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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Or keep the amplifier and use efficient horn speakers
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?Amplifier RMS power ratings are based on the ability to run a 1/8th power continuously for one hour, before testing at full output. The 1/8th power preconditioning usually brings an amplifier up close to its thermal limits. ...
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?
Whatever in a car.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.
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?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
Same design with 2 different enclosures would be quite a lot more expensive per unit, so poor engineering since the existing one does the job properly.
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.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.
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
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). The percentage of THD+noise at this power level was an extremely low 0.0005% with the AHB2 fully warm.
I tested the Parasound Halo JC 1+ with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). I preconditioned the amplifier by operating it at one-third the specified power into 8 ohms for an hour with the output-stage bias set to Normal. (With a class-AB output stage, one-third power results in the maximum dissipation in the output devices.) At the end of this time, the side-mounted heatsinks were hot, at 116.7°F (47.1°C). The top panel was a little cooler, at 98.9°F (36.7°C).
Usually, before doing any testing of a power amplifier, I precondition it by running it at one-third power into 8 ohms for an hour. (With an amplifier having a class-B or -AB output stage, this power level results in the highest thermal stress on the output devices.) However, the 2HP-D is a very powerful amplifier, and I don't have a test load that could handle both channels running at 250W for an hour without overheating. So I wasn't able to precondition the SAE before testing it. However, I did leave it running at a lower power for an hour or so; at the end of that time, its heatsinks were too hot to touch, at 141.4°F (60.8°C), and its top panel was also hot, at 93.2°F (34°C). A switch on the 2HP-D's rear panel activates a cooling fan; when I continued the testing with this fan switched on, the heatsink temperature never rose above 134.6°F (57°C). Even so, this is an amplifier that will need plenty of ventilation.
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
Right. People often get this wrong.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.
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?
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 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.
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 AHB-2 is sold as a studio reference amplifier or an audiophile's domestic amplifier. It's not sold as a sound reinforcement amplifier intended to run at constant high power, a night-club, bar, or as a live music instrument/vocal amplifier. It's going to have a nice easy life in 99.9% of installations and will likely last for many decades.
Now you all know my views on the watering down of the FTCs 1/3 power preconditioning to a measly 1/8 power to appease the consumer electronics companies and save them money, but at the end of the day, if the playing field is level, things can be compared fairly. I don't have a problem with the Benchmark as long as it hits all its rated FTC specifications.
If you want an amplifier that can run an all weekend Bourbon fueled, AC/DC party in the backwoods someplace without overheating and going into "protection", either buy pro gear, or dig up some older big power amps built to different long term thermal standards.
So, I can't get full power from it in my U2 flight package then?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. ... 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.
This is the end in Amplifier History?
Sad...