AS78 Dual FET Peak Limiter

AUDIOSCAPE PROUDLY INTRODUCES THE AS78!

This is the resurrection of a legendary two-headed beast that was described at the time of its original release in 1980 as a dual channel version of the most widely used compressor/limiter in the world. Employing a Dual FET-based topology, the AudioScape AS78 perfectly tracks in the selectable Stereo mode. In this mode, Input and Output levels are controlled individually, per channel, while the single, ganged Attack and Release pots control both channels simultaneously. In Stereo mode, the loudest signal from either channel controls the GR equally for both channels. In the A/B mode, while Attack and Release are still single, ganged controls, the individual dynamics of each channel determines each channel’s GR. This makes the AS78 a uniquely versatile stereo/ dual peak limiter.

In AudioScape’s updated design, they added a Sidechain HPF, switchable 80 or 120Hz, to allow for more nuanced sidechain triggering by filtering out high energy low frequency information. With this kind of control, you can easily tame wild dynamics with surgical precision. The unique design of the AS78 allows the user to crush transients without the buzz-kill of sonic artifacts, or simply and subtly soften transient peaks in the 2-mix transparently. Strapped across the stereo buss…inserted over the BG vox tracks or stereo acoustic guitars…adding depth to the drum stem, AudioScape’s AS78 is an indispensable bit of kit in the sonic toolbox.

A must-have? Oh yes!

The Story?

The creation of the AS78 started with the user. Every die-hard AS follower has been clamoring to experience AudioScape's take on this for years, so AudioScape answered the call! Manny Nieto was kind enough to send AudioScape his original saying, “This is the perfect unit to model, I’ve heard a bunch and this one rules”. Manny is the man! So AudioScape went to work on their version in concert with his original, which was used to verify the ‘core design’. The AS78 is 1:1 with his original and has exactly the same behavior in both the subtle and the most extreme settings. The last picture shows AudioScape's prototype underneath his original 1178. It was so useful to have an original to make sure everything was the same before AudioScape ripped into any ‘mods’. One thing AudioScape noticed with modifying this circuit was the company could definitely go TOO FAR and lose a lot of its original character and charm. So AudioScape was very measured with their mod approach and chose the most flexibility, while retaining the ‘least intrusive to the core design’ modifications. At the end of the day, the user wants an accurate representation of the original, not something that is compromised and watered down. This was very much in the front of AudioScape's mind during the development phase.

How did the mods come about? Around the time Ryan Hewitt was mixing ‘Unlimited Love’ by the Red Hot Hot Chili Peppers, he reached out and got a few pieces from AudioScape. He was also requesting a few new designs and an AS78 was at the top of the list. He was saying if AudioScape does it, they should add a blend control and some simple sidechain high pass values. And sure enough, these were amazing and useful ideas; so every time the user uses these mods on their AS78 they can say ‘Thank you, Ryan’ ;) Also, a very special shoutout to David McDonald for doing the pcb design for this product and making these must-have mods a reality. AudioScape drove him crazy going back and forth on whether the blend function should be a toggle or an actual control…

At AudioScape Engineering Co., the company believes in creating boutique analog hardware for a reasonable cost. No Compromises. No BS. Many years of research, development and experimentation have gone into each product resulting in units that can be the user's daily-driving, rock-solid workhorses for years and years to come. Each and every unit AudioScape sells is hand made in small batches, one at a time in the USA - right here in their Daytona Beach, Florida facility!

FEATURES & SPECS:

• Handcrafted in the USA
• Custom-Wound Cinemag Steel Output Transformer (for maximum character)
• NOS transistors (found in the original units) utilized in Crucial Areas of the Compressor/Amplifier Sections
• Period-Correct Attack & Release Time Constants
• Cornell Dubilier Silver Mica Capacitors
• Wima Coupling Capacitors
• Period correct Carbon film resistors used in the original circuitry, 1% precision resistors used for the modification sections
• Fully Variable Input/Output and Attack/Release
• Attack On/Off Switch (Bypasses Compression; Use the AS78 as a Line Amp for it’s Exhilarating Saturation and Harmonics!)
• Additional Blend control option added
• Additional Sidechain High Pass Filter options added of 80/120Hz
• Original Style Push-Button Ratio Control (4:1/8:1/12:1/20:1)
• Alpha & CTS Potentiometers
• Electronically Balanced +4dBu circuitry
• Custom Vintage-Styled dB Gain-Reduction Meter
• Original-Style toggle switches and Pilot Light
• Highest-Quality US made Recreation Knobs
• Real Metal Neutrik XLR Input and Output Connectors
• Triad International Series Toroidal Power Transformer
• External 120V/240V Power Supply for lowest noise spec

**specifications, parts & pricing subject to change because sh*t happens ;-)

TECH RANT:

There’s a reason a 78 style circuit hasn’t been replicated properly until now, obsolete and unattainable parts! Everything about the AS78 is going after the vintage OG circuit without too many unnecessary mods that take away from the original charm and vibe of the unit. Every time you add something you take away something else. There’s no free lunches. Sourcing the obsolete 2n6716 and 2n6728 transistors along with a custom made Dual Fet was huge, and in my opinion, the only proper way to do this circuit justice. Original carbon film resistors, even the same type of silver mica capacitors around the dual fet that were in Manny’s unit are used here. Finding the most accurate taper input and output controls like the original was another challenge, even tweaking the brightness of the meters and power led to perfectly match the original; no detail was overlooked! Another extremely difficult component to source was the original value Dual Attack control with the ‘OFF’ switch function. They had to have this part specifically custom made and it came at a great cost both mentally and financially. It would have been easier to add a mod function (instead of an OFF switch) with an basic dual pot here but accurately replicating what the circuit is makes the most sense if you’re ‘going for it’.

AudioScape started to see some other “78” versions that make bold claims about original parts and then you stare at a pcb and what do you see? The wrong type of resistors or the wrong wattage compared to the original, the wrong capacitor types. It truly begs the question if any of these companies actually care to recreate the character of the original, cause if they did they would rock those original parts. Don’t fall for the nonsense…

Lastly, there are no shortcomings in the 78 circuit, It is such a lovely compressor in it’s stock form and was used on countless hits ‘as is’ for a reason. If you’re looking for the MOST accurate, no BS recreation of the original 1178 with a few tasteful additions, made by hand in the US, like the original, the AS78 is the ticket!

DOCUMENTATION:

• AS78 QUICK-START