Positive Grid "SPARK" Smart Practice Guitar Amp & App.

Started by admin, December 03, 2019, 09:45:39 PM

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OK Plugged and using an Android Tablet (Galaxy Tab S3) to run the Spark Application

The PG Spark is Easily TWICE as LOUD and Clean TONE vs the Fender Mustang GT 40

I could actually play solo gigs at a coffeehouse with this amp alone

The Spark app is a bit annoying as it only runs in Portrait Mode, and will not do much until you are 100% logged in with your Positive Grid Account

This explains much of the PG Spark delay - the final FCC Report was just completed March 5, 2020

Internal pics on the FCC report

I can see they originally planned to a have a separate subwoofer power Amp - but its not needed

And its 24bit A/D,

32 bit D/A

ST 32F427 Cortex M4 CPU/DSP

Headphone amp is Class AB Ti Directpath 25mW Amp

ATS2625 Bluetooth 5.0

GL850G USB Hub
https://www.kean.com.au/oshw/WR703N/GL850G USB Hub 1.07.pdf
Just a bummer that USB Audio Out is only Mono for recording

But it does receive Stereo USB Audio at 24 bits 48kHz
This is the source of the PG SPARK ASIO Driver

This is the OEM
Guoguang Electric Co.,Ltd


Have to admit - this thing sounds wonderful !! and actually was worth the wait

Many of the SPARK app Backing tracks are sourced here -
Elevated Jam Tracks
but when used with the SPARK APP , you get matching chord charts that follow along with each tune

Thanks to Bluetooth 5.0 The Spark App synchronizes and compensates for any Bluetooth Audio Latency vs Video timing delay ( like many smart video player apps already do)
(A/V Sync)

It gets plenty loud, Backing tracks are loud ( use the top Music Volume Knob to adjust USB Audio, Rear Aux input Audio, and Bluetooth Audio
and the large OUTPUT Volume knob on far right controls everything

and of course spin the far left AMP Type knob full clockwise to Metal , and crank the Master and Output to max - and SPARK is nearly as loud as a Vox PathFinder 15R - louder than i could play at a few recent gigs with my tube amp

And the internal speakers NEVER flap / fart or spoil the fun

Now if they could do a firmware update to get it to work with the Positive Grid Blueboard remote footpedal, could be fun -

Swiftly Changing presets between the 4 Preset buttons on the top of the amp while still playing guitar results in a 250 millisecond gap of silence between patches

But I'm already connected via USB and getting loud stereo audio from all Windows Audio player apps, Youtube, and it sounds better than one of those $400 Marshall Stanmore II Bluetooth Stereo Speakers

(this is review of 1st release SPARK 40 firmware May 2020
My only Spark Amp complaint is the effects signal chain is set in stone , can not alter the effect order, so cannot place the Spring Reverb 1st in the signal chain - necessary to get vintage Surf Tones - its stuck in a 1980's idea of correct signal chain and zero allowable deviation From this

Noise Gate Pedal > Compressor Pedal> Booster / Drive Fuzz Pedal > Amp / CAB Sim > Modulation Pedal >Delay > Reverb

No Stereo Effects - All sounds are mono only - explains why there is only one "
" Left USB Audio Channel 1) available as Audio Source Input in Reaper DAW app,

Its essentially an update to the the effects and Amp Modeling of Positive Grid's JamUp Pro (which is also Mono only) , there are no alternate Cabs, Each Amp type has a specific Cab Model associated with it,  and no ability for user to change the Cab type, no third party Cab IR Loading  - but PG SPARK AMP sounds good out of the box.
Its a nice looking 2 x 20 watt dual 4" speaker amp and very loud and clean + the Spark App (IOS/Android)  makes practicing fun


Quote from: Ringleader42, post: 30497929, member: 62769Huh, that is confusing given their stated specs as 2x2. Wonder what happened there. And then I'm assuming the physical aux in doesn't route to the USB audio stream, probably just to the internal speakers/headphones?
The only Stereo occurring is from the external signal feeds
* Stereo USB Audio Input,
* Stereo Rear Aux Input,
* Stereo Bluetooth Audio Input

You get only one of the above at a time

None are routed to the USB Recording out, only one mono channel which represents the Internal Jamup Pro level  Guitar FX/Amp Modeling , and the SPARK AMP ToneCloud presets I recognize as being the same as the legacy of  8 years worth of Jamup Pro (IOS) Tonecloud presets
( They do not want to kill their BIAS FX2 business model)

Multiple external audio sources are not possible  - So Not possible for mixing Aux IN + USB In, or Aux in + Bluetooth Audio In - Only One at a time , all controlled by a common small "MUSIC VOLUME" knob near headphone jack  and all are only fed to the internal Stereo Speakers, or Stereo Headphone out , which mutes the internal speakers
( I smell a simple mod I'll implement soon to allow simultaneous Internal Speakers and Headphone Out as a DI Output  )
and the large OUTPUT Volume knob on far right controls everything

QuoteI see you've been busy, but if you have a chance to see it if is recognized as an audio interface by iOS with a powered USB3 adapter or CCK/powered hub that would be great.

Gathering my USB adapters now!


Steve, glad to see you finally got it, and already cracking it open  :o :) After reading your thoughts and impressions on it, and the USB thing, I'm kinda glad I canceled my Spark order and took advantage of the Bias FX2 Elite special they had @$179.00. After comparing the abilities between the two, when I started thinking and really looking thru the app, I knew I would be happier with the software as I have plenty of options to amplify it, and wasn't disappointed. Fully customizable signal chain, dual amp capabilities, tons of amps, effects, cabs, etc.. I just do to much stuff with stereo. It sounds like from your descriptions that it is a nice amp though. Congrats!
Gibson Les Paul Custom
Epi Les Paul Standard
Gibson SG 50's prototype
Squire classic vibe 60's
Epi LP Modern
Epi SG Pro
Martin acoustic

Princeton chorus 210

Helix LT
Waza Air Headphones
Boomerang III

And, a lot of stuff I DON'T need


Make a user account and post your request , and read prior requests, bugs, workarounds, solutions )

Here's a Mobile Spark using a Laptop 19VDC Battery Power brick



February 18. 2022 - Spark firmware

Spark App Power Update is here! Make sure to update your app to Android v2.3.0.4397 / iOS v2.3.0.4695 and update your Spark amp to the latest firmware to unlock the following new features and enhancements:

The (much requested) in-app tuner
Tap Tempo feature for modulation and delay pedals
Creative Control for Spark Control users introducing custom wah features
Experience Jimi Hendrix™ pack users can now simultaneously use the J.H. Legendary Wah with Vintage Delay or Echo Tape pedal



Bought one of these as well as bias FX 2 for my DAW. Why? The presets available for both. Got the pearl edition and its a ton of fun and it sounds great.



There's a very active Spark modding community online, and people have devised various tweaks and improvements to it, including ways to address the bass‑heavy response.
The Spark Amp Mods Facebook group
already has over 11,000 members at the time of writing, and people have experimented with different speakers, added a line out and created a downloadable custom programme to build a Bluetooth‑compatible switcher, which controls the four channels and pedals (https://github.com/happyhappysundays/SparkBox).

The grille is held on with Velcro and thus easy to remove, which makes stuffing the port and damping the cabinet a quick‑win modification.
One aspect of the Spark's design is really handy if you want to tame the bass: as the front grille is held on with velcro, you can pull the grille off to access the bass port and speakers. Simply stuffing the bass port (you need only stuff a piece of sealed‑cell foam or even a sock in there) removes plenty of the 'fake octave' it generates, and instantly makes things sound a bit less boomy. Partially filling the cabinet with wadding will damp the resonances even further. To do this, I used some polyester packaging that came with a food delivery, but you can buy wadding on Amazon and elsewhere. All of this is all easily reversible, too.

If you're feeling braver, you could experiment with a capacitor soldered between the positive terminal of each speaker and the appropriate cable. This will act as a simple high‑pass filter, thus turning down the bass; the filter's turnover frequency depends on the value of the capacitor you choose.

Speaker swapping is another possibility, since the Spark's four‑inch drivers are a standard shape. Some modders, for example, have tried installing various four‑inch dual‑concentric car‑audio drivers, which include a dedicated tweeter, in order to extend the treble response. If you go down this road, it's worth remembering that using less sensitive speakers than the stock ones will result in a lower overall volume coming from the amp.





Control all Spark amps from MS Windows with Soundshed

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