensive than was considered appropriate. However, there's still 
quite
a lot going on in there beyond simple accessing memory and mixing. Also, a
lot of the cost goes into things like good internal power supplies, large
amounts of memory, and rugged sheet metal chassis, leaving less for 
processors.

as for the samplers you are talking about (presumably the boss sp202, which
lists for $395, not $200 - that's the only sampler I know of that's even
close in price to the various loopers) the case is fairly different, and
such a price comparison doesn't really hold up. some points about it are:
        a) only 4 voice polyphony and using much lower sample rates, 
           so its not doing as much processing as you think. 
        b) not doing anything like feedback. (although it has some simple
effects,
            which lower polyphony when you use them.)
        c) not full duplex, you can't record and playback at the same time
        d) has minimal user interface 
        e) not required to have very low latency controls
        f) designed by large Japanese companies that can risk the R&D on
            designing custom ASICs for one product (and can afford it), or 
are
            able to reuse asics from other products. 
        g) are able to support much larger sales volumes, since basic
samplers are 
           much more popular than loopers. this lowers costs and 
           makes things like custom ASICs more appropriate - loopers like
           the echoplex are not large volume products and have to rely on 
more
           expensive parts.
        h) using cheap wall-warts and built into a flimsy plastic case -
much cheaper, 
           but don't step on it!
        i) has only 1/2 MB of memory built in. (and uses expensive memory 
to
expand)
        j) very minimal midi (in only), and not other control input
        k) no sync
        L) etc....

Now I don't mean to knock the boss unit, it's a cool little thing for what
it does. But Roland and Oberheim (and Lexicon and Boomerang too) made
radically different design decisions in creating the features for these
things. Basically, Roland put all of the cost in the custom processor,
leaving little left for anything else, Oberheim put much more emphasis on a
sturdy design, high quality audio, and a large user interface. not to
mention completely different features requiring different processor needs.

anyway. as you can see I didn't do any work today. Been on jury duty...:-)

kim


At 08:21 PM 8/11/98 -0400, The Unit Circle wrote:
>Sorry Travis,
>
>I really don't think so.  $200 samplers do this.  I think the only reason
>that this isn't a feature in the current loopers is because it is a
>user-interface nightmare.  I assuming that since the EDP lets you undo a
>loop addition,  it's already storing your add-ons separetely from the main
>loop and doing on the fly mixing.  The only difference between this and
>different-length loops is adding a tiny bit of overhead to keep track of
>the different beginning and end points and current location in the 
>sample. 
>
>Kevin
>
>> 
>> Kevin wrote:
>> 
>> >Uh, no.  If the EDP had the multiple different length loops, it would 
>have
>> >been the extra needed justification for me to buy it and spend the time
>> >with it.  
>> 
>> My recollection is that the EDP will allow you to have multiple loops 
>of 
>> different lengths, but you can only play one at a time.  My 
>understanding 
>> of digital playback systems is that playback of multiple independent 
>> "tracks" (loops in this case) requires more processing power, driving 
>the 
>> price up.
>> 
>> Travis Hartnett
>> 
>
>
>
_________________________________________________________
Kim Flint, MTS                     kflint@chromatic.com
Chromatic Research                 408-752-9284
http://www.chromatic.com