I've loved X (the band, not the social media thing) since I was a kid. About a decade ago, my lovely spouse scored some tickets to see them in downtown LA. New York Dolls were the opening act. Now, both bands were by then well past their prime, but the NYDs owned the stage that night. X was ok, but the Dolls were aaaaawwwwesome.
Poor DHL guy. 30 kg aluminium. And a dummy load under making. 2x12 ohm and 2x18 ohm configurable. For load testing 2x18 and 2x24 vac pass-size trafos for load, heat, pesky sounds and capacitance allowance on first C, that sort of stuff. Gonna bolt a few fans on it to so I can bbq it hard. Have a nice weekend dodos.
Attachments
We went to see X in Seattle a few years ago and John Doe seemed to be enjoying performing as much as when I first saw them in Orange Co back in the mid 80's. He was definitely the glue holding it all together.
Maybe it was Whistler, shaking some snow off. Good that you are safe Cal! Otherwise, how would we be?
Cal, nice to hear that you are doing fine. Not a good feeling, earthquake. They are not so common in Canada I think? Also, the perception. I once freaked out at a very mild one. But then I watch Japan. If you were in Japan, this one would pass as "very mild"...
Over a cup of morning coffee still in bed I asked Perplexity Deep Research how many watts an Aleph J outputs. Pretty amazing how it summarizes, and the need for spending half a day scrolling threads and documents becomes unnecessary. Well, one ofc has to take the info with a certain amount of salt, but still.
# The Power Output Characteristics of the First Watt Aleph J Amplifier
The First Watt Aleph J amplifier, designed by Nelson Pass, represents a refined iteration of the classic Aleph series, blending technical innovation with a focus on sonic purity. This report examines its power output specifications, contextualizing them within the amplifier’s design philosophy, performance characteristics, and practical usability.
---
## Technical Specifications and Rated Power Output
The Aleph J’s nominal power output is 25 watts into an 8-ohm load at 1% total harmonic distortion (THD) when measured at 1 kHz[1][3]. Under clipping conditions, the amplifier can deliver up to 30 watts[2][3]. These figures are achieved with a power consumption of 200 watts, reflecting its single-ended Class A operation[2][3]. The disparity between input power and output wattage underscores the inherent inefficiency of Class A topologies, which prioritize linearity and low distortion over energy efficiency[3][4].
The amplifier’s gain is specified at 19.6 dB, requiring an input signal of 1.5 volts to achieve its full 25-watt output[2][3]. This moderate gain structure ensures compatibility with both solid-state and tube preamplifiers, particularly those with high output impedance, thanks to the Aleph J’s input impedance of 242 kΩ (RCA) and minimal capacitance[1][3].
---
## Design Philosophy and Performance Context
Nelson Pass designed the Aleph J to address listeners prioritizing “naturalness and musicality over specifications”[3]. By reducing negative feedback by 15 dB compared to earlier Aleph models and eliminating electrolytic capacitors from the signal path, the amplifier achieves a distortion profile dominated by second-order harmonics, a trait often associated with tube amplifiers[1][3]. This design choice results in a subjectively “liquid” sound signature while maintaining measured performance comparable to modern solid-state designs[3].
The Aleph J’s damping factor of 20 indicates moderate control over speaker driver motion, making it best suited for high-efficiency loudspeakers (≥90 dB/W/m)[2][3]. While this limits its utility with low-impedance or complex loads, the amplifier’s stability remains uncompromised, as noted in its ability to drive any load without risk of damage[1][3].
---
## Thermal Management and Practical Considerations
Operating in pure Class A, the Aleph J dissipates significant heat, with users reporting heat sinks reaching temperatures requiring caution during prolonged use[4]. Anecdotal evidence from DIY builders indicates that heat sink surfaces can exceed 60°C in ambient room temperatures, necessitating adequate ventilation[4]. Despite these thermal challenges, the amplifier’s reliability remains a hallmark, with no reported failures attributable to thermal stress in the reviewed documentation[1][3].
For users requiring lower power output—such as those with high-efficiency full-range speakers—modifications to rail voltage and bias settings can reduce heat generation. For example, lowering rail voltages to ±11 V could theoretically yield a 5-watt output variant, though this requires careful recalibration of the current source and power supply components[4].
---
## Comparative Analysis with Predecessors and Competing Designs
The Aleph J distinguishes itself from earlier First Watt models like the F1 and F2 through its voltage-source architecture, a departure from the current-source designs of its predecessors[1][3]. This shift improves compatibility with conventional loudspeakers while retaining the Aleph series’ characteristic simplicity. Compared to the original Aleph 3, the J variant offers 15 dB lower noise and improved power supply filtration, reducing voltage ripple by 20 dB[1][3].
When contrasted with tube amplifiers, the Aleph J achieves similar harmonic richness without the maintenance demands or output transformer limitations. Its frequency response (-3 dB at 6 Hz and 80 kHz) exceeds typical tube designs, ensuring extended bandwidth for modern high-resolution audio formats[2][3].
---
## Conclusion
The First Watt Aleph J delivers 25–30 watts of single-ended Class A power, optimized for high-efficiency loudspeakers and listeners valuing tonal accuracy over raw output. Its design refinements—including reduced feedback, JFET input stages, and robust thermal tolerances—make it a compelling choice for audiophiles seeking a bridge between solid-state precision and tube-like musicality. Future iterations could explore adaptive biasing for improved efficiency, though such changes must carefully preserve the circuit’s core sonic identity.
For potential users, pairing the Aleph J with high-sensitivity speakers (≥95 dB/W/m) and a high-quality preamplifier will maximize its performance, ensuring that its modest power rating translates into satisfying real-world dynamics.
Sources
[1] Aleph J https://www.firstwatt.com/product/aleph-j/
[2] Review: First Watt Aleph J Power Amp https://forum.polkaudio.com/discussion/199702/review-first-watt-aleph-j-power-amp
[3] AJ Power Amplifier.PDF https://www.firstwatt.com/wp-content/uploads/2023/08/prod_aj_man.pdf
[4] Low watt Aleph J https://www.diyaudio.com/community/threads/low-watt-aleph-j.179662/
[5] Aleph J - Recommended Preamplifier? https://www.diyaudio.com/community/threads/aleph-j-recommended-preamplifier.394414/
[6] NELSON PASS designed Aleph J class A 25 watt power amp with balanced inputs only | eBay https://www.ebay.co.uk/itm/286047063632
[7] First Watt Aleph J Build (Introduction)
[8] General Asylum https://www.audioasylum.com/cgi/vt.mpl?f=general&m=751548
[9] 6moons audio reviews: First Watt Aleph J https://www.6moons.com/audioreviews/firstwatt3/alephj.html
[10] First Watt Aleph J Power Amplifier https://www.firstwatt.com/pdf/prod_aj_man.pdf
# The Power Output Characteristics of the First Watt Aleph J Amplifier
The First Watt Aleph J amplifier, designed by Nelson Pass, represents a refined iteration of the classic Aleph series, blending technical innovation with a focus on sonic purity. This report examines its power output specifications, contextualizing them within the amplifier’s design philosophy, performance characteristics, and practical usability.
---
## Technical Specifications and Rated Power Output
The Aleph J’s nominal power output is 25 watts into an 8-ohm load at 1% total harmonic distortion (THD) when measured at 1 kHz[1][3]. Under clipping conditions, the amplifier can deliver up to 30 watts[2][3]. These figures are achieved with a power consumption of 200 watts, reflecting its single-ended Class A operation[2][3]. The disparity between input power and output wattage underscores the inherent inefficiency of Class A topologies, which prioritize linearity and low distortion over energy efficiency[3][4].
The amplifier’s gain is specified at 19.6 dB, requiring an input signal of 1.5 volts to achieve its full 25-watt output[2][3]. This moderate gain structure ensures compatibility with both solid-state and tube preamplifiers, particularly those with high output impedance, thanks to the Aleph J’s input impedance of 242 kΩ (RCA) and minimal capacitance[1][3].
---
## Design Philosophy and Performance Context
Nelson Pass designed the Aleph J to address listeners prioritizing “naturalness and musicality over specifications”[3]. By reducing negative feedback by 15 dB compared to earlier Aleph models and eliminating electrolytic capacitors from the signal path, the amplifier achieves a distortion profile dominated by second-order harmonics, a trait often associated with tube amplifiers[1][3]. This design choice results in a subjectively “liquid” sound signature while maintaining measured performance comparable to modern solid-state designs[3].
The Aleph J’s damping factor of 20 indicates moderate control over speaker driver motion, making it best suited for high-efficiency loudspeakers (≥90 dB/W/m)[2][3]. While this limits its utility with low-impedance or complex loads, the amplifier’s stability remains uncompromised, as noted in its ability to drive any load without risk of damage[1][3].
---
## Thermal Management and Practical Considerations
Operating in pure Class A, the Aleph J dissipates significant heat, with users reporting heat sinks reaching temperatures requiring caution during prolonged use[4]. Anecdotal evidence from DIY builders indicates that heat sink surfaces can exceed 60°C in ambient room temperatures, necessitating adequate ventilation[4]. Despite these thermal challenges, the amplifier’s reliability remains a hallmark, with no reported failures attributable to thermal stress in the reviewed documentation[1][3].
For users requiring lower power output—such as those with high-efficiency full-range speakers—modifications to rail voltage and bias settings can reduce heat generation. For example, lowering rail voltages to ±11 V could theoretically yield a 5-watt output variant, though this requires careful recalibration of the current source and power supply components[4].
---
## Comparative Analysis with Predecessors and Competing Designs
The Aleph J distinguishes itself from earlier First Watt models like the F1 and F2 through its voltage-source architecture, a departure from the current-source designs of its predecessors[1][3]. This shift improves compatibility with conventional loudspeakers while retaining the Aleph series’ characteristic simplicity. Compared to the original Aleph 3, the J variant offers 15 dB lower noise and improved power supply filtration, reducing voltage ripple by 20 dB[1][3].
When contrasted with tube amplifiers, the Aleph J achieves similar harmonic richness without the maintenance demands or output transformer limitations. Its frequency response (-3 dB at 6 Hz and 80 kHz) exceeds typical tube designs, ensuring extended bandwidth for modern high-resolution audio formats[2][3].
---
## Conclusion
The First Watt Aleph J delivers 25–30 watts of single-ended Class A power, optimized for high-efficiency loudspeakers and listeners valuing tonal accuracy over raw output. Its design refinements—including reduced feedback, JFET input stages, and robust thermal tolerances—make it a compelling choice for audiophiles seeking a bridge between solid-state precision and tube-like musicality. Future iterations could explore adaptive biasing for improved efficiency, though such changes must carefully preserve the circuit’s core sonic identity.
For potential users, pairing the Aleph J with high-sensitivity speakers (≥95 dB/W/m) and a high-quality preamplifier will maximize its performance, ensuring that its modest power rating translates into satisfying real-world dynamics.
Sources
[1] Aleph J https://www.firstwatt.com/product/aleph-j/
[2] Review: First Watt Aleph J Power Amp https://forum.polkaudio.com/discussion/199702/review-first-watt-aleph-j-power-amp
[3] AJ Power Amplifier.PDF https://www.firstwatt.com/wp-content/uploads/2023/08/prod_aj_man.pdf
[4] Low watt Aleph J https://www.diyaudio.com/community/threads/low-watt-aleph-j.179662/
[5] Aleph J - Recommended Preamplifier? https://www.diyaudio.com/community/threads/aleph-j-recommended-preamplifier.394414/
[6] NELSON PASS designed Aleph J class A 25 watt power amp with balanced inputs only | eBay https://www.ebay.co.uk/itm/286047063632
[7] First Watt Aleph J Build (Introduction)
[9] 6moons audio reviews: First Watt Aleph J https://www.6moons.com/audioreviews/firstwatt3/alephj.html
[10] First Watt Aleph J Power Amplifier https://www.firstwatt.com/pdf/prod_aj_man.pdf
Sweden is quiet ”tall” so it depends. In the south it’s probably spring. North (Norway it was) had seasonal record warm temps I read in the (digital) paper.
Here in Stockholm we have plus 6 Celsius now and a shy sun peaking out sometimes.
I’m sure there is good info here and there but I haven’t thought of this quick way of having a quick compilation in 5 seconds. The crawlers are everywhere…
Here in Stockholm we have plus 6 Celsius now and a shy sun peaking out sometimes.
I’m sure there is good info here and there but I haven’t thought of this quick way of having a quick compilation in 5 seconds. The crawlers are everywhere…
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I also love the stuff Doe & co. did as the Knitters and with Dave Alvin. It's only in the last year, thanks to @Gyuri, that I've recognized the genre as "Americana." So Sarah Jarosz, Molly Tuttle and Sierra Ferrell (4 Grammies this year!) get a lot of air time at home.
The punk band I'd see again in a heartbeat is L7. Last time I saw them was in the early 90s. Awesome show, except for the ******* sexist hecklers. Why pay to see a band you don't like?
I'm not in a really good mood at times like this.
I'm reading now that Gene Hackman has died, and at the same time, Károly Mécs has died in Hungary.
I'm reading now that Gene Hackman has died, and at the same time, Károly Mécs has died in Hungary.