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Adcom GFA-535 ii listening review or: Never meet your heroes

CMOT

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Feb 21, 2021
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I take it you didn’t document this experiment? Because there‘s a paucity of documented tests replicating your results. If you heard a difference under properly controlled circumstances it was likely obvious in the measurements (e.g. huge variance in impedance matching, frequency response, distortion or output).

Sorry, no. Other than I bought an amp that - over repeated trials, I statistically preferred more than others. It could measure worse or different. I don't know. I could just pick it out reliably. I wasn't trying to prove anything other than that I would only be willing to buy something that I could reliably discriminate (and prefer) from other things. Otherwise just buy the least expensive. And the one I bought was one of the least expensive. And I wasn't trying to prove anything with my post (I am entirely on board on using objective measures) other than some amps do sound different from others - for all sorts of objective reasons - and I didn't have a test bench more much else besides a SPL meter, so double blind listening with repetitions was the only way to make any decisions besides price. As one poster said, amps can sound different for all sorts of reasons - all measurable - and they do interact with preamp output, speaker impedances etc. so one can either model it all with an appropriate array of measurements or, failing that, do careful double blind listening with matched loudness and many repeats of every condition. Then analyze the data. I think you took me wrong in trying to claim magic subjective differences. I entirely agree it was in the measurements - I just didn't have a way to make them and they weren't readily available (pre-internet, etc.) I have no idea if modern solid state amps vary much from one another or not - the debate seems to continue as to whether some measurement differences manifest as audible differences or not. In such cases, good double blind, otherwise matched listening experiments might be the answer. Maybe we need someone Amir to set up a lab for that sort of testing - but it would require having people send in multiple pieces of equipment to compare. So 1) get measurements; 2) test whether they matter (sometimes it will be obvious, but other times, we would need to test). Cheers!
 

kevind267

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This.

One other point, though- if the OP is using the iPhone, he may want to check the file formats. iTunes, for example, seems to use a lossy compression. It's not night and day different than uncompressed, but it's not totally transparent, either.
This is unrelated to this post. I just searched the adcom gfa 535ii because I have a question but no idea who to ask!? I am clueless with this stuff. I am trying to setup equipment that belonged to my recently deceased father. I have this adcom gfa 535ii amp and Boston acoustic a60 speakers #D060485. I am looking for info on reciever to use. I have a Kenwood vr-509 and a Yamaha rx-v371. Can I use either of these? If not what is a good reciever to look for that would work? Thank you.
 

tmtomh

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This is unrelated to this post. I just searched the adcom gfa 535ii because I have a question but no idea who to ask!? I am clueless with this stuff. I am trying to setup equipment that belonged to my recently deceased father. I have this adcom gfa 535ii amp and Boston acoustic a60 speakers #D060485. I am looking for info on reciever to use. I have a Kenwood vr-509 and a Yamaha rx-v371. Can I use either of these? If not what is a good reciever to look for that would work? Thank you.

In the early 1990s I had an Adcom GFA-535 (first version) and Boston Acoustics A40s (little brothers of the A60s). Nice gear! And my condolences on your father's passing.

The Adcom is a power amplifier. It can work by itself with a source component - CD player, DAC, smartphone, etc. - but you need the proper adapter cable and your source component must have its own volume control because the Adcom, as a power amp, has none of its own. The source component must also have sufficient output level since there is no preamplifier in this scenario. A preamp, like the name says, traditionally takes a "line level" source (again, CD player, DAC, whatever) and amplifies it somewhat before sending it on to a power amp. But if your speakers are efficient enough, and the amp provides enough gain and power, and the source component has a volume control, and you only want to use one source (no switching between sources), then you can do without a preamp.

With all that said, the receivers you have combine a preamp and power amp - so you get preamplification, a volume control, and the ability to connect and switch among multiple source components. A receiver will also have an AM/FM tuner built in, and if it's a home theater receiver then it will likely have more than two audio channels, and also probably some video outputs and such.

At any rate, you don't need the Adcom with a receiver, because the receiver already has power amplification built in.

Some people prefer to use a separate power amp with a receiver, though, on the theory that the power amp is of better quality than the power amplification circuitry built in to the receiver. If your receiver has "pre out" jacks on the back, then you can plug it into the Adcom - the receiver will send the output from its internal preamp section to the Adcom instead of sending that output to the receiver's own internal power amplifier.

Hope this helps!
 
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