The Lightning Boy Audio Opti-Mu Prime is an analog compressor pedal that puts the working of a vari-mu studio compressor into a stomp box. Premier Guitar's press release described it as a pedal that "delivers the distinctive qualities of a vari-mu studio compressor in a stomp box format," and called it "a whole new breed of compressor pedal"1. It was announced in late June 2013 and sold directly from the maker1.
How the circuit works
The Opti-Mu Prime is built around two 12AU7 tubes and an optical gain-control circuit, a design Lightning Boy Audio describes as unique1. The two tubes have distinct jobs:
- The first 12AU7 drives the optically controlled vari-mu circuit1
- That circuit constantly readjusts the plate voltage of the preamp tube based on how loud the instrument is being played1
- The second 12AU7 serves as a preamp and is the only tube in the audio path4
In plain terms, the compression happens by changing the operating point of the tube itself as you play harder or softer, rather than by squashing the signal with a separate gain element. Vintage Guitar's report describes the same arrangement: "One drives the optically controlled vari-mu circuit, which constantly re-adjusts the plate voltage of the preamp tube, based on how loud the instrument is being played"4.
"Opti-Mu Prime delivers the same stunning beauty of a serious vari-mu studio compressor in a stomp box format."
Build quality and components
The pedal's construction got specific attention in the trade press. Guitar Interactive Magazine's Jonathan Graham reported that the Opti-Mu Prime is hand wired point to point with silver plated Teflon insulated wire, and that Lightning Boy equipment uses low noise Vishay/Dale metalized film resistors to prevent unnecessary resistor noise2. Vintage Guitar's report matches the hand-wiring detail4.
The capacitor choice is also part of the design story: paper in oil caps are utilized, according to Graham, "for their ultra-transparent sound and smooth tone"2. For a player, these are the kinds of parts choices makers point to when they want a compressor to stay out of the way of the instrument's tone, which is consistent with the transparent, natural-sounding compression the maker and press attributed to the vari-mu design23.
Price and availability
The Opti-Mu Prime carried an MSRP of $299, reported by Delicious Audio at the June 2013 launch3. Guitar Interactive Magazine also reported a pre-release price of $299.00, available through the end of the summer NAMM Show on July 13th2.
At launch, the Opti-Mu Prime was available exclusively on the Lightning Boy Audio website, not through dealers12. Both availability and pricing date from the 2013 announcement, so a player looking for one today should treat those figures as historical.
If you are comparing it with other dynamics tools, see the site's overview of Compressor Pedals.
Videos
gearmanndude
Questions
How many tubes does the Opti-Mu Prime use?
The Opti-Mu Prime uses a pair of 12AU7 vacuum tubes. One tube drives the optically controlled vari-mu circuit, and the second serves as a preamp and is the only tube in the audio path. The vari-mu circuit constantly readjusts the plate voltage of the preamp tube based on how loud the instrument is being played.
What does vari-mu compression mean?
Vari-mu compression is the approach used in classic studio compressors, where the gain of a tube stage changes with the strength of the input signal. In the Opti-Mu Prime, an optically controlled vari-mu circuit readjusts the plate voltage of the preamp tube based on playing loudness, which the maker and press described as natural, transparent compression in a stomp box format.
Is the Opti-Mu Prime analog?
Yes. The Opti-Mu Prime is an analog pedal built around a vacuum tube circuit, with a pair of 12AU7 tubes at its core. It also uses paper in oil capacitors, which Lightning Boy said were chosen for their ultra-transparent sound and smooth tone, along with low noise Vishay/Dale metalized film resistors.
Where can you buy the Opti-Mu Prime?
At its 2013 launch, the Opti-Mu Prime was available exclusively on the Lightning Boy Audio website, according to both Premier Guitar and Guitar Interactive Magazine. It was not sold through retail dealers at that time.
How much does the Opti-Mu Prime cost?
The Opti-Mu Prime carried an MSRP of $299, as reported by Delicious Audio at the June 2013 launch. Guitar Interactive Magazine also reported a pre-release price of $299.00, available through the end of the summer NAMM Show on July 13th.
Sources (4)
- Opti-Mu Prime: Lightning Boy's New Tube Compressor, Premier Guitar, 2013-06-29
- Lightning Boy Audio Introduce the Opti-Mu Prime, Guitar Interactive Magazine, 2013-07-04
- Lightning Boy Audio Launches The Opti-Mu Prime Compressor, Delicious Audio, 2013-06-26
- Lightning Boy Audio Offers Opti-Mu Prime, Vintage Guitar magazine, 2013-07-01