Huge Longjohns
long-serving member
Joined: 10/04/03
Posts: 1376
Loc: Where the black rocks stand gu...
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When is an 'analog' delay in fact a digital delay pedal?
#943151 - 25/09/11 07:07 PM
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Doing a bit of web research on analog delay pedals and there seems to be a strong
indication that a lot of the new pedals marketed as analog delay are in fact just analog
delay sounding ie they are digital pedals that are voiced to sound like analog. Artec are
apparently guilty of this according to many forums etc. So I'm wondering whether all the
cheapish Belcat, Biyang, modtone, Guitar Tech (many of which look spookily similar in
layout etc) pedals are all really digital and thereby guilty of deliberately misleading
us to cash in on the craze for old analog gear?
-------------------- "Ignorance more frequently begets confidence than does knowledge" Charles Darwin.
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RhinoTime
Joined: 01/04/08
Posts: 455
Loc: West Sussex UK
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#943164 - 25/09/11 07:35 PM
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I must admit it's a bit of a mystery to me why the analogue ones are desirable.
I still have an Ibanez AD-80 which I bought new nearly 30 years ago. It doesn't do
anything special as far as I can tell, unless you are fond of short muffled repeats. Always thought tape delay was nicer to be honest. And there are a lot of great
digital delays available as well. Personally the only reason I still have an anlogue
delay is laziness that prevents me shifting it on ebay.
Sorry, guess that
doesn't contribute to answering your question.
-------------------- I've never liked a solo violin, you need at least five for a proper fire.
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Folderol
Joined: 15/11/08
Posts: 2599
Loc: Rochester, UK
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#943165 - 25/09/11 07:38 PM
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The thing is, what exactly do you mean by analog?
IMHO the only truly
analog delays are tape systems (I suppose you could sort-of include spring reverbs)
The BBD delays that most people think of as analog are actually time sliced
analog samples that are then step-wise cascaded though a lot of sample/hold elements.
It's not much of a jump from there to stuff the first sample into an A/D
converter, rattle this down a digital buffer then recreate the sample at the end.
The main characteristics of the BBDs is a relatively high noise floor and
high-ish distortion. The fairly tight filtering needed also adds frequency response
'character'.
The fully digital version can be made to emulate these fairly
well, but are intrinsically much quieter and cleaner.
However, if the
makers are doing that and calling them analog, then yes they are being very naughty.
-------------------- It wasn't me!
(Well, actually, it probably was)
Edited by Folderol (25/09/11 07:39 PM)
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Huge Longjohns
long-serving member
Joined: 10/04/03
Posts: 1376
Loc: Where the black rocks stand gu...
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#943368 - 26/09/11 03:28 PM
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Quote:
I must admit it's a bit
of a mystery to me why the analogue ones are desirable
I have a Line 6 digital delay and (apart from
the fact that it won't sit on a power supply with any other 9v pedals r!) it
does an excellent Analog emulation (and tape too) so I have no axe to grind one way or the
other. I'm just interested to see whether all these pedals are actually being illegally
sold as Analog (in the sense that one would assume the actual delay circuitry were analog)
if they actually harbour AD/DA circuitry.
-------------------- "Ignorance more frequently begets confidence than does knowledge" Charles Darwin.
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Octopussy
Joined: 01/09/04
Posts: 559
Loc: Melbourneo
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#943372 - 26/09/11 03:44 PM
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I'm guessing that an analogue delay is storing sound in a limited buffer without
converting it into zeros and ones. So, no encoding and decoding through A/D and D/A
converters.
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thefruitfarmer
Joined: 01/09/04
Posts: 1672
Loc: Kent UK
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Octopussy]
#945576 - 06/10/11 10:01 AM
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This "number one
echo" from Electro Harmonix is pretty good. Basic echo pedal and the demo
vid talks about the gritty repeats things. I have one and I am happy with it.
It is pretty basic and the thing I would maybe like which is does n't have is the ability
to sync the repeats to MIDI or a tap.
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AllyB
active member
Joined: 07/03/04
Posts: 1030
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#947046 - 13/10/11 07:01 PM
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As an analogue delay user I've always been able to tell the difference between analogue
sounding and proper analague delays when shopping.. maybe it's because I'm looking for
brucket brigade or more specific words like that...
T-Rex chameleon will power
your line 6 along side 9v pedals btw!
-------------------- Producer etc
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nathanscribe
Joined: 19/01/07
Posts: 722
Loc: Yorkshire, by gum.
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Octopussy]
#948135 - 20/10/11 09:38 AM
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Quote Octopussy:
I'm guessing
that an analogue delay is storing sound in a limited buffer without converting it into
zeros and ones. So, no encoding and decoding through A/D and D/A converters.
This. An anlogue delay doesn't
convert the signal to digital information before processing it; a BBD (bucket brigade
device) uses chains of capacitors and transistors gated on and off alternately to pass an
analogue signal along. As Folderol said, there's signal loss a s it goes and filtering is
needed to reduce clock whine (the BBDs are clocked fast, but if you want long delays
without using lots of chips you have to clock them within the audio range).
Many of the so-called "analogue" delays found for cheap these days are as you say
digital - using the PT2399 sampling chip, for example - which is a 44.1kHz thing with
onboard RAM but an analogue feedback loop so you can filter the feedback as you like. For
what it's worth, I think they sound pretty good, but they do have their own character.
Not all cheap delays labelled "analogue" are digital - I believe Artec produce two
with that label but one is digital, the other (more expensive) using BBDs. I might be
wrong but that's what I read somewhere. I know the cheaper Belcat and the Biyang are
digital, but the Behringer VD400(?) is a BBD unit, as is their VM-1.
One of my
favourite delays is digital - the Digitech RDS1900. Later RDS units used custom
processors, but early models used off-the-shelf logic and RAM chips to give 8-bit sampling
with fairly limited bandwidth - and they sound great. Pretty flexible and can be found
for dirt cheap.
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dmills
Joined: 25/08/06
Posts: 2133
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#948436 - 21/10/11 04:09 PM
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Well the get out for the 'analogue' pedals is of course that they have analogue gain
stages, filters and probably an analogue signal in the clock generator feedback loop (oh
and the power supply probably uses linear (analogue) voltage regulators)......
I don't see them claiming to be BBD delay line pedals, so as far as I can see, marketing
bullshyt but well this side of the 'trade descriptions' act line.
Regards,
Dan.
-------------------- Audiophiles use phono leads because they are unbalanced people!
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Folderol
Joined: 15/11/08
Posts: 2599
Loc: Rochester, UK
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: nathanscribe]
#948458 - 21/10/11 06:24 PM
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Quote nathanscribe:
Quote Octopussy:
I'm guessing
that an analogue delay is storing sound in a limited buffer without converting it into
zeros and ones. So, no encoding and decoding through A/D and D/A converters.
This. An anlogue delay doesn't
convert the signal to digital information before processing it; a BBD (bucket brigade
device) uses chains of capacitors and transistors gated on and off alternately to pass an
analogue signal along. As Folderol said, there's signal loss a s it goes and filtering is
needed to reduce clock whine (the BBDs are clocked fast, but if you want long delays
without using lots of chips you have to clock them within the audio range).
Not thinking of the SAD1024 by any chance
 With a 10kHz clock you'd get just over 100mS delay, but I seem to remember most tape
delays at the time were around 300mS.
-------------------- It wasn't me!
(Well, actually, it probably was)
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nathanscribe
Joined: 19/01/07
Posts: 722
Loc: Yorkshire, by gum.
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Folderol]
#948509 - 21/10/11 10:54 PM
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Quote Folderol:
Not
thinking of the SAD1024 by any chance
With
a 10kHz clock you'd get just over 100mS delay, but I seem to remember most tape delays at
the time were around 300mS.
Nah, just BBDs generally. They come with different numbers of stages, as you probably
know, and the shortest one I've seen was only 128, the longest 4096 - though they can be
chained. Many old delay pedals used the MN3005 or 3205, which where 4096 stage devices,
and ran them to give about 300ms of max delay. I've not heard any that have escaped clock
whine totally, though some are better than others. I have two JHS Mini-Echotec MX99 units
(cheap 80s job) and one uses a 3008 (2048 stages) the other a 3005 - but to give the same
overall delay time range. The 3008 model is noticable rougher and whinier, which can be a
good thing for deliberate grunge.
For info, my only recent BBD unit is the
EHX Memory Boy, which uses 4 chained 3208s, so 8192 stages in total. It's not whiney, but
does grit up nicely at the longer times.
I built a delay for someone awhile
back which used a single 3007 to give chorus, flange and echo - I managed to push the max
delay time to about half a second i think, by which time the repeats were just mush -
lovely, broken, garbled mush.
Regarding the digital pseudo-analogue units of
recent times, I have a Biyang AD-7 which from what I gather was originally labelled
"analogue delay" but became "analogy delay". Ahahaha.
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Huge Longjohns
long-serving member
Joined: 10/04/03
Posts: 1376
Loc: Where the black rocks stand gu...
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#948568 - 22/10/11 02:46 PM
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Quote:
ut well this side of the
'trade descriptions' act line.
Hmmmm,
not sure about that. I work in advertising myself and if you sell something deliberately
using language that will make the consumer think it's something different to what it is
actually is I think you're walking a tightrope. "Clearly m'lud, these companies are trying
to cash in on the current vogue for old grungy bucket brigade pedals which go for a
fortune on ebay etc, by pretending these digital pedals use the same, entirely analog,
technology. And they don't, even if they can sound similar." Analogy is what it is,
exactly, analogish, but surely not analog (or, indeed, analogue).
-------------------- "Ignorance more frequently begets confidence than does knowledge" Charles Darwin.
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Folderol
Joined: 15/11/08
Posts: 2599
Loc: Rochester, UK
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#948582 - 22/10/11 05:05 PM
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@ nathanscribe I confess to being a little disingenuous  The
SAD1024 was one of the first (if not the very first) BBD to be commercially available to
us plebs - still bloody expensive though and quite easy to pop. I had an
indulgent boss at the time who allowed my to buy a couple and experiment with them in
quiet periods. One thing I discovered that was a bit disconcerting at first was that the
clock 'whine' was dependent on the signal waveshape and level! Balance it for near zero
with no sig and as soon as there was any input there was the whine too. Minimise it for a
sinewave input at moderate amplitude and switching to a square wave, changing the
amplitude or frequency would all result in more whine  I have been rather surprised that I've seen no commercial use of another discovery I
made. If you run at a fairly high clock speed and use a VCO as the clock oscillator, then
applying a LFO to this will give you instant vibrato - quite interesting on a recording of
a piano especially if you fiddle with both the LFO amplitude and frequency. Alternatively
a DC sweep will give you portamento
-------------------- It wasn't me!
(Well, actually, it probably was)
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nathanscribe
Joined: 19/01/07
Posts: 722
Loc: Yorkshire, by gum.
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Folderol]
#948587 - 22/10/11 05:37 PM
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Quote Folderol:
I have been
rather surprised that I've seen no commercial use of another discovery I made. If you run
at a fairly high clock speed and use a VCO as the clock oscillator, then applying a LFO to
this will give you instant vibrato - quite interesting on a recording of a piano
especially if you fiddle with both the LFO amplitude and frequency. Alternatively a DC
sweep will give you portamento
I used that in the unit I mentioned
above. The 'official' way to clock a BBD is with the dedicated driver IC (eg. MN3101 or
equivalent) but I used a 4046 fed by a summed LFO and manual osc CV. I've seen various
other methods including discrete oscs. If even I can make this work it can't be too
obscure.
Also, the old Boss VB-2 vibrato pedal used a BBD to generate
vibrato in a similar way.
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Folderol
Joined: 15/11/08
Posts: 2599
Loc: Rochester, UK
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Re: When is an 'analog' delay in fact a digital delay pedal?
[Re: Huge Longjohns]
#948599 - 22/10/11 07:21 PM
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Oh bugger! All I can say is see my current sig!
-------------------- It wasn't me!
(Well, actually, it probably was)
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