What About Preamps?
How many of us have wondered from time to time about preamps?
All of our guitar amplifiers have a preamp section and a power amp section. The preamp section converts the output from the guitar or bass into a line level signal that goes to the power amp section for reproduction through speaker systems. We all get this fundamentally.
What happens in the preamp section, is the initial amplification of the signal from the instrument and typically eq, bass and treble at its simplest, a graphic eq like on a Boogie at a more complex level. Some preamps also include their own drive section, so you can get what is effectively a signal boost going into the tubes or circuits that do the preamplification to create an overdriven signal. As users we see these most often as channels, such as the clean channel, or the crunch channel or the hot channel. Some preamps are readily overdriven, whereas others stay clean right until the end. We say that preamps that stay clean have lots of headroom.
Standalone Preamps
In recent years, we have seen an influx of off board preamps, that can act in front of the amplifier preamp, or replace it entirely. Victory Amplification has done a number of these, basically pulling the preamp out of one of their amps, and putting it in its own box, so the owner can choose to use the amplifier’s native preamp, or the Victory preamp. It’s some nice flexibility at a price.
As with regular amplifiers we can find preamps that use solid state technology to provide the preamp functionality or preamps that use vacuum tubes aka valves to do this. I’ve used both types, and for my ears, I prefer a tube drive preamp. There are fewer of these than the solid state type, and my preferences include the tube preamps from Kingsley Amplification and the Effectrode Blackbird pictured at the head of the article and discussed in greater detail below.
Another mechanism is to use a preamp that via it’s line level output (presuming that it has one) is to take that output and run it direct into a dedicated power amp connected to the speaker cabinets of your choice. This was initially popular in the rack amplifier days, but still works if you can put your hands on a nice power amp and already have speaker cabinets that you like. One can find decent deals on tube based power amps from the likes of Mesa Boogie if one looks, as did Mick Taylor from That Pedal Show.
Potential Confusion
As can happen, some pedal makers refer to their pedals as preamps, when in fact they are not actual preamps. A preamp can output a signal that goes direct into a power amp, and does not need to go into the front end of a guitar amplifier. There do not appear to be any rules on the use of the nomenclature so this can be problematic for buyers. Documentation is often sparse and even misleading. Look for a line level out, either as a balanced TRS, an unbalanced TS or an XLR out. It may say out to power amplifier as an alternative to Line Out.
Benefits for The Gigging Musician
For gigging musicians who don’t want to carry a lot of gear, a preamplifier with a line out can go direct to the house PA, eliminating the need to carry big amps at all. Very handy.
The latest mechanism of favour is to run the preamp balanced line outs direct to the inputs on your recording device. I say balanced as reference to a balanced line out, as opposed to unbalanced line out. Many preamplifiers have TRS or XLR balanced line outs as part of their configuration. This is not unlike using a Kemper or Quad Cortex or Helix into the interface, just smaller and less expensive. I recently purchased an Effectrode Blackbird for this specific purpose.
Another option that is quite nice is to run the line out from your preamp directly to an FRFR powered speaker cabinet. While I use these mostly with the Kemper or the Quad Cortex, they work a charm, particularly if like the Strymon Iridium they have speaker Impulse Response capability.
Effectrode Blackbird
Tube based preamp joy!
I wanted to be able to record in my DAW direct from my interface but did not want to use plugins for the amp emulation. The Effectrode Blackbird is an all tube preamplifier. You can see the three tubes in the accompanying image. It has a clean channel, a classic overdrive channel, which adds a modifier to make the classic overdrive a creamy overdrive. This can negate the need for a separate overdrive pedal, if you can get the overdrive tones that you want. In my case, I absolutely can. If I could not, as has happened with other devices of this type, I can run a pedal board into the front of the preamplifier as on any amp, with an overdrive on the board. I am not using a board with the Blackbird, because I have amazing UA plugins for delay and reverb, but your mileage may vary.
The Blackbird is built like a stomp box. It’s a tough steel enclosure with separate controls for the two primary channels. Since mine is an always on, never bypassed device, a simple jumper change under the base plate changes the bypass foot switch to all change from Classic to Cream if that channel is selected.
Three 12AX7s perform the pre-amplification duties
You can see that the Blackbird has separate tone stacks for its two unique channels, as well as a Gain control for the overdrive channel. The outputs can go to the input of a regular amp, but I am using the 600 ohm low impedance output into my Universal Audio Apollo. This is a microphone level input, so I have a lot of headroom available.
The Pre-Emphasis switch provides a modification to the tone curve. You choose the switch position that suits your likes. Since my Blackbird is my preamp and is always on, I followed factory instructions to set a jumper inside the case so the Bypass switch selects between Classic and Creamy. I thank Charles at electricmojoguitars.com for this tip. I get all my Effectrode gear, along with plenty of others from Electric Mojo Guitars.
In my first forays into recording this way, I used a Strat with Fralin Pure ‘54s which have glorious tone, albeit at very low output. My other guitar used in my testing is a PRS SC245 with fairly punchy humbuckers. It sounds great as well and the only work to do on the Blackbird is adjusting the channel settings to suit the pickups, just like on any amplifier.
Even in the overdriven modes, the Blackbird is not noisy. This reduces the need for gates in the DAW, and the simplicity of the connection keeps the tone pristine.
Once the tracks are recorded, I can apply effects if desired via plugins, and if I need to simulate a speaker cabinet to get the sound the way I want it, the Torpedo Wall of Sound plugin from Two Notes provides me with all the choices that I need. For more information about Wall of Sound, it’s a plugin that you get access to that uses your Torpedo cab sims. If you already own a Torpedo and have not installed Wall of Sound in your DAW, you are missing out on value that you already own.
Conclusions
I am loving the Blackbird. I vacillated on the purchase for over a year, wondering what difference it would make on a pedal board. I have since concluded that while it would work, that’s not where it excels. Far better in front of an interface or connected directly to an FRFR speaker. And the tone from those tubes…excelsior!
Thanks for reading and until next time, peace.
