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Benchmark AHB2


moray james

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First time I ever bought an amplifier without an audition but I have a very good feeling about this one. The Benchmark Audio AHB2. This is actually a very hot-rod version of an amp I have used a lot, the Quad 405. The AHB2 has a better balance bridge than does the Quad and it has multiple voltage rails to deliver lots of power in a compact package with the lowest distortion there is. Will arrive home to me on Friday this week.

   I also recently picked up a very fine Mertum non oversampling DAC which is so analog sounding it is astounding. My ability to listen into recordings is amazing with the Metrum and it will get very much better once the Benchmark is installed. Volume control is via a Tortuga light dependent resistor attinuator which is as quiet as it can be with one light actuated variable resistor in the signal path. This is the way to detail resolution and dynamics. Regards moray james.

Benchmark AHB2.jpg

Benchmark AHB2 2.jpg

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I can't imagine that there was a amplifier company on earth that has not experiment with current dumping amplifiers there was every kind imaginable designed and built. The Quad 405 and the Sumo 9 are the two most interesting new amplifiers in the last 50 years. Every amp out there is a variation of a variation of some other older amp and it matters not if they are analog or digital. Regards moray james.

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That could start some time in late July but I don't plan on anything more than voicing with custom made bypass capacitors and some tweaks to the supplies. This amp is one of those pretty much done at the factory builds nothing circuitry wise that I would change out from stock. The stated noise specifications are astoundingly low and there is some argument they may actually be much lower. I don't plan anything until it has been running for a full month. There may be caps that I could change for ones for which I have a preference that remains to be seen. But that won't happen before the fall. Got to build up a set of interconnects and a new power cord for these tomorrow. This is going to be better than Christmas and my birthday rolled into one all at the same time.

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Yeah, I agree that the Quad was among the more interesting circuits.  Why they never licensed it I cannot fathom, as it's simpler, lower maintenance, and superior to traditional a/b as it completely side-steps crossover distortion.  I seem to recall the old Stasis amps using it.  It looks like Benchmark appropriated the feed-forward error correction part, but used a modern supply and better a/b amps for the dumpers.  And it does look nice.  Good thing (for the wallet at least) I don't presently have need for a SOTA amp, but if I did, that Benchmark would be at the top of the list.  

 

Any budding DIY-ers looking for an interesting case study in circuits should google up the Quad current dumpers, just for their own edification.  

 

 

 

  

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  • 2 weeks later...

I own two Benchmark AHB2's. Truly remarkable amps. Incredible value. Cant touch the performance for anywhere near the cost. I have owned any number of amplifiers and these are the only solid state amps that stayed in my system for any length of time. I will certainly be interested in your impressions. I posted about the AHB2 in the past and I think most here thought it should be compared to a chip amp. Not even close. These are serious pieces of audio state of the art engineering and implementation.

 

Josh

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I got tied up with things and did not turn the amp on until this evening. Stone cold brand new out of the box first note was impressive and it only got better from there. I played it for about five hours and it was getting better all the time. Stone cold quiet and the balance is astounding, tremendous control extremely fluid never heard anything to equal it and it has not even had a chance to burn in yet. Very impressed. I would agree nothing out there even comes close to this super Quad amplifier. These are the real deal and my first thought was for a second one. Chip amps are not in any way in contention next to this amplifier. I have had a number of seriously modified 405 Quads and there is a resemblance but this is simply so much better in every way. This is a whole other level which I did not think existed until now. Five stars are not enough to describe the performance level of this amp. I could see this being the last amp any audiophile in his right mind ever wanting wait there's more they get even quieter when they are bridged Hmmmmthat means I need four of them, help! Regards moray james.

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The first set of speakers I ran this amp on were Ambience hybrid ribbons from Australia (new they were around 12K CND) which are on the low side so far as sensitivity goes at only 87db. I chose that set up to see how the 100 watt per channel Benchmark amp would fair against the owners big 65lb 200 watt/channel Spectral power amp. We ended up playing louder with the Benchmark than than I think we ever did with the spectral. The Benchmark never got hot and  it never clipped. Then I played the Benchmark on my much modified H3 using a Tortuga passive LDR volume control. I need to adjust the impedance compensation adjustment on the volume control to better match the Benchmark. I am really pleased with the SQ of this new amplifier. This is a keeper in no uncertain terms. Regards moray james.

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41 minutes ago, Schu said:

How do you adjust the impedance on that passive pre? Dip switches? And how do you determine when the match is optimal?

The functioning is software driven so you can set up a number of different impedance's and then remotely switch back and forth on the fly while you are listening.

So you can either adjust by ear or you can simply match the input impedance of the unit which by all right ought to be optimal match.  It is a very slick piece of gear. Only one variable resistor soldered into the signal path you can't get any lower noise than that.

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  • 1 year later...

Just bouncing this up again. I recently put the Benchmarks back in play and have to say again - By far the best Solid State amplifier I have heard. If anyone is interested the application notes on all things audio written by John Siau , the designer of this amplifier as well as the well regarded Benchmark DACs , are always a good read. Here is one on speaker sensitivity. Most of what is written in this article is well known to folks here as he uses the Heresy as one of his examples.

https://benchmarkmedia.com/blogs/application_notes/speaker-efficiency-and-amplifier-power

 

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