3/7/2023 0 Comments Simple delay pedal schematic![]() The anti alias and post delay filters are the typical design used on the DM-3, CD-10, etc as you can see by cross checking the schematics. On the AD3208 (and every other BBD Delay), if you do a experiment where you set it for 200 ms delay using two 3208s (clock of 10 kHz) and then compare that to using two 3205s with the clock at 20 kHz, the shorter delay line with 2 3208s definitely sounds better for a 200 ms delay. There is also a tradeoff between sound quality and length of BBD delay line. Keep in mind that marketing departments have been known to stretch the truth also. ![]() I am aware that there are analog delays that claim 600 milliseconds from two MN3205s, but this would require a much steeper slope post delay filter and/or rolling off at a lower frequency in the post delay filter. The clock could be run slower, but there needs to be a margin between the highest frequency you want the post delay filter to pass and the clock frequency or high pitched clock noise will be heard. If you use two MN3205s, you will have an 8192 step BBD line which computes to 410 milliseconds at a clock speed of 10 kHz. Good conservative design is the clock frequency is no less than 3 times the rolloff frequency of the post delay filter, or in the case of the AD-3208, 3 kHz and a minimum clock speed of 10 kHz, which computes to 205 milliseconds. It can also accept two MN3205s for a 8192 step delay line, which doubles the delay time to 410 milliseconds. It was designed it to accept two of the currently manufactured B元208 chips, which give a 4096 step delay line, the same length as the DM-3 and CD-10, for a maximum delay time of about 205 milliseconds at a clock speed of 10 kHz. I picked the design elements from each as well as a few other delays to produce what I consider the best overall design. The AD3208 is based upon the later analog delays that used the lower voltage MN32xx series of BBD chips like the Boss DM-3 and the Ibanez CD-10 Delay Champ. If you were only building one of them, I would probably recommend the PT-80 since its simpler and cheaper to build, and offers a longer delay time, but if only BBD will do for you, here is the project. The PT-80 was designed to get as close to the analog delay sound as possible, so this makes sense. Having designed and built both, I can tell you that the difference is subtle. A BBD delay does give a very slightly different character to the repeats, and with the recent availability of B元208 BBD chips, I decided to design an old school BBD delay around them. Those of you who have built or seen my PT-80 project may be wondering why I developed this one. This project is for a true BBD analog delay. AD-3208 Delay Ready-For-Transfer Printed Circuit Board Layout PDF FileĪD 3208 Build Information Copyright 2003 by Scott Swartz, all rights reserved Circuit Design.AD-3208 Delay Bill of Materials text file.All the ICs are available from Small Bear Electronics LLC or other sources. ![]() An analog delay project from Scott Swartz.
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