[AudioI] AudioInjector and Guitar
Randall Reichenbach
randaji at gmail.com
Mon Feb 21 03:24:56 UTC 2022
My project, named pi-Stomp (https://treefallsound.com - mentioned in the
first link Matt referenced), uses the AudioInjector Zero and is mainly used
as a guitar/bass/keyboard digital effects processor and synth engine (synth
modules triggered by MIDI input). One of the effects you can have on your
virtual pedalboard is a looper. It's not super functional though, just
single loop record/playback.
Harold, regarding whether can you just plug a guitar into the soundcard,
yes you can, but you likely won't love the results. I measured the input
impedance of the Stereo and Zero cards to be less than 30k Ohms. Most
guitar pedals and amps shoot for 1Meg Ohm. Your pickups are likely 5 to
9kOhms, so putting 30k in parallel with that, loads them down considerably,
reducing dynamics and rolling off a lot of high end.
Gain-wise though, most pickups can drive the AudioInjector inputs fairly
well. pi-Stomp includes a unity buffer to present a 1Meg input impedance
but doesn't include any gain. You can control the input capture gain
digitally via alsamixer.
If you do add an onboard preamp or buffer, you might want to check out what
I wrote here regarding powering it:
https://lists.audioinjector.net/pipermail/people/2020-December/000157.html
Bottom line, if you can power it via battery, that'll save you some
headaches with noise and provide you more headroom. If you do use the Rpi
power, regulate and filter it well cuz it be super noisy.
Please post your project back here if you can. I'd certainly be interested
in a looper!
Cheers!
On Sun, Feb 20, 2022 at 5:07 PM JONATHAN RIZZO via People <
people at lists.audioinjector.net> wrote:
> Hi All,
>
> I’m just curious, what are these guitar projects for? Is the Pi being used
> to record these signals?
>
> The reason I ask is because I use Matt’s products for very low frequency
> radio signals.
>
> Thanks
>
> Jonathan
>
> > On Feb 20, 2022, at 6:28 PM, Joseph DiVerdi via People <
> people at lists.audioinjector.net> wrote:
> >
> > Similarly, I can mention https://www.muzique.com/ which is a pretty
> broad and perhaps a bit cluttered assortment of the electronic side of
> electronic musical instruments (broadly defined). It is but one of a number
> of sites like it which vacillate between home-builders and buyers. Many are
> pretty old (both the site and the author). This analog stuff enjoyed a real
> lift-off (if that is the proper term) starting in the late 1960s with a
> heyday in the 1970s. j
> >
> >> On Sun, 20 Feb 2022 4:19 PM, hugh crawford wrote:
> >> Forgot to mention this
> >> https://www.guitarfetish.com/Neovin-Active-PreampEQ_c_147.html <
> https://www.guitarfetish.com/Neovin-Active-PreampEQ_c_147.html>
> >> The guitarfetish site is sort of an uninformative mess, but Googling
> the products will turn up their old more descriptive web pages.
> >> On Sun, Feb 20, 2022 at 2:59 PM Joseph DiVerdi <diverdi at xtrsystems.com
> <mailto:diverdi at xtrsystems.com>> wrote:
> >> I have some of this kind of work on my website. Here is an example
> of an amplifier (and much more) I installed in a bass guitar including
> (relevant to this discussion) a pickup amplifier and final low impedance
> output buffer which is capable of driving looong cable lengths with high
> fidelity. The guitar details can be found at <
> http://xtrsystems.com/music/20201222%20bass%20guitar/20201222%20bass%20guitar.pdf
> <
> http://xtrsystems.com/music/20201222%20bass%20guitar/20201222%20bass%20guitar.pdf>>
> Other relevant items (including my planned installation of a Ultra
> audio-injector (another of Matt's fine products) and a raspberry-pi into a
> big amplifier and speaker system. One possibility for this is a Sonic-Pi
> application for synthesizer. Another is for looping. Big goals, limited
> time to work on them.
> >> The guitar electronics were intentionally designed to operate on a
> single (9V) battery knowing full well there would be some power on/off
> transients (clicks). This was a prototype project (perhaps "throw away").
> Two batteries would help or a negative rail DC generator. One of the
> helpful aspects is that the line voltage output is so high that I had to
> construct an in-line 10x attenuator that sits at the amplifier input
> (helping control line impedance and minimizing frequency roll-off, reducing
> line noise and the on/off transients).
> >> I'm happy to discuss electronic circuit design in this context or
> others. I have been doing this stuff for many years and enjoy sharing the
> experiences.
> >> Joseph
> >> On Sun, 20 Feb 2022 3:42 PM, Matt Flax via People wrote:
> >> > *** Caution: EXTERNAL Sender ***
> >> >
> >> > Do you know any circuits online of guitar preamps which are known
> good ?
> >> >
> >> > One idea is to design one up - possibly using the Pro soundcard
> first - because of its available power rails and low noise design and the
> AIABS inteface which would make it reusable.
> >> >
> >> > We could work through the design of a preamp there seems to be
> some interest.
> >> >
> >> > Matt
> >> >
> >> > On 21/2/22 09:37, hugh crawford wrote:
> >> >> I was really excited to see this because I thought maybe
> somebody had figured it out. Imagine my disappointment to see that it was
> pointing back to me. I have not actually figured this out. I am dealing
> with six extremely low power output single coil pickups and the noise is
> six times worse than one would get from a regular setup so it’s sort of
> worst case scenario here.
> >> >>
> >> >> I am also building the actual guitar so I have been occupied
> with a multitude of other problems.
> >> >>
> >> >> Some ideas that I am considering but have not yet tried are to
> run the guitar signal through some sort of effects box, a booster for
> instance, that will do impedance matching and deliver a more useful signal
> to the audioinjector.
> >> >>
> >> >> In my case I’m thinking of trying six cheapish noise gates since
> hardly ever am I playing all six strings at once.
> >> >>
> >> >> Another idea involves using a high impedance Phono preamp as a
> buffer.
> >> >>
> >> >> My advice would be to build your device, then if necessary visit
> your friendly guitar store and try out different stomp boxes as buffers.
> That’s what I plan to do soon now that they are open to in person business.
> >> >>
> >> >> On Sun, Feb 20, 2022 at 1:46 PM Matt Flax via People <
> people at lists.audioinjector.net <mailto:people at lists.audioinjector.net>>
> wrote:
> >> >>
> >> >> Hi Harold,
> >> >>
> >> >>
> >> >> Some people in the past have build guitar rigs, there is
> most likely good information here :
> >> >>
> >> >>
> https://lists.audioinjector.net/pipermail/people/2020-December/000157.html
> <
> https://lists.audioinjector.net/pipermail/people/2020-December/000157.html
> >
> >> >>
> >> >> http://forum.audioinjector.net/viewtopic.php@t=5797.html <
> http://forum.audioinjector.net/viewtopic.php@t=5797.html>
> >> >>
> >> >>
> >> >> You can also contact those people directly if you don't get
> a response here.
> >> >>
> >> >>
> >> >>
> >> >> Matt
> >> >>
> >> >>
> >> >> On 20/2/22 07:02, Harold Désert-Legendre via People wrote:
> >> >>> Hello Audioinjector Users,
> >> >>>
> >> >>> I bought the audioinjector soundcard (stereo in/out via rca
> connectors) in order to build a guitar looper pedal. Will I need to adjust
> the guitar signal in term of gain? Or Can I directly plug the guitar into
> the soundcard (just physically transforming jack into rca).
> >> >>>
> >> >>> If anyone has experience with it, thanks for sharing your
> feedbacks!
> >> >>>
> >> >>> Regards,
> >> >>>
> >> >>> Harold
> >> >>>
> >> >> --
> >> >> Checkout the community email list :
> >> >> https://lists.audioinjector.net/mailman/listinfo/people <
> https://lists.audioinjector.net/mailman/listinfo/people>
> >> >>
> >> >>
> >> >> --
> >> >> People mailing list
> >> >> People at lists.audioinjector.net <mailto:
> People at lists.audioinjector.net>
> >> >> https://lists.audioinjector.net/mailman/listinfo/people <
> https://lists.audioinjector.net/mailman/listinfo/people>
> >> >>
> >> > --
> >> > Checkout the community email list :
> >> > https://lists.audioinjector.net/mailman/listinfo/people <
> https://lists.audioinjector.net/mailman/listinfo/people>
> >> >
> >> >
> >> >
> >> -- Joseph A. DiVerdi, PhD, MBA
> >> XTR Systems, LLC
> >> ChemIntelligence for Hemp & Cannabis
> >> +1.970.980.5868 - www.xtrsystems.com/ <http://www.xtrsystems.com/>
> >> us02web.zoom.us/j/9460709393 <http://us02web.zoom.us/j/9460709393>
> >
> >
> > --
> > Joseph A. DiVerdi, PhD, MBA
> > XTR Systems, LLC
> > ChemIntelligence for Hemp & Cannabis
> > +1.970.980.5868 - www.xtrsystems.com/
> > us02web.zoom.us/j/9460709393
> >
> > --
> > People mailing list
> > People at lists.audioinjector.net
> > https://lists.audioinjector.net/mailman/listinfo/people
>
>
> --
> People mailing list
> People at lists.audioinjector.net
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>
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