Benchmark AHB2 Bridged Monoblocks -

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JCollins

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I am considering the purchase of a few different amplifiers. On my amp short list includes:

1. Sanders Magtech - Very powerful, built for ESL speakers, handle very low impedance loads (i.e. 1/3 ohm) with ease, S/N ratio is good at 110 and THD is good.
2. Musical Fidelity M8-700m - Very powerful monoblocks, bridged configuration, S/N ratio is very good at 120 with minimal THD.
3. Benchmark AHB2 - Moderately powerful, S/N ratio is the best in the world at 135, THD is almost immeasurable.

If I go with the AHB2, I would like to purchase two amps, and run them in bridged mode to power my ML 13a. My main goal is to have amplification that is powerful, yet transparent, detailed, quite and doesn't colour the music in anyway. There has been a lot of great things said about the AHB2 online and various forums. My main concern with these amps is running them in bridged mode with speakers that dip to circa 0.7 Ohms at 20khz. Has anyone experienced any issues running these amps at reasonable listening levels? Do they clip/cut out? I don't generally ever go above 90db at the listening position. Thanks.
 

Russr

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I'll go with my stock-in-trade recommendation... look at Bryston.

Some iteration of the 4B ST line, or if you're more into the monoblock thang, the 7B STs. My rationale: They're used in a bunch of recording studios, and no matter how much some of us audiophiles might fight the notion, we're unlikely to squeeze more out of our sources than them folks laying it down!

Good luck with your selection process!

Russ
 

barjohn

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Theater reference level is 85db at the console position with a peak level of 105db. If you are like most of us, you probably do not play your speakers at reference level, even when watching movies because 85db is quite loud in a home. To go from 85db to a peak of 105db means you need 20db of headroom. ESL speakers tend to be relatively efficient at around 92db for 1W at 1M. Assume your speaker has an efficiency of 85db for [email protected] At 4M you would need 4W of power (using 3b loss per meter). To go up 20db you need to double the power about 7 times meaning you would need a peak power of 512W. Note that this is not RMS power because the power does not have to stay at that level for any length of time. Therefore a 250W amplifier would be sufficient to meet the headroom requirements (peak power being roughly equal to 2X RMS power). Given ML speakers are rated for a max power of from 300W to 1,300W (ESL to Neolith) and you do not want to drive your speakers at max power and risk damaging them, this should provide some idea of the power you need. Don't waste your money buying more than you need unless you are willing to risk damage to your expensive speakers so you can tout the power of your amplifiers. Attached is information for multi-channel sound for the theater recordings.
 

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spkrdctr

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If you never really go above 90db, any amp will do. Just get the cheapest that your interested in. That would be the Benchmark. Lets say your speakers are actually only 87db efficient. So, you are at 90db where you listen with 2 watts of power. Then you can do 93db with 4 watts. 96db with 8 watts. 96db is very loud for a steady state volume. Really too loud for a lot of listening. Lets say you wanted to listen at 96db, this would still give you and enormous amount of headroom. The Benchmark is an awesome rig and doesn't cost an arm and a leg, only an arm! Good Luck with whatever you do.
 

JCollins

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Thank you for your responses. They all make sense. Sounds like even just one AHB2 would likely be sufficient into 4 ohms nominal given my room dimensions 14' x 16' x 9' and listening position at 10' from the front of the speakers. I am still keen to know if anyone has experienced issues with the AHB2 clipping or cutting out/shutting down at higher volumes likely due to inability to handle a low impedance load.
 

Robert D

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That benchmark AHB2 looks similar to my Aaragon amp. Similar output at least. My Aaragon is able to drive my Prodigy speakers, and the panels are larger than the 13 a I think. The Prodigy also doesnt have a powered woofer, so my amp has to drive that too. If the amp youre looking at is as good or better than mine then youll be fine. My amp has never turned off, and ive had it up loud before.

Aragon - Titanium (aragonav.com)
 

spkrdctr

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You would need to be at a volume around 105db at least to get the Benchmark really working hard. Sustained volume at that level is not realistic. It can EASILY handle what you need. One Benchmark will take care of you. Now, if you want to just spend money to have a cool exotic looking setup, then you can get two of them. But in reality, they will not be running more than 4 watts average. I would think about asking guys on here about room treatments before splurging on an expensive cool looking setup. Your return per dollar will be much, much higher. Let us know what you end up doing. Thanks!
 

barjohn

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Unless you just have a lot of money you want to spend there are many alternative solutions and I suspect the differences would be inaudible if you didn't know which solution was being applied. I use DIY Hypex 250W mono blocks I built. The Hypex amp and the Purifi both rate at 105 db SINAD vs. the Benchmark at 113 db SINAD on Audio Science Review's testing. These rate above all of the other amps he has tested (a lot), see attached chart and pictures. Note: My Amps are wireless hence no RCA inputs, small connector on back is a special USB port for making settings on the receiver.
 

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barjohn

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I am using WISA 8 channels 24 bit 48 KHz or 96 KHz. This is a prototype of a product line I am developing using WISA. I am working with the companies (Summit Technologies and WISA). I have also made a prototype receiver that can be used with any amplifier, pictures below. I am doing a lot of testing and trouble shooting, especially in Spatial Audio (Atmos) to ensure the product will work well and be easy to set up. WISA is currently the best wireless technology with a maximum latency of 5 msec and speaker to speaker sync at 1 micros or less. It uses a part of the 5 GHz band that used to be reserved for the military. For the transmitter I use the WISA SoundSend or the Axiim Q-UHD (for 5.1, no Atmos) or the HTX (not currently available for sale, I have a prototype). The SoundSend and the HTX support Dolby Atmos in a 5.1.2 configuration. You can have up to 4 subs share the channel. I can't share much more because the products aren't complete and I can't look at production until all of my testing is complete and I am satisfied that it meets my requirements.
 

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