Slow Gear build report

[mdh]

I put together a Slow Gear from the GGG layout (http://generalguitargadgets.com/index.php?option=content&task=view&id=113&Itemid=159) today, so I thought I'd share my experiences.

Substitutions:

1. 741 op-amp (not a substitution, but worth mentioning).
2. 2N4401 NPN BJTs in place of BC549. I just happened to have a whole pile of them acquired in search of low-gain NPNs for a Si Fuzz, but they turned out to have hfe ~250. They have the opposite pinout of BC549, so they're flipped around relative to the GGG parts layout.
3. 2N5485 in place of 2SK30A. The pinout is DSG, whereas the 2SK30A is DGS, so I had to twist the leads to get the gate in the middle. I didn't pay any attention to the relative positions of the drain and the source, b/c this doesn't seem to matter with JFETs.
4. 5.1V zener in place of 5.6V zener. It's what I had, and I figured that since it was serving the same purpose as the 5.1V zener in the Phase 90 (in which I used 2N5485s, too), there was a chance that I would get away with it. I did, with some possible caveats (see below).

The layout:

I hesitated to build this circuit for quite awhile, because I wanted to redo the layout. I was hoping to fit it into a 1590B, but my early attempts at a more compact layout weren't working out. So I decided to push forward with the GGG layout. It worked out, but one thing worth mentioning is that the transistor pads are very small, and spaced more closely than 0.1 in. This makes it sort of impractical to use sockets for the transistors, which is fine for the BJTs, but maybe not for the JFET (the stock part is hard to find, so you may need the option of swapping). I just soldered the BJTs in directly, but managed to cram in an old style transistor socket with bendable leads for the JFET. Had I noticed the lead spacing before I etched the board, I probably would have at least jiggered the layout around enough to accommodate 0.1 inch spacing for the transistor leads. If I ever build another, I'll definitely play around with the layout a bit. If one of the resident layout geniuses wants to take this one on, you would have my undying gratitude, though I can't speak for others

The sound:

By my reading of past threads, I'd say that the Slow Gear seems to be the Rodney Dangerfield of effects... it gets no respect. Maybe that's a harsh characterization, but people do seem to be a bit disappointed with it in general. I have to say that I really like it for what it is. It doesn't turn my guitar into a violin, but along with my Phase 90 and a little chorus from my amp, I can do a pretty good organ imitation, which is what I was looking for. Maybe kind of a one trick pony, but a neat trick, nonetheless. Previously, the best organ imitation I could do was Neutron->Phase 90->Chorus, with the Neutron on downward sweep, low range, kind of medium-ish resonance and mid-to-high sensitivity, and of course the Phase 90 on a pretty fast rate. I'm still not ruling the Neutron out of the organ-sim FX chain, but the Slow Gear adds another dimension to the sound. Mark Hammer has recently written about this dimension pretty eloquently, so if you're interested, you might take a look at this thread: http://www.diystompboxes.com/smfforum/index.php?topic=54164.0.

I also think that the Slow Gear effect alone has a lot of potential for expressive passages. It's the kind of effect that you just have to sit back and work with, letting it constrain you... in a good way. As others have commented, technique is important in getting the most out of this effect, and I think the main technique is patience. Leave... some... space.

Aforementioned caveats:

I suspect that I'm not even getting the full bang for my buck out of this effect. R.G. has stated in previous threads that the ideal JFET for the Slow Gear would have a Vgs_off of around 3-4V. I used a 2N5485 with Vgs_off of 1.990V, as measured with R.G.'s improved JFET matcher (see geofex.com if unfamiliar). This is in the same ballpark as the JFETs I used in my Phase 90. As I understand it, the idea behind the zener diode plus trimmer arrangement is to make it possible to set the DC voltage on the gate of the JFET such that the JFET is turned off when there is no input, but only just. In practice, I wound up setting the trimmer in my Slow Gear to one extreme -- wiper shorted to ground -- to get the most out of the effect. My intuition suggests that I want either a smaller value zener, or a JFET with a Vgs_off closer to 3 or 4V, but I concede that I could be completely off base. I could do with a more formal education on this subject, so if anyone wants to offer any equations governing the behavior of such circuits, I'm game. ODEs are alright, if you've got 'em

Summary:

This is a very cool effect. The layout is a little problematic, but workable. If someone can fit it into a 1590B, you're my hero. Otherwise, the GGG layout should fit a 1590BB. I think the Slow Gear is most effective in combination with other modulation effects, or simply with a little patience.

[Processaurus]

Good report, you can try lower zeners just by clip leading them in parallel with the 5.1v one in there now, the lower one will turn on before the 5.1v, so it won't matter its still in the circuit. 

I'd still like to get longer swells out of this one...

[markm]

Any opinions from you fellas as to how well this circuit would emulate pedal-steel volume swells?

[scotsman]

Any opinions from you fellas as to how well this circuit would emulate pedal-steel volume swells?

The swell time is not quite long enough in my opinion..  Try raising the value of C6 - to 2.2µf - that should give you some longer swells...  Assuming I read the schematic correctly.

Also,  put your compressor in front of it! 

[markm]

Any opinions from you fellas as to how well this circuit would emulate pedal-steel volume swells?

The swell time is not quite long enough in my opinion..  Try raising the value of C6 - to 2.2µf - that should give you some longer swells...  Assuming I read the schematic correctly.

Also,  put your compressor in front of it! 

Interesting.
I have thought so many times of building one to use for the purpose of pedal-steel type effects but, haven't worked up the courage to try it! 

[oldrocker]

I think this will be my next build also.  I've been contemplating this effect for quite some time.  I'm going to substitute the transistors for this.  I was thinking an MPF102 for T2 and 4401's for the rest.  I will probably go with a 5.1 zenor as well since I have one laying around.  Hopefully my wife won't have a fit since I promised her I'd take a break from it.  Damn I'm so addicted.

[markm]

I've made that statement soooo many times OL, my wife knows how I am though and, so do I ! 

[mdh]

Good report, you can try lower zeners just by clip leading them in parallel with the 5.1v one in there now, the lower one will turn on before the 5.1v, so it won't matter its still in the circuit.

Thanks for the tip, I hadn't thought of that!

[LOTUS]

'Any opinions from you fellas as to how well this circuit would emulate pedal-steel volume swells? '   I have an origInal and that is what i use it for. No compressor needed . it is awesome !!!!!  For the bckwards thing . Ya need fuzz.

[markm]

‘Any opinions from you fellas as to how well this circuit would emulate pedal-steel volume swells? ‘   I have an origInal and that is what i use it for. No compressor needed . it is awesome !!!!! 

Really?!
Well, you're convincing me!!

[LOTUS]

Robbie robertson from the Band secret weapon . You can see him use one in the Last Waltz.The only mod i did was put a new jrc 741 for the op-amp.

[oldrocker]

Since I read that the slow gear is really a noise gate modified to slow up the attack, how much trouble would it be to make a Slow Gear type circuit out of an MXR noise gate circuit.  I was curious about that.  I have all the parts I need to build the Slow Gear but I was thinking I could just modify the Noise Gate to get the same result. 

[Processaurus]

good thinking, I'd love to get my NS-2 to do that.

[rockgardenlove]

Robbie robertson from the Band secret weapon . You can see him use one in the Last Waltz.The only mod i did was put a new jrc 741 for the op-amp.

What songs from the Last Waltz?  I've got the CD set, what an amazing concert.
I watched the video too, didn't notice it.  Where exactly?

[mdh]

I don't know about noise gate modifications, but I do have some really quick clips that I made to get across what I mean about organ-like sounds. Both clips were recorded with a dual-hb guitar, both pickups, tone and volumes dimed, through a ROG Condor cab sim and into a lousy PC sound card. The first clip is just the Slow Gear, with attack on max and sensitivity somewhere in the middle. In the second clip, I go for overwrought organ sounds with:

DOD FX75C Flanger->Slow Gear->Phase 90

The flanger is set to a chorusy flange and the phaser is set to a fast rate. I haven't really played with the fx order much yet, but I like what I hear so far. It's just a few chords, strings plucked with 4 or 5 fingers. I found that strumming was a little bit more problematic, because the swell effect makes you want to drag the pick over the strings slowly, but that actually kind of defeats the purpose, as strings you hit later have more attack. I guess that's because it's really a slow noise gate, so as long as you let a string ring, other string attacks sound pretty normal. The files:

http://two.ucdavis.edu/~holland/music/fx/SlowGear_1.mp3
http://two.ucdavis.edu/~holland/music/fx/SlowGear_2.mp3

It definitely has limitations, but I've been able to get some really cool sounds without much thought or effort. I like it!

[LOTUS]

What songs from the Last Waltz?  I've got the CD set, what an amazing concert.
I watched the video too, didn't notice it.  Where exactly?    On the video you can hear and see him use it during a joni mitchell , coyote song.Very short . 

[LOTUS]

Nice clip mdh.   Sounds a little cleaner then mine. I have been able to make it sound like a organ too. I love bending notes or sliding Into them

[rockgardenlove]

^At around 1:45 on Coyote?

EDIT:
2:45 too now that I listen to it? 

[sfr]

That's some nice sounding stuff - but I'd love to hear what this thing can do with a faster playing?  Not to sound rude, but all the Slow Gear sound samples I hear are slightly akin to what you've put up here in the demo, in as much as I haven't heard anything I can't do with a volume pedal.  (I also thought the part about emulating pedal steel volume swells was interesting for the same reason - because don't pedal steel players get those sounds with a volume pedal?)

I don't mean to sound negative; (and congratulations on the build!)  I'm just curious what sorts of things one can get out of a Slow Gear that I couldn't get out of a volume pedal, or what sorts of things become easy enough with the SG to warrant using it rather than a volume pedal - just like auto-wah's have their own place even though we have wah pedals, I'm sure the SG has it's place even though we have volume pedals - I'm just not sure what that place is.

I gues I'll have to track down that stuff from The Band that was mentioned.

[mdh]

sfr, point taken. I'd like to hear what it sounds like in faster passages with good technique, but alas, I lack such technique I also just built the thing Monday, so I haven't had a lot of time to live with it and get to know exactly what I can get out of it aside from the slow swells that could be done with a volume pedal.

I can make some observations based on my experience with it so far, though. One of the limitations, for example, I alluded to earlier in the thread: since it acts as a slow noise gate, once it swells to full volume, you get full-on pick attacks until the input falls below the threshold. As a practical matter, this means you'll be doing slow swells that you could probably do better with a volume pedal, or you'll be playing quick passages of single notes with the articulation on the end of the note, rather than attack at the beginning. Hence, the "backwards-playing" references that people make. In order to make this work, though, you have to provide quite a lot of articulation between notes to get the gate below its threshold. So, probably not so good for the nice legato passages that you may imagine at first.

In summary, maybe it's not really that flexible of an effect, but I haven't really lived with it long enough to know that for sure. I'm sure there are digital devices out there that can do backwards and legato effects much better, but this thing's diy-able, and quite amusing to play around with, especially in conjunction with modulation effects. I can't really address the volume pedal issue, except to say that I don't have one, so this thing gives me an ability I didn't have before