Rack Extensions: Has Reason invited a trojan horse?


For many years Reason, “the music program with all the cables”, has always been fully self contained. Where other audio workstations (“DAWs”) supported the so called Virtual Studio Technology (“VST”), Reason has always opposed the idea of using such extensions.

And the reasoning behind it made fully sense. Because allowing 3rd party software to be part of your own brings risks. Its not uncommon that a poorly written VST crashed an entire DAW, sometimes making the unfortunate user lose all their work.

Its one of the many reasons many people consider Reason to be rock solid. But as of version 6.5 even Propellerhead have changed their ways a bit by allowing 3rd parties to extend on the Reason rack with so called Rack Extensions. In the overall all is well, of course you will always have discussions on specifics such as pricing. But a Rack Extension which manages to crash the Reason rack…  THAT is something new.

The idea and risks behind VSTs

VST is a software interface designed by Steinberg Multimedia Technologies and it basically sets out a standard which allows 3rd parties to write their own extensions and use those in DAWs which support them. These extensions can include instruments and effects. For many people this feature allowed for some massive extensions on their DAWs, often even for free (for example; your author is very keen on the ‘TAL’ plugins from Togu Audio Line).

The advantage should be obvious…  Some companies, such as Native Instruments (“NI”), fully focus on sound and the sound experience instead of dealing with a DAWs workflow. If you buy an instrument from NI you get yourself something which you can use in any VST supporting DAW you like. From Reaper to Cubase or ProTools…


Of course there are also disadvantages; sometimes these extensions can extend on a DAWs functionality quite heavily. For example: In Ableton Live it is not possible for a MIDI instrument to receive incoming audio. Nor can you send MIDI data to an audio effect. Side-chaining obviously is supported out of the box.

However; if you use a VST instrument which supports both input types then this becomes an option. Even in a DAW such as Ableton Live.

It should come as no surprise that using VSTs was a tradeoff. While you could expand on your DAW you also took a risk with instability. A bad VST can crash your entire DAW, thus making you risk losing all your work. Its the way things work and a bit of a trade off.


So it should come as no surprise that Reason has always had the name of being rock solid, and rightfully so. Not only because Propellerhead never wanted to take this risk, but also because Reason as a whole hardly ever crashed.

Not trying to bring back bad memories here but even Ableton Live has had severe issues with software crashes in the past, and VST’s weren’t always involved. Reason otoh…  “A common Reason user can likely count the number of crashes on one hand” (comment from one of the Propellerhead forum users).

But now, it seems as if that could very well change…

Rack Extensions

As of Reason 6.5 Propellerhead software has released a so called Software Development Kit (“SDK”) which allows 3rd parties to make extensions for the Reason rack. These extensions can include both instruments and audio effects. Or better put: Instruments, Creative-FX, Studio-FX and Utilities (which are the four device categories used within Reason).

The setup is quite good. Owners of Reason need to be registered on the website to activate their product. This also gives them access to the “PropShop” where they can buy Rack Extensions. Even better: users are allowed to try any RE they want, 31 days, for free. No strings attached; no “it’ll hiss in demo mode” or “it will stop working after 5 minutes”. One month to use the full deal and make up your mind about it.

And obviously the devices need to qualify to some very specific standards. Although hardly anything is been made public about this (developers need to sign a non-disclosure agreement) I think it is safe to assume that Propellerhead Software takes great care that nothing can ‘taint’ Reasons reputation of being a rock solid piece of software. For example; only companies can apply to develop and sell Rack Extensions.

But the question is: how much can and will the Props do when something does go wrong ?

ReStereo Rack Extension

ReStereo, product page here, is a Studio-FX extension which can widen your sound. When you send in a mono signal it will apply several effects which will give your signal a stereo effect.

Restereo RE device
The Restereo Rack Extension by Numerical Sound

Unfortunately this device has a rather nasty problem: It can do the impossible by actually crashing Reason.

This is currently under heavy discussion in the Propellerhead User Forum which, unfortunately for “outsiders”, is only accessible by registered users of one of the many Propellerhead products (Reason, Reason Essentials, Record, ReCycle, etc.).

But it boils down to an unsatisfied user stating: “this has to be the MOST unstable RE in the entire lineup..” and “Take this as a warning if you are thinking of buying it..“.

Strong words indeed. To which the developer replied: “Other than the small bypass bug ReStereo works just fine. It was designed for mono sources only and I really wish users such as TheodoreM would take the time to email me the exact problem they are having with screen shots of their rack routing settings.“.

Instability issues

So what is happening here?

A Reason sound effect has 3 main settings, apart from on and off it also has a bypass mode. This will make the device sent the incoming audio signal through without processing it.

This option is extremely useful when you’re automating the device. Because although you can turn an audio effect off, then it is really off. As in quiet; no music, the sound of silence.

But if you set this Restereo device to bypass mode, save your Song, and then later load it again it will actually result in a crash:

Restereo crashing for no reason
The error you get when saving with Restereo set to bypass.

Which the author considers to be a minor issue.

Fortunately Reason doesn’t crash entirely, but even so this should give you some food for thought…  Do you really feel comfortable to continue working on a Song where one of its devices crashed like that?

Numerical Sound comments

Because of the impact (no other Reason device has ever reacted like this) as well as the heat of the discussion we contacted Numerical Sound and asked them if the above comments were really theirs and if they had any comments on the matter as a whole.

Mr. Cholakis from Numerical Sound lets us know: “I did post on the forum on this thread which is untrue and inflammatory. ReStereo was carefully tested and is fully functional. Please try it yourself. In the forum as in the manual I explained how to properly route ReStereo but clearly some 30 day trial users have not read the manual. There is a small bug with the bypass switch that will be addressed in an update however this does not effect the unit from working properly.“.

Well, I invited some people over this evening; we studied the manual thoroughly and tested the device. As can be seen above we got the same results. The manual which Mr. Cholakis mentioned is a PDF file which isn’t included with the device itself but can be picked up from the Numercial Sound website, here is a direct link (a Quick start guide).

Our Restereo experiences

When it comes to the sound quality of the effect then we have little to complain. There are fields where it performs better than others but that should be expected. What we do fail to understand is why both the manual as well as the author seem to be under the impression that there exists something as “improper routing” in Reason. That makes no sense to us. None at all.

Issues with the Restereo RE and its manual

“Mono synthesizer”

The manual (see previous link) tells us how one can connect the “1 MONO/LEFT” from Thor to Restereo’s audio-in left.

What the author apparently doesn’t seem to know is that this will result in Thors right signal getting automatically routed as well. Because you see; first of all: Thor is not a “mono synthesizer”.

I’d like to point your attention to page 605 of the Reason manual, the part about Thor’s audio outlets: “Thor has 4 outputs: 1 Left (Mono)/2 Right – these are the main stereo outputs“.

But second…  If a device is only build for handling mono signals, then why does it have a stereo audio input connector?

Restereo back side
The back side of the Restereo rack extension.

So quite frankly; the comment that people are not properly routing it is in our opinion preposterous. Even the manual itself clearly shows that when you connect Thor it connects both channels.

But there’s more…

Incorrect instructions in the manual

It is our opinion that the author himself doesn’t fully understand how to properly route a device in Reason. Because according to the manual this is the way to use the Restereo audio device as an insert effect on an audio track: by using the direct output from the audiotrack device and connecting this to the Restereo device. Which output should then be connected to a mix channel, like so:

Connecting a device the restereo way
The “proper” way to connect an audio track to the Restereo device.

Why?!  First this will break internal routing in Reason; you end up with a “dead” audio track which you can’t properly use in the main mixer section anymore.

Second; Audio track devices have an FX section where you can place insert effects. That is the proper place for this device, mono signals or not.

But most of all… take a look at the back of the Restereo device again. Those small graphs at the right side aren’t there for show. These tell us that Restereo accepts both a mono input as well as a stereo input. And here is where it gets important: When connecting a stereo signal both signals will be processed individually. When connecting a mono source otoh. then this signal will be processed and sent out of both outlets.

Put differently: there is no reason – what so ever – to connect Restereo in the way the manual describes. In fact; that is basically equal to breaking up your routing quite dramatically without any extra benefit. You only end up with a ‘dead’ strip in your mixer section. This is how you should connect the Restereo device to an audio track instead:

Connecting restereo
The right way to connect Restereo to an audio track.

Please pay extra attention to the single cable going to the audio in of Restereo. That wasn’t our doing; this is an example of Reason’s own intelligent auto routing capabilities.

Quite frankly we can’t understand why the author gives such odd advice in the manual and still claims that the users are doing it all wrong.

Which I think shows a potential issue with Rack Extensions in general…

Reason philosophy

One of the basic ideas of Reason is that you can use it any way you want. You’re not bound by rules or restrictions on how you should use it. Reason, as Ableton Live I might add, positions itself as both an audio workstation as well as a digital instrument fully aimed at self expression.

For those of you who didn’t got the message yet:

So quite frankly, in my opinion there is more to building a Rack Extension than simply porting an existing device onto the Reason rack and expect people to use it as you intended it to be used.

Because you see; that is not the way Reason works. It is how Reason can work, sure, but Reason as a whole allows for experimentation, radical ideas and plain out “sillyness” in general.

And even if people do something silly within Reason they can always expect the environment to behave the way it should or was intended. As said before: there is no “right or wrong”.

So what happens if the author of a Rack Extension didn’t got that message yet? Was there any quality control at all with the Restereo device and its manual?

We now had one crash, wrong instructions in the manual, what could be next?  Could Rack Extensions pose a possible threat to the stability and consistency of Reason in general?

I don’t have the answer to that, but I do think this experience shows us that even though Rack Extensions are “Reason only” we cannot assume that the authors of these devices know all about Reason.

Which, as I said earlier, leaves quite some food for thought.



  1. You forgot to mention our tests; or did that make the article too long? 😆

    But if u use a squarewave u can really see that when using low frequencies this device creates a nasty rattle sound. Pete; could you add the pictures?

    Edit by editor:

    Low freq. squarewave, generated by Pulsar & sent through Restereo

    Same squarewave with minor glitch.

    Used with E1 key, plain Pulsar squarewave.

  2. first a week silence, now one post a day? 😛

    i agree that the routing looks odd. cant believe thats in the manual bcause that will cut the option to solo your tracks:

    solo the output mixdev and the audiodev goes silent. solo the audiodev and the output mixdev goes silent.

    thats dumb

  3. you raise a good question, but answered ur own too: PUF. when bad things happen it will get there, for all to read.

    and the re crashed NOT Reason!

    1. Well, I guess there’s one way to find out.. We’re planning to check up on the Restereo device in approx. one or two months to see if the author has indeed come up with a fix for the crash. That should tell us a whole lot more I think.

  4. I never tried ReStereo, but it DID get me to think/learn about “Stereo/Chorus”;
    I was having a Blast with DDL-1s, and some Spiders (Screams, etc) in a Combinator…

    – then ReStereo steered me to the to DC-2 Re in REASON, and the Blue CAT Chorus4… OUT.
    so I could hear how it sounds when it just.. works (btw, the “Offset” on the VEQ… nice.)

    I figured I’d get around to trying ReStereo – because, if it just Worked… that’d be cool…
    as stated in the “Our Restereo experiences” pp.. – Glad I waited.
    I wish Numerical some luck with the Numbers… if it takes 2 months, and all…

    And, this is one BEAST of a Blog. Thanks for the Words.

    1. The main problem of ReStereo is that it suffers from much prejudice from many people. And I can even include myself to that list. It has made a bad start, but it has also made quite the comeback. Do keep in mind that this article focusses on Rack Extensions in general and merely used ReStereo as an example. The criticism here isn’t focussed at ReStereo but more at Propellerhead Software for apparently not doing much on quality control.

      But speaking of ReStereo: within the next 2.5 weeks you can expect a full review of the device. It would have been posted sooner if it weren’t for me getting sick and being confined to bed for 1.5 weeks :/ Right now I’m slowly recovering and picking up where I left off.

      Anyway, thanks for the compliments and hope you’ll continue to enjoy the blog & site!

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