Mad Bean Pedals Total Recall, Быстрый старт

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At long last, the vintage Memory Man™ project is here! The Total Recall is a clone of the big box DMM which allows you
to use either two MN3005 or four MN3008 (if you include the optional expansion board; the TRXPN). With the recent
release of the Xvive MN3005 clones this project is suddenly much more viable for builders not lucky enough to get their
hands on NOS MN3005 chips (which can go for as much as $40 a piece these days, if you are lucky to get a non-
counterfeit one). The good news is that the Xvive chips seem to work very well in the Total Recall. Tests were done
comparing them to 2xMN3005 (NOS) and 4xMN3008 (NOS) and they performed very comparable (at least with the two
Xvive chips I have on hand). While I won't get into any machinations on precision MOJO between the NOS and new
production chips, I am satisfied that the Xvive are fine for this project and the end result sounds great. Perhaps they are
even slightly cleaner in output (which is not terribly surprising when you compare recently manufactured IC's with those
made 30 years ago).
Some important notes before considering this project

It's hard. Not the hardest DIY project ever, but pretty challenging. You need to have enough patience to work
through the building AND setting it up properly. This means NO BOXING BEFORE ROCKING. You must test this
project adequately with a multi-meter AND audio probe before wiring it up in an enclosure. There will be
no mercy
for tech threads started on the forum by those who ignore this :)

It's positive ground and it requires a wall-wart. There's no getting around it. If you want the true vintage DMM, you
have to design it to use a wall-wart or AC power plus a transformer. I use, and recommend, an actual EHX 24v
supply. It's not too expensive and it works perfectly for the project. And with it, my two builds are dead quiet. You
can get the power supply here:
http://www.amazon.com/Electro-Harmonix-US24DC-100-24V-Power-
Supply/dp/B0042RHT4M . You
should
be able to use an 18v supply instead of the 24v one listed above, although
this has not been tested. You will need to do a couple things: 1) Lower the value of R57 from 240R 1W to
something like 22R 1W, and 2) make sure you know what the polarity of your 18v power supply is before hooking
it up to the TR PCB!

It's expensive. Granted, building your own is still way cheaper than buying a vintage unit, but all in all you can
expect to drop $100 or more on this project including the PCBs, power supply and two BBDs.

The Total Recall does have some differences with the DMM. I use 1uF film caps instead of non-polar electrolytic
(as a matter of personal preference), the "overload LED" circuitry is not used due to space limitations and finally
the GAIN1 trimmer is located between BBD stages 3 and 4 instead of 2 & 3 (if using the TRXPN board only,
otherwise it is between the two BBD stages when using two MN3005). This last one is the most important. While it
does not seem to pose any limitations when using four MN3008, I would not recommend plugging in four MN3005
(as some might be tempted to do) to get 1 second of delay instead of 550ms. Four MN3005 should work for all
four BBD spots, but it has not been tested and the extra delay time may prove problematic for the gain recovery.
XVIVE MN3005 : http://smallbear-electronics.mybigcommerce.com/mn3005-re-makes-xvive-audio/
Controls
DELAY: Total delay time from slap-back to approximately 550ms.
FDBK: The total number of repeats from one to many to self-oscillation.
LEVEL: The input gain of the circuit. This control can create mild overdrive when turned up.
BLEND: The dry/wet ratio of guitar and delay.
MOD: The
depth
of modulation applied to the delay signal. The modulation
rate
is fixed.
CH/VB: This switches between chorus and vibrato type modulation.
Biasing Controls
BIAS1, 2: These trimmers set the input biasing of the BBD chips.
GAIN1, 2: These trimmers set the gain recovery after BBD1 and BBD2.
BAL: This trimmer balances the two outputs of the second BBD.