marshall crunch - Zvex BOR or BSIAB II?

[slacker]

yeah that's supposedly what the BOR is, a couple a SHO type blocks with Big Muff tone control on the end. Not sure why people keep calling it a BSIAB tonestack when all that is is a BM tone stack with different values.
The "other place" has a schematic 

[markm]

Okee-Dokee! 

[snoof]

Not sure, I think rail to rail opamps will state this on the datasheets. The TL07XX datasheets I've got show the maximum peak output voltage compared to the supply voltage so you can see how close to the rails they can get.

cool, thanks for the info...

[burningwater]

so has anyone compared the MI crunch box and the BSIAB2 side by side. Im wondering if the BSIAB is worth checking out if it does the same thing as the CB. If it is less compressed Id be interested.

[wampcat1]

so has anyone compared the MI crunch box and the BSIAB2 side by side. Im wondering if the BSIAB is worth checking out if it does the same thing as the CB. If it is less compressed Id be interested.

Different tonality. Think Marshall Guv'nor on the Crunch box, and the bsiab (booster 2.5/ sweet thing/ etc) is a truely new design in the world of stompboxes, it is smoother and more responsive IMO.
bw

[burningwater]

Thanks man, looks like I may need to build the BSIAB and the Thor.

[markm]

I should add that the tone control on both the BOR and BSIAB is very useable and offers alot of "flavors"!

[burningwater]

Hey guys, so I built up a BSIAB2. Definitely has the VH thing going on. Seems like theres a lot of upper mids. One thing thats bugging me is that there is a lot of noise with the pedal. I dont think its anything with my build, but rather with 5 transistor stages and a healthy amount of gain I would imagine it would be noisy.

I wish I still had the crunch box to compare it to but from what I can remember the CB was less noisy but had less dynamics - maybe cause it was opamp rather than trannies. I like how this pedal feels but I would need to run a noise gate to make it usable.

Any ideas how to reduce noise - its more gain than I need so I dont mind loosing gain. I know the obvious answer is just turn the gain knob down but I think it may sound really good to just remove one of the stages. - Suggestions?

[John Lyons]

My BSIABII is quiet. A small amount of hiss at high gain settings but not really noticeable.

Here's a sound clip of my Box Of Rock without the boost. www.mrdwab.com/john/soundclipspage.html
Just scroll down to the bottom of the distortion clips. Starts with gain on "1" and then progressively more gain.

John

[96ecss]

Hi burningwater, I've built 3 BSIAB2's so far and none of them were noisy. Is yours boxed up?

Dave

[blanik]

i never heard BSIAB or BOR before so i downloaded both demos/clips... i don't like the BSIAB much, it sounds like a distortion pedal with what sounds like much compression, but boy did i get something when i watched the BOR video, sounds so natural...!! 

i read that the BOR is a Super-Duper (wich is 2 SHO in series with a master volume) with tone stack and a 3rd SHO for the booster but i found the schem and there's a fourth SHO in there!  boy did Z got milleage out of the SHO!! 

[John Lyons]

The BOR and BSIABII are not that similar in sound but they both sound very good. The BSIABII isn't compressed sounding to me. It really isn't too much different than the BOR as far as a quality/refined cranked marshall type sound.
Listen to the clip on my site linked above. There are a bunch of BSIAB clips and two BOR ones.

John

[Baktown]

Is there a VERO layout of the BOR anywhere that you guys know of?  I really like the sound clip of that one, plus the DOD 77 Overdrive.

Rock on!

Axl Bundy

[ubersam]

...One thing thats bugging me is that there is a lot of noise with the pedal...
Any ideas how to reduce noise - its more gain than I need so I dont mind loosing gain. I know the obvious answer is just turn the gain knob down but I think it may sound really good to just remove one of the stages. - Suggestions?

In my case, I built the BSIABII with all J201s because that was all I had, I also used carbon film everywhere - that was noisy. So, I got some 2N5457 and used those for Q1 and Q2 and replaced some resistors with metal film - that brought the noise down to what I consider acceptable. Oddly enough, when I took out the reverse polarity protection diode, a 1N4148, the noise performance seemed to have gotten better.

[JHS]

Any protection diode adds hiss and noise but a 10n-47n wired parallel filter the noise out and furthermore you can use a low noise rectifier diode. The SHO is noisy at at higher gain settings and the BOR with 3 cascaded SHO-type circuits is even noisier on higher gain settings.

The noise in the the BSIAB and the BOR can be reduced by "noiseless biasing" and a stable BIAS-devider, the OKKO Diablo( BSIAB-derivate) ist relative silent with this kind of biasing.

Tubeamps with 5 or 6 stages are noisy too (for ex. the Peavey EVH amp is hissing like hell).

JHS

[petemoore]

  Why noiseless biasing ?
  No need for 2x=value, very large resistors, something I tend to run out of.
  I usually have 2x=value, ~10k comp. resistors laying around to twist a bias string with.
  then I can longleg a huge value to the base, from the divider, above board [placing the body of the R where I might want insulation..next to the Q drain pin], to the stage I'm wiring and easily play with that value, put say a parallel 2m2 on it and see what that does...this R position would be the one to mess with first to see what kind of noise can be wrung out [also the input stage would be where the noise would then get multiplied the most, and resistor diddling results would be most apparent.
  Boiled down to 'why not NB?' on my Mu builds, i could find no reason, carbon comp, not very noisy.
  I generally put the Mu on, then something else before it, and the somethings elses seems to be where the controlling share of the noise comes from.

[Ed G.]

I build my bsiab2's with carbon film resistors and I don't find them noisy at all for the amount of gain you get.
I imagine using metal films would quiet it down some. I never felt the need to quiet it down any further, and take a chance at changing the tone.

[burningwater]

Duh, played with it today and figured it out. Its the voltage trimmer for Q5. I originally trimmed it by ear for optimal volume and dynamics assuming that was where it should be. But by backing it off I see it acts as a noise gate. The result is a somewhat less ampy tone than the more open setting but the noise level is greatly reduced. It still sounds best to me with the trimmer in the original noisy setting with a gate after it (MXR). The trimmer trick really works well but you get a bit of sputtering with it when playing softer. You seem to really need to adjust the trimmer to match the gain knob.

Tried it next to a BOR today and though it was very different. BOR having LOTS of bass which got very flubby where as the BSIAB2 has much more gain and is a lot more crunchy. The BOR seems very vintage sounding and has a really nice tube amp quality to it. I might want to get one and get in there to reduce bass a bit which will balance it and perhaps loose some of the looseness.