Boss BF2: can't handle higher output guitars?

EdBoogie

Hi,

I have an old Boss BF2 black label/MIJ from the early 80s - I bought it a while ago for a project and just started using it.

I've noticed that it has no headroom - if you hit it with a Les Paul, it will clip/distort.

If I plug in a a Fender Jag, it sounds pretty nice and clean. Everything else (strat, tele etc) is somewhere in-between, obviously single coils fair better.

The distortion sounds kind of cool, and I have a compressor pedal with an output control on it before it, so I can really lower the input into it, so I can get by.

People who have BF2s - is this normal?

If not, has anyone tried messing with the internal trim/bias pots? I don't have an oscilloscope/am not an electronics engineer but know how to turn a screw with a screwdriver. But the core 'tone' of the pedal is great and I don't want to mess anything up.

Cheers!

Ed

Bidley

I'm mainly a metal player, so I have a couple of guitars with higher output, but my BF2 has never clipped to my knowledge.

Mine has the curious volume boost thing that a lot of them had, that's it.

I've never fiddled with the innards to be honest!

Not much help am I

ICBM

DO NOT fiddle with the trimmers. From memory they require specialist test equipment to set correctly.

I don't think mine does distort, but I'll check. If you've got one that does, chances are that one or more electrolytic caps is failing, this is become quite a common problem on older pedals now, including Boss - some are over thirty years old now.

webrthomson

I've got an older one too and I've never had any issues - I tend to use SD Blackouts and EMG most of the time too

steamabacus

I've had a BF-2 for 30 years or so and I've never noticed this problem - back in the day I had a DiMarzio Super Distortion loaded guitar and no issues.

thermionic

ICBM said:

I don't think mine does distort, but I'll check. If you've got one that does, chances are that one or more electrolytic caps is failing, this is become quite a common problem on older pedals now, including Boss - some are over thirty years old now.

They often used electrolytic caps as coupling caps if a high value was needed. I've replaced them with tantalums in my OD-1 and CE-2, but didn't bother with the ones not in the signal path (like the power supply). My CE-2 had a little audible distortion when I bought it, it sounds pristine now.

DesVegas

ICBM said:

DO NOT fiddle with the trimmers. From memory they require specialist test equipment to set correctly.

Nah, open it up and fiddle away, you are bound to find a better sound using the three trim pots, probably best to mark them before you adjust though, but fiddle on!

http://s3.postimg.org/6xktwmn9r/BF_2_in_2.jpg

EdBoogie

Thanks all the replies lads!

Firstly I now realise that you're supposed to run it at 12V instead of 9V, which I'm now doing. Unfortunately this doesn't change the way the unit distorts. At least the LED is brighter now, though!

It only distorts when engaged, by the way.

I will try it with a battery to see what's what, but it's looking likely that someone's messed with the internal trim pots - it's just a bit of a 'mare to set the bias trims without 'proper gear'. I can generate a test tone, but the oscilloscope is apparently supposed to be very accurate, etc.

Thanks for confirming that it should be no problem with humbuckers!

Cheers,

Ed

Gadget

Ignore me...

thermionic

Trimpots are sometimes marked with a pen when they've been set, have a good look to see if there is anything that can be lined up by eye.

One of the trimpots will probably be for adjusting the virtual ground of the circuit via a voltage divider. This is easily set to halfway between the power rails with only a multimeter and is probably the best place to start. 

EdBoogie

Hi all,

Sorry I buggered off - finally have some time to look at this now. The trim pots don't have any markings on them.

I see sites like this: https://sites.google.com/site/cctsim/home/boss-bf-2-callibration

But it's a bit daunting for me - I don't have an oscilloscope, although I'm sure I could find a software version (i just downloaded a trial version of schOPE). I can use Logic to generate a 200Hz sine wave, although I'm unsure how to convert from dBFS in a DAW to DBm...

I can post a picture, although I imagine it won't be very useful. I have a multimeter and I'm good at following instructions... 

Anyone able to hold my hand through this process?!

Cheers,

Ed

ecc83

Hi Ed. Yes, you can generate sine in a DAW but you will need the computer  (mac?) to run the scope software. Do  you have a gash laptop that can act as a sig genny? You could burn the test signals to a CD and play out of that. You then need a pot to set precise levels. 10K better 5k and probably linear would be easier to set.

Hook the mmtr across the output of the pot to set the level. If you are just running at 200Hz fine, but if you need say 1kHz do check the meter gives the same reading as 200Hz, many even quite expensive digital meters are a dB of two down even at as low as 1kHz. Many dive off a cliff at 5kHz!

It makes life a LOT easier if you can leave a meter on the signal source and use another on the output but you could use the scope waveform once you have calibrated it. You will need a lash up/breadboard arrangement of jack and croc leads and listen to ensure hum is not intruding (most DAWs have an analyser mode and you can look for 50/100Hz spikes)

Remember, scopes show you peak to peak.

What audio interface do you have?

Dave.

EdBoogie

Hi Dave, thanks for your reply!

I have a fancy SSL Alphalink SX, which outputs at +4dB (balanced). I can generate a 200Hz (or any frequency) sine wave in Logic, but not sure what volume to output it at (in dBFS) to make sure that it's the correct voltage. What about impedance? Balanced/unbalanced?

I have enough ins/outs so I can output a sine wave and also get an incoming signal too.

Do you mean I need to hook up a random pot to adjust the output level of the sine wave, so that it's the correct level?

"You will need a lash up/breadboard arrangement of jack and croc leads and listen to ensure hum is not intruding " - starting to get that feeling that I'm a bit over my head, here! 

Cheers,

Ed