Time FX : MN3205 Low Voltage 4096-stage BBD

[Transmogrifox]

Does anybody know anything about this IC?   What is a good IC to use for an analog delay, and what is a maximum delay time I should be able to expect from a single BBD IC?

I am thinking about tinkering with chorus and flanging projects as well, any suggestions of BBD chips for this application?

[ExpAnonColin]

4096 is just about the highest I've seen.  I know that if you want to do a chorus or flanger, you should try a Reticon SAD1024 or a MN3007, both of which are 1024 stage BBDs with about 50msecs of delay time... just about right.  Go datasheeting!

-Colin

[Mark Hammer]

Any of the "xx05" chips (3005, 3205, 3305) is good for about 300-350ms delay time each with reasonable bandwidth.  You can push them a fair amount farther but past about 350ms the amount of lowpass filtering required to keep clock noise out of the way starts to become confining.

For longer delay times, the digital chips such as the Princeton PT239x series are best bang for the buck, delivering longer times at equal or better sound quality for a fraction of the cost.

Chorus and flanger effects generally work best with BBDs in the 1024-stages or less zone.  For flangers, a BBD of 256 (MN3009) or 512 (MN3004) stages can provide desirable outcome since it is easier to achieve very short delays without having to work too hard.

[george]

Hi Mark

What clock speed would be required to give a delay time of 300-350ms
for the MN3x05?

Regards
George

[smallbearelec]

Check out Scott Swartz's designs at GeneralGuitarGadgets. The PT-80 uses the digital chip with external compression to reduce noise. More recently, he did a BB design that can use either the MN/BL3208 or the MN3205.

Did you find an MN3205? If so, good job! I have a few but have not seen any more offered at any price. The BL3208 is in good supply if you care to try a 2K chip.

Regards
Steve Daniels
www.smallbearelec.com

[C Bradley]

Hi guys,

I thought I'd chime in here since my next project is stripping an old Radio Shack electronic reverb unit and using the MN3102 and MN3207 for a delay. I'm probably going to use the same basic circuit that the Radio Shack effect has, but make it work for guitar.

The circuit in the spec sheets for the MN3207 shows AN6550 opamps. The RS effect has TI4558's. Will the 4558's work with the circuit on the spec sheet?

I like the radio shack reverb for it's "splat tone".    I don't like it because the preamp overdrives and sounds nasty.

Chris B

[Mark Hammer]

The AN6550 is simply a Matsushita dual op-amp, and Matsushita makes/made the MN3207.  Nothing really special or necessary about it in this application.

The 4558s will work though obviously pinouts will differ.

[Transmogrifox]

Are there any BBDs manufactured anymore at all?  It seems like they're all NOS or salvage, and either way, very expensive to buy.  Digital is great, but I already have a digital processor with a good delay.  I want to build an "analog" delay (using BBD) just for the fun of the project, not necessarily for any perceived advantage over digital delays.

[Mark Hammer]

Official releases from Matsushita indicate the BBD has essentially gone the way of the dodo bird several years ago.  As a means of producing long delays it is simply uneconomical and cumbersome compared to the current generation of all-in-one digital delay chips.  Perhaps more importantly, expectations for maximum delay time are pretty high right now and generating expensive 800ms delays (more or less the very top end of what the stock implementation of the Matsushita chips will deliver) doesn't hold nearly as much consumer attraction as a second or more of delay for a fraction of the price.  Digital also lets you do backwards, which people have come to expect now too.

That being said, there is a thriving culture of karaoke machines and karaoke repair, and probably enough demand for analog chorus and flanger pedals (something which analog does much better than digital at a fraction of the cost) to keep devices of 1024 or less stages alive for a while.  The older MN3007 is second sourced by ECG/NTE, and the MN3207 is second-sourced by Beiling (and available from Steve Daniels at Small Bear).  Some commercial manufacturers (e.g., Electro-Harmonix) can probably put in a custom order for a run of MN3005s or 3205s, but that is separate from whether the provider is willing or interested to take on the responsibility of listing them in the catalog and supporting the chip.  Just because one customer wants it and is willing to make a big enough order to warrant a special run doesn't mean it's worth treating it as a "normal" product.  For instance, Moogerfooger pedals had an analog delay pedal, but from the get-go this was going to be a limited-run pedal and was described as such in all their literature.  The price point and set of features meant that Bob Moog was going to have to depend on a cache of NOS chips rather than be able to order a custom run from whomever, and when he ran out of chips, the world would run out of those pedals.

That means that the rest of us will most likely have to subsist of NOS chips for the forseeable future (with the exception of the BL3208, second-sourced by Beiling).