Back In Black Tone Project Update (“Critical” info inside, from Mr. Townsend at Avid)

28 Mar Back In Black Tone Project Update (“Critical” info inside, from Mr. Townsend at Avid)

Due to the incredible availability and kindness of Mr. Chris Townsend at Avid – I would like to remind you that Mr. Townsend is Lead Guitar Products Architect at Avid, and he is responsible for all algorythms for FXs and amplfier modeling inside both the Eleven Plug in for Pro Tools AND the Eleven Rack – I have been exchanging emails – feverishly from my side of the ocean lol – talking about my experimentation to debunk, dissect and reproduce faithfully Mr. Angus Young’s guitar sound on the whole Back in Black album.

As this is my personal life-dream (guitar wise), this is all very meaningful to me; so I will take a chance to thank again Mr. Townsend for all of this (thank you, Chris!).

Here is his take on the compression side of the Schaffer Vega:

Chris Townsend wrote:

Hi Fil,

I definitely agree that there was some sort compression (companding) in the Vega system, but I think your preset had way too much compression to match what’s going on in the Vega.  There would be a lot more noise on the original recordings if they used that much compression.

And generally these systems used companders, which compress the signal going into the transmitter and expand the signal coming out of the receiver, which in theory should give you back the same signal coming out of the guitar.  Of course, in practice that ideal is definitely not achievable, and you end up with some compression/expansion “artifacts” (e.g. pumping), but overall the signal is neither compressed nor expanded.

Also, the compression/expansion ratios of these noise reduction companders are typically about 2 to 1, so it’s relatively mild.  On the other hand the Grey Comp, has a nearly infinite compression ratio.  I think you might be better off using the Dyn3 Comp with a 2:1 ratio, although of course to really to get the effect right we need to follow it with a 1:2 expander, but currently the Dyn3 expander is not available in Eleven Rack, although you could use plug-ins at least for experimenting.

I think that until we can implement an expander, using zero (or maybe mild) compression will give you the closest result to the Schaffer-Vega system.  Regardless, all that really matters is how the end result sounds, so I’m very much waiting to hear what you find with your next tests.  🙂



I find this information to be really critical. More on it in later updates.

Please note: while I will be away (India) for a two weeks long business trip (hopefully will have some leisure time, too) I will still be 24/h, 7 days a week online with you.

I “just” won’t be able to play guitar, but will still be here with you.

Fil 🙂


Still working massively on this. Actually, it’s almost the only thing I am doing.

While I was working on the Eleven Rack, I thought “why not to try the newly discovered signal path on the Rack just for kicks?”.

So I did. I applied the same exact signal chain that I think was there in the studio for Back in Black:


Guitar -> [Vega Transmitter -> internal boost -> internal compressor] – > wireless signal -> [Vega Receiver -> Boost] -> Amp [2203/1959 for rhythm] [2203/2204/1987 for solos] -> Cabinet with Greenbacks 25watts -> Neumann U67/U87 – Board – EQ – Tape


PLEASE NOTE: it is still unclear to me as what goes first, be it boost or compressor! This can dramatically change the outcome. With my “real gear”, the sound you heard on the previous attempt has the BOOST first, then compressor; putting the compressor before the boost completely changes the sound and responsiveness of the guitar, so I think the boost goes FIRST, then, compressor. Once the circuit of the Schaffer Vega/CETEC Vega is debunked, we will know exactly what goes first. This is extremely important.

On our gear translates as:

Guitar -> boost -> compressor – > amp – cab – mike – equalization – hard disk


On the Elven Rack sample linked below, I used:

Guitar (1971 SG) – > “White Boost” – > Gray Compressor – > amp -(JCM800) – > 4×12 cab 25w – U67 off axis – > my EQ in protools -> disk

For settings, please see below.


(long one huh lol)


Here’s the result. Do NOT listen with a preconception: listen with a clean mind.


I think it’s as close probably as my last one done with real amps.

I applied my equalization curve (on the Sonnox ProTools plugins) which I think is THE good one, though there is still an intervall of small changes to be made/can be made.

So the Rack comes out to ProTools “unequalized”, i.e., the only equalization is performed on the amp within the Rack. The equlization curve applied in post is ONLY on the Sonnox plug ins, to emulate the studio signal path of back then.

I think I was saying this is also a good one (surprisingly good; yesterday I was in awe, today I’m again on the rational side of myself) because:


1) Demostrates how good Modelers are (well, THIS ONE is)

2) It really allowed for a sort of verification of my “theory” (i.e., Schaffer Vega compressor & boost), letting me almost duplicate my results done with “real gear”.

This second point is a winner for me/us: I always said that IF it was duplicable, then it was… true.


Reflections; I am massively thinking that rhythm tone was from a 2203 (in fact, I used a JCM800 as the amp model in the Rack; the Pexis didn’t work for me; I may be wrong, trying the wrong settings etc. Still a LOT of work to nail it!). I have an unmodded one here with my that I tried for the first time this morning (came in last week) and it’s a BEAST.

All for now.

One bad news: I must leave for two weeks from next monday. I iwll still be connected most of the time via email/internet here on solodallas.com, however I won’t be able to experiment further for two long weeks. It’s also good on a side because my ears are really fried this time. I have a bad case of ringing that scared me last night. Better this morning, but it didn’t go away.


All for now, talk later.


Love indeed,


Fil 🙂

Back in Black Eleven Rack



Please note that I might have exaggerated with the compressor; you can hear that because of the “reactiveness” of my touch and you hear my hand too much on chord switching.

This, or the wrong type of compressor. I still have to learn how to set the compressor properly.

As for the boost, it is still unknown to me whether I have to boost it up all the way and keep a lower setting of master volume and preamp volume on the head, or viceversa, boost less and drive more the head.

As of today, on both real amp and modeler I am using:


– boost at max

– master volume 8, preamp 8

– tones: bass 6, presence 0, treble 5, mids 3-4



Fil "SoloDallas" Olivieri

We Are Rock 'N Roll People.

  • avatar
    Posted at 22:56h, 25 September

    solodallas,send me the patch to my email please. asier_merino_92@hotmail.com

  • avatar
    Posted at 20:21h, 03 June

    Lots of terrific info here Fil, thanks a bunch!

  • avatar
    Posted at 19:00h, 31 March

    Hey Fil,
    The compressor/expander method is a simple form of noise reduction which was used by the famous DBX noise reduction system. If you remember back in the analog cassette days the recorders had either Dolby B or C and/or DBX.

    the way it works is that if the noise floor is 30 dB (for argument’s sake) below the highest signal level you have a ‘window’ of sound before noise becomes apparent.

    like on a cassette tape, if you record loud signals the signal masks the noise, but if the signal is quiet the noise becomes quite a bit more obvious and you can’t really get a good sound.

    by compressing the signal you basically keep it loud even on soft passages so that the end result is that the perceived noise level is always BELOW the level of the guitar signal.

    On the receiver-end you will have an expander which will THEORETICALLY and to some extent in practice restore original dynamics by doing the exact opposite of what the compressor did.

    now as far as boosting the signal keep in mind that unlike a guitar pedal which is designed to keep the same level in and out more or less, the wireless system will have an output which will be variable so that it can be interfaced with many types of gear (usually, although I can’t say for this specific model you speak of)

    so as a total system there isn’t really a ‘boost’ but an output signal-amplifier which is probably capable of giving you a higher output signal than what goes in..

    the kind of distortion which these devices impart is partly due to the FM encoding and decoding and partly due to whatever components were used for the Voltage Controlled Amplifiers which are the heart of compressors and expanders.

    you might hear a bit of warble on chords, a bit of softening of the pick-attack and generally the sound will soften-up a bit too..

    so you get the boost from turning it up of course and you also get a sound which is a bit rounder IMO 🙂

  • avatar
    Posted at 14:45h, 31 March

    I’ve been listening to BiB (the whole album) for days, and I think I realized a few things about the tone:

    1. Low-end drive: This means that the bass frequencies are driven (more than usual). This might be the result of the combination of cranking the bass knob, and speaker distortion. Maybe the bass was reduced after the recording, but I’m not sure with this. Let me explain the differences between adding bass on the amp, and adding it after the recording:
    If you have the bass knob relatively low on the amp, then the low-end is not driven that much. So if you add bass after the recording, you will only amplify the “clean” bass signal. But if you crank the bass knob on your amp, that will cause the phase inverter tube to drive the bass more, and THAT is what I hear on the BiB album.

    2: Mic position: I clearly hear the marks of an on-axis miking on BiB album. Ok, I’m not sure that is exactly on axis, but must be very very close to that. And the extra high end that you get this way, was rolled off AFTER the recording. It came down from listening to the album for days, and I’m pretty sure about this one.

    3: Noise gate: I’m sure that there was some sort of a noise gate on You Shook Me All Night Long (I couldn’t find any marks of it in other songs, but in this song, it’s definitely there). I don’t know if it was applied in the actual guitar chain, or after the recording. But it’s there. If you listen carefully to the chords, it’s clear that the very begining and the very end of every chord is cut off – this must be the result of a noise gate.

    That’s all I could find out by listening. I hope It was helpful in some ways.

    Rock on,

    • avatar
      Posted at 14:55h, 31 March

      Very good finding. I always asked myself how they got the soft attack at the beginning of YSMALN, could be fading in, but could be a noise gate too.

      • avatar
        Posted at 15:01h, 31 March

        I believe it’s a noise gate. The reverb makes it a bit hard to detect, but I think it’s a noise gate anyway.

        • avatar
          Posted at 15:04h, 31 March

          Hm, well…maybe I should try one out then…very interesting topic.

          • avatar
            Posted at 17:30h, 31 March

            Let me know your results 🙂 I think you shouldn’t use too much “threshold”, but just eough to kill your noise when you don’t play the strings. But not more than that

    • avatar
      Posted at 20:17h, 03 June

      Interesting… should look into that! 🙂

  • avatar
    Posted at 04:19h, 30 March

    If its the pre amp tubes what kind should I replace them with

    • avatar
      Posted at 16:06h, 30 March

      The brand is your preference but you replace with 12AX7 type. I like JJ. It’s always a good idea to keep spare tubes around, today’s tubes are notoriously unreliable. If your amp begins to sound like crap then most often it is the cause.
      1. turn off amp and unplug it. Allow tubes to cool down.
      2. locate preamp tubes-remove metal protectors
      3. remove V1 tube by pulling up in a slight circular motion being carefull not to bend the pins.
      4. insert new tube using same circular motion.
      5. play amp and listen for improvement. If no result, move on to V2 and so on. If your preamp tubes are all OK then you probably need to take it to tech.

      CAUTION! These amplifiers have dangerous voltages present inside even when unplugged. Don’t poke around inside chassis unless you are experienced and know how to properly drain voltage.

  • avatar
    Posted at 04:16h, 30 March

    Fil Im going to check the tubes but if I remember right you said the 2204 get muddy easily right? Im not sure if its the tubes because it does not sound bad just kinda deep

  • avatar
    Posted at 00:42h, 30 March

    hey guys,

    i’m asking myself wether it is possible to use the avid software somehow with my computer through my usb interface or do i have to buy the digidesign hardware to use this thing?

    thanks for your help

    • avatar
      Posted at 20:16h, 03 June

      Well you used to have dedicated hardware.
      But since the (recent) release of PT9, you can use it on any interface, even cheap audio cards through ASIO4ALL drivers.

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