Nothing Sounds Good

[seedlings]

I've breadboarded a dozen or so drive circuits in the last couple of weeks from a double SHO to BSIAB to ROG stuff, Peppermill, 2 or 3 J201 variants, same with BC170 circuits and combinations of the two.  Everything sounds to have a fizz decay like mis-biased; using low output or medium output pickups in different guitars, different amps.  Careful to use correct components and check bias per schematics... eben using the oscilloscope to see how the clipping goes from component to component.

Some of the opamp circuits sound OK.  I'm trying to figure out why some circuits sound nice in videos or sound clips, but I always hear it differently when I play even one chord..  The only circuit I really like and use is a Ge Fuzz.

CHAD

[pappasmurfsharem]

I've breadboarded a dozen or so drive circuits in the last couple of weeks from a double SHO to BSIAB to ROG stuff, Peppermill, 2 or 3 J201 variants, same with BC170 circuits and combinations of the two.  Everything sounds to have a fizz decay like mis-biased; using low output or medium output pickups in different guitars, different amps.  Careful to use correct components and check bias per schematics... eben using the oscilloscope to see how the clipping goes from component to component.

Some of the opamp circuits sound OK.  I'm trying to figure out why some circuits sound nice in videos or sound clips, but I always hear it differently when I play even one chord..  The only circuit I really like and use is a Ge Fuzz.

CHAD

What are you plugging into?

[seedlings]

Any one of three low-gain (one or two gain stage before PI) tube amps I've built.  One has a 6SJ7 V1, the other two have V1 12ax7, and of those, one is 100k/1.5k and the other is 100k/820r.  I've been mindful to keep the output of the breadboard circuit low enough to prevent clipping of V1.

CHAD

[Mark Hammer]

A few summers back, a local buddy asked me for some help finding a suitable overdrive pedal or booster to complement his recently acquired Ampeg.  I piled up about a dozen things I had into a box, ranging from the pristine AMZ MosFet boost to somewhat dirtier-sounding units, both op-amp based, discrete, and invertor-based; stuff I had cloned, and stuff I had designed.  He tried them all out, and came to the conclusion that nothing sounded particularly good to his ears, when pushing that particular amp.  he ended up selling the amp.

I am hesitant to generalize too much from this incident, but I think it is not all unreasonable to suggest that some amps just do not like being pushed hard, unless the signal doing the pushing is preconditioned/shaped in a very selective manner so as to not bring out certain unpleasant qualities in the amp.

[Seljer]

I once had the same issue, after three iterations of various multiple JFET stage overdrive/distortion pedals I couldn't get the final decay to sound nice and soft. You could always discern the clipping it at the very end when it's almost clean and it's only cutting off the tips on one end of the waveform. So yeah, good sound for everything-to-the-wall distortion, only so-so for softer overdrive. I ended up giving up on the concept on going back to opamps and diodes 

[seedlings]

Your comments are appreciated.  Without direct experience with a hundred commercially available products, I might be looking for something that isn't there.  If I were to directly play some of these pedals demoed online, maybe I would hear the same thing that I hear on the breadboard.  IOW, I'm probably picking at something that isn't there, or is presumed to be present.

Last night's excursion involved using pre-clipping diodes like in the ROG Azabache.  (I also found that a decent drive can be made with a couple of Ge diodes to ground across the guitar signal alone.) I also am trying the similar technique that Joe Davisson uses on the Vulcan circuits with the diode off the gate, then on to the bias resistor.  There is perhaps some improvement.

True, those other circuits can sound like a wall of marshalls with power chords, but whatever the fuzz pedal does, just always sounds more musical with picking dynamics and decay.  Usually the signal clips after the very first gain stage with a jfet or mosfet giving that hard buzz fizz decay.

CHAD

[midwayfair]

A ton of drives sound awful through the blackface channel on my amp, which otherwise sounds great. A lot of stuff sounds uninspiring through my Hot Rod Deluxe as well. There are lots of amps I actually hate the overdriven sound of (and it's enough amps that part of me wonders if I actually dislike tube distortion). I had a lot of the same complaints you had when I was messing around with overdrives: Everything had this weird crackle on the decay, or it sounded too dark/congested, or the fuzzes all sounded misbiased. Then I switched over to the lead channel, which has a flatter response (no scoop), and all of a sudden a bunch of stuff sounded good. SO maybe it's an EQ thing. I notice that a lot of the stuff you've described is made to either push an amp or work as a "foundation" drive that emulates an amp -- in which case it might simply not mesh with your amp's EQ.

And you like a germanium fuzz ... That's because fuzz is awesome. Many, many people have concluded that it's the right distortion sound for them.

You might also try stacking some low-gain stuff into your amp set clean, and/or stacking with your fuzz on a mild setting. You may find that improves things. One of my favorite sounds is a Ge fuzz on a mild setting into a FET-based overdrive with the treble cut a little into a clean amp.

But keep hammering at the breadboarding, and try every technique you can get your hands on. Somewhere, there is a solution that will work with your setup. It might take a while to find it, though!

[pappasmurfsharem]

Do you like your DIY amp with a booster in front?

[Mark Hammer]

Said it a thousand times, and I'll say it again: when amps get overdriven, they generate more harmonic content, because that's what overdrive tone IS.  Feeding an amp near breakup with a bright signal is asking for trouble, since it will produce harmonics of harmonics, and they sound awful.  Any booster worth its salt, whether clean or offering some pre-coloration, needs to have a useful treble cut, so as to compensate for what you don't want the amp to do.

[Mark Hammer]

Just an addendum question: Does the palatability of a booster pedal depend on the gain of the first preamp tube?  In other words, if one replaces a 12AX7 with a lower-gain type (AY7, AT7, AU7, etc.) or increases the cathode resistor, or maybe even places a small resistance in series with the cathode cap to reduce gain, does that change the sweetness of a stronger front-end push in any consistent manner?

[seedlings]

Do you like your DIY amp with a booster in front?

I see where you're going with this line of thought, and you could be onto something.  I have a rangemaster with a beefier coupling cap on a switch.  I also have a plain jane opamp clean boost.  I do not recall 'turning them to 11' straight into any amp yet.  I use the rangemaster in front of fuzz and distortion (wampler trip wrek clone).  The opamp boost sometimes goes after the signal chain to give a slight overall boost of everything when a song required that.  But, tonight I'll slam them into the front end of some amps.  If they don't sound great, could be the amp - I see that now, or the EQ as midwayfair suggested.  My 6SJ7 amp is an 'jones octal one', no EQ or tone, just 6SJ7 >1M vol> single-ended KT88 (I know, I know).  My main amp is a 12ax7>plate fed marshalish tone stack >other half of 12ax7 > 12AU7 PI > KT66 cathode biased push-pull.  The 3rd amp is a gutted silvertone 1483 and re-built like a marshall, but with 6L6 tubes, and the undersized factory silvertone OT.

I will say again that I have kept the output signal of the circuit low enough (similar to bypass levels) to prevent clipping the first valve.

Said it a thousand times, and I'll say it again: when amps get overdriven, they generate more harmonic content, because that's what overdrive tone IS.  Feeding an amp near breakup with a bright signal is asking for trouble, since it will produce harmonics of harmonics, and they sound awful.  Any booster worth its salt, whether clean or offering some pre-coloration, needs to have a useful treble cut, so as to compensate for what you don't want the amp to do.

The KT66 amp is bright.  The 6SJ7 amp is not... but I am going to experiment further.

CHAD

[pappasmurfsharem]

Do you like your DIY amp with a booster in front?

I see where you're going with this line of thought, and you could be onto something.

Yeah, I'm curious if the amp just doesn't sound nice when boosted.

[thelonious]

My experience is that it's tough to get amps that sound great clean or lightly pushed - "chimey", "sparkly", "[insert your favorite onomatopoetic amp descriptor here]" - to sound great when pushed hard. That's one of the reasons behind multichannel amps (even though I often don't like 'em much because they force my playing into either-or). You can try adding an effects loop to one of your amps so you can insert a multiband EQ between preamp and power amp. In fact, with a little relay work and planning, you could get your distortion/overdrive/booster pedals to turn your effects loop EQ on when you turn on an overdrive or booster.

Also, are you playing at low volumes? Check out this thread about the Fletcher-Munson effect.

[seedlings]

Also, are you playing at low volumes? Check out this thread about the Fletcher-Munson effect.

^That is a great and helpful (comforting?) discussion!  Tonight I will start with the fuzz pedal set so that bypass sounds nice, and effect sounds nice, at a moderate (louder) volume than I've been using.  And then start to try the current version of a two stage BS170 on the breadboard.  Perhaps A/B with a known good effect will help.  This means the pedal board will have to come home for testing.

CHAD

[seedlings]

>Full 9V clean boosted signals to the 6SJ7 pentode pre/ single ended amp I did not like

>Full 9V clean boosted signals to the 12AX7 / KT66 PP amp I liked very much

With the breadboard drive circuit:
>I flattened the EQ on the amp by leaving the mids on full, and turning both the bass and treble down full, which should be pretty flat according to Duncan's Tone Stack Calculator which made a marginal difference at low volumes

>Turning up the (~40 watt) amp master volume to full (simple crossline PI) made a noticeable improvement with the breadboarded circuit

>Turning up the gain on the amp made an even larger improvement

I am not sure what to conclude.  With the amp set to soundman's nightmare volume, the circuit does mostly what I hoped it would do: amp to edge of loose breakup, and use the drive pedal for 2nd channel medium gain.  The fuzz already covers this ground, but there has to be a guitar volume adjustment along with engaging the fuzz.  With the amp set at lower volumes, the circuit is less impressive.  It did sound better on the 6SJ7 amp with the master cranked up than with the master low.

Now I am adding a 3rd gain stage to the circuit with the hopes of regaining some of the 'amp-already-turned-up-ness'.  Or, perhaps it's just some compression that I'm needing... I don't have a compressor yet.

I do believe this dialogue is very helpful for me!  Many thanks for sharing your patience and wisdom!

CHAD

[thelonious]

You might be into amp-modding territory next. Fortunately or unfortunately, depending on how much work you're up for.

>Full 9V clean boosted signals to the 6SJ7 pentode pre/ single ended amp I did not like

6SJ7's can be tricky. If what you built is a 5C1 Champ or something similar, make sure you're not using the 5M grid leak bias method. That bias method is known for not taking pedals gracefully. If you already have the 6SJ7 cathode biased, you might need to mess with the bias point until you're happier. You can also increase the screen resistor value to get it to compress more.

With the amp set to soundman's nightmare volume, the circuit does mostly what I hoped it would do: amp to edge of loose breakup,

It's a pain, but you might want to try installing VVR/power scaling. It's pretty effective at getting cranked-amp tones at lower volumes.

Or, perhaps it's just some compression that I'm needing... I don't have a compressor yet.

Compression on the front end might help, but if it sounds better to you cranked... probably you should be looking for compression at the other end (i.e., the power tubes and your ears). You can't fix your ears to compress at lower volumes, but you can power scale to make your power tubes compress at lower volumes.

[seedlings]

depending on how much work you're up for

Again, advice much appreciated.  The 6SJ7 is cathode biased, pretty close to schematic values (been a couple of years since building) http://www.freewebs.com/jonesamps/JonesOctalOne.pdf .  Not a problem to open it up at some point for tweaking.

I have a VVR in a project amp (in the back of the closet somewhere), so I have done that mod before, and it might be worth revisiting!

CHAD

[davent]

For my Octal One i ended up with very diifferent preamp values in the quest to give it some sparkle and crunch. I'm pleased with the way it works with pedals but then i used a baby output tube, 6aq5, so can run it flat out without too much negative feedback from the residents. It's also power scaled but don't really need it much for this small output tube.

[amptramp]

^

This seems like a very high screen resistance - 220K would work there.  The cathode resistor could go up to 1.5K just to keep the grid below cathode voltage for all inputs.  My Stromberg Carlson PA amp uses 220K screen and 1.5K cathode with the same 6SJ7 tube in a similar stage.  The tube is running at 0.8 mA cathode current (0.96 volts across the 1.2K cathode resistor) which seems to be a little low.

[seedlings]

I went back through, and my 6SJ7 has 367V on the rail node, which drops through the 220K to 212V at the anode, and through a 2M2 to 27V on the screen (bypassed to ground with a 47n).  Cathode resistor is 1k5 // 2.2uF sitting at 1 volt.

I will try decreasing the screen resistor, and perhaps a beefier bypass cap from the 2.2uF.

CHAD