Author Topic: Vox Amplug Ac30 - anyone cloned it?  (Read 345 times)

yxwvut

Vox Amplug Ac30 - anyone cloned it?
« on: June 06, 2022, 09:59:27 AM »
Back in college I owned the 1st gen amplug modeled on the ac30 for playing in my dorm room. I didn't have any experience with Vox amps at the time, and at first I hated it as it sounded nothing like my amp back home, a hot rodded marshall type. However, after a little while acclimating to the sound I realized that it really nails the Vox tone. It's one of the better top boost Vox emulations I've heard from anything but high-end stuff (definitely better than the Tech21/Joyo, any free VST plugins or my Nux mg500's vox emulation, to my ear at least).

I've seen a schematic floating around on the other stompbox forum of the meat of the pedal, and I wondered whether anyone's tried that out. Pretty high parts count though, so given that the things are only like $30, the lazy solution would be to just rehouse it into a 1590b and replace the switch, pots, and jacks (SMD challenges and crazy high output notwithstanding). Or, even lazier, just loop it through one of those bypass boxes people make for the vintage plug-in effects like the Dan Armstrong stuff.

r080

Re: Vox Amplug Ac30 - anyone cloned it?
« Reply #1 on: June 06, 2022, 02:10:51 PM »
I have never played one, and certainly have not seen a clone. I am betting the strength of it relies on the simulated inductors. If I recall correctly, the tech21 pedal has two sallen key low pass filters for the speaker simulation. With at least the 3 gyrators (look like all different values) in this, there could be some more variation to the peaks.
Rob

r080

Re: Vox Amplug Ac30 - anyone cloned it?
« Reply #2 on: June 06, 2022, 02:43:22 PM »
Result of quick calculations: looks like the amplug speaker simulator has a hump around 200Hz, a sharper peak around 2k, then a moderate peak around 5k before dropping off, whereas the tech21 liverpool has a peak at 3k and then a fast dropoff. There are a bunch of other filters around both, but it does look like a more interesting approach than tech21 took.

With that in mind, it seems much of the point is speaker and cab sim, so trying to use it in front of an amp could be weird. Going direct and skipping the gyrators would probably not sound as good. It could be interesting to try the first section as an overdrive pedal.
Rob

vigilante397

Re: Vox Amplug Ac30 - anyone cloned it?
« Reply #3 on: June 06, 2022, 04:11:58 PM »
There's a schematic on the other forum, easy to find with a quick search. Looks like they use gyrators for the tone shaping to emulate the response curve of the amp, no inductors in the signal path.
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r080

Re: Vox Amplug Ac30 - anyone cloned it?
« Reply #4 on: June 07, 2022, 10:20:41 AM »
Yeah, I wasn't sure of the rules for linking. I have seen the below format before, so let's try that. Replace the asterisks with the name from the other forum.

https://www.****stompboxes.org/download/file.php?id=14937&sid=1ee744e285f38fd64866093ee713de80&mode=view

Also, would we not call these gyrators simulated inductors?
Rob