The Effectrode SR-71 Blackbird Drive/Preamp is an all-valve drive and clean preamp pedal, built around three dual triode valves12. It belongs to the small group of preamp pedals that use real tubes rather than solid-state or digital circuitry, and MusicRadar's reviewer Trevor Curwen called it "one of the best all-valve preamp pedals money can buy"1.
Controls and channels
The SR-71 carries two channels with their own sets of controls1:
| Channel | Controls |
|---|---|
| Drive | Gain and volume, plus separate EQ |
| Clean | Single volume control, plus separate EQ |
The two footswitches toggle the clean and drive channels and bypass, so switching between sounds and going clean to the amp is done from the pedal itself1.
What changed from the original Blackbird
The SR-71 is a new version of Effectrode's best-selling SR-71 preamp, with significant enhancements over the earlier Blackbird drive pedal1. Two changes stand out:
- Pretty much every resistor and capacitor in the signal path has been adjusted in order to improve the musicality of the Blackbird's distortion1.
- The speaker-emulated output in earlier versions has been replaced by a transformer-isolated balanced output1.
If you are comparing the SR-71 against a used earlier Blackbird, the output stage differs: earlier versions have a speaker-emulated output, the new version has a transformer-isolated balanced output instead1.
The design goal behind the circuit, according to the review, is minimizing blocking distortion. Phil Taylor says this is what Alexander Dumble was also working towards in his preamp sections in his custom amps in the 70s1.
What reviewers said
MusicRadar's Trevor Curwen found the new Blackbird exceptionally quiet, with almost inaudible hiss and hum levels, and described the drive as covering vintage and modern tones from Dumble-like smoothness to aggressive bite with practically endless sustain1. On the clean side:
"The clean channel is beautiful, with a pure, glassy treble that's reminiscent of the best Blackface amps."
For recording, the balanced output was found to retain plenty of real-amp dynamics and to take analog and digital EQ nicely for an infinite range of high-quality recorded sounds1. The overall verdict was that the SR-71 is unique and superbly made, but not cheap1.
Videos
Effectrode
Brett Kingman
Mike Hermans
Questions
Is the Effectrode SR-71 Blackbird all tube?
Yes. MusicRadar's review describes it as one of the best all-valve preamp pedals money can buy, and the pedal runs on three dual triode valves. Effectrode's pedals are valve-powered as a design approach, which is what sets the SR-71 apart from solid-state drive and preamp pedals.
How many footswitches does the SR-71 have?
Two. According to MusicRadar's Trevor Curwen, the two footswitches toggle the clean and drive channels and bypass. That gives you direct access to the clean sound, the drive sound, and true bypass without a separate controller.
Does the SR-71 have a speaker-emulated output?
The new version does not. It replaces the speaker-emulated output found in earlier versions with a transformer-isolated balanced output, intended for recording. The reviewer found that balanced output retains plenty of real-amp dynamics and takes analogue and digital EQ nicely.
What is the difference between the SR-71 and the original Blackbird?
The SR-71 is a new version of Effectrode's best-selling SR-71 preamp with significant enhancements over the earlier Blackbird drive pedal. Pretty much every resistor and capacitor in the signal path has been adjusted to improve the musicality of the Blackbird's distortion, and the speaker-emulated output has been replaced by a transformer-isolated balanced output.
Does the SR-71 have a clean channel?
Yes. The SR-71 has two channels: a drive channel with gain and volume controls, and a clean channel with a single volume control, each with separate EQ. MusicRadar's reviewer called the clean channel beautiful, with a pure, glassy treble reminiscent of the best Blackface amps.
Sources (2)
- Effectrode SR-71 Blackbird Drive/Preamp review, MusicRadar, 2017-05-18
- Effectrode SR71 Leveling Amplifier review, MusicRadar, 2017-06-01