Sunday, November 30, 2008

Call Me Lightning: the Pioneer SA-606 Integrated Amplifier

Dum Dum Dum Do Day
Dum Dum Dum Do Day

See that girl who's smiling so brightly,
Dum Dum Dum Do Day

Well I reckon she's cool and I reckon rightly,
Dum Dum Dum Do Day

She's good looking and I ain't frightened,
Dum Dum Dum Do Day

I'm gonna show you why they call me lightning.
Dum Dum Dum Do Day

This particular Pioneer integrated amp is called Lightning because that’s what blew it up.

This SA-606 was born somewhere around 1973 (Orion is clueless) and died violently in what Mike delicately terms ‘an event’. That event took out half the power supply diodes and every single transistor short of the outputs, tone control circuit included. This amp probably should not have been restored based purely on cost benefit. It ran away on the Sencore, so we pulled the nicely mounted heatsink, and tested the outputs. They were intact so we figured re-cap it and figure it out from there. After my re-cap and Mike walking through transistor carnage we found ourselves committed to a very significant cost in time and parts.

Yes, even the little 3-legged beasties in the tone cardlet at the front left were torched. All caps were replaced except for the relatively modest main filters. This was a relatively easy amp to work on, but Pioneer made the bottom cover too small and several caps were very difficult to reach.

The interesting thing about the effort is the end product was essentially an electronic clean slate up to the outputs, lots of new parts in an old box. So, how does it sound?

Very, very good it turns out. This amp is not a power house, but it is a very lively performer and well suited to a bit of Cobwebs and Strange. Now where is that Who CD? Entwhistle’s bass leads on ‘Happy Jack’ or ‘Call Me Lightning’ are running through my head now hours after crappy YouTube renditions. Ahh, the sacrifices my art demands.

Anyway, this SA-606 is a bit rough around the edges cosmetically, but it sounds great.

Tuesday, November 25, 2008

The JVC JR-S200 Receiver

Ah, here we have yet another under appreciated Japanese receiver manufacturer. JVC's styling is, er, distinctive, and I confess not to my taste until recently. But I have a new found appreciation of this line after working on this unit and also getting a gander of the very impressive JR-S600. The S200 is 2nd in the line that extends from the S100 through the S600, and is listed at 35 watts per side. Orion says it was sold from '76 to '80 and retailed for $300.

While a bit glitzy and slider-dominated it is a handsome unit to my newly acclimated eye. The thumb wheel tuner is a bit angled and much smaller than that of the Marantz tuners and receivers of the era. The end caps are interesting, sort of plasticky, faux heat sinkish. Definitely, the JVC designers were not running with the Pioneer/Marantz/Yamaha crowd with wood cases.

Wow, my photo skilz were not exactly shining the day I took these snapshots. The chassis was not too bad to work on although there were a few difficult to change caps on the amp board at the right. The tuners are in the center; the phono section in the center, back right, just to the left of the heat sink. I replaced 57 caps with Panasonic FCs. Then Mike pointed out that there were 4 more buried in the tone control board mounted vertically in the front, behind the sliders. That board was a bit of a challenge.

The JVC is a perky sounding little receiver. It is not exactly a powerhouse, but has enough slam to sound better than 30 watts should. Pick one of these up if you find one. If you ever stumble across the big brother S600, buy it in a heartbeat. It is one seriously flashy, large receiver and at 120 watts per channel can run with any of the big dogs.

Friday, November 21, 2008

The Nikko NR 815 Receiver

Nikko is one of the underrated receiver manufacturers of the vintage era. Their build quality is very good, their styling has held up well, and they are very easy on the ears. They tend to be undervalued on ebay, a shame. The Alpha/Beta/Gamma series of separates from Nikko does garner a reasonable amount of respect, however.

This NR 815 was an ebay purchase and it worked well out of the box (always a worry.) The trusty Orion Blue Book says it was manufactured between '77 and '82. I suspect that range is a bit wide, but close enough. The 815 seems to have been the middle of a very broad offering with the 315 being the entry level and the 1415 being the top of the line. When I grow up I want an NR 1415 with 175 watts per channel! The NR 815 has 55 watts and retailed at a hefty $470. This is a largish receiver:

Large usually makes it easy to work on:

The 815 is fairly well laid out with one major exception. The phono section, situated, as usual, in the back right of the chassis, sits underneath the tuning capacitor. Whatever was Nikko thinking? One of the first rules of receiver restoration is never mess with the tuning string, so the capacitor had to stay in place. I had to fish out and replace caps from underneath via what little dexterity have remaining in my left hand. I love vintage, but vintage digits really suck at that dexterity thing.

The drive card is mounted vertically in front of the heat sinks. I was able to re-cap that without removing. The relay ciruitry is just in from of the drive card and the regulator circuitry in front of that. The tuners are to the right.

I am usually obsessive about the cap replacement count, it's sort of a solder monkey's counting coup. However, I managed to misplace my coup stick, er, slip of paper with the exact total. It was something over 70, I swear.

Re-capped with the controls spritzed this a nice sounding unit. The overall presentation is a bit mellow and would fit very nicely with a digital source. At 55 watts a side a bit of care needs to be taken with speakers if you are wanting to fill a largish room with Led Zeppelin. But, all in all, the NR 815 will eat your Fry's HT black box for breakfast and lunch, and look good doing it.

Sunday, November 16, 2008

Subwoofer Pas de Deux

A while back Parts Express offered a deal that seemed too good to pass up: the Spherex XBox system with 5 satellites and a subwoofer carcass, minus the amp and remote for $99.00. Plus free shipping! (I see now that the price is $75, a deal!) The Spherex system was well reviewed and the satellites use technology from Mirage. The sub contained a 6 channel amp that apparently was failure prone, so the systems have been a PE close out for a while, sans amp of course.

I sprung for 2 and scattered the satellites among work room, kid's room and friends. But what to do with the subwoofer carcasses with a hole in back?

Apex Jr. came to the rescue.

I purchased the M&K 150 and the Audiofile VRS 1205 amps since they seemed to have nearly the correct dimensions for the cut out. Each is a bargain at $99.95 and nominally rated at 150 watts. These are real amps with real transformers, not digital amps. Here are the finished products:

The Spherex boxes have a downward firing 8" driver with a port. Fit and finish is good and I love the handle on top. The driver is a respectable performer, but the amps probably deserve a bit more than the Spherex carcass can provide. I shouldn't complain since I spent just a bit more than 2 hours assembling the pair. Both amps required a bit more than an inch off the width and just slight shaving off the height of the opening for installation.

Both amps are well made with the M&K having the edge in performance, but the Audiofile having the edge in gadget factor. The first photo above shows the remote sensor installed on the front of the Audiofile. Oh yeah, that is a new hole you will have to cut on the front. The remote works well and allows you to crank the volume for the good parts of Con Air and drop it back to realistic levels for music.

If you already have a home theater receiver you can have a very respectable 5.1 system for under $200, definitely a deal. This is a killer system for the kids' game room or a budget theater system. Break out the jig saw and get some sweat equity in a subwoofer!

Monday, November 10, 2008

The Signal Sucks: FM Side Band Hiss

Does your FM station sound like crap these days?

Is the sonic gravel getting you down?

If so, I bet you are listening to the modern sound of side band garbage through a vintage FM tuner.

The FM frequency spectrum is increasingly being crammed with signals that were never envisioned by the designers of medium decades ago. Here in Austin, the classical FM station KMFA has broadcast a benchmark quality signal since its inception, but these days you are wasting our ears trying to listen to it with a vintage tuner. Recently KMFA sold off the edges of its frequency range to another signal, and you can hear it as hiss behind the music.

The FM signal broadcast is not just a single licensed frequency but includes 130 kilohertz of bandwidth above and below the designated frequency. According to KMFA's consultant engineer the FM broadcast system originally used the entire licensed spectrum to minimize distortion, and our vintage tuners reflect that philosophy. They tend to grab the full width available with broad filters. However, the modern broadcast signal now lives in a much narrower portion of the licensed band (15 khz) , and the edges of that band are a business opportunity.

What is that business opportunity? There are a number of possibilities, but in all likelihood the offender is HD radio. I highly recommend this Wikipedia article. Note the FM spectrum images down the page on the right. The second image is of the signal that gives your vintage tuner a hard time. According to the article only 1% of the station's power is devoted to the HD signal. A move is afoot to increase this to 10% in order to improve the quality of the HD signal at the expense of the analog signal. (Shudder.)

So what prompted this little rant? I hadn't listened to the wonderful KGSR in a week or two on my Advent 300 receiver, but tonight the hiss was just depressing. I recently restored this little Henry Kloss/Tom Holman gem using Elna Silmic II caps with a few 1 mfd films and the tuner is sounding great. I guess I need to learn something about FM filters...

Sunday, November 9, 2008

The Sansui 1000 Receiver

The Sansui 1000 is very different from the Sansui 1000a. Via this site it seems the relatively common 1000a was manufactured from '64 through '72 (!) and uses the formerly rare 7591 output which is now being manufactured by several vendors. The very rare 1000 apparently was manufactured in '63 only and uses the oddball 25E5 (PL36/CV10341) output with the distinctive anode on top.

The Sansui 1000 is to my eye much nicer looking than the 1000a and the 25E5 has the advantage of actually being relatively cheap for an NOS pentode. Here are some photos of a customer unit take at Austin Stereo:

Note the connectors to the tops of the outputs at the top of the second picture. Make sure you label them when removing the tubes. They need to go back to the correct tube! The build quality is top notch, as one can always expect from Sansui. You gotta love those transformers. The 1000 is a very nice sounding receiver with a fine tuner and enough power to drive full sized speakers.

For those interested, here is a close up of the 25E5/PL36/CV10341 output tube.

Saturday, November 8, 2008

In Memoriam: the Automatic Radio OMX-9843 8-Track Receiver

To paraphrase an old joke about motorcyclists sans helmet: what do you call an 8-track receiver? The answer, of course, is: an organ donor.

I recently found a Technics SA 303 receiver in excellent shape except for a broken bass control pot. What to do? I did not have an appropriate vintage pot to repair the unit and I doubted that I could find a new one that would suffice. Luckily, I stumbled onto an early '70s vintage 8-track receiver from a brand I assume is long gone, Automatic Radio, from Melrose, Massachusetts. Today, there is pretty much no one who is interested in such a device. But, the moral of today's blog is: do not judge a receiver by its cover.

The OMX-9843 was an entry level combo receiver marketed by an American-based company, but made in Japan. The $159.95 price sticker was still on the bottom. From its appearance this was not a mainstream, hifi retailer unit. It was probably sold at a local furniture store or a regional chain like Gibson's here in Texas. The case was the typical vinyl over Philippine mahogany (why did they do that??), and inside was essentially two units: an 8 track player on the left and a very minimalist am/fm receiver on the right with lots of small bolts and nuts holding it all together. The 8-track player scavenged power from the receiver via an internal plug in a manner that suggests that something else might fit on the left. I wonder if someday I might stumble on a cassette version of this beastie? The Matsushita amplifier outputs produced a hefty 6 watts a side, low even by the standards of the early '70s.

The point of all this? Back when manufacturers cared even the most entry level of electronic products were well made. For example:

The pots in the photo above were made by Alps. The tiny driver card has 4 small can transistors by Matsushita, the same as the two on the tone control card. Sorry, the cute Matsushita outputs were donated to Austin stereo before this picture was taken. The switches are still crisp and the hardware is very high grade and about half is non-magnetic. This is all high quality stuff, and will see service in other gear from the era.

Who woulda thunk that parts from an Automatic Radio would extend the life span of a Sansui or Technics receiver?