There are several types of BBDs and Clocks that work with the ABDX
The ABDX accepts different types of BBDs and their clock counterparts. The following chart illustrates the advantages and disadvantages of each. Note that the
Clock type does not contribute to the pros/cons. They are simply the appropriate chips to use in each circumstance.
BBD
Clock
Steps
Pros
Cons
MN3005
MN3101
4096
Best sounding. Can run at up to 15v for added
headroom
Out of production, rare, hard to find (up to $80 for a pair)
MN3205
MN3102
4096
Also great sounding. Lower current consumption than
the MN3005
Out of production, rare, hard to find. Requires lower voltage to
operate.
MN3008
MN3101 or
MN3102
2048
Sounds every bit as good as the MN3005. Can be run
up to 15v (MN3101 only).
Out of production, rare, hard to find. Half the delay time of the
MN3005.
BL3208B
BL3102
2048
Very good alternative that is currently in production.
Low current consumption. Used by EHX for some of
the modern DMM.
Half the delay time of the MN3005, MN3205 and v3205.
V3205
V3102
4096
Cheap. Same delay time as the MN3005.
Worst sounding. Lower headroom than the BL3208B even
when operated at nearly the same voltages.
This chart pretty much explains the order in which you should choose your BBD type from top to bottom. If you can find the MN3005 and afford it, then use it. If you
are limited to current production chips, then choose between the superior sounding BL3208B with half the delay time or the inferior v3205 that will give you a full
500ms of delay from the ABDX.
Please keep in mind that these evaluations are in degrees, not absolutes. IOW, it is entirely possible to build the ABDX with the v3205 to get the max delay and still
get a very acceptable amount of fidelity (the design has mods to help with this). It’s just never going to sound as good as the MN3005 running at 15v, period.
The great thing about the ABDX is that you can change the chips out at will simply by changing two jumpers on the board. So, you might build it with a BL3208B or
v3205 now, and then replace them with the MN3205 or MN3005 later if you are able to source them. It’s that simple (you will have to re-calibrate the delay when
doing so).
Note: I have not personally tested the MN3205 with the Aquaboy for the simple reason that I have never found any legitimate chips. I have tested all other
configurations.
A word about sourcing BBD chips
Whenever you try to locate and purchase out of production chips like the MN3005 and MN3205 you are running the risk of getting ripped off, either through malice
or ignorance on the seller’s part. There are a lot of fake chips out there and quite a few sellers that make a living by selling counterfeits to hapless gear geeks like
us. So, use caution. Don’t just throw money down the toilet at whatever Asian eBay seller claims to have a true MN3005 because most likely it is a fake. Rather, if
you want to get these chips, ask around on trusted forums. There are some fellow DIY’ers that may be willing to part with some of their stash from time to time or
point you toward a reliable source. It takes time but it’s also worth the effort.
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