Scott's AD-3208 Analog Delay Project

[jsleep]

is posted:

http://www.generalguitargadgets.com/v2/index.php?option=displaypage&Itemid=156&op=page&SubMenu=

Looks fantastic! Have fun!

JD

[EdJ]

Great!
Thank you very much,
Greetings,Ed

[dubs]

Looks good! What is max delay time on it? 300ms?

[Scott Swartz]

With 2 BL3208, its a 4096 long BBD, so delay at 10 kHz clock (as low as I like to go) is 205 milliseconds.

All the typical analog delays Ibanez AD-80,AD-9, Boss DM-2, DM-3 are 4096 BBds.

With 2 MN3205s it doubles to 410 milliseconds.

[ohmen]

Have been searching for a good DIY analog project for some time. My frustration of not finding anything almost led me to buy to all to expensive Maxon ad-900, which seemed to be the best analog delay currently on the marked. As I have read the ad-900 originally came with two MN3205 chips which were later replaced with 4 MN3208 due to the scarcity of the MN3205. My question is; the ad-900 is said to produce good quality delay at up to 600ms. Why does the AD-3208 produce only 400ms?

[Scott Swartz]

Read in here about clock speed and post delay filters

http://www.generalguitargadgets.com/v2/diagrams/pt80techinfo.pdf

There needs to be a margin between the highest frequency you want the post delay filter to pass and the clock frequency.

Good conservative design is the clock freq no less than 3 times the audio freq or in the case of the AD-3208, 3 kHz and a minimum clock speed of 10 kHz, which computes to 410 ms for a 8192 BBD line.

You can clock it slower for more delay time, obviously that's what Maxon is doing, but you may hear some high pitched clock noise in the repeats at that lower clock speed.  You could adjust the AD3208 for any delay time the Maxon will do simply by tweaking the delay clock trim pot.

[Gil]

http://www.adirondackguitar.com/effects/maxon/ad900.htm

450$ .....

Well, does the Maxon produce the same annoying high pitched noise at the lower clock speed ?

Anyone came with a DIY analog delay project that is able to procdue 600ms or so without that noise ? I definately need something like that  !

[Scott Swartz]

It will unless it has a much steeper slope post delay filter and/or starts rolling off at a lower frequency.

There is also a tradeoff between sound quality and length of BBD delay line.

On the AD3208 (and every other BBD Delay), if you do a experiment where you set it for 200 ms delay using 2 3208s (clock of 10 kHz) and then compare that to using 2 3205s with the clock at 20 kHz, the shorter delay line with 2 3208s definitely sounds better for a 200 ms delay.

[Daniel B]

I was just wondering what the digital delay times where for pedals. Is it about 2 seconds? Do you need heaps of BBD's for longer times or what? Is it possible to get even 1 second of analoge delay?

Anyway, i have just purchased an analog delay (Ibanez AD-9). It was kinda expensive so it better be worth it (I haven't got it yet). ($NZ300, $US150).

Daniel