Audio Research Reference 600 Mono Block Amplifier Troubleshooting And Repair!

#restoration #electronics #repair

[mistermac]

Audio Research has always made quality audio equipment with great design engineering, reliability, and sound quality. No audioflake nonsense.

[PentiumMHz]

The NE614 chip has a logarithmic signal level output, so that's why it is used in the amplifier - to make the meter have a log scale. This is quite cool.

[TooMuchMiddle]

Mr. Carlson, never in a million years have I ever considered using a pair of AR monoblocks as a welder. Really puts the output ability of these beasts into focus. My favorite quote from this episode would have to be "for those of you who like to drive dead shorts".

[hestheMaster]

OMG these babies weight in at 72.2 kg ( 170 lbs) each! The physical and electronic design of the units are very well
thought out. Impressive mid 1990's amplifier tech.

[DeadKoby]

Nothing to really "hate on" with those amps. The design is pretty classic, and that makes things fixable when needed. Very cool.

[sficlassic]

Great video. $34, 000 a pair. Somebody has a lot of money. Back in the 80's I had the chance to listen to the ultra high end equipment. Now that I'm a lot older I couldn't tell the difference. Once again, love to seeing the innards of those !

[rickmartin]

This was one of my favorite videos you've done in a long time. I love it when you analyze the design and schematic of a piece of equipment. This amp demonstrated simple elegance in its design, which is a joy to behold.

[albanana]

Oh the heady days of the comeback of serious audiophile tubes in the late 1980s. Audio Research were at the forefront, and these beasts set the benchmark in many ways. I had to console myself with a pair of Vacuum Tube Logic MB300 monoblocs. Only 8x 6550 on each side. No solid state control circuitry for a soft start, just a big thump and the odd trip of a breaker when powered on. They were supposedly 300W. They crossed the pond a few times, last one was to the UK, and a ham radio guy, obviously, diid the voltage conversion, and replaced all the caps etc. He was impressed with the design, but told me that the 300W claim was wrong, they measured at 350W. But that was 20-20K Hz into a regular 4-8 ohm load, nothing like a crowbar at near DC that the AR monsters can manage. The VTL MB300s are my forever amps.

[MakoVette]

I greatly appreciate your review and analyses of the design. Calling out the ham radio engineering influences, wisdom in the parts selection and so on is very valuable. Bravo!

[Jvavolerpareil]

I used to work for an Audio Research dealer of Montreal, by the end of 80's. One time, a costumer that moved from UK to Canada and took her pair of 300 Watts M-300 mono blocks and a SP-11 preamp. The only problem was the 220 V only main voltages. We ordered 120 V primary power transformers. They sent us 115/230 V universal models. I think they should had installed those transformers at the factory, but they may have a reason for that choice.

I had the opportunity to listen this system with a pair of Martin Lpgan electrostatic speakers and a Velodine sub woofer. WOO !!! It sounded just AMAZING ! I felt like Keith Jarrett was THERE, in front of me on his Steinway grand piano. I could ear not only notes, put the subtile noises of wood hammers and felt mute between notes. I could also ear brass players breath before starting to play, in a symphony orchestra. That was absolutely delicious ! My bus was so happy of my job, that he let me listen whatever I wanted, on this system, for a full hour of my job time.

In 1988, one M-300 mono block costed 5 000 $. I let you imagine the price of the whole system ... :-)

[andershammer]

I own several Audio Research Amps and preamps. SP2, SP6, SP6B, D50 and D90. All working except for the D90 which has 4 6550's per channel and one in the power supply. It worked and sounded great when put in storage over 15 years ago. I got it out of storage and hooked it up but it didn't sound good and something went pop and a hum came out of both speakers. What went pop was the regulator pass transistor for the bias supply. What would cause excessive current draw from a bias supply ? I changed the transistor and it heated up and popped again. I bypassed the transistor with a resistor and it worked but it hummed. I decided to change all the output tube sockets but I lifted some traces when I pulled the first socket out so I've given up for now. Would love to hear that amp working again. I'm over 60 now but I may be even more sensitive to differences than I used to be. At least at certain frequencies.

[terrym]

Mr C👍👍 I can see why you say "two thumbs up" to the designers and engineers at Audio Research for a job well done. These amps are obviously expensive to own and operate, probably not for your normal home theater use I'm guessing. Thanks for another great video. 73

[johnny-z]

Beautiful! AR is top dog! From Brooklyn Ctr/ Mpls.

Audio Research is world class in High End. Please post more high end audio. Cheers from Minnesota.

[douglasmoore]

I look forward to every new release from "Carlson Studio's"
I've never learned as much in a short time.
Well done Paul!

[Dave-yott]

You are a very good teacher. I was surprised that you missed the opportunity to talk about "parallax" when describing the meter design. Actually, I was also surprised that these units didn't have the back-plate mirrors on these meters with so much meter function.
Thanks for the continued teaching videos!

[ec]

Multitaskers! Audio, welding, cooking and whole home heating.

[sparkyskinner]

Fantastic Video about a classic amplifier highly regarded in audio circles from a world class company ! Thanks Mr Carlson.

[adeletanner]

As a young ham radio operator just out of high school in 1972 Bose hired me and I worked testing and repairing Bose 901 Equalizers as they came off the production line and I would often assist the sound engineers in their large, state of the art sound room they had isolated out back. Here, we tested every other manufacturers speakers using a couple of audio amps, each powered by two 4CX1000A's capable of loafing at over 1000+ watts..! The idea was to test the speakers frequency response, efficiency, etc, and then lastly, their power handing capabilities. You haven't lived until you've seen the speaker coils of a JBL, KLH, Sansui, AR, Klipsh, etc, begin to glow dull red, turn bright red, smoke, and in some cases, actually catch fire..! I use to play Claptons Layla back there at unheard of sound levels using those old megawatt tube amps... My Central Electronics 100V Transmitter used two 6550 tubes as finals. Probably selected for the Audio Research amps due to its excellent linearity. Best regards!

[robertburrows]

You only got to look at a piece of electronic equipment, and it will scream at you if it's quality. As soon as I saw the notification for your video I knew we were in for a rare treat.

[JCWise-sfww]

It's videos like this on unique audio amplifiers that's exciting to watch and makes your YouTube channel one of the best on electronics. Amazing specs for a tube amplifier, the output transformer circuit design reminds me of the high end amplifiers built by a well known HiFi manufacture in Binghamton NY USA.