First Watt Amplifiers

Special amplifiers for special speakers. These are amplifiers designed and built by Nelson Pass (the designer of Pass Labs, Threshold, and other top quality amplifiers). They are specifically designed as low wattage amplifiers to be used with high efficiency speakers.


B5 Electronic Crossover:

Long awaited and finally in production. This is the Nelson Pass designed electronic crossover meant for use with open baffles. The various options can be switched in and out on the board, no need to specify a crossover frequency or slope when purchasing it, only to find out your needs have changed. Just throw the switches and change to fit your new system.

The first section is developed for a fullrange/widerange driver on an open baffle. It can be adjusted up to 300 hz, with either first (6dB/octave) or second (12 dB/octave) slopes.

The woofer section has a low pass section that can also be adjusted up to 300 Hz, either 1st or 2nd order slopes. This section also has a high pass section to protect the woofer from turntable thumps, excessively low bass, etc. It also allows for a bass boost at the high pass point, so you can compensate for baffle cancelation at low frequencies.

Simply a joy to use. Discrete J-Fets, no op-amps, are used in the construction.

The rear panel has 6 RCA jacks, 2 input, 2 out for the woofer, 2 out for the fullrange/widerange. The front has two controls that adjust the relative output of the high and low filter sections to properly balance the sound coming from the different drivers.

List price is $1,500

Our Price is $1350, including shipping in the continental US. These are presently shipping.

B4 Electronic Crossover:

In the final stages of design and testing. This crossover was the result of many request for a crossover for normal speakers, with an extended range beyond what the 300 Hz range of the B5.

The final design has crossover frequencies adjustable from 20 Hz to 1,260 Hz in 20 Hz steps, and from 200 Hz to 12,600 hz in 200 hz intervals (No, I did not have a typo, yes there is a fair amount of overlap between the two zones).

Slopes can be adjusted between 1st, 2nd, 3rd and 4th order. (6, 12, 18, or 24 dB/octave)

Normally supplied with Butterworth slopes, you can special order the Linkwitz-Riley slopes. This is the only option that you cannot switch back and forth on. Standard is the Butterworth slopes, if you do not specify Linkwitz-Riley this is what you will get.

List price is $1,500. Price is $1400. Price includes shipping in the continental US. Production is starting this month, and shipping will begin towards the end of the month.


We used 2 amplifiers at RMAF that we really can't sell as new, but they were used over 3 days and then packed up again. So near new, but demo pieces. Full warranty. Think of them as being well tested, at a reduced price. J2 demo was sold.

M2: Normally $3595. This unit $2895 including shipping to CONUS

There are a few used/demo pieces on Used Stuff page. Present offerings are as follows:

Normal Stuff

Well, normal for Nelson Pass! Great stuff by anyone else's standard:

J2 Power Amp: A J-Fet based push-pull design that has the sweetness of a tube amplifier. 25 watts per channel. List price is $4000

Our price $3595 including shipping.

M2 Power Amp: Using an autoformer gain stage, this unit has captured the heart of the Asian market and reviewers. Sounds like a slightly older tube design, with just a slight rounding of hard edges. Extension at the bottom that tube amps dream about. 25 watts per channel. List Price is $4000

Our price $3395 including shipping.

B1: This is a simple line stage, with no gain, but acting as a buffer to drive loads that your DAC or phono stage can't do with a passive. List Price is $1000

Our Price: $800

B4: Electronic crossover. After an initial production run a decision was made to re-design them for ease of production. So no more units will be available for awhile. Read more information here:

Right now, pricing information is not available.

B5: Electronic crossover. These are designed specifically for open baffle speakers. A built in bass boost (not defeatable) for full range open baffle systems which need low end augmentation. Limited to a maximum of 200 hz hi pass filter.