BSIAB2 build. First DIY pedal!

Ok , I just ordered one of these

https://www.generalguitargadgets.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=21&category_id=7&option=com_virtuemart&Itemid=45

Brown Sound In A Box= Massive distortion, cranked marshall tone. Hopefully. Should go well with my Fender Deville super cleans. Great reviews all over the net.
Pretty much my first time build (I've 'helped' build pedals in the past). I've done wiring on guitars and made a volume box so I hope thats experience enough!

I'm thinking I'll build it following the original instructions first, then mod it later if I feel the need...
I might be stopping by for some tips every now and then, and to give a review of the sound when Im done. Anybody built one of these? Any thing I should know?

The BSIAB2 seems easy enough, and fun, so wish me luck!

It's a cool build - I built one last year.

I suggest that you socket the transistors in case you get the pinout wrong (i.e. backwards).

One thing I would suggest right off the bat is to use 2N5457's in all slots, not just the ones calling for them. Unless you need a chainsaw at full tilt amount of distortion, the 2N5457's are a bit warmer and rounder than the J201's, due to their lower gain.

I think that you're in for a treat - the BSIAB2 is basically the "original" Box of Rock, only it uses jFET's in the mu amp configuration, as opposed to Vex's love for mosFET's. Vex even lifted the entire tone circuit from the BSIAB2, chapter and verse!

I seem to remember doing some other things to reshape the EQ, but it's really a subjective preference thing. So once you build it, if you find that it's too bright or bassy, you've come to the right spot to get some pointers on what to adjust.

...You might also be interested to know that the Dirty Little Secret isn't really very far off from the BSIAB2 circuitry, as well. They both share multiple mu amp stages.

... Vex even lifted the entire tone circuit from the BSIAB2, chapter and verse!...

:lol::lol::lol: Them's near fightin' words!

Looks like another life ruined through solder and components, barkley :razz:

Let us know how you go.

:lol::lol::lol: Them's near fightin' words!

Luckily for Zachy boy, Ed Guidry stayed cool about the entire incident.

From another forum (FSB):

Quote:
I wonder if he paid any royalties to Ed Guidry and his designer friends for DIRECTLY copying there tone control and output filter design


I don´t think so, somebody wrote me this:

Quote:
I found it funny that Zach Vex copied the 'back end' of the BSIAB component-for-component. Is this really correct?
If so, I don't resent it, I posted the schematic, after all. I'm actually kind of flattered that he used it.


The rest is private talk....

Thanks for the advice and encouragement guys!:smile:

11 gauge: At the risk of sounding like a complete noob (1st diy pedal remember!), what exactly is a socket? I'm assuming its like a plug that I can solder direct to the board and then fit the transistors into it without soldering (for easy removal perhaps?) ? Are they really that easy to put in wrong?
I have a vague notion as to the difference between jfets and mosfets, but as for a 'mu amp' I dont have a clue. Hope I'm not in over my head!! :shock:

As for the sound of the pedal ,yeah, chainsaw at full tilt sounds like a good start! I already own a few distortion/fuzz/OD pedals but this time I'm looking for something really massive and face melting:twisted:

As for the tone stack, I'm led to believe that its not too hard to add in a 'contour' mids knob and that this can give you much greater control over the tone. Might give this a shot.

Thanks again!

At the risk of sounding like a complete noob (1st diy pedal remember!), what exactly is a socket? I'm assuming its like a plug that I can solder direct to the board and then fit the transistors into it without soldering (for easy removal perhaps?) ? Are they really that easy to put in wrong?

It is an op amp socket that is cut to have 3 pins in a row. It allows you to plug in different transistors, so that if there's the issue of having them in "backwards" you can just flip them around, and it also allows for easy tweaking on the fly - in your case you can audition different jFETs until you find a combination that you really like.

Even though I've built many, many pedals, I still occasionally run into issues where the transistor pinout doesn't work, and it's really a PITA and very discouraging typically, even for me. I built a Colorsound Overdriver for someone recently, and I went with transistors that were most similar to the original ones - 2N3704's. The different pinout made that build a real PITA. Usually it's just a case of flipping the thing around, but it's still a hassle when it's 3 tiny terminals just a few mm apart!

If you want massive and face melting, by all means stick with the J201's that Ed designed the pedal around. For slightly less gain and more roundness, you could always listen to a clip (http://www.cmatmods.com/SoundClips/Brownie.mp3) of pedals like the CMATMOD's Brownie (http://cmatmods.com/brownie.html), which is a BSIAB2 clone with the '57's in all slots. And the contour control is probably a really good idea, so you'd probably be well served to at least prepare for it, even if you find it to be unnecessary.

My only other qualm with a stock BSIAB2 is that they are really bright, but that's almost a "duh" revelation. I typically crank the tone back to about 9:00, and then end up modding the circuit so that I have more range to work with (sometimes 7:00 is still a touch bright). But I have a feeling that I'm in the minority on this one, but nonetheless prepare yourself for one of the brightest distortion pedals that I've ever used!

Luckily for Zachy boy, Ed Guidry stayed cool.... [/I]

Something Zachy can't seem to do :wink:

barkely, take your time and you'll be fine. That's all the advice i can offer.

G'day Barkley

I strongly recommend socketing your transistors as 11 Gauge has suggested. I note you are in Canberra so I'd recommend going to Jaycar at either Fyshwick or Belconnen and getting a supply of DIP-6 sockets (DIP-8 will also do). When you get home get a small pair of snips and cut one down the middle, between the two rows of pins. You now have 2 transistor sockets for the price of one DIP-6 socket.

If you end up with DIP-8 sockets I'd suggest removing one of the end pins (either one) so you don't get confused with 3 pins on the transistor and 4 sockets to put them in, if you know what I mean. DIP-6s are a better way to go.

Dedicated transistor sockets are not readily available here in Oz and are expensive to buy in.

I was looking to do two things soon, build a pedal (never have done one before) and find a good distortion pedal to go with my DeVille, so this thread grabbed my eye. Make sure to keep us posted, because I may end up doing one of these if it goes well with the DeVille.

Am I right in thinking thier is some kind of love story between metulmykal and .011? :razz: :grin: :wink:
seriously tho, good advice and mykal, I'll be sure to take it slow!!
Seems like this pedal has a bit of a history to it yeah?

hoodie , cheers for the aussie advice, good to hear. :grin: I'll check out the dip6's at jaycar.

Billaftermath *high five* go the deville!

Ok, It arrived a day or two ago and I finished it tonight after two bouts of soldering, each lasting about 4 hours. Hooray, it works!!! First try no less!!

Haven't had a chance to crank it out of the deville yet (my 9 month old is asleep) but it sounds pretty good thru my headphone amp.

Here is a few things Ive noticed so far:

- The 'tone' knob is a bit funny, being completly muffled untill about 2o'clock where it starts to go pretty bright. Not as super bright as 11 guage had me believe, but pretty bright. This might change when i hear it thru a big amp tho.

-Its appears to be very loud. I know its a distortion pedal, but this thing is buzzing and huming like nothing else the second I stop playing. When I hit a string, this buzz stops and then its just the guitar sound coming thru.

-Maybe a metal sound? It definetly distorts the highs, like a top boost.

-Easy to build, Ive had almost no experience but did this pretty quickly with only minimal dire need of the instructions (apart from wiring diagram that is!)

One question / problem I had... There were these 3 resistors... 2 were Brown,red,black,black,brown (120 ohm) and 1 was Brown,black,black,red,brown (10k)...
For the life of me I couldnt tell which was which. They looked exactly the same, so I just kinda guessed which was which and put em in there. Could this drastically change the sound?
Would it ruin anything?
What is the function of resistors in a circuit like this, what do they actually do?
How can i tell the two types apart?
Thanks!

-Its appears to be very loud. I know its a distortion pedal, but this thing is buzzing and huming like nothing else the second I stop playing. When I hit a string, this buzz stops and then its just the guitar sound coming thru.

-Maybe a metal sound? It definetly distorts the highs, like a top boost.

One question / problem I had... There were these 3 resistors... 2 were Brown,red,black,black,brown (120 ohm) and 1 was Brown,black,black,red,brown (10k)...
For the life of me I couldnt tell which was which. They looked exactly the same, so I just kinda guessed which was which and put em in there. Could this drastically change the sound?
Would it ruin anything?
What is the function of resistors in a circuit like this, what do they actually do?
How can i tell the two types apart?
Thanks!

Yeah - it's a LOUD buzzsaw, especially with the J201's. If you want it a little more mellow, replace those with 2N5457's. And go easy with the gain control. :wink:

Metal film resistors are a PITA to remember the bands on. And ink over top of light blue can be harder to distinguish than on beige (carbon films).

The best thing to do is get a multimeter. Any cheap meter that reads resistance is fine, but you might want to invest in a nice little digital multi.

Putting the wrong resistor in the wrong spot can definitely affect the sound. The BSIAB2 actually only uses one 120 ohm resistor, and it belongs in R10's spot. I'm assuming you got that one right, or Q3/Q4 would not bias correctly with a 10K.

...And there are TWO 10K resistors, which go in R17's and R18's spot. If you accidently put a 120 ohm in one of those, it would make the pedal a bit brighter, as they are part of a fixed tone circuit that takes off some of the shrill top end.

You can't hurt anything by what you did - it will either function or it won't, albeit maybe not as intended.

A workaround for the tone control would be to reduce R8 until it doesn't sound so muffled at around 12:00. It would probably be easiest to replace the stock 82K resistor with a 100K trimpot, and bring the resistance down until you have the right balance. You can then either replace it with a resistor that's closest to the measured value on the trimmer, or just leave it in there.

If you still want to finesse the top end a bit, increase or decrease R17 and/or R18, but only do one at a time, and go gradually. Increasing higher than stock (10K) will remove more top end - try 15K or 18K in ONE slot and see if that helps. Decreasing less than stock will restore more top end - try 4.7K in ONE slot and see if that helps. Beyond that, you can keep increasing/decreasing, and even do the same to the second 10K if you need it still darker or brighter.

The BSIAB2 actually only uses one 120 ohm resistor, and it belongs in R10's spot. I'm assuming you got that one right, or Q3/Q4 would not bias correctly with a 10K.

...And there are TWO 10K resistors, which go in R17's and R18's spot.

I knew it was something like that! Thanks for the clarification. I'm thinking I put them all in the right spots now too as the pedal isnt extremely bright.

Excellent idea on using a trimmer in R8, this will allow me to set how high the tone control can go? (if you know what i mean?). If I cant notice too much of a change I'll give R17 and R18 a tinker.

Thanks heaps for the advice!

Also, using sockets was a great idea too!

Excellent idea on using a trimmer in R8, this will allow me to set how high the tone control can go? (if you know what i mean?).

Yeah, something like that. You can set it at the stock value (~82K) and start decreasing the resistance to make the end of the sweep towards treble brighter, with the hopes of being able to get the knob to around noon for the best balance. If you go really low (on the resistance) you risk scooping the midrange, but chances are you'll stop turning the trimmer well before that. Or you may like it scooped - it exaggerates the perception of distortion.

It's a little counterintuitive, because folks would think, "why make it any brighter?" The reason is so that you can get the overall mix right. That tone control is simply a high pass filter on one side and a low pass filter on the other (Big Muff mixer control). In the case of the BSIAB2, the high pass is set so LOW (~20Hz) that it's almost a bandpass mixer (doesn't really "boost" treble). The low pass is a little more typical (~154Hz). I typically have the best results with the treble shelf at around 800Hz, which would mean that you need to drop the trimmer down to around 2K.

...But many low pass filters are set to around ~400Hz, to give you somewhat strong bass but without it sounding too boomy. If you are having problems with the mids sounding too sucked out, try changing R7 from 47K to 33K or 22K. Alternatively, you could replace R7 with a 50K trimmer, but you could drive yourself nuts adjusting things. The good part is that if set to max resistance, it's basically the same as stock.

I generally hate trimpots, but they are a great way to dial things in. The Big Muff style tone control can be tricky.