Thursday, January 17, 2013

Alembic F-1X Bass and Keyboard Preamplifier Review


I guess it is time to do a write-up of my Alembic F-1X preamplifier, which has been a neat addition to my assortment of bass amplification products. It has been in the studio for about 6 months, and its simplicity and tone have really grown on me.

You have surely heard of Alembic, the Northern California guitar maker that has produced beautiful (and expensive) guitars and basses with innovative electronics for the likes of Jerry Garcia, Jack Casady and Stanley Clark. You might not be as familiar with their other electronic products, but they have made some truly amazing pre-amplifiers over the years, one of which is the F-1X. The F-1X is essentially a mono version of their popular F-2B preamp, and it has been designed to work best with bass or keyboard applications.

The F-1X is not a stand-alone unit, and you will need to use it with a power amplifier, and probably some sort of quality equalizer (more on the EQ in a bit). This pre-amp fits into a single standard-sized rack space and just oozes handmade quality. The case is made out of heavy gauge powder coated steel, and it has an impressive heft. All of the pots, jacks and switches are quality components and they are easily serviceable. The power cable socket is the heavy-duty removable IEC C-14 type, so different types of power cables can be used. It is switchable for the different voltages that are used overseas and a jumper lead inside the chassis will need to be moved to accomplish this.

It is not terribly complicated to use. On the front you will find two input jacks, a volume knob, three tone controls (bass, middle and treble), bright and deep switches, a direct out socket, direct out pre/post and ground switches, and crossover frequency and level controls. Alembic put the power switch, a full-range out, high and low crossover outs and effects loop jacks on the back. That’s it!

Using the F-1X is straightforward once you know what everything does. The two inputs are not the same, as input 1 is a regular input and input 2 is padded by 6dB. It would be nice if Alembic labeled these inputs to indicate this. The volume knob controls the level of the full range and crossover outs.

The tone controls can be a little confusing, as they a passive interactive type, so it is important to know how they are wired. When one knobs is moved, the other two will not remain the same. So, if you want more treble, you can accomplish this by turning treble up, or by reducing the bass and mids. There really is no “flat” setting, but Alembic says that setting the knobs to 2:00 (bass), 10:00 (middle) and 2:00 (treble) will get you the closest. Many users are unable to get as much EQ adjustment as they want, so they usually add a quality EQ to their rack system.

The bright switch boosts the extreme treble range, and is progressively less effective as volume is increased. The deep switch cuts the lower midrange and leaves the lower frequencies untouched. The deep switch really tightens up my tone, and I find that I rarely use the bright switch.

It is nice to have two output choices, you can have the option of running a bi-amped or running a simpler single amplifier system. I only have one power amp, so I have only used the full range out, but the crossover system seems simple enough. There are high pass and low pass outputs that are controlled by a crossover frequency knob that might not work like you think it would. It allows you to select a frequency at which: above the frequency, low pass output decreases 12dB per octave and below the frequency, high pass output decreases 12dB per octave. The high level knob can change high pass output by a range of +/- 10dB to obtain more equal speaker cabinets volumes.

All of these neat features don’t mean much if the unit does not sound good, but there is nothing to worry about in that department. I did not mention that this is a tube-driven unit, did I? The F-1X is loaded up with a 12AX7 tube to provide the pre-amplifier’s gain. This is situated before the volume control and is powered at 300 volts to allow plenty of headroom for large transients without distorting.

This preamp sounds incredibly warm, and goes a long ways towards attaining my perfect bass tone. The low end is very round, and very punchy mids can be dialed in. This kind of warmth and natural sound is hard to come by, but Alembic has put together a very good package. Don’t mistake the Alembic F-1X with the cheaper amps you have head with tube pre-amp stages. This is the real deal, and provides real tube tone and characteristics.

I have also had good luck using the F-1X as a DI box, and having the XLR out, ground lift and pre/post switch on the front are a godsend, particularly with a rack-mounted piece of equipment. On the other hand, having the power switch on the back of a rack mount unit is a pain in the butt, and I do not buy Alembic’s rationale that everybody uses power conditioners. I still want to be able to get to the power switch easily.

The Alembic F-1X pre-amplifier is built to last forever and sounds wonderful, and of course it is not cheap. The list price on these is $1375, and the cheapest price I found online for them was $1099. Not many retailers carry them, and they do not show up very often on the used market. But, if you crave a wonderful tube pre-amp there is no substitute. Happy hunting!



  1. I saw one for 700.00 excellent condition at atomic music in Maryland, I didn't get it because I have two (red knobs and the blue face) and I had mine for 23 years and I wouldn't want anything else.

  2. I have one in excellent condition for $700

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  4. Dude. These sell regularly for £400 in the UK...