I've been struggling with finding a desktop, near-field amplifier that has a low enough noise floor that I can't hear constant hissing from my speakers. In the chance that anyone else has the same problem, here's a collection of amplifiers that are probably quiet enough to be inaudible and some related notes.
The results of my experience with 86dB sensitivity speakers on a desk are as follows: 347uV is incredibly distracting, can hear it clear across the room. 70uV is quiet but still always noticeable. 16uV is approaching inaudible at the listening position- I can clearly hear it with my ear against the tweeter but can only follow the hiss ~1.5 feet before I lose it. I have never had an amplifier that is truly inaudible in a quiet room but it stands to reason that <4uV would be approaching "can't be heard without tool assistance" levels of performance. Therefore my arbitrary determination for this list is that <50uV is worth mentioning and <20 uV is good.
If there are any additional amplifiers that fit these noise requirements please do let me know. I probably won't continually update this post but I might make a spreadsheet if there is enough new info.
Benchmark AHB2 (Power Amp)- 7.1 uVrms A-wtd
Hypex Nilai500DIY (Amplifier Module)- 27 uVrms un-wtd (High gain), 15 uVrms un-wtd (Mid gain), 9 uVrms un-wtd (Low gain)
Neurochrome Modulus-86 (DIY Power Amp)- 13.7 uVrms A-wtd, 17.2 uVrms un-wtd
Purifi 1ET400 (Amplifier Module)- 11.5 uVrms A-wtd (Unbuffered)
Schiit Rekkr (Power Amp)- 4 uVrms A-wtd
Soncoz SPG1 (Integrated Amp)- 9.8 uVrms A-wtd
Topping LA90/Topping LA90D (Integrated Amp)- 3.4 uVrms A-wtd (high gain), 1.8 uVrms A-wtd (low gain)
Honorable Mentions:
Hypex NC2K OEM (Amplifier Module)- 20 uVrms un-wtd
Notes:
Most of this information is available elsewhere on this forum albeit scattered. I'm mainly compiling all of this for my own research and to keep the discussion alive. Credit to this thread for inspiration and particularly @staticV3 for listing a bunch of these already.
All of the info comes direct from manufacturers, whatever number is specified as maximum residual noise. Computed values assume SNR is relative to the highest stated total output.
There are many additional parameters that I find useful (multiple inputs, balanced architecture, amplifier class, idle power consumption etc.) but I'd rather not make this too encyclopedic. Purposely omitted are:
Compact vs. Not compact is roughly equivalent to "is it smaller than a textbook?". This has nothing to do with topological spaces. It is important to me that a desktop amplifier actually fits on a desk.
Some of the DIY Hypex and Purifi amps could theoretically be made compact as monoblocks or with separate power supplies but I went with common implementations e.g. VTV to determine that they are all not compact. All of the units listed as "Amplifier Module" either require significant assembly or are only available from assemblers such as VTV, Buckeye, Nord etc. Most are designed as pure power amps with no integrated volume control. Actual performance depends on implementation and, in general, noise levels will be higher than listed here but still acceptable.
I omitted from this list anything that would be classified as vintage or long discontinued. Devices which overwhelmingly failed to make it on the list were 1) Basically every TI, Infineon etc. chip amp (excluding LM-3886), including those that power most desktop amps that are popular on this forum. Some of the ICs are theoretically capable of good noise performance but good implementations are few and far between and 2) Basically every AVR, although I did not search too thoroughly.
The results of my experience with 86dB sensitivity speakers on a desk are as follows: 347uV is incredibly distracting, can hear it clear across the room. 70uV is quiet but still always noticeable. 16uV is approaching inaudible at the listening position- I can clearly hear it with my ear against the tweeter but can only follow the hiss ~1.5 feet before I lose it. I have never had an amplifier that is truly inaudible in a quiet room but it stands to reason that <4uV would be approaching "can't be heard without tool assistance" levels of performance. Therefore my arbitrary determination for this list is that <50uV is worth mentioning and <20 uV is good.
If there are any additional amplifiers that fit these noise requirements please do let me know. I probably won't continually update this post but I might make a spreadsheet if there is enough new info.
Benchmark AHB2 (Power Amp)- 7.1 uVrms A-wtd
- Has low gain mode (9.2 dB Low Gain, 17.0 dB Mid Gain, 23 dB High Gain)
- No volume control
- Not compact
Hypex Nilai500DIY (Amplifier Module)- 27 uVrms un-wtd (High gain), 15 uVrms un-wtd (Mid gain), 9 uVrms un-wtd (Low gain)
- Has low gain mode (Low Gain 11.86 dB, Mid Gain 21.75 dB, High Gain 27.88dB)
- Without buffer has low gain of 12.4 dB. Buffer implementation depends on assembler, some have switchable gain.
- Without buffer has low gain of 11.5 dB, otherwise 26.8 dB with stock buffer.
Neurochrome Modulus-86 (DIY Power Amp)- 13.7 uVrms A-wtd, 17.2 uVrms un-wtd
- No finished units for sale. Requires significant assembly including acquiring a case and soldering components.
- Release spec was 33 uVrms A-wtd, 42 uVrms un-wtd and later changed to new spec. I'm not sure if there's any documentation of the improvements made or third party measurements of the new performance. Source
- Compact
Purifi 1ET400 (Amplifier Module)- 11.5 uVrms A-wtd (Unbuffered)
- Without buffer has low gain of 12.8 dB. Buffer implementation depends on assembler, some have switchable gain.
- Not compact
- Without buffer has low gain of 13 dB. Buffer implementation depends on assembler, some have switchable gain.
- Not compact
Schiit Rekkr (Power Amp)- 4 uVrms A-wtd
- Manufacturer does NOT provide residual noise spec, the value is computed from SNR and output specs.
- Fixed low gain of 12 dB
- Extremely low output (3Wx2 at 4 Ohms)
- No volume control
- Compact
- Manufacturer does NOT provide residual noise spec, the value is computed from SNR and output specs.
- No volume control
- Compact
- Manufacturer does NOT provide residual noise spec, the value is computed from SNR and output specs.
- No volume control
- Not compact
Soncoz SPG1 (Integrated Amp)- 9.8 uVrms A-wtd
- Manufacturer does NOT provide residual noise spec, the value is computed from SNR and output specs.
- Not compact
Topping LA90/Topping LA90D (Integrated Amp)- 3.4 uVrms A-wtd (high gain), 1.8 uVrms A-wtd (low gain)
- Has low gain mode (9.4 dB Low Gain, 19.4dB High Gain).
- Original LA90 is discontinued.
- Compact
- Potentially serious reliability issues.
- Original PA5 is discontinued.
- Compact
- Compact
- No US-based reseller at time of posting, only direct from AliExpress.
- Not compact
Honorable Mentions:
Hypex NC2K OEM (Amplifier Module)- 20 uVrms un-wtd
- Has fixed low gain of 20 dB.
- Without buffer has low gain of 11.6 dB.
- Not sure if you can buy this anywhere
- NC502MP is slightly worse at 47 uV un-wtd.
- Not compact
- Not compact
- Not compact
- Has sort of low gain mode (20 dB Low gain, 26 dB High gain) with resistor swap during assembly.
- Compact
- Has sort of low gain mode (20 dB Low gain, 26 dB High gain) with resistor swap during assembly.
- Not compact
- Compact
- No volume control
- Not compact
- Totally different price category and market. If you are considering one of these you most likely do not need this list.
- The only members of this list that function as Stereo Receivers. Some of the only modern devices with a bunch of varied inputs AND subwoofer out AND tone controls AND acceptable noise floor. Very safe bet if reliability is a concern.
- Most specs assume CD input with PURE DIRECT or CD DIRECT AMP mode and SNR loss with tone controls on is not documented. DAC performance is unknown.
- Not compact
Notes:
Most of this information is available elsewhere on this forum albeit scattered. I'm mainly compiling all of this for my own research and to keep the discussion alive. Credit to this thread for inspiration and particularly @staticV3 for listing a bunch of these already.
All of the info comes direct from manufacturers, whatever number is specified as maximum residual noise. Computed values assume SNR is relative to the highest stated total output.
There are many additional parameters that I find useful (multiple inputs, balanced architecture, amplifier class, idle power consumption etc.) but I'd rather not make this too encyclopedic. Purposely omitted are:
- Distortion and power specs as I don't think they are relevant for most of the entries on this list.
- Price as it is variable but suffice it to say only a handful of these devices are "affordable".
- SNR spec as it is in relation to total power. Generally any device with meaningful output needs >110 dB SNR w.r.t peak output to have a low noise floor. High output devices likely need >120 dB SNR. Add another 10 dB to these requirements if you want noise inaudibility. This is also all relative to speaker sensitivity and listening distance.
Compact vs. Not compact is roughly equivalent to "is it smaller than a textbook?". This has nothing to do with topological spaces. It is important to me that a desktop amplifier actually fits on a desk.
Some of the DIY Hypex and Purifi amps could theoretically be made compact as monoblocks or with separate power supplies but I went with common implementations e.g. VTV to determine that they are all not compact. All of the units listed as "Amplifier Module" either require significant assembly or are only available from assemblers such as VTV, Buckeye, Nord etc. Most are designed as pure power amps with no integrated volume control. Actual performance depends on implementation and, in general, noise levels will be higher than listed here but still acceptable.
I omitted from this list anything that would be classified as vintage or long discontinued. Devices which overwhelmingly failed to make it on the list were 1) Basically every TI, Infineon etc. chip amp (excluding LM-3886), including those that power most desktop amps that are popular on this forum. Some of the ICs are theoretically capable of good noise performance but good implementations are few and far between and 2) Basically every AVR, although I did not search too thoroughly.
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