You are here

When is an 'analog' delay in fact a digital delay pedal?

For all things relating to guitars, basses, amps, pedals & accessories.

When is an 'analog' delay in fact a digital delay pedal?

Postby Dr Huge Longjohns » Sun Sep 25, 2011 7:07 pm

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?
User avatar
Dr Huge Longjohns
Frequent Poster
Posts: 2257
Joined: Wed Apr 09, 2003 11:00 pm
Location: Gallifrey

A goal without a plan is just a wish


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby Random Guitarist » Sun Sep 25, 2011 7:35 pm

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.
Random Guitarist
Regular
Posts: 480
Joined: Mon Mar 31, 2008 11:00 pm
Location: West Sussex UK

I've never liked a solo violin, you need at least five for a proper fire.


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby Folderol » Sun Sep 25, 2011 7:38 pm

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.
User avatar
Folderol
Jedi Poster
Posts: 4625
Joined: Sat Nov 15, 2008 12:00 am
Location: Rochester, UK

Save paradise, Pull up a parking lot!


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby Dr Huge Longjohns » Mon Sep 26, 2011 3:28 pm

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.
User avatar
Dr Huge Longjohns
Frequent Poster
Posts: 2257
Joined: Wed Apr 09, 2003 11:00 pm
Location: Gallifrey

A goal without a plan is just a wish


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby Octopussy » Mon Sep 26, 2011 3:44 pm

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.
Octopussy
Regular
Posts: 146
Joined: Tue Aug 31, 2004 11:00 pm

Re: When is an 'analog' delay in fact a digital delay pedal?

Postby thefruitfarmer » Thu Oct 06, 2011 10:01 am

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.
User avatar
thefruitfarmer
Frequent Poster
Posts: 510
Joined: Tue Aug 31, 2004 11:00 pm
Location: Kent UK

Re: When is an 'analog' delay in fact a digital delay pedal?

Postby AllyB » Thu Oct 13, 2011 7:01 pm

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!
AllyB
Regular
Posts: 220
Joined: Sun Mar 07, 2004 12:00 am

Re: When is an 'analog' delay in fact a digital delay pedal?

Postby nathanscribe » Thu Oct 20, 2011 9:38 am

Octopussy wrote: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.
User avatar
nathanscribe
Frequent Poster
Posts: 858
Joined: Fri Jan 19, 2007 12:00 am
Location: Wakefield, for my sins.

I have no idea what I'm doing.


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby dmills » Fri Oct 21, 2011 4:09 pm

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.
dmills
Frequent Poster
Posts: 1543
Joined: Thu Aug 24, 2006 11:00 pm
Location: High Wycombe, UK

Audiophiles use phono leads because they are unbalanced people!


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby Folderol » Fri Oct 21, 2011 6:24 pm

nathanscribe wrote:
Octopussy wrote: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.
User avatar
Folderol
Jedi Poster
Posts: 4625
Joined: Sat Nov 15, 2008 12:00 am
Location: Rochester, UK

Save paradise, Pull up a parking lot!


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby nathanscribe » Fri Oct 21, 2011 10:54 pm

Folderol wrote:
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.
User avatar
nathanscribe
Frequent Poster
Posts: 858
Joined: Fri Jan 19, 2007 12:00 am
Location: Wakefield, for my sins.

I have no idea what I'm doing.


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby Dr Huge Longjohns » Sat Oct 22, 2011 2:46 pm

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).
User avatar
Dr Huge Longjohns
Frequent Poster
Posts: 2257
Joined: Wed Apr 09, 2003 11:00 pm
Location: Gallifrey

A goal without a plan is just a wish


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby Folderol » Sat Oct 22, 2011 5:05 pm

@ 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
User avatar
Folderol
Jedi Poster
Posts: 4625
Joined: Sat Nov 15, 2008 12:00 am
Location: Rochester, UK

Save paradise, Pull up a parking lot!


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby nathanscribe » Sat Oct 22, 2011 5:37 pm

Folderol wrote: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.
User avatar
nathanscribe
Frequent Poster
Posts: 858
Joined: Fri Jan 19, 2007 12:00 am
Location: Wakefield, for my sins.

I have no idea what I'm doing.


Re: When is an 'analog' delay in fact a digital delay pedal?

Postby Folderol » Sat Oct 22, 2011 7:21 pm

Oh bugger!
All I can say is see my current sig!
User avatar
Folderol
Jedi Poster
Posts: 4625
Joined: Sat Nov 15, 2008 12:00 am
Location: Rochester, UK

Save paradise, Pull up a parking lot!



Who is online

Users browsing this forum: No registered users and 2 guests