Building the Voltage Controlled Amplifier
Most of the components are pretty straightforward, with a few exceptions. As usual Solder in the Potentiometer in last. Take care with the polarity of the Tantalum capacitor, putting this component in wrong is not fun. Finally, there is the question of the BA6110/BA622A. The x0xb0x ships with a BA6110, because the BA662A is no longer built by the manufacturer. You are probably going to want to mount this on a SIP socket. Some people claim that the BA662A is essential for the sound, however, LadyAda has performed some tests on a scope, and the only difference (with the Q1-Q4 current mirror in place) is the BA662A is slightly less noisy. This makes sense, seeing as how it only really affects how the envelope is applied to the sound.
You can buy the sip sockets here http://www.allelectronics.com/cgi-bin/item/SIP-30/search/SNAPPABLE_30_PIN_SIP_SOCKET,_.1%22#34;_CENTERS_.html. Note that this is also the place the docs recommend you buy other supplies. You may want to pick up the other supplies at the same time to save on shipping.
If you are installing the BA622A, then you need to make sure that you do not solder in Q1-Q4. If you are using the BA6110, solder in Q1-Q4 like normal.
Switching to a BA622A later
You might find a BA662A somewhere else (see BA662ASources). If you want to keep your options options open, you would mount Q1, Q2, Q3, Q4 and IC15B on SipSockets, and an empty socket on IC15A. When you get ahold of the BA662A, you can unsocket everything, and socket it into IC15A (in its proper location, lest you will fry your shiny new BA662A!). Do not leave Q1, Q2, Q3 and Q4 in, take them out if you use the BA662A.
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