BA2018 linestage

Wayne Colburn's Linestage from Burning Amp Festival 2018.

Absolutely fantastic sounding circuit, can even drive headphones (very nicely) with optional big output transistors.

Read the text.

Look at all the photos (Mouseover or touch to view thumbnails)

Read the text again :)

You can click into the photos and they will open at maximum resolution in a new window.

This kit contains all the parts to stuff the audio circuit PCB.

It contains extra parts so you can choose to use the big output transistors or the standard.

Not all included parts are exactly as-shown in the photos, substitutions of equal or better quality will be made depending on what is available at the time kits are packaged.

Please note the 10pF capacitors are the two on the tape, the 5pF are loose.

The blocks all have small dovetails to interlock together.

Yes, there are ten of the small SMD transistors. In case you drop one on the floor or, god forbid, sneeze...

The Dale RN/CMF series are 3-digit + multiplier.

The bottom, marked "1003" is 100K, since you have 100 and three zeroes. The one marked "1002" is 10K.

"1500" is 150 ohm, as the value is 150 plus zero zeroes. This is not 1.5K

Below 100 ohm the letter "R" is placed at the decimal place, "27R4" is 27.4 ohms, and "10R0" os 10 ohms.

Banded resistors follow the 5-band standard code.

But even with that easy system, Measure All Resistors before stuffing and soldering.

Kits packages in spring of 2022 include the the very nice, but small, premium, European-made, Vishay MBA series resistors. Albeit a small package, these are ceramic bodied and 0.4W (almost 1/2W) max dissipation, and we are using them in lieu of the more common 1/4W (0.25W).

The “large” resistors in the photos are normal-sized 1/4W (although the brown ones are 0.4W…)

Please note that the PCB shown stuffed is setup for using the “big” output transistors, where R11,12, 32, 33 are 15ohm, and R23, 46 are omitted.

Insert wisdom here.

Yes, the SMD transistors are very small. It's not a big deal though, we'll show you how to position and secure them for soldering in the next step.

Get some masking or painter's tape and cut into a 2-3" (50-75mm) strip that is very thin.

Tape the transistor in the middle of the tape, feet down, and use the rest of the tape to align it on the pads.

Secure the transistor with the longer pieces of tape and solder one leg.

Once you have one leg soldered, the other two are easy as it won't move around anymore.

All three legs of each transistor must be soldered for proper operation.

Resistors are next.

Neatness counts, bend the leads so the value is showing on the top and align them in the holes so they read left to right and bottom to top.

Banded resistors put the brown tolerance band on the bottom or the right.

Doing this greatly aids troubleshooting in the forum. (Because we can read the values in the photos)

Long leg in the square hole.

Also note that looking into the structure of the LED itself, the cathode is the parts that actually lights up and it's physically bigger than the anode.

Yes. There will be parts left over. This is normal.

The store kit includes parts for both the standard configuration and the 'large output' option. As well as two extra 2SK209 SMD transistors. (Extras provided just in case you sneezed...)

Hold the PCB up to a light and look at all the holes. If you miss any solder joints they will be obvious.

You can see the pad I missed soldering on one of the central transistors,

Insert wisdom here.

Insert wisdom here.