Boss TR-2 Tremolo

Boss-TR2

What is it?
Boss TR-2 Tremolo. Unknown manufacture date. No serial, as the label has vanished at some point alolng the way. This came to me in a trade as a defunct unit. Gladly, it was just polarity protection diode and one burned resistor. No visible damage to the board itself.

Of all the tremolos i’ve played, this one just seemed solid by construction and sound. Nothing special or anything that made me go wow. Just one of those tools that are good to have. TR-2 was first released to the public in 1997. The Pb-Free label on the board suggest that this is quite new unit, maybe around 2010-11.

Boss-TR2-Guts1

As the photo above shows, all the opamps are SIP-chips. The LFO and gain recovery amps are M5218/NJM4558, while the modulation amplifier is M5207 VCA. The factory schematic (found on the internet) shows how the LFO is created – and how the modulation is applied to modulation amplifier. Neat and simple. Design is pretty straightforward and does not peak my interest more. Controls offer good range, while the wavefrom control is too subtle for my taste.

Boss-TR2-Guts2

Traces on the back of the board show neat soldering, but dull design. Almost machine-like autorouted feeling to it.

Some people have reported that the output level of this design is lower than unity, aka volume drop. I would mostly blame that on human brain perception or psycho acoustics, but the issue can be dealt in other ways too.  As the modulation recovery amp is wired as standard inverting amplifier, there is one resistor responsibe for the output level. That resistor being R12, the feedback resitor of IC2A in the schematic. Original value is 22K, but you could swap it for 27K or try on different values to tweak the output to your taste. You could even replacce that resistor with 50K pot to get control over the output level. Other option to try is to snip the C4 Р100nF capacitor taming the oscillator output. One more option is to lower the value of input limiting resistor of the modulation amp. This being R9, the 10K resistor. 6.8K should offer unity or slight boost. One more mod would be to remove C7. This will omit the high frequency taming at the recovery amp and let more highs through.

One could of course play with all of the above to tune it just perfect to your ears.

How does it sound?
Decent. Not too special, but nothing’s amiss or wrong. Mass tremolo with no personal character to it. LFO wave control leaves me a bit puzzled. It could be a lot better or just a bit more drastic. Not a bad thing to have. Wouldn’t buy this as a new unit, but i’m glad i got.

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