[sdiy] [AH] Custom ARP Avatar

[Nathan]

Re: enabling more than one string on the Avatar - It's designed to track
all six strings under normal use, or you can deactivate them if you only
want to use it for bass or track a single string, etc.

Each string has its own trigger extractor. The triggers drive a multiplexer
module with last note priority, so the most recent string will always be
the one going into the pitch to CV converter. The triggers also influence
the pitch to cv converter, to keep it with an expected range for each
string.The service manual explains the theory of operation very thoroughly,
it's really good.

I restored one for a customer a few years ago and the tracking was pretty
nice even on my guitar with the wrong bridge spacing. Hex fuzz also sounded
fantastic.

best,

Nathan


On Sat, Mar 29, 2025 at 12:04 AM brianw <brianw at audiobanshee.com> wrote:

> Hi Rob,
>
> You're right that the Roland pickup would be easier - in some ways - than
> a 13-pin guitar.
>
> You're also right that Roland had three cables.
>
> 1) The original GR-500 used a Centronics connector, and I believe it's
> compatible with the GR-300 and GR-100 units, but I was completely ignoring
> that era for any AVATAR project since it would be a massive pain to adapt
> that connector type (unless you buy one of the break-out boxes that folks
> made for the Centronic connector).
>
> 2) The standalone pickup is passive, and has a simpler cable, and would
> probably be electrically easier to adapt to the ARP AVATAR. The Roland
> electronics could be skipped in this case. The down side is mechanically
> mounting the pickup.
>
> 3) Not sure whether 13-pin came before or at the same time as Roland's
> GK-2 GK-3 add-on pickup kits, but there are now many guitars with a 13-pin
> jack already installed, along with the preamp. I assume that Roland's GK
> series uses the 13-pin standard after the interface box. At least the
> Roland synths have a 13-pin input and not the passive pickup cabling (to my
> knowledge).
>
> I am a guitarist, so I'm way more picky about modifying a guitar to add
> another pickup, given the drilling and alignment issues, much less finding
> a place to squeeze it in between the strings and the body. I prefer to
> fidget with electronics or wiring and leave the mechanical guitar work to
> the professionals, but someone else might find wiring adapters and piecing
> together a power supply more trouble than building a custom guitar.
>
> The down side to the 13-pin guitars is that they have an active preamp
> inside, and need that +/-7V power supply. Without power, you'll get
> nothing. There are people who make breakout cables so that you can provide
> power and then access individual strings. You can ignore all the extra
> controls on the 13-pin connector - besides +7V -7V and ground - and then
> just use the 6 pins for individual strings to connect to the AVATAR.
> There's a 7th pin for the standard mono guitar output from the non-hex
> pickup if you want to mix standard guitar sounds with the synth (and hex
> fuzz) sounds.
>
> There are even some companies besides Fishman making hex pickups these
> days, but as I mentioned, I prefer to work on wiring electronics and not on
> building a physical guitar where the pickup might get bumped or never even
> start out properly aligned for good performance.
>
>
> As for the AVATAR - yes, the synth section is mono, but ARP did an
> interesting thing by supporting a hex pickup with 6 individual inputs into
> the synth. Of course, you have to select which string is active. I'm
> curious what happens if you enable more than one string and then play a
> chord. I've never owned an AVATAR, so maybe I should read the User's Manual
> in depth. Do they mix the polyphonic hex fuzz output with the monophonic
> synth output?
>
> In any case, if I started down the path of connecting a guitar to an
> AVATAR, I would end up wanting *six* AVATAR synths so that each string
> could drive its own mono synth. I doubt that would be affordable unless
> Behringer allowed it. In my case, I used an 8-channel audio interface to
> bring the 7 guitar signals from a 13-pin guitar into a soft synth that I
> wrote which has six voices and can track each string separately. Not as low
> latency as dedicated analog circuits, though.
>
> Brian
>
>
> On Mar 27, 2025, at 7:19 AM, rob at secret-secret.com wrote:
>
> Hi Brian,
>
> First I’m going off memory from the early eighties so I could be totally
> mistaken. My understanding of the Roland and Avatar systems is that they
> are vastly different. The Roland cable contains a number of control
> signals. And there are two or three Roland standards.
>
> The Avatar is much more like a traditional guitar cable, but with six
> lines. All the amplification is done in the synth. So to use a Roland pick
> up you just need to wire the pickups one each to the six lines, and use the
> shield for ground. The order is likely from the low E to the high E, but
> maybe from high to low. Very simple, and very straightforward.
>
> I remember the connector being a screw in on the synths so that it
> wouldn’t fall out, and it was long, like 25 feet or so. Many of the Roland
> cables are long too. Now a Roland cable that had enough lines could be
> used, but it would have to be modified at both ends. It is likely that some
> of the Roland lines are the pickup signals, so you could probably just use
> those lines at the synth end, and just ground the other lines, or come up
> with a way to use them as control lines the way that Roland used them.
>
> Also, you don’t need the whole Roland setup at the guitar, just the
> pickup. Now if you did get one of their later setups you might be able to
> hijack it a bit.
>
> For instance if you got a GK-2 or a GK-3, those would have the pickup
> connected to a box with other interfacing. And you don’t need all of that.
> If you look at the photo on this page for a GT3, you’ll see how the pickup
> is a separate piece. Roland use to sell the pickup from the GR-700 system
> as a single part too. It was around $25. Again, I think Sam could be very
> helpful here as he can get Roland service parts, and he’s a very wise dude.
>
> https://www.musicstore.com/en_US/USD/Roland-GKKITGT3-/art-GIT0007925-000
>
> I don’t have the docs, and my findings were all from using a multimeter. I
> didn’t have access to the internet back then.
>
> A couple of years ago I picked up a Roland GR-1, without doing proper
> research on it. It turns out that they removed the hex distortion, and the
> internal synth is one of their Romplers. I found this very disappointing,
> but I’ll mess around with it at some point. I was very much looking forward
> to the hex sound again. But there are other ones.
>
> The very best sounding of the Rolands, which you can hear on King Crimson,
> and Police albums is the GR-300. It’s all analog, and has a seriously nice
> portamento. The next was a GR-700, which was a JX-3P. This didn’t do the
> nice portamento. But it’s a nice synth. Then they did the bass synth,
> something 77, which used the JX-8P, another nice synth, and it might be
> possible to control it with a guitar. After that they started using
> Romplers, and to my ear didn’t sound as good.
>
> There was one before the 300, but I don’t remember the name, and I think
> it was mono like the Avatar. Korg also did some stuff, as did Yamaha, but
> these didn’t sound as good as the Rolands. For me the Holy Grail is the
> 300, but because they are very old now I don’t think I’d mess with one. I’m
> much more likely to try and make a guitar synth since the tools/knowledge
> we have available today are insane. But I’d also be much more likely to get
> one of the Fishman units.
>
> I know some of the pickup companies do custom windings. It might be
> possible to get them to do individual lines, but that would probably be too
> expensive. I think Fishman uses a hex pickup too, and it’s possible that
> the pickup from that system could be employed. But most likely getting a
> Roland hex pickup is the path of least resistance.
>
> -Rob-
>
> On Mar 27, 2025, at 12:19 AM, brianw <brianw at audiobanshee.com> wrote:
>
> Is there a convenient documentation of the wiring for Avatar pickup?
>
> What sort of connector is on the Avator for connecting the pickup?
>
> A quick search for the AVATAR Owner's Manual suggests that it's a DIN-6
> that must use the shield for ground. I didn't see anything that shows which
> string is on which pin.
>
>
> The industry seems to have standardized on Roland's 13-pin connector,
> although you don't have to buy the Roland pickup and mount it yourself.
> Companies make (or made) guitars with the 13-pin connector built in. Godin
> Guitars had a line called SynthAccess (that you might find used - a really
> well-made guitar). The only challenge with the 13-pin is the +/-7V power
> supply needed. Roland synths like the GR-70 have the power, but do not
> allow external access to the guitar strings.
>
> You could probably buy a Roland 13-pin cable at Guitar Center, cut off one
> end, and hand-solder a DIN-6 connector on the other end.
>
> I suppose there could be an issue if the 13-pin electronics boost the
> signals too hot for the Avatar inputs.
>
> I've designed a few circuit boards to provide the power to the 13-pin
> guitar and break out the individual strings as separate balanced signals
> (on DB-25 or a bunch of TRS jacks). Nothing as a finished product, though.
>
> Brian
>
> On Mar 23, 2025, at 3:50 PM, Rob Secret wrote:
>
> Hi Ben,
>
> It’s been quite a while, but the last I did research on this subject the
> Roland pickups can be made to work with the Avatars. Mostly it is just
> wiring them up—Arp didn’t do anything fancy between the pickup and the
> Avatar. And from what I remember Roland sells just the pickup as a service
> part too. It was pretty affordable at the time. Something like $25, but
> that’s probably changed a bit by now. Sam could probably get you one.
>
> -Rob-
>
> On Mar 23, 2025, at 8:49 AM, Ben Stuyts wrote:
>
> Hi Rob,
>
> I’d love to try it with the hex pickup, as you say for the hex fuzz.
> Unfortunately the pickup is missing from my Avatar. It still has the D and
> E boards inside, but one of them has the power cable disconnected. So
> there’s probably something broken there. I have a search on ebay and other
> sites for the pickup, just in case. Does anybody know of any other hex
> pickups that would work?
>
> Ben
>
> On 23 Mar 2025, at 07:17, Rob Secret wrote:
>
> To me the coolest thing about the Avatar was its Hex Fuzz. Nothing sounds
> like that, well maybe the Rolands did, but that sound is really cool. You
> can play more than just 5ths with a very warm tone.
>
>
>
>
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