Few questions on Highway 89...

[chris_d]

Right, so this was the most recent one i built, and it works fine, but i have some questions.

1. What is the purpose of the .68 uf cap? I had to remove the one i was using as it was physically too large to fit on the stripboard without causing trouble. I have a 0.47uf in there now instead. What will that cause?

2. The 4.7M resistor. I didn't have one so i have a ridiculous-looking chain of  4 series 1Ms and a 470k to get close-ish to the right value. Is 4.47M close enough for the purpose of this resistor? What would more or less resistance cause here?

3. I am also running 5088s instead of 5089s, as that is all i had around the house. How will this change the sound from the specified trannies?

The reason i ask about the subs, is that i have some questions about the operation of the pedal. It is interesting, like a treble booster, when the guitar volume is backed off, and more like a fuzz when i roll the volume up to max.

This is fine for lower output pickups, and on my tele(with low output single coil sized rail humbuckers) it makes a very nice distortion in the bridge position. On the neck position however, the pedal sounds good with the guitar volume backed off, but when i spin the volume up to max on the guitar, the neck pickup produces a very bass-heavy crusty fuzz tone. It actually makes it sound as though i backed off the guitar tone knob all the way to zero on my fuzzrite copy, very long sustain, and what sounds like a huge amount of treble attenuation. I have noticed the same effect with any of my guitars that have humbuckers, actually. The higher output the pickup, the more noticeable the bass fuzz effect. Much less obvious on my very other low output single coil tele or my equally low output strat...

This isn't necessarily a bad thing, and it is actually king of cool to be able to get such a wide variety of very different sounds from the pedal, but i was curious as to whether this is something inherent in the pedals design, or something due to my numerous substitutions.

Thanks for any input!

-chris

[oldrocker]

I'm not too sure about the component replacements you made and what would be the effects if any.  The 5088 should work good.  I used 3904's in mine and I think it sounds great.  The circuit does have some fuzz associated with it at higher gain.  Nature of the beast.  But some of the milky tone you get when playing leads is amazing.  Some think this a high gain fuzz and others think of it as an OD.  Matter of opinion I guess.

[Barcode80]

i dunno if it was specific to my build, but my gain was OVER THE TOP on this one. so i can't say i've experienced the characteristics you are experiencing. the cap likely just sets a knee frequency somewhere in the circuit, and lowering the value is likely why yours is trebly. IIRC, the 5089 is the same as a 5088 only typically lower noise, so your choice of 5088's might be the reason for some extra fuzziness. just my .02.

[John Lyons]

The 4.7M is a biasing resisor. You will not notice a difference between 4.47M and 4.7M, that's fine as you have it.

The .68 cap is a coupling cap and setts the low end roll off. .47 will have a little less low end. May not be noticeable though...
Actually, to be honset I don't know how the .68 and the.22 relate to each other sound wise....
You might want to put the .68 cap back in and under the board flat and see if it fits better there.
You can get smaller .68 uf  caps, might want to order some and make sure...

2N5088's should be fine. It's the same as an 89 but 89's are supposed to be a little quieter I believe.
2N3904's will have about half the gain of 2N5089's (roughly)

The Hwy 89 is a very thick and "round" sounding pedal. The neck pickup is usually pretty bassy so it's probably just too much for the pedal to sound right with that selection. You could make some changes to the circuit but that would throw off the main sound with the bridge PU.

It is a fuzz and distortion type sound. Pretty cool I think

John

[oldrocker]

Well it seems I'll need to pick me up some 5088 or 89's and try it.  I didn't realize there was that much less of gain from the 3904's.  Although I love the pedal now but I might like it even more with the right trannies in.  I meant to put the right ones in but I liked so much I never got around to it.

[momo]

About the fact that the pedal does seem to have too much output, at least that is how mine behaves, and I seem to remember other people that mentioned the hot output and possibly a change of values for the output pot, has this been updated?...anyone else seem to find the output too high?
I guess it does not matter much, as you can set the volume where you like it, but Im not experimented enough to know if that change would improve/messup the tone on this great pedal.
Im using all stock values and 5089's.

[oldrocker]

Yes I find the Hwy89 super loud.  To get unity I set the volume around 10 O'clock or slightly less.  Even with the 3904's it kicks out the volume.

[Barcode80]

my gain is out of control on it. i have to keep it at about 8 oclock just to be usable, but i think that's because i'm used to my tubescreamer

[squidsquad]

I had to tweak that last stage bias resistor(or maybe 2?).
I think I used a 2meg pot with a couple extras Rs on each side...dialed in a sweet spot.
Replaced the pot w/a custom *chain* to hit just the right value I wanted.
Of the dozens of things I've built...this one goes to the gig tomorrow night...I LOVE the sound!
However...it doesn't quite clean up...& now I'm wondering if I should try & dial-in the front stage. 
I confess...I'm not sure which resistors to tweak on that section...so any help would be appreciated.
I have a 9.5v supply powering it.

[John Lyons]

There isn't much clean up on the gain knob but a lot of cleanup on the guitar volume knob. SO I guess you could put a pot on the input to limit the signal as a guitar volume pot does. I'm not sure how the gtr and input pot would interact but it should be fine.

The output is way over the top on mine as well. I would imagine a 100K-A pot would cure that. I'll have to try it. 500K is pretty high impedance for an output. Lestening the level would be better done by reducing the output of the last stage though as squidsquad did.
An audio probe would be best to see where the main gain is coming from as far as finding a way to tame the beast... or at least add in a knob to do so.

John

[chris_d]

Yeah, lots of output and lots of gain here too.

Actually, the output i don't mind(as long as it will do >unity and can be made to do unity, it is fine with me), and the gain i prefer. I set the level at like 10:00, the gain at like 3:00, and use the guitar volume to control it. My main amp is a simplified marshall 18 watt, so i am used to using the guitar volume to clean it up anyhow.

I think i will try the "correct" 5089s at some point and see if/how that flavors the pedal, but otherwise i will leave it as is i think. The  way it blasts into bass-heavy fuzz at full tilt is really starting to grow on me.

The sound/operation of the pedal is actually quite unique amongst the other distortions and fuzzes i have messed with. My Fuzzrite cleans up to treble boost similarly, but just is on a different planet with the knobs cranked. This one's distortion is so well behaved and articulate compared. I enjoy pedals that can be run from the guitar volume quite a bit.

Thanks everyone for your input, information, and experiences.

-chris