bikehorn
Transmission Line Junkie
A few hours ago I came home with a Yamaha P2100 power amp I found on craigslist for $100. It has some battle scars from its musician days but I plan to give it a long and comfortable retirement driving my IMF TLS50s. It'll be driven by my NAD 1020 preamp. The ad said the amp had been bridged, so I assumed someone had permanently modified it to operate in BTL mode. I figured if I couldn't unmodify it I'd just replace the amplifier PCBs with an ESP P101 for some lateral MOSFET deliciousness. Just the chassis, power supply and heatsinks were worth much much more than the paltry $100 I was paying. Oh yeah, this thing being a true professional power amp...has got balanced and unbalanced inputs as well as outputs, rack ears, big capacitors(2x 15,000uF Nippon Chemicon), bigger heatsinks and a seriously huge transformer(back of the chassis says 370 VA but the transformer looks bigger than that). I won't be able to test the bass for a while(till I fix the woofers in the TLS50s) but I am expecting thunderous and highly defined bass.
Some output ratings from the Yamaha Pro site:
85 Watts into 8 ohms with less than 0.05% THD (Total Harmonic Distortion), 20Hz to 20kHz, both channels driven.
140 Watts into 4 ohms with less than 0.05% THD (Total Harmonic Distortion), 20Hz to 20kHz, both channels driven.
Obviously there are more powerful amps out there but this is the biggest piece of iron I've ever owned. It weighs a ton, I would hazard a guess of at least 50 pounds. EDIT: Actually, it only weighs 31 lbs, and I am a weakling.
Happily, when I opened it, I could find no evidence of anyone modifying anything. There was nothing added, nothing appears removed, no signs of soldering and no random wires anywhere. On the Yamaha site the only way of bridging the P2100 appears to be through the use of an external balancing transformer(or other balanced line driver, I guess) so I think maybe the seller, though very knowledgeable about recording gear and techniques, just did not understand bridging. There's a stereo/mono switch on the amplifier's main PCB which when I found it was definitely set to "stereo". Possibly at some point a balanced line driver was being used, but there was no mention of that. Whatever. I measured DC offset on both channels, left was 12 mv and right was 20 mv. Tomorrow I'll test both channels with a crappy speaker to see what happens. At this point though, I believe it to be fully functional and that the seller just was uninformed. :yes:
I neglected to measure the power supply voltage, but some Googling yielded the following from a thread on DIY Audio. There's 2 pairs of output transistors. Oh...and not a single opamp to be found either! All discrete. :thmbsp:
+/- 50 volt rails
370VA consumption from 120vac supply
2SA814/2SC1624 drivers
2SA747/2SC1116A Sanken outputs
Okay okay picture time...yep they are huge(sorry to those with slow connections or low resolution, but I like big pictures), I resized them but was reluctant to knock the picture quality down since I already had lots of digital noise from using a high ISO.
Some output ratings from the Yamaha Pro site:
85 Watts into 8 ohms with less than 0.05% THD (Total Harmonic Distortion), 20Hz to 20kHz, both channels driven.
140 Watts into 4 ohms with less than 0.05% THD (Total Harmonic Distortion), 20Hz to 20kHz, both channels driven.
Obviously there are more powerful amps out there but this is the biggest piece of iron I've ever owned. It weighs a ton, I would hazard a guess of at least 50 pounds. EDIT: Actually, it only weighs 31 lbs, and I am a weakling.
Happily, when I opened it, I could find no evidence of anyone modifying anything. There was nothing added, nothing appears removed, no signs of soldering and no random wires anywhere. On the Yamaha site the only way of bridging the P2100 appears to be through the use of an external balancing transformer(or other balanced line driver, I guess) so I think maybe the seller, though very knowledgeable about recording gear and techniques, just did not understand bridging. There's a stereo/mono switch on the amplifier's main PCB which when I found it was definitely set to "stereo". Possibly at some point a balanced line driver was being used, but there was no mention of that. Whatever. I measured DC offset on both channels, left was 12 mv and right was 20 mv. Tomorrow I'll test both channels with a crappy speaker to see what happens. At this point though, I believe it to be fully functional and that the seller just was uninformed. :yes:
I neglected to measure the power supply voltage, but some Googling yielded the following from a thread on DIY Audio. There's 2 pairs of output transistors. Oh...and not a single opamp to be found either! All discrete. :thmbsp:
+/- 50 volt rails
370VA consumption from 120vac supply
2SA814/2SC1624 drivers
2SA747/2SC1116A Sanken outputs
Okay okay picture time...yep they are huge(sorry to those with slow connections or low resolution, but I like big pictures), I resized them but was reluctant to knock the picture quality down since I already had lots of digital noise from using a high ISO.
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