Or keep the amplifier and use efficient horn speakers
The noise floor and first watt performance become more important with horns.
After a number of bourbon filled AC/DC parties, noise floor ceases to matter.
- Rich
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Review and Measurements of Benchmark AHB2 Amp
- Thread starter amirm
- Start date
The noise floor and first watt performance become more important with horns.
After a number of bourbon filled AC/DC parties, noise floor ceases to matter.
- Rich
Forgive me if I have misunderstood the whole point here, but, an AHB2, operating with free air around it (say 25C), cannot output more 12.5W/chan into 8 ohms, indefinitely, due to heatsink thermal capacity?
In the Stereophile testing the AHB2 was subjected to 1/3 power for one hour.
https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements
digitalfrost
Major Contributor
Well the manual states you could run it in the Predator jungle, since:
- 0° C to 50° C (32° F to 122° F) Ambient Temperature
- Up to 80% Humidity - Non-condensing
Whatever that means for max power/temp I don't know. But I find these numbers mighty impressive. Find me other equipment besides special industrial/military equipment that can operate under these conditions.
- 0° C to 50° C (32° F to 122° F) Ambient Temperature
- Up to 80% Humidity - Non-condensing
Whatever that means for max power/temp I don't know. But I find these numbers mighty impressive. Find me other equipment besides special industrial/military equipment that can operate under these conditions.
Whatever in a car.
Easy spec (body electronics) - 40 to 70 degC
Tough spec (Powertrain) - 40 to 115 degC
Thanks. "As the AHB2 is specified as having a maximum power output of 100Wpc into 8 ohms, I preconditioned it before measuring it by running it at one-third that power into 8 ohms for an hour. Following that period, the top panel was warm, at 106.7°F (41.5°C), though the heatsinks were hotter, of course, at 117.3°F (47.4°C)." Nothing to concern me here. Perhaps the limit of ~1/8 max power is into lower impedance loads, while also in a high ambient temperature, at a high altitude?
Except for the issue if there is a backlog, because there is some non-zero number of customers who just buy something else because the AHB2 is unavailable.
Well maybe, but also maybe not as many as chose not to buy it at all because it was more expensive due to the extra cost of more than one enclosure.
Here is a quote from the AHB2 Stereophile 100 WPC (13.5 lbs) stereo amp:
Here is the preconditioning of the Parasound JC-1 450 watts (83 lbs) monoblock amp:
https://www.stereophile.com/content/parasound-halo-jc-1-monoblock-power-amplifier-measurements-0
Here is the preconditioning of the SAE 2HP-D 600 WPC (98 lbs) stereo amp:
https://www.stereophile.com/content/sae-2hp-d-power-amplifier-measurements
As we can see, the AHB2 passes the 1/3 power warmup and its heatsinks are not hotter than others, even those also using fans. The hottest was the SAE (ATI) 600P whose heatsinks reached 141 degrees idling and 134 with the fan on.
- Rich
The heatsink isn't really what matters, it's the junction temperatures of the power components. Certainly higher heatsink temps aren't a good sign, but depending on the thermal conductivities of the path from the air to the junctions, different designs could have hotter heatsinks with cooler junctions. It depends on how well the thermal interfaces (like thermal grease or heatsink compound) and the power component packages themselves conduct heat. 141 F is still only 60 deg C, and semiconductor junctions are rated at up 150 C. I don't like to run them much above 105 C, but in other industries it is common to run them higher. Although I doubt the stereophile tests were done at worst case room temperatures, etc.
Right. People often get this wrong.
The 1/8 pre-conditioning was a change made for multichannel (HT) components (at the request of the manufacturers if you believe all the notes; I tend to believe they slid one by on us). Stereo components should still be pre-conditioned at 1/3 power, the "old" rating.
Thanks. I suspect my worst case 'continuous' uses are not much above 1/8, if that. I didn't buy a high "fidelity" amp to listen to it, clipping, with extremely compressed signals. I'm not sure my speakers, or neighbors, would thank me for that, either. For me, the ability to provide 1/3 rated power, continuously, is more than sufficient for real world music listening, and higher than I ever actually use. I just couldn't believe the AHB2 was thermally limited to 1/8 of rated output, or 12.5W/chan, continuously, into 8 ohms.
The peak-to-average power in music was tested long ago and shown to be around 17 dB, a power factor of 50. So arguably even 1/8 is too stringent, though I prefer an amplifier with a stated continuous power rating would meet that rating "forever".
Handwaving: The 1/3 requirement has to do with the way most class AB amplifiers are biased and where the crossover point is from constant power irrespective of signal (class A) to changing power with signal (class B). It can be shown (not by me, too lazy to do it again) that at ~1/3 power the internal dissipation of a push-pull class AB stage is near maximum. Below that point, less power is dissipated in class B, and overall power drops until it reaches pure class-A operation and stays constant. Above that point, more power is dissipated by the class B stage, but in class B only "half" the outputs operate at a time as the signal transitions from (+) to (-) parts of the signal, so overall power does not increase "much".
HTH - Don
Handwaving: The 1/3 requirement has to do with the way most class AB amplifiers are biased and where the crossover point is from constant power irrespective of signal (class A) to changing power with signal (class B). It can be shown (not by me, too lazy to do it again) that at ~1/3 power the internal dissipation of a push-pull class AB stage is near maximum. Below that point, less power is dissipated in class B, and overall power drops until it reaches pure class-A operation and stays constant. Above that point, more power is dissipated by the class B stage, but in class B only "half" the outputs operate at a time as the signal transitions from (+) to (-) parts of the signal, so overall power does not increase "much".
HTH - Don
digitalfrost
Major Contributor
DIYed myself some cables for the AHB2. Canare 4S11. Neutrik NL2 plugs. WBT bananas.
Cut outer isolation according to assembly instructions https://www.neutrik.com/media/11065/download/bda-348---speakon-nl2fx---nl2frx-1.pdf?v=1 by 25mm. Then deisolate one inner cable my 12mm as stated, and deisolate the other one so they will nicely wrap around each other.
WBT bananas need 20mm deisolated, so you can push them in there, catch the isolation with one screw and the copper with other. If you're feeling fancy, golden crimp plugs are offered by WBT.
Cut outer isolation according to assembly instructions https://www.neutrik.com/media/11065/download/bda-348---speakon-nl2fx---nl2frx-1.pdf?v=1 by 25mm. Then deisolate one inner cable my 12mm as stated, and deisolate the other one so they will nicely wrap around each other.
WBT bananas need 20mm deisolated, so you can push them in there, catch the isolation with one screw and the copper with other. If you're feeling fancy, golden crimp plugs are offered by WBT.
DIYed myself some cables for the AHB2. Canare 4S11. Neutrik NL2 plugs. WBT bananas.
Cut outer isolation according to assembly instructions https://www.neutrik.com/media/11065/download/bda-348---speakon-nl2fx---nl2frx-1.pdf?v=1 by 25mm. Then deisolate one inner cable my 12mm as stated, and deisolate the other one so they will nicely wrap around each other.
WBT bananas need 20mm deisolated, so you can push them in there, catch the isolation with one screw and the copper with other. If you're feeling fancy, golden crimp plugs are offered by WBT.
The 1/8 power was a typo. The AHB2 was tested by preconditioning at 1/3 power for 1 hour before conducting full power tests.
The AHB2 was not tested to the watered-down multi-channel specs. Sorry for posting the wrong number.
Stereophile measured 117.3 F on the heat sinks and 106.7 F on the top cover after one hour at 1/3 power. You will find many similar test results from other reviewers including Amirm.
This equates to a temperature rise of 45 F or 21 C. At an altitude of 5000 feet, the temperature rise is 10 % higher (49.5 F or 23 C).
At an altitude of 20,000 feet the temperature rise would be 48% higher (67 F or 31 C). This means that the amplifier would reach thermal shutdown at or near the end of the 1 hour preconditioning at an altitude of 20,000 feet.
Amplifiers will always run warmer at higher altitudes.
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So, I can't get full power from it in my U2 flight package then?
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