Monday, June 30, 2008

The Rotel RX 802 Receiver

This is a truly unique receiver. It is 24" wide by 14.5" deep by 5" high and weighs in at a very nice 30 pounds. There is definitely a European feel to the design. It is rated for 440 watts so should produce something in the neighborhood of 100 watts output per channel. The '93 Orion Blue Book says it was a late '70s model and sold for $500.

For the detail oriented reader, the beer at the back is a Shiner Hefeweizen.

Here is a view of the unit with the top off.
Construction quality is first rate. The Toshiba output transistors are mounted on a heat sink that runs along the back and bottom of the unit. The output board is very elegantly laid out and is immediately in the front of the outputs. All caps were replaced with Panasonic FC's. The relay board, immediately in front of the output board, had a problem with one cap in failure. All caps were replaced and the relay burnished. The AM board is the small board at the back right in front of the tuning capacitor. The FM board is immediately in front of the AM board. All caps were replaced. The phono board is at the far right of the FM board, mounted vertically and shielded. Again, all caps were replaced.

The tone control board is mounted at the front, immediately behind the controls. This board is barely visible from the top, under the lamp shield for the display, and is upside down in relationship to the other boards. This board was a challenge to replace all the caps, so I had no objections when Mike was motivated to do it. Thanks, Mike.

Here is the bottom of the unit. A small shield has been removed from the FM board for clarity. The tone control board is visible at the front.

Listening has just begun and it sounds very nice despite a complete lack of burn in. I will provide an update once it has a few hours on the caps.

With the exception of the tone control board this unit was a pleasure to work on. Approximately 80 capacitors were replaced. Only the two 6800 mfd main power supply caps were not changed. All switches and potentiometers were cleaned with Deoxit Gold or Blue Stuff as appropriate.

UPDATE: I am very pleased to announce that this unit has passed the very difficult Robert listening test when matched with the very respectable Kef Coda bookshelf speakers. Robert is a very senior and skilled technician and a musician to boot, so his unsolicited praise is highly valued.

Monday, June 23, 2008

The Yaqins are coming!

Yaqin makes a line of amps and integrateds that are designed in Japan. The parts are also Japanese and then they are assembled in China. I took a chance after much reading and ordered their top model (power wise) the MC100B, a 65 wpc @ 8ohms dual mono block integrated using 4 KT-88 tubes along with 4 6SN7's and a pair of 12AX7's.

As recommended by many forums, we upgraded some of the caps and the front end tubes which yielded a good improvement. It's had a couple hundred hours now and it sounds really good. A considerable step up from my very fine modified Dyna ST-70. For the money, (I hate that expression), it is a superb sounding amp. I would gladly put this up against a Conrad Johnson Premier 11 to see what all those extra thousands actually deliver.

As much as I would like to buy only American made products, the destruction of our currency has placed most of hifi out of the reach of the middle class. Even the Yaqins are steadily going up.

Very happy with the MC100B, I tried out the next smaller model, the MC-10L. This is a single power transformer 52 wpc @ 8ohm integrated using 4 EL-34s and 4 6922s for the front.

Again, an upgrade of a dozen or so French tin foil film caps, some photo flash electrolytics to beef up the power section and some NOS 6922s yielded very good results. It is still breaking in but it's amazing to hear sound this good for this little money.

Why aren't we building amps like this? The quality of the assembly and soldering does not suggest slave labor but real care. They are of course built to a price point but honest quality is offered for the money with most of the cost going into the Japanese made transformers.

I think whether we like it or not, the Asian hifi industry is making real inroads here. These units along with many others by similar manufacturers should not be dismissed as "Chinese junk". Have a look and a listen yourself.

Long live Conrad Johnson!

Monday, June 16, 2008

Sounds and Current rigs

I have the great pleasure to be listening to the best system I've ever had. It's been a slow wonderful journey so far and the ears just keep growing ;-) I'm not really a gear head, for me it's real purpose is the music, although I love tinkering and soldering. (I may have to eat those words as I find my self falling in love with great equipment that has been fixed up and saved from the land fill).......
Being a serious guitar player for more than 30 years I traded in some of the gorgeous old guitar amps of the 60's that I had acquired for a serious journey into tube hifi.
From the sixties to the nineties I listened mainly to those fabulous Japanese receivers from the 1970's, the golden era. Over the years I bought new the Sansui 3000A, 5000, and the 9090. Those powered my Rectilinear IIIa's and later the stacked Advent A3's for a good twenty years. I kept my tube equipment for guitar playing and that nice clean SS sound for home hifi. That is until I ran into Mike Manulik, owner operator of Austin Stereo. I came there originally to have my Sansui repaired and over the following years came to meet a great bunch of wonderfully eccentric audiophiles. Mike is a passionate audiophile not to mention a very experienced and intuitive tech. Everything he touches sounds better when it's done. I learned a ton from Mike and the other members of our stereo club circle. I'm now happy to say that every time I spin some vinyl there are 18 tubes glowing in the dark. No SS can compare...;-)

Present main rig: Austin Stereo modified YAQIN MC-100B tube amp, Conrad Johnson Premier 10 preamp, Conrad Johnson EV-1 phono preamp, Austin Stereo modified Samsung HD-841 DVD & SACD player, Technics SL1200MKII turntable with AT 440MLa cartridge and a pair of KEF R107 speakers. Custom interconnects by Austin Stereo, plus ZU Oxyfuels. Speaker cables are ZU Julians.

Sunday, June 15, 2008


Gear porn is a guy thing. In fact it seems to be mostly an old guy thing. And we are legion.

You see us hanging around flea markets and thrift stores hoping to discover a vintage piece of gear. It might be something we have never seen before. Or it might be something we never could have afforded back in the day. Or it might be something we owned long ago and want to own again. It could be tube or solid state. Buyer's regret is rare, non-buyer's regret is guaranteed. And the garage is always full.

I date my addiction to 1987, and I still have my first purchase: a Mac 1900 receiver in a wooden case that I bought for 75 dollars. It sort of worked. I have had it so long it probably needs another restoration.

Gear doesn't have to work since I know the guy who can fix it. (That's you, Mike.) Cosmetics are important. I am often more interested in how a component looks and feels more than how it actually works. Back in the day I spent real money restoring my Mac. But one primary focus of this blog will be the fixing of gear. Most of the posters on this blog will be amateurs so mistakes will be made.

Sometimes we get all esoteric and excited about vacuum tubes, transformers and capacitors. I have seen people snatch tubes out of the hands of others at ham fests. I was amazed someone didn't lose teeth. Part of this blog will describe our emotional involvement with such tiny inanimate objects.

In the coming weeks several of us will begin to document our restoration projects. My first is going to be a Rotel RX-802 receiver from the late '70s. It worked ok but just got a fresh spritz of caps and a good cleaning, hopefully sufficient to give it another reliable 30 years of making music.

System #1

Here's the system that gets the vast bulk of the listening in my cave. Yes, that is a Toshiba SD-3950 DVD player atop the legendary Technics SA-150 receiver. High res it is not, but good enough for my purposes. These two pieces are physically very shallow and work flawlessly. So far...

Note the smeared 'Technics' above the power switch. It is a reminder to always test whether Windex is safe to use on your gear. It obviously was not on this early '80s , bottom of the line receiver.

I use this rig to A/B small speakers on my desk. Near field listening for fun and profit. There is just an 'A' at the moment, the quite lovely Mission 750 Limited Edition. The Missions sound quite nice, although I prefer the little A/D/S 400 speakers. Bass is respectable with an overall polite presentation. I need to get them up a bit to get their best impression. That tweeter at the bottom is a bit challenged.

Note in the back left: the smallest of the Indigo speakers from the great white north, badge askew. I will write those up in the future. They were a bit lifeless on the desk top, the little Technics was not up to driving them adequately.

Also in the future: various Minimus 7 tweakings, a scrufty pair of Braun minis, and a Dana Audio revisit.

bat's current gear

Source: Krell KPS 30i CD player
Preamp: Jeff Rowland Consonance (w/o phono)
Amp: Conrad Johnson MF-2250
Speakers: Axiom M60 II (stereo pair)
Interconnects: AudioQuest (mid?-level)
Speaker wires: samo
AC power source: 2 pairs of PS Audio "Power Ports", each one fed by a
separate 12awg cable back to separate breakers, and feeding nothing else. The Amp is fed by one and the rest of the system is fed by the other, via an 8 outlet Belden surge protector, which plugs into one section of the other PP, the preamp having the second section to itself.
The power cables for the Amp and Preamp are 10 & 12awg resp.
both ends terminated with hospital grade connectors.