Boss TR-2 mods - anyone done this?

[grolschie]

Mainly interested correcting in the volume drop. Some say replace R9 (10k) with a 4.7k. Some say replace  R9 (10k) with a 4.7k or a 6.8k. Which is better? Best value resistor to use? I am thinking maybe a 10k trimpot might be good, but for which resistor - R9 or R19?

Also, would replacing ceramic caps with polypro or metal ones make alot of difference?

Thanks in advance.

Cheers,
grol.

edit:  Here is the schematic if that helps.

[George Giblet]

After looking at the data sheets and doing some estimates/calculations,  it seems to me that when the depth pot is on minimum (ie. the tremolo is active but the depth of the tremolo is as if it were a clean signal) then there should no drop in audio level.   Yes?  That would indicate R9 is actually the correct value as is.  You can confirm this by pressing the footswitch with the depth control on minimum the volume should stay the same.

Assuming that is the case, the R9 mod might seem ok when the depth is advance but it will produce a gain as the depth control is decreased - clearly not a good general solution.

It seems to me that pulling R28 (10k) is a better solution.  If that produces too much gain (when the depth control is advanced) then try changing R28 to say 33k.

[grolschie]

Thanks George. I will try ruling out R9 by doing what you said tomorrow (it's late where I am). So R19 is not the one?

[George Giblet]

Decreasing R19 would increase the depth more than anything!  R19 doesn't affect the gain when the depth control is on minimum and it does help the gain imbalance a tad when the depth control is advanced.  I don't think R19 is the best solution either.

[96ecss]

R9 is the resistor that controls volume. I've found that you can't just lower it to 4.7K. In mine, when I went to 4.7K it actually raised the volume. I had to adjust to 5.6K to get unity volume.

Dave

[Barcode80]

it's worth noting that the 4.7k value was likely determined because a slight boost was desired. though when played by itself the 5.6 might be unity, it is likely that in a ull band setting it will be perceived as a drop in volume. it's just what this particular effect does as a byproduct. many choose the 4.7k because although it boosts when playing alone, the boost is more naturally perceived as unity when in a full band setting. the sharp drop in the valleys of the amplitude give the illusion of a volume drop to some, so the 4.7k is to compensate.

i hope that all made sense... 

[grolschie]

After looking at the data sheets and doing some estimates/calculations,  it seems to me that when the depth pot is on minimum (ie. the tremolo is active but the depth of the tremolo is as if it were a clean signal) then there should no drop in audio level.   Yes?  That would indicate R9 is actually the correct value as is.  You can confirm this by pressing the footswitch with the depth control on minimum the volume should stay the same.

Assuming that is the case, the R9 mod might seem ok when the depth is advance but it will produce a gain as the depth control is decreased - clearly not a good general solution.

It seems to me that pulling R28 (10k) is a better solution.  If that produces too much gain (when the depth control is advanced) then try changing R28 to say 33k.

It's exactly as you said. When depth is at lowest setting, then there is no volume drop. So that rules out changing R9 for a general solution I guess. 

[grolschie]

I ended up simply replacing R9 with a 10k trimpot as that I could adjust the amout of boost. It's really a good option. I like it set to around 6k. Thanks to y'all for replying. 

One thing that annoys me looking at the circuit board, is that Boss uses crappy carbon resistors and caps throughout for the sake of saving themselves a few cents on each component! I'd rather pay a few dollars more and have high quality parts. 

[diezel]

speaking of tr-2's can anyone help here. my led is not working on my tr-2 after i changed it to blue. the led is fine as i tested it but when its hooked up it aint lighting. got the orientation correct. if i place it over diode d5 it lights up. is there a resistor controlling it that may have burned out? can anyone tell me please? cheers

[Barcode80]

even though you got the polarity correct, turn it around for fun. boss LED stuff is odd, i've had some reversed even though they should be correct.

[gogostar]

I've just modded my TR-2.

C4 seems "does nothing"!.

I didnt touch R19.

R9 is the just solution for volume drop!

I used a DPDT toggle switch for R9 position & soldered original resistor (10k) at a side and 5k6 at the other side. 10k gives volume drop again but 5k6 is almost at the same level with the effectless signal. I think some higher values like 6k will fit best.

Now pedal is more worthy i think. Everyone should try this mod.

[grolschie]

I wonder how much difference it would make to replace all the crappy resistors and caps with quality ones. Or is this part of the mojo?

[gogostar]

As i remember, Keeley is changing some of them with the same values in DS-1.

[thehallofshields]

Has anyone tried swapping any of the IC's for higher quality op-amps? I'm curious if anyone knows which IC's would be relevant to upgrade.