M Jarve
Audio Geek and NGE Freak
I don't know whether this unit really qualifies as "vintage" by everyone's standards (it does in mine), but I wanted to post my thoughts on it anyways.
Yesterday evening while I was in Duluth (a dark and stormy night...) I stopped at Pawn America as I often do and saw the GFA-545 in the pro-audio section. I could not remember the specs on it, so I called up doucanoe, and he was able to refresh my memory. We also shot the breeze about some of the other toys in there (Paradigm Atoms for $99, etc.), and I decided to take it.
After bumming around Duluth for a while, Becky and I came back to Virginia and I got to play with the new toy a little.
As I have taken to doing lately, I checked the amp out on the bench for any major defects before I connected it up to anything I really like. I connected it to my bench pre-amp (Mitsubishi DA-P10) and multi-meter to run some basic tests. Imagine my surprise when I found the right channel outputting 14.3-volts DC! If I had connected any of my speakers to the amp (save, perhaps, the Infinity's), they would have turned their toes up! I disconnected the preamp on the possibility that it was the culprit, and the DC output jumped to 28.5-volts! Holy-moly! I checked (on instinct) for any DC at the input terminals and found over 14-volts of output! Surprise does not even begin to describe my feelings at the time.
I was getting ready to hunt down my receipt to make a return when I decided, almost in passing, to take the lid off, just to see if maybe a poorly placed paperclip had found its way into the bowels of the beast. I noticed a blown fuse in the right channel. On a whim (instinct may be more appropriate a term), I replaced the fuse and tried it again. It did not blow and DC offset was a much more sane -80mV and dropping (towards zero). After about 10 minutes of uptime with no load, the amp seemed to settle at -0.1mV in the errant channel and 3mV in the other channel. As there is no DC offset adjustment in the amp, I left it alone. If the above episode taught me anything (aside from reaffirming my commitment to testing an amplifier before wantonly destroying my speakers), it is that the GFA-545 is really a direct coupled amp.
I decided to take it to work with me today and had it connected to my computer via the above mentioned DA-P10, while driving my Wharfedale Diamond 7.2's. Keeping an eye on things, I left it playing the streaming MPR classical station while I worked for the day, occasionally checking the offset with a handy DMM. Towards the end of the day, I threw in a newly bought Norah Jones CD and really let it rip. Pretty darn impressive, I have to say.
When I got home this afternoon, I moved the Citation and Crown out of the rack and installed the Adcom in my main setup. As an aside, after looking at the rack with the Citation and Crown in there, the Adcom seems positively diminutive in there. I've got it playing an Evanescence CD now, and will put it through its critical listening paces tomorrow.
My initial impressions are very favorable. Very clean and smooth sound, almost flowing from the speakers; sweet sounding is appropriate. For a 100WPC amp, it seems to have almost effortless dynamics and does not seem to be easily strained. It seems to have a particularly good bass response. Clean and punchy or sonorous and deep when needed and in perfect measure. It will be interesting to see how it measures up against the Citation.
I would also like to comment on the innards, as is my want. I have to say that I have rarely seen so simple, clean, and efficient of a design. It is said that Nelson Pass had a hand in designing this amp, and unlike many amps that are (incorrectly) attributed to Pass, this one certainly could be. It is a statement to KISS design, without even the normal inductor at the output. Perhaps someone who knows more could confirm or deny his handiwork in it, but I would place money on that he did. That said, it is not quite as over-built as some of the classic amps I have owned or seen. The transformer, for instance, while good sized, is nothing near the 1kW beast that the Crown possesses. It is, given the geometry of a toroidal transformer, probably about as well proportioned as the one in my Yamaha CA-1010 (which is rated at close to 700VA). The power design is what I refer to as "dual power", using a single transformer with dual secondary windings and separate rectification and filtering for each channel. The main power capacitors (two 10,000uFd units per channel) are interesting... Very tall and narrow. Heatsinking and cooling seem adequate. All during the day, the amplifier never became even warm to the touch, let alone hot. We will see what a more demanding speaker and higher volumes bring, though.
There are my first thoughts. I'll update the thread as warranted.
Yesterday evening while I was in Duluth (a dark and stormy night...) I stopped at Pawn America as I often do and saw the GFA-545 in the pro-audio section. I could not remember the specs on it, so I called up doucanoe, and he was able to refresh my memory. We also shot the breeze about some of the other toys in there (Paradigm Atoms for $99, etc.), and I decided to take it.
After bumming around Duluth for a while, Becky and I came back to Virginia and I got to play with the new toy a little.
As I have taken to doing lately, I checked the amp out on the bench for any major defects before I connected it up to anything I really like. I connected it to my bench pre-amp (Mitsubishi DA-P10) and multi-meter to run some basic tests. Imagine my surprise when I found the right channel outputting 14.3-volts DC! If I had connected any of my speakers to the amp (save, perhaps, the Infinity's), they would have turned their toes up! I disconnected the preamp on the possibility that it was the culprit, and the DC output jumped to 28.5-volts! Holy-moly! I checked (on instinct) for any DC at the input terminals and found over 14-volts of output! Surprise does not even begin to describe my feelings at the time.
I was getting ready to hunt down my receipt to make a return when I decided, almost in passing, to take the lid off, just to see if maybe a poorly placed paperclip had found its way into the bowels of the beast. I noticed a blown fuse in the right channel. On a whim (instinct may be more appropriate a term), I replaced the fuse and tried it again. It did not blow and DC offset was a much more sane -80mV and dropping (towards zero). After about 10 minutes of uptime with no load, the amp seemed to settle at -0.1mV in the errant channel and 3mV in the other channel. As there is no DC offset adjustment in the amp, I left it alone. If the above episode taught me anything (aside from reaffirming my commitment to testing an amplifier before wantonly destroying my speakers), it is that the GFA-545 is really a direct coupled amp.
I decided to take it to work with me today and had it connected to my computer via the above mentioned DA-P10, while driving my Wharfedale Diamond 7.2's. Keeping an eye on things, I left it playing the streaming MPR classical station while I worked for the day, occasionally checking the offset with a handy DMM. Towards the end of the day, I threw in a newly bought Norah Jones CD and really let it rip. Pretty darn impressive, I have to say.
When I got home this afternoon, I moved the Citation and Crown out of the rack and installed the Adcom in my main setup. As an aside, after looking at the rack with the Citation and Crown in there, the Adcom seems positively diminutive in there. I've got it playing an Evanescence CD now, and will put it through its critical listening paces tomorrow.
My initial impressions are very favorable. Very clean and smooth sound, almost flowing from the speakers; sweet sounding is appropriate. For a 100WPC amp, it seems to have almost effortless dynamics and does not seem to be easily strained. It seems to have a particularly good bass response. Clean and punchy or sonorous and deep when needed and in perfect measure. It will be interesting to see how it measures up against the Citation.
I would also like to comment on the innards, as is my want. I have to say that I have rarely seen so simple, clean, and efficient of a design. It is said that Nelson Pass had a hand in designing this amp, and unlike many amps that are (incorrectly) attributed to Pass, this one certainly could be. It is a statement to KISS design, without even the normal inductor at the output. Perhaps someone who knows more could confirm or deny his handiwork in it, but I would place money on that he did. That said, it is not quite as over-built as some of the classic amps I have owned or seen. The transformer, for instance, while good sized, is nothing near the 1kW beast that the Crown possesses. It is, given the geometry of a toroidal transformer, probably about as well proportioned as the one in my Yamaha CA-1010 (which is rated at close to 700VA). The power design is what I refer to as "dual power", using a single transformer with dual secondary windings and separate rectification and filtering for each channel. The main power capacitors (two 10,000uFd units per channel) are interesting... Very tall and narrow. Heatsinking and cooling seem adequate. All during the day, the amplifier never became even warm to the touch, let alone hot. We will see what a more demanding speaker and higher volumes bring, though.
There are my first thoughts. I'll update the thread as warranted.
