Guild TRIOCT (whhhaaaaaaat??)

[armdnrdy]

I suppose you would like me to fabricate a pick up for this thing? 

Do you genuinely make hex-style pickups, etc?

I've never even made a basic single coil pick up but...as it is said, "necessity is the mother of invention."
Nothing is beyond the scope of imagination and.......information gathered from the internet. 

[theehman]

Do it the cheap way with 3 P-bass pickups.  Use a section for each string and align the polepieces with the string.  6 of them together should look like some major Music Man pickup.

[Mark Hammer]

Dino, did you happen to measure the DC resistance of the individual coils on the PU?  All these years, and I never did it. 

I'm also curious about what the AC output is from each coil.  Knowing that might provide some pointers regarding what might adequately sub for it. 

[liquids]

I think he put it on the schematic...around 640R-650R (ohms) of resistance per coil, give or take...

[liquids]

seems like most 'hex' pickups are spec around the same...and it seems the most critical differences (if any) are individually humbucking or not.  Though I've not seen the innards of this one, it does seem to be much larger than the roland or gvox hex pickups. Certain ones seems to get into the 820R impedance range...
I imagine that most of them use what is available given what is practical within space confines, consistency, and such...

Paul with "Ubertar" offers hex pickups that at least fit in standard single or humbucking cases for mounting in standard positons (thought he suggests bridge positions...).  There's another hex pickup that I've seen which is a humbucker, and touts significantly higher coil resistances (and a few variations in coil resistance at that)...but that is just from browsing the web a bit.

I got an old Gvox at the reccomendation of the great Mr. Harry Bissell.  Available fairly cheap on ebay, though not perfect (your wishes and your guitar and wiring skills permitting...). Seems like it will do the deed for most peoples hex needs...not that I've gotten all that far with it. And I'd certainly say, if you're right handed and interested enough, spend for a roland since it's ubiquitous and more plug-and-play with many guitars...Gvox may be perfect for some anda big savings...or merely a good way to cheaply explore (like it may be for me, when I get to really going forward with it expirimentally)...

Electric-guitar piezo saddles seem like they offer some of the best cost/benefit ratio if on can work on the circuitry needed to reign-in the frequency response, and deal with those quirks with minimal modification, depending on the guitar involved...

I wouldn't turn down a good, standard sized magnetic hex pickup option by any means though, if it were something that worked for whatever I was hoping to do, affordable in a cost/benefit ratio sense, and didn't lead to hum problems...doesn't seem there are many people offering them though!  

[Mark Hammer]

I think he put it on the schematic...around 640R-650R (ohms) of resistance per coil, give or take...

Ah, can't see the schems at work and don't have particularly good internet access at home.

Just as a side note, while it may not apply to many reading this thread, a great many folks misconstrue DC resistance as equivalent to output.  They aren't the same thing, strictly speaking, although #turns = output and if the identical gauge is being used on the identical coilform, higher and lower DC resistance correspond to higher and lower outputs.  Just realize that there are a lot of different ways to arrive at the same #turns, and when the turns are wound around a single measly magnet, you can pack on thousands of turns and still come out with a VERY low DC resistance.  The difference between one hex pickup and another may measure a mere 200 ohms per coil, but actually reflect a much bigger difference in #turns, as well as in magnet strength.   On a Strat pickup, outside turns on the coil are generally in the range of one turn = 1 ohm. Not so when the total circumference of a turn is <1/2".

In the case of this particular circuit (Tri-Oct), there is a fairly specific objective in mind (polyphonic octave division), rather than some sort of "omnibus" functioning anticipated, such as would be appropriate for a synth that uses digital processing to identify the fundamental.  As such, there may well be some properties of the hex pickup that are optimized for the circuitry.  I certainly don't know that for a fact, but merely raise it as a possibility.

[liquids]

Very good points, as usual, Mark!  Basically - given that 'tone' may be less critical for hex pickups since plenty of processing ensues post-pickup...and the fundamental is what we want...one could make a hex pickup with the smallest, thinnest wire, be able to do a ton more windings, and hence, output closer to the average pickup by comparison...?

I know that the output from the gvox pickup is rather low, by comparison to even my PAF humbucker...which is lower output range for a humbucker...it's a duncan "Seth Lover" if that helps...I used a massive amount of additional pre amplification to get equivalent output from each of the strings.  I'm thinking thats the norm from what I read, discuss, and hear, but certainly that may not only be wrong, it may be highly variable depending on what hex pickup one has.

[Gus]

A thread from another forum about a hexpickups first and last posts
http://www.groupdiy.com/index.php?topic=48856.20

Has anyone checked the link?

[snufkin]

may I suggest buying a powergig guitar hero type controller they can be had for $20ish and you get a hum-bucker size pickup with independent outputs

and as a bonus you also get some potentiometers some very weird cheap guitar hardware (good for experiments) some components and if the mood for a guitar synth really struck you a split fret board with pre colour coded wiring

http://www.ebay.com/itm/Power-Gig-for-Xbox-360-Rise-of-the-SixString-Game-includes-Six-String-Gutair-CD-/130962983901?pt=US_Other_Video_Game_Accessories&hash=item1e7e008bdd

[digi2t]

may I suggest buying a powergig guitar hero type controller they can be had for $20ish and you get a hum-bucker size pickup with independent outputs

and as a bonus you also get some potentiometers some very weird cheap guitar hardware (good for experiments) some components and if the mood for a guitar synth really struck you a split fret board with pre colour coded wiring

http://www.ebay.com/itm/Power-Gig-for-Xbox-360-Rise-of-the-SixString-Game-includes-Six-String-Gutair-CD-/130962983901?pt=US_Other_Video_Game_Accessories&hash=item1e7e008bdd

Hmmm... very interesting. Gonna check this out for sure.

[snufkin]

http://www.vguitarforums.com/smf/index.php?topic=3115.0

someone did here

[liquids]

Anyone have the basic (or complex) reason hex pickups, primarily used for 'tracking' kind of stuff, tend to be as close to the bridge as possible, when it seems that the fundamental is strongest as one gets closer to the 12th fret/middle of the string?

I've been thinking...maybe more in regard to monophonic than hexaphonic, though my monophonic approaches have worked all but without issue by now, for ME (ie my guitars, my playing style, the circuits used for note "detection")...

I was listening to different pickups on the SD site as I do from time to time.  Some sound very 'dark' and are typically high out put, as do others sound rather harmonic-laden ('bright') which are mostly low output, all else being equal (and it never is), and knowing that this need not be the case, it's just the trend...

Anyhow, listening to some pickups makes one hear what might sound 'muffled' from a tonal perspective and comparison perspective....but effectively, in some way, by "EQ curve" and/or other complex mechanical, electro-mechanical, and audio factors, may mean it is emphasizing fundamentals and de-emphasizing harmonics. Tonally this sounds 'dark' by comparison...guitar strings are not putting out sine waves of course...but, I suppose that the ideal monophonic or hex (Etc) magnetic pickup that was designed for fundamentals would be on the 'dark' end of the spectrum of what is available on the market, or made so as to be even darker.  If hex...maybe even each pickup would sort of be 'tuned' to be sure to accomodate the frequency range of the string it's pickuping up...

Of course...I suppose that the whole thing may be negligable importance since on can do controlable filtering post-pickup....except that some are of the persuasion that while extreme EQ filtering to get down to the fundamental range is ideal on one hand, it adds phase issues and the miliseconds of adding more and more filtering via circuitry adds up since most analog and digital approaches are complex enough to yield latency issues if modification of the fundamental isn't done directly, but there is some tacho or other circuitry that does P/V (pitch to voltage) feeding a VCO, etc., etc., etc., so having a "pickup" that does a fair amount of the EQing, if not unreasonable, might have that advantage...

I've looked at both the power-gig hex pickup thread, the group-diy hex/stereo pickup thread (xaudia's pickup), and also http://www.ultramagnetics.org/ before, amongst others...    

[PRR]

> the fundamental is strongest as one gets closer to the 12th fret/middle of the string?

Middle of the *speaking length* of the string.

When you fret at the 12th fret, the maximum fundamental is at the 24th fret. Playing the 20th fret, you find max-fund at the 40th fret. Which falls about 10% of the open (unfretted) length. About 2.5 inches.

[liquids]

> the fundamental is strongest as one gets closer to the 12th fret/middle of the string?

Middle of the *speaking length* of the string.

When you fret at the 12th fret, the maximum fundamental is at the 24th fret. Playing the 20th fret, you find max-fund at the 40th fret. Which falls about 10% of the open (unfretted) length. About 2.5 inches.

touché!

[Gus]

A DC sim of a guess of what might be the output section I don't know why they might have used two .1uf for a .2uf when .22uf is common.  Can you check the output section again?

[digi2t]

Here's a redraw of the string amp section.



I've gone over it, and it matches up to the unit.

Gus, didn't have time to check the output section yet. I'll do that tomorrow, though it's simple enough, I don't think I messed that up. There are indeed two 0.1 caps in parallel. No idea why they didn't use a 0.22.

EDIT: Gus, I'm getting 3.304v between R2 and C2 (as shown on your sim).

[liquids]

How does the sub-octave sound compare to other variations you've heard?

[digi2t]

How does the sub-octave sound compare to other variations you've heard?

I'm going to let you be the judge on that one shortly. First off, here are the definitive schematics for the Trioct. I've gone over them with a fine toothed comb (which explains why this thread has drifted a bit), and I'm 99.9999% sure they are error free.









And finally, a new installment of "The Hen's Tooth Café", featuring this rare clucker. Enjoy.

[Mark Hammer]

Nice summary.  Thanks for that.

I know *I* never have, and I suspect you haven't either, played with the sensitivity trimpots.  Perhaps there is better sound possible from it, particularly the "treble", though maybe not.

I will say that there is a reason why guitar synths use either piezo saddles or hex pickups jammed up against the bridge; tracking is simply very difficult to maintain when one does not take radical steps to prevent bleedthrough from adjacent strings.  I'm still curious to know what it does when a GK-2 or similar is used with it.

Something mentioned to me some time ago was that the unit would have been introduced when a great many of us were playing medium-to-heavy gauge flatwound strings - of the sort you'd buy in the local department store.  The stiffness of those would have assisted the isolation of what each coil on the hex pickup was detecting.  As Dino amply demonstrates, sticking it in between a neck and bridge pickup, and using contemporary strings (10-through-46, I'll wager?), is unlikely to extract the fully polyphonic octave down it was intended to produce, though more gentle strumming of, say, 2 notes at a time should be able to achieve harmonies that include the octave down.

In any event, the marvel here is not what it can do or sound like - certainly we have better these days, and my Micro-Pog makes the Tri-Oct look like a stupid choice - but rather the mere fact that it existed, and so long ago.  I wish I could find someone with some insider knowledge of its development, and demise.  I tried contacting Mike Biegel, but never got a reply.  Anybody know how to reach Dave %^&*erell? (the guy who developed the EHX Microsynth).

[Gus]

I searched for octave divider circuits that might have been used or in books at the time the effect was built

http://www.nshos.com/HammondX66-8.htm was interesting

Q3 looks wrong, look at the PRR post, the E and C look like they should be flipped.

At the time of this post you have the input and output caps at the output amp section BOTH going to the input (base) of the transistor stage I would think the .2uf goes to the collector

when I have a good length of time I might redraw the string section.