AC-30 Sim

[changes]

long time ago there was an ac-30 sim layout
i think in R.G.'s site
is there any schem for that?

[cd]

Try a search.  The circuit values are protected by legal agreement.

[Jason Stout]

It's not available, and when it was the designer required people to sign a non-discloser agreement before he released it to them.

[sir_modulus]

Isn't there one at Run Off Groove? The English Channel (Fet emu of Vox AC 30 Top boost).

[cd]

Isn't there one at Run Off Groove? The English Channel (Fet emu of Vox AC 30 Top boost).

That one's different.  The one changes is talking about is opamp based and was widely available on the 'net (provided you signed the NDA) 4-5 years ago.

[MarkB]

I believe that Stephan Moeller (the designer) sold the design..
he stopped giving out the component values.

As far as I know - at least one successful clone was built using his design and  RG's layouts.
"-(

[mat]

long time ago there was an ac-30 sim layout
i think in R.G.'s site
is there any schem for that?

This page: http://www.unibw-hamburg.de/EWEB/ANT/English/research/dafx/voxac30/voxac30.html
has sound clips of it, i think. it does not sound as good as the ROG stuff IMO.

cheers,
mat

[Steben]

That's a digital simulation.

[Steben]

The best way to emulate the AC-30 is the way with FET's I assume.

Just copy the schematic with the tubes and tweak some values.
Filtering and tone control are very very important to aim for the AC-30. Copying the schematic (at least the passive parts) will get very close there. The "British channel" is something like that.

[cd]

The best way to emulate the AC-30 is the way with FET's I assume.

Just copy the schematic with the tubes and tweak some values.
Filtering and tone control are very very important to aim for the AC-30. Copying the schematic (at least the passive parts) will get very close there. The "British channel" is something like that.

If by "close" you mean 50% of the way there, you're right.  Even if you ape the preamp, there's the free-running, no negative feedback cathode bisaed EL84 output stage, the output transformer, Bulldog speakers, etc.

[R.G.]

The best way to emulate the AC-30 is the way with FET's I assume.

That would be an incorrect assumption.

While JFET and MOSFET devices do sound nice if done properly, you cannot simply replace a tube with a FET and call it an accurate simulation. Think about it - replacing tubes with FETs is not a new idea. If that was all it took, there would be no tube amps today.

[Torchy]

I found the best way to simulate an AC30 at medium volume was my AC15  :oops:

[stm]

Regarding Stephen's AC-30 Sim, it goes one step further in the sense that the sim included a second PCB exclusively for cabinet and speaker sim, because the whole unit was conceived as a headphone sim.

I haven't tried it, but if it works good on headphones it is worth it, since so far every attempt I have seen trying to connect headphones to a guitar amp is nothing less than CRAPPY (BTW, what can you do at 1:00 AM when the wife and neighbours don't want to listen to your guitar?  :twisted: To make things worse I live in an apartment building.  :cry: )

Finally, Stephen claimed that the sim was so accurate with respect to the particular amp he was using as the model, that he changed tubes/valves and the overall tone change was bigger than the tone difference between the actual amp and the sim.

[RDV]

I don't know about it sounding just like an AC-30(I've never played through one), but the English Channel really makes my rig sound nice & clear. I like the tone controls a whole bunch. Arpeggios sound very jangly and Beatlish IMNSHO. I can't have the other one, so F@*#! that.

RDV

[cd]

Believe me, if you played through a real AC30 you wouldn't want to use a FET emulation  The emulation has the EQ and some of the gain characteristics but not the singing, shimmering high end.

Funny enough though: one of the best uses I've found for a commercial FET emulation is into a real AC30.  The emulation, when cranked up, exaggerates the amp's own qualities.

[stm]

You mean the English Channel at ROG, don't you?

In any case, ROG's emulation do not sim the cranked speaker sound, or the coupling transformer impedance, which can add some shimmering (due to introduced harmonic distorion).  In this case, it's up to the actual speaker to be cranked enough to add some of this effect.  Also, if the speaker/cabinet is not the right type (let's say a closed box for instance) it won't get close.

By the way, maybe it is possible to get even closer to the shimmering by increasing the cutoff frequency of the final low-pass filter (like changing
those 2.2nF capacitors to 1.5n or maybe even 1 nF). Also, in this respect perhaps a shelving filter that raises highs let's say 3 to 6 dB, like a presence knob could help.  I understand you will never get identical sound with an emulation, but can get closer and closer if you perseverate and refine your circuit!  :wink:

I have found a circuit that sounds nicely as an overdriven speaker, based on the TAPE SATURATOR from the Naked Church site. It really adds compression and more harmonic content without destroying your tone, and you can make it very subtle if you like.  It is great as a bass overdrive also.

Maybe a circuit like this could be applied at the end of FET simulators to push simulation one step further. Of course if you are going to play loud you should not use this kind of device, otherwise your sound may end up overprocessed (too much of a good thing is not necessarily good!  :wink: )

[Steben]

What schematic would that be?

[stm]

Some months ago I was looking for an equalizer and some circuit to add more brightness to my guitar for clean playing.  I also wanted to have a very mild overdrive, just for warmth, which my SD-1 couldn't give, because IMO it sounds crappy at low drive settings.

So I implemented a two band Eq plus a variant of an Analog Tape Saturation emulator circuit.  The results were very interesting.  The modified tapa saturation, which I finally called "Speaker Saturation Simulator" added that extra brightness I was looking for in such a way that it was better than just using the HIGH control of the EQ.

The circuit is posted below, and contains a link to the original schematic that inspired me.



Have fun!

[Elektrojänis]

If the schematic that the original poster was looking was here: http://sound.westhost.com/project47.htm

Then you can consult wayback machine (www.archive.org) to find this: http://web.archive.org/web/20030627114822/http://www.sound.westhost.com/project47.htm

Of cource it does not give you the missing part values, but at least you get the basic schematic.

[kugua]

does stephan.moeller has another deleted web address?