SUN STORM: vacuum tube audio compressor. It's an optical compressor, but also not exactly.
First of all, what we are looking at and talking about is a fully functioning prototype. The images here as of 11/30/24 are of the prototype(s) #3/4. I number them by the half rack, since that's how they are built. This represents the 3rd and 4th prototype, which introduce a pile of new features over the previous prototype. New to this is stereo linkage, a release control, and a whole ton of cosmetic upgrades and new circuit boards. New features too! So much is borrowed here from my past work in developing the Trinity, which is now a bust. That particular product is a failure because I couldn't figure out how to manufacture it in a profitable way. There were other factors involved, which were equally as ending... I lost the schematic for the power supply section in a hard drive failure. That power supply was something that took me several years and thousands of dollars to develop. It was the bees knees in my book and losing that was a major set back. I painstakingly recreated it for this product by looking at physical examples of the most current circuit board, examining the latest existing schematic, and doing something a bit smart for me.... I sectioned up the power supply into different voltage sections and created a discrete circuit board for each section. This was critical in making sure I could find my mistakes if I made any when copying things over. The next step will be recombining those sections into one big power supply board.
There are many voltages involved. The Sun Storm's power supply is an evolution of the Trinity's power supply. In this system (Sun Storm) It has 2 tubes instead of 3 per channel as in the Trinity channel strip. The exact tubes used may change in the end, but currently V1 is a 12AT7 and V2 is a 12AX7.
|
Each tube has it's own separate B+ power supply, with one at around 190V DC, and the other around 210V DC. These voltages are generated internally with an LBA designed ultra-low-noise DC-DC multi-channel boost converter. There's also a linear-regulated 12V section onboard to power the tube filaments, the relays, and the VU meter's backlight. Each channel gets it's power from a 15V DC line-lump switch-mode power adapter, specially selected for low-noise. Unlike the Dark Storm, I feel like daisy chaining off of one power adapter isn't an option here. The power consumption of the Sun Storm is actually sort of insane in comparison to a Dark Storm. Typically the requirement to power 1 (mono) channel Sun Storm is 1.5 Amps at 15V DC. That's a lot. 3 Amps for a stereo channel. I plan to include a power adapter with the sale of each mono Sun Storm. I haven't decided on the stereo pair yet. An LBA power supply is also in development if you haven't seen the Thunder Power prototype yet. That thing can power a stereo Sun Storm and a pile of Dark Storms. Once that gets fully developed it'll be a product too.
|
|
|
On to the cool stuff! The Sun Storm is a combination of several different compression topology concepts. That is to say it isn't trying to be anything in particular and it certainly isn't trying to be a typical optical compressor. My goals were relatively simple in concept (difficult to achieve). I have a 1960's Altec variable-mu tube compressor, which has taught me a lot. Most of that teaching happened as I modified it to have more functionality. It's a cool tool, but I find it's a bit too colorful for most tasks. I also wish it was capable of much faster attack times. The Altec distorts if you set the attack too fast for it's liking. I assume this is standard with all variable-mu compressors since I spent a lot of time trying to correct that issue to no avail. Negatives aside, it has so much freaking mojo I can easily forget all its shortcomings when used sparingly on just the right source. I wish I had a compressor with that kind of mojo on every source, but not quite so much color. The Sun Storm itself is an evolution of my Op-2 Comp FX pedal, which was a dual tube optical compressor pedal. It's becoming so different now that I can't even compare them, so I won't. In the Sun Storm, there is a zener diode that sets the threshold, so a fixed threshold. There's a control voltage involved, which has to cross the zener diodes threshold in order for the compressor to work. That control voltage is something I think is probably unique to this design. It's manipulated by a vacuum tube.
|
|
Basically, a vacuum tube stage (the compression knob) pushes the control voltage so that it can surpass the threshold. However, the more the tube is pushed, the more it distorts. This tube distortion is directly related to the compressors ratio. As the signal ratio increases over the threshold, the compression ratio increases as well. If that's not different enough from other opto designs, there is also the inclusion of attack and release controls. I know some other opto designs include these controls, but I doubt with such a wide range of functionality. We're talking nano-seconds to as much as seconds of attack and/or release. These controls work in conjunction with LBA's proprietary high speed Opto-Cell, model 1A.
|
Probably an understatement here is the pile of audio transformers made in-house. Each channel has 3 audio transformers, so 6 in total for a stereo compressor. That's not all the cool beans though. When you engage the power switch what happens initially is the VU meter's back light blinks and no audio passes. This happens for about 30 seconds. During this time the tube filaments are powered on with 12V DC and begin to warm up. After about 30 seconds the tube filaments are warm and the B+ power automatically switches on. When this happens, the VU meter backlights switch from blinking to a solid on status. The meters themselves only indicate gain reduction (same as my Altec 438c). Under the hood is a set screw to zero the meter if necessary. This time-delay start-up sequence is necessary to extend tube life. I want your tubes to last a long time!
|
While the Sun Storm is already very developed it is still considered a prototype. Some refinement is necessary. No release date is set at this time, but you may request a prototype for a very reasonable fee by simply emailing sales@lightningboyaudio.com.