Boss T-Bone Distortio/Octave/Trumpeter

[m4j0rbumm3r]

After an evening with the multimeter, checking the voltages at trannies, all the actual resistances etc, I still hadn't found it. Reheated of the solder joints, quadruple checked that there were no shorts across the copper strips, but still no improvement... Then this morning I found out I put a 0.022uF cap where there should be a 0.0022uF cap. D'oh! But also.. Woohoo!

The wrong cap value would explain why mine only affects the lowest notes, and just sort of muffles the high strings. I'm off to buy the right cap as soon as I can, so I can hopefully get those sweet tones at last.

edit: Also, Jimi, your vero layout lists C5 as 0.0068uF whereas Alex's schematic shows a 0.068uF. More importantly though, C5 should connect to the emitter of Q2, not to its base. I think this is an error in the vero layout. Could you verify that?

[pinkjimiphoton]

good catches, both.

the schematic does indeed show .068. i definitely used .0068

also, c 5 as shown should connect to the emitter, not the base as you also noted. mine as built does not, mine is as the vero shows.

will update the vero to show the corrections...gpod eye, sorry ya had the hassle. we both learned something here i think!!

here's the corrected layout..



i dunno what the hell i built, but it still sounds pretty good...lol.
another new fuzz i guess. gonna have to fix this one!!

thanks brother!! again, i apologize for the inconvenience!!!!

[m4j0rbumm3r]

Haha, no worries. This is my first build and you helped a lot regardless. Glad I could contribute anything other than ignorance to the discussion 

Just so you know, I first built it with C5 connected to Q2's base as well, and it did indeed produce a useable fuzz. Of course, you demo'd it so you would know. But then, I was looking for those horn sounds, and I couldn't get those.

Now that I've made some corrections, including the connection of C5 to Q2's emitter, mine is starting to sound a lot more like Alex's demo  I get the trumpeting going in a pretty wide range of settings actually. For high notes, it works better high on the neck using the wound strings than with the thin strings on lower frets. I used a multi-purpose wall-wart to change voltages even more drastically. Going from 9V to 7.5, 6 and even 4.5 (these are its settings, haven't checked the actual output voltages...). Gives an even wider range of sounds!

I'm really liking it, the only mod/addition I'm considering now, after playing with it, is a drastic passive tone control to roll off high end. On the settings where it trumpets most easily, the overall quality of the sound gets a little harsh in combination with my usual amp's EQ settings. It's perfect when I roll off the all highs and turn up the mids on my amp though. So, I'd like to do that on the pedal output signal and be able to keep the rest of my setup the way I like it. That would promote this pedal onto my pedal board I think.

[pinkjimiphoton]

awesome bart,
glad ya got it going! i am torn between making another fuzz that's RIGHT and fixing this one.. i kinda like it like it is, but really want that trumpet thing. maybe another switch to change the position of the cap?  between base and emitter. wonder if it would pop?

thank you for verifying that i'm an idiot...lol. it's all good, the important thing is you got it running, found, recognized and reported the problem, and we both learned from it...thank you!

i got a couple things on my bench at the moment, i'm gonna try adding a switch to mine on that cap...then i can have my cake, and eat it too!

[pinkjimiphoton]

hey guys, opened it up....the results are here: http://www.diystompboxes.com/smfforum/index.php?topic=98085.new#new

[m4j0rbumm3r]

Glad to hear you like it with the changed cap values as well Jimi!

I'm still trying new combinations of sag and attack settings, each time thinking I was setting it up all wrong 5 minutes before and that this time I really nailed it. Like you (noted in the other thread), I found that sliding up into notes really enhances the brassy sensation.

Strangely, today, with 'fresh ears', I'm at a loss what I was thinking yesterday, blabbering about the need for high frequency roll-off. Now, I actually like it best with the lows rolled back and highs turned up on my amp    Of course, I am using different settings for the pedal controls now.

Well, I guess I just need to use it for some more time before I will decide on how to mod it further, if there is any need at all. But then... perhaps I should just go ahead and add a single knob high cut (1) to high boost (10) control as described here: http://www.muzique.com/lab/swtc.htm
A polarity protection diode might be a good idea though, didn't yet put that in.

The thing is, once you are in a bout of manic soldering, it is very hard, scary even, to think of boxing up the pedal and unplugging the soldering iron.

[pinkjimiphoton]

yep....you're addicted!!!

i played with this thing for HOURS last nite...it was a gas!!

thanks for noticing my mistakes bart...the pedal is as different now as night and day!!

[m4j0rbumm3r]

I just wasn't that sleepy or hungry the past 72 hours, so I figured I might just as well tinker with the pedal a tiny bit more. It's all under control, really!

That said, although some settings sound pretty cool to my ears, I haven't yet been able to match Alex's most extreme sounds.

On a side note: with this fuzz pedal placed after a buffer, it sounds very different. Not nearly as interesting IMO.

edit: I also just found out that a change on C5 from 0.068uF to 0.090uF alters the brass character pretty dramatically - and, to my ears, for the better.

[Quackzed]

if upping the input cap from .0068 to .068 got it trumpeting good for pinkjimi maybee a 1uf or 10uf input cap would kick in the a$$ a bit more...
slam it! with a bigger input cap!

[m4j0rbumm3r]

if upping the input cap from .0068 to .068 got it trumpeting good for pinkjimi maybee a 1uf or 10uf input cap would kick in the a$$ a bit more...
slam it! with a bigger input cap!

Yeah I upped C5 a bit like Jimi did. Totally worked.    It's the cap that connects the emitter of the second transistor to the diode stage by the way, not the cap on the effect input, directly after the attack pot.

[Quackzed]

oops right! my bad. not the input cap, but c5! input cap is already .1u so making it bigger probably wouldn't do much...
... i KNOW i had some 3906's somewhere ?!?....
probably good i can't find em, i should be packing for vacation!

[midwayfair]

Hey, guys, I got a small perf layout done up.



It's got a few notes and reflects a few of my personal preferences. I sat down with every transistor I had on hand and plugged them into the circuit to see what got the best trumpetting. I found that having Q2 a little LOWER than Q1 enhanced the effect. I also kinda dug a germanium in Q2 ... it gates less at maximum sag ... less bladt but a little more "toot"! But I stuck with silicon because I thought it got too dark otherwise and because I definitely want the option for full spitty gated fuzz out of this particular box.

Also, per the most immediate discussion above, a .47-1uF cap on the input DOES make a difference. It will gate less (a little more input signal), and get a little woolier. I stayed "stock" on mine for the same reason as the Si transistors -- I wanted some spitty gating available.

[pinkjimiphoton]

post clips!

[alex frias]

I see a nice job has been done here, thanks guys. As a lot of time passed I didn't remember clearly wich one I used, the circuit with an error related to the original Bosstone, or the corrected one. But I think I used the second, corrected. I must verify that...

The resistor used in order to put the first transistor gain down a bit is 470 Ohms, not 47. Sorry, I even don't use it that much, as the ultra hi-gain is necessary to achieve the trumpetism!

You see, I´m very happy with that as it is, but I like those non-stable functions, I found interesting learning to deal with them variating pickups, guitar volume and tone controls and picking techniques. In order to get it to the max it is important your guitar is connected directly to the BossT-bone.

After 2 years this one still figures in my pedalboard as the first fx after the A/B box (passive one):

[pinkjimiphoton]

right on! i'll have to re-visit mine, i think i may have used 47r instead of 470.

it's a bear to get the "sweet spot"...but proper reverb and phrasing matter a lot, too.

this was a great project, thanks alex and everyone else...

hey larry, i'll check the one you sent me, maybe the issue was that resistor...if it is,  i'll replace and mail it back to you
with them 105k's you asked for that i endlessly forget...

glad to see it has a spot on your board, alex...it's a really nice sounding fuzz any way ya set it!

mine self-oscillates, on some setting of the sag control...anyone else's do that? just curious...

[Mark Hammer]

I already had a Bosstone boxed up, with some switch lugs available for duty, so I thought I'd try out some of these mods last night.  It had an on-off slide switch for power, so I just decided to straddle the two lugs with a fixed resistor for a "sag" preset, and setting the switch to the "on" position would shunt the resistor and provide normal unstarved power. I found the full 100k created problems, so I left it at 47k.

A second 3-position slide switch provides "normal" tone, a 2nd parallel .22uf input cap, or a treble-cutting cap in parallel with the clipping diodes for a warmer rounder sound.  I tried using the addional contacts to introduce the lower Q1 gain in one of the switch positions.

Unfortunately, rather than reading through the entire thread  , I went with the first drawing I had, which mistakenly showed the Q1 emitter resistor as 47R, rather than 470R.  The combination of more sag and the slightly reduced Q1 gain caused problems, including howl that would not abate until I adjusted both the Attack pot and the guitar volume.  Ironically, the least howling was produced with the added input capacitance.  Don't know why that is.

[pinkjimiphoton]

doesn't having an input capacitance in series act as a filter? all caps have some resistance to them too, so i guess it either acted as a filter, rolling off above/below certain sub/harmonics...

or the series resistance made the pedal see an input current instead of a voltage? or maybe i got that backwards.

i was just reading a mod article on the archive that mentioned using an input cap in series in a fuzz face circuit (the os mutantes fuzz, remember that one?) to help reduce intermodulation
distortion artifacts when playing a diad or more..

neat!!

i found too, mine definitely oscillates at some settings of the sag control, which can be kinda cool for some things...definitely makes it different...

did you find the sought after "trumpet tone", mark?

[Mark Hammer]

The trumpet appears to still be in its case, but with normal Q1 gain, and sag set at 47k, I did find myself getting a host of interesting and pleasing octave effects, both above and below (though not simultaneously).

I should add that, although I don't know exactly how critical Q1/Q2 hfe is, I have absolutely no idea what trannies I'm using or how they were selected.  The perfboard is pretty crowded (it's about a dozen holes square).  I'll have to bend them back and hold up a magnifier to see what's in there.

[pinkjimiphoton]

 

i doubt it really matters what the trannys are as much as the biasing of 'em.

it's a cool circuit, i can't get much out of it with octaves, at least not predictably enough for me.

but i do like the brassy sound you can get out of it.

gotta run...just traded a crappy ts-9 for one of them old digitech two pedal two second delays.

[radio]

It's some time ago I tried this,but I only got octave below

on the 6th and 5th string while trumpeting on the other ones.

Though I was so fascinated being a '2 transistors Pat Metheny'

I didn't try in-between sag values.