Triple SHO

[deaconque]

I brought this up in the Member's forum a while back to see if anyone thought it would be worth building.  Apparently, this is what Box of Rock is but  I decided to go ahead with it anyway.  So I built it up using a schematic I found here and right now it sounds nothing like a BOR.  This thing is seriously mean sounding, almost a Dual Rectifier type of sound. 
I came across a couple of issues while debugging though so any help would be appreciated.

1.  I used a 5k pot, as a variable resistor on the source of the last BS170, for the drive control but even when all the way down I still get quite a lot of distortion.  I've tried using trim pots in various places and moving the drive pot to different BS170's but didn't get any better results.
2.  Although it sounds good, it's sound is a little on the sterile side.  I tried changing out the 10M resistors for a lower value and also changing random parts with different values just to see what would happen but still didn't see improvement.  I love the character and amount of the distortion but I would like it to sound a little more, dare I say, "open".

Those are really the only 2 issues I've found so far.  This thing has a ridiculous amount of volume and distortion on tap and is the quietest pedal I've ever built.  So without further ado:
http://i293.photobucket.com/albums/mm62/deaconque/3sho.gif

If anyone wants to look it over and let me know if you see anything that should be fixed the I would be grateful.

[deaconque]

forgot to mention that even though it looks big on the layout, while building I minimized the length of the traces and the whole board ended up being about the size of a Fuzz Factory board

[tcobretti]

If memory serves, the BOR has the BSIAB tone control tacked on the end, and then another SHO that is switchable for boost.  That tone circuit will change the sound a bunch.  I haven't heard the BOR, so I can't comment about the Mesa-like sound you describe.

[deaconque]

this started as an experiment so I elected to leave the tone stack out for now just to be able hear the tone at it's purest.  for my setup I don't really require any tone adjustment but I could see it being a little bright for some amps.  I originally set out to get the marshally sound of the BOR but, as Bob Ross says, I had a happy accident.  I'm not setup for recording right now so I think I'll throw together a cabinet simulator so I can post some clips.

[WGTP]

I can't see the schematic here at work, but...

For the "Drive" control, you may need a 100k pot after the first stage.

Have you measured the bias?  Might work with that some for additional warmth/less sterility.

Also, might try some 1n caps to 9v or ground to roll off some highs.

[earthtonesaudio]

Another suggestion for the drive control: put it on the first stage, rather than the last, for more range of distortion/clean.
And I think you could make one bias voltage divider (using smaller value resistors for less noise) and then take your 1M-4M7 resistor to the gate of each MOSFET from that point.  Maybe.  It might oscillate though, depending on the phase shift from stage to stage.

[deaconque]

i'll try moving the drive pot to the first stage and see how that works.  the bias is good though.  q1- 4.56, q2- 4.6, q3-4.8.  oddly enough these were the bias readings from the very beginning.  i didn't have to adjust them at all.

[WGTP]

The bias looks good, but going higher or lower might be more to your liking. 

[puretube]

Tripple? ? ? : page 3: Quinto/Penta...   

[WGTP]

Well, Crap, it never ends.  Always something new to try.  Looks pretty cool to me.  If someone will tell me the values, I'll draw a schematic.   

http://www.aronnelson.com/gallery/main.php/v/WGTP/Enhanced+Mode.GIF.html

[deaconque]

that looks interesting.  how would it sound with just one capacitor in there?

[DougH]

As I already mentioned in the members thread you will probably need some attenuation/filtering between the stages to get the sound you want. Look at the BSIAB or Booster2.5 for clues. Also, in the 2nd and 3rd stage, 5MEG of Zin is *way* overkill. Lowering that will lower the gain and can help smooth it out.

So now you have discovered (as others already have) that slapping three gain stages (boosters) together in a row does not make for a pleasing distortion sound. So now you have to put some work into and learn what does make a pleasing distortion.

There were lots of ideas, hints, and clues in the members thread. Use that as well as the wiki and other resource areas on the forum to learn how to tune this into something that sounds good.

[deaconque]

If you read through this thread you will notice that it's not the sound of the distortion that is a problem.  Really the only problem I have right now is getting the drive control to be more effective.  Yesterday I finally got to listen to this circuit at a reasonable level (not bedroom volume) and it sounds pretty amazing as is.  Here's a link to the layout again with the parts that I changed already http://www.aronnelson.com/gallery/main.php/v/deaconque/

I changed:
R1,R2 from 10M to 5.1M
R6,R7,R11,R12 from 10M to 1M
Removed the cap and resistor coming from the 9V

I'm going to try moving the drive pot to one of the other stages and add a pot b/t the battery and circuit to cut the voltage.  With a full 9v it sounds Mesaish but with a couple less volts it can get into cranked Marshall territory.  This is by far my favorite project so far

[puretube]

For the innocent bystanders: the other thread...

[DougH]

it's not the sound of the distortion that is a problem.

Too much gain, not enough headroom, ineffective gain control, sterile sound, etc- it's all related to the stuff I mentioned.

[deaconque]

OK so here's an update.  I have revamped the schematic a little to include a tone stack and a couple value changes.  It sounds great at the moment with one exception: it is lacking a good bit in the low end.  I've done everything i could think of so far and nothing seems to help.  The weird thing is I can take many of the components out of the circuit all together and it has no effect on the sound (very weird to me  ).  I can also reverse the polarity of the EL caps and it doesn't change the sound either.
After testing it along side some of my good sounding distortions, I've come to the conclusion that I need a boost in the range of about 80-110hz to get the sound I'm after.  I've tried changing the input and output caps to drastic degrees but even when I completely bypass them I get the same sound.  This thing has the potential to be a serious beast if I can get it right.  Any suggestions, Please??




p.s. I have taken R16 out of the circuit and C1 is socketed with a .027 (at the moment)

[Gus]

You don't need 3 zeners you only need one at the first stage.  Do you know what they are for and what they protect against in the mosfets?

R4, R9, C2, C4 are not needed
C3 and C5 1uf with a 500k load?

Doug gave some good information

[deaconque]

i read in a post by zvex about the super duper 2 in 1 that the zeners were to protect the BS170's so i put them on every stage out of ignorance.  C3 and C5 are actually .1uf, the schem's kind of hard to read.  C2 and C4 were also on the SHO schem so I included them, again out of ignorance.  The only info I could gather from Doug's posts was stuff that would end up lowering the gain and that is far from what I'm trying to accomplish.

[BaLaClavaAa]

Could we hear a sound clip, sounds interesting

[DougH]

I can't read the schematic at all.

The only info I could gather from Doug's posts was stuff that would end up lowering the gain and that is far from what I'm trying to accomplish.

It's not about lowering the gain. It's about contouring the frequency response so you get the gain in the frequency bands that sound good.

Dude- You've posted basically the same idea 3 times now. I've made suggestions to improve it twice at this point. If you don't read the tips/mods material Aron has had posted elsewhere on this site for years and try any of the ideas- there's not much anyone can do to help you.

The definition of insanity is repeating the same behavior over and over and expecting different results...