Audio Equipment

[michaelman2]

Apparently time has really passed me by. I went to buy an audio receiver and some decent speakers so I could play my music loud with decent, deep bass and decent mid and high frequencies.

All that I could find at Best Buy (I know...)were people trying to sell me home theater set ups that could "really handle what I am looking for". Small speakers with small woofers are not what I had in mind. I have several Bose systems but really they do not put out what the old larger speakers did.

Anyone have any knowledge or advice on vintage audio. I have found two Yamaha tower speakers with 15" woofers. I am on a quest for a decent (and ample) vintage amplifier/receiver that will drive these and possibly two more large speakers..

My son "borrowed" my favorite Marantz 2270 and well...it is no longer (he was almost no longer when I recently found out about it..I digress)

Suggestions for a decent set up?

 

[hydralique]

Check in at audiokarma.org, lots of advice on vintage gear. The ability to drive multiple speakers is affected by the impedance of the speakers in question. I would tend to look for a power amplifier and a preamp rather than a receiver as power amps often had somewhat sturdier electronics and they're simpler to repair if needed - remember that lots of old electronics will need new capacitors to work properly.

 

If you really want to rock the whole neighborhood be on the lookout for some old horn loaded speakers like Klipschorns or some of the Altecs. They won't be cheap unless you're really lucky and they're too large for many rooms but they will make vast amounts of sound with comparatively little power. Like the electronics, speaker crossovers often need new capacitors so be ready for that.

 

[whirlcool]

I bought almost all of my stereo equipment on Ebay. All of the equipment is top notch and in perfect working order.

System

SAE P101 Preamp
SAE A301 Amp
AR-3a Speakers (overhauled and recapped by me) (A)
JBL 4311 Speakers (B)
Dual 701 turntable Pickering XSV-3000 cartridge

It's a great system. SAE equipment is great, but the preamp uses a LOT of switches and solenoids. These get sticky from time to time. And those parts are now NLA.

Don't overlook a pair of Bang & Olufsen S70 speakers. I have a set that's in my office now. They sound great and are usually less than $100.00 per set. These speakers sound much more expensive than they really are.

 

[kb0nes]

Hey Michael,

I'm not sure what your fidelity requirements and taste are, but I am sensing you have the need to be able to move some air at times At home I play a bit of the hifi game but I have worked as a live sound tech so I know the need for some volume at times too.

As for speakers you would likely do well with some 90's or earlier vintage Cerwin Vega or Klispch. 80's vintage JBL's could be great to but command a far greater price. Klispch KG4's would be a great choice and I often see pairs in good condition on my local craigslist for $250 or so. I have used a few different pairs of Yamaha speakers and overall I was never too impressed, but you could do a lot worse.

In general I am a bit leery of vintage speakers as age often doesn't do the surrounds and suspensions a lot of favors. When buying watch out for speakers that have foam surrounds, at about 15-20 years they often dry rot and crumble. They can be replaced/repaired but you should be on the lookout.

As for electronics I'd suggest again staying with offerings in the mid 80's or so. Much earlier then that and you may be looking at more restoration work. Replacing capacitors in 30 year old audio gear is almost mandatory. Its not all that tough if you are comfortable with the work but again be advised. Brands I think I'd recommend would be Yamaha and NAD for integrated amps. If you were to consider separate components I'd look at Hafler or Adcom perhaps. I can't offer a lot of advice on receivers, I have always avoided them, I want my tuner to be separate and away from the power amp heat.

 

[mattl]

Allen, what was involved in overhauling the Ar3a's?   Got a pair of AR's in my bedroom with very scratchy high range controls that I've thought about doing the same to.  Where did you get caps and what did you do.

 

[NYCWriter]

Do NOT do ...

… anything prior to 1980.

The "electronicization" of the '80s and beyond is what killed high fidelity.

Look for good solid equipment from the '70s from Pioneer and Kenwood.

 

[yogitunes]

the satellites and subwoofer are nice additions to a superior system, but not as a replacement in my opinion.....

its obvious to shop CL or ebay, and if possible an older style Stereo/TV repair house....we have one here, and they have some killer stuff, if not already refurbished, they have a room of soon to be units you can pick from.....I am holding out for a reel-to-reel to add to my setup......

I have a full seperate components of Pioneer from 1987.....nothing like the sound, and 4 huge endtable/nightstand speakers with 12" woofers(size matters)....which as mentioned the foam has fell apart, but nothing that can be repaired....and sounding good as new...and the programable remote operates 'everything'.....the best part is I can make the lights in the house flicker!!!...

may take some searching, but you will find exactly what your looking for...without spending a fortune....

I like speakers like this for additions or replacements......a variety of sizes and configurations and watts, wheels and stands available.....I always prefer 4, one for each corner....I am not one for surround with the echo, I like 4 speakers with full sound coming from each....something like these would run about 75-100 dollars each

 

[wayupnorth]

Speaker repair

My 30+ year old Bose Interaudio SA 1000's woofer foam surrounds were shot. I stumbled across a company called Simply Speakers out of FL and were able to buy new surround kits for under $20. It took less than an hour to install and they sound even better than new now. I recommend that company highly as they deliver what they promice at a very fair price.

 

[whirlcool]

When I overhauled my AR 3a's I put in new attenuator controls (sounds like you need them too) and replaced the capacitors with Solen caps. Depending on the model AR speaker you have most of the classic ones have fabric surrounds. Unlike foam surrounds which need replacing every 16-20 years or so fabric surrounds last forever. But if you take your time even a foam surround is not all that hard to do.

What model AR speakers do you have? The -3a's are considered by some to be the best speakers ever made. They sound so clean and clear.

There is a guy on Ebay in upstate New York which used to be an AR dealer. He has most all the parts for AR speakers reproduced at a higher quality. The controls he sells will never have to be screwed with again.If you can solder with a soldering iron, then you can overhaul your speakers. This guy even reproduced the original cabinet staining kit so you could sand your AR's down to the original wood finish (not veneer) and restain them and they'll look like new. Even the speaker cloth with AR logo's is still available.

I think the years 1982-86 were the best for stereo. After 86 all the stereo equipment manufacturers started to spend their R&D bucks on "Home Theater" and development of stereo just stopped right there.

 

[NYCWriter]

I respectfully disagree ...

I believe the best years for stereo ran from about 1966 - 1979.

Post-1980, we started seeing too much "digitization" and more bells and whistles that required more elaborate circuitry that only degraded the final signal going out to the speakers.

The "sweet spot" for audio was probably 1975-1979.

 

[kb0nes]

Ahh the 1980's

My earliest involvement with hifi was about 1977 and I first started acquiring equipment in the early 80's. I worked for a time as an audio service technician after graduating from electronics school in 1985-86.

Starting somewhere in the early 80's there was indeed a divide in the hifi audio world. I named it the "mid-fi slide" where many of the manufacturers that made decent hifi slid down into mid-fi to try to grasp the mass market. Some brands did this earlier then others, most of the common "receiver' brands for instance Pioneer, Marantz, Onkyo, Sony etc. Yamaha seemed to hold off another year before they took the dive about '86. Companies like NAD for instance never felt the need to slip. The sad thing was the many companies that slid up into the lunatic fringe hifi world where prices went through the roof and people are senselessly bilked out of money for "imaginary" improvements.

My personal take is that later is better provided you are still buying hifi gear, not mid-fi mediocre stuff. There were improvements that came to be in the late 70's that improved hifi electronics, the MOS-FET comes to mind as a major one. I don't subscribe to the luddite approach of "older is always better". To do that is to cast off technology improvements which have improved the state of the art. You can still buy great quality hifi today, although it is no longer mass market and you have to be really wary of not buying silly hype (of course you are likely to pay a lot more too). But if someone tries to tell you which direction to install your cables run away! Same thing for a $1000 AC power conditioner, I'd laugh in their face.

Old audio, greater then 20-30 or so years will very likely require a fair bit of service to keep it sounding good and maintain its reliability. As someone that enjoys that kind of tinkering/POOGeing (Progressive Optimization Of Generic Equipment), I like playing with gear, but others may want hassle free equipment. I very much enjoy the "agreeable distortions" of my old Heathkit and Dynaco tube amplifiers, but I'd never suggest them to someone that doesn't feel comfortable with a soldering iron in hand!

 

[firedome]

Having written and edited for a vintage audio magazine...

for a number of years, imo the later tube era mid-late '50s to early '60s was the true Golden Age, as the pioneering mid to late '60s transistor units often used Germanium transistors and were notoriously unreliable and often noisy. The first Fisher receivers as well as other early SS amplification attempts were terrible and known for odd-order harmonics generation, the main reason that Saul Marantz refused to go to solid state as late as he did. The mid-to-late '70s were the apotheosis for SS transisitor units, if you prefer the reliability of SS, and the dual power transformer Sansui units were some of the best, I only got rid of my AU717 finally last year, it was incredibly tube like, but still... In general Japanese stuff '72 or so up to around '80-ish was the best of that type, until they started to eliminate transformers and engineering in general fell to the machinations of the bean counters, as per usual.

Efficient AlNiCo magnet horn loaded or ported speakers in large cabinets work best with tube, we have JBL L-36s and Altec Valencia 846a with our tube powered amps of various stripes, had Klipschorns but find them a bit shrill. Best bang for buck in vintage tube amplification is imo properly restored Fisher, HHScott,or Sherwood units, common on eBay but be careful who you buy from , always best in person. Some cities have people who rebuild and sell this stuff, Atlanta would likely have some.

 

[yogitunes]

I had the so-called surround sound setup before surround sound was even thought of.....at the time, everyone was watching Michael Jackson's "Thriller" video thru their TV and a simple little 3x5 speaker......my thought was how to get the same sound and effect as if I was playing the actual album!......

most TV's did not have RCA output jacks for sound, not to mention video....it was mainly inputs only......thru my VCR/VHS/Beta, I used the outputs and with patch cords hooked into my reciever playing MTV in true stereo sound...not to mention movies....regular TV too as long as I used the VCR's tuner....

even the guys at the Stereo Supply House, after showing and explaing what I wanted to do, said I was wasting my time and swore it could not be done...and were shocked when I did it....not to mention anyone who seen and heard the system.....

 

[firedome]

Audio technology advances in recent years...

are, no doubt, best exemplified in speaker technology, and the many significant engineering breakthroughs since Edgar Villchur's acoustic suspension AR's by people such as Thiele and Small, Q factor, crossover advances, electrostatic and thin-film drivers, have contributed to speakers that are light years ahead of what tends to harmonize well with old tube stuff, however I like vintage-style sound for the 30s to 60s stuff I listen to. Many of these newer-principle speaker designs are quite expensive, and require upgrade of all the links in the audio chain, what I call the audio-phool trap, a constant desire to upgrade.
The wonderful electrostats and Magneplanars require very high power super-clean amps costing thousands, to be at their very best, and old ears can no longer resolve that degree of perfection. However the trend back to tube amplification, in guitar amps, and especially by ultra-high-end amplifers, and we're talking amps in the $10 to 80 thousand range, while marketed to some of those audiophool types, is for some very good reasons... a story of discovery that began in the late 1960s with an early-jazz loving French-Japanese gent named Jean Hiraga, but that is a story for another time.

 

[cfz2882]

best japanese era

for me,i think the best Japanese equipment era is ~1972-84,much after '84 seems Japan's labor costs started to go up and they started to really cut costs-my '88 onkyo cassette is decent enough,but nowhere near the quality of my '81 onkyo."silver"era pioneer-roughly up through 1983-is Waaay better than the later"black"pioneer in my opinion even though some of the "black" pioneer is still pretty good even though it is more cheaply made(I have quite a few "black"pioneer CD players and changers and a 1990 LD player)For stuff made early in the era mentioned,i once had a 1973"superscope"4ch. receiver that was really good.

 

[whirlcool]

I had a 77' Onkyo TX-2500 receiver for awhile. I bought it when the dealer told me that the Pioneer SX-727 I wanted was out of stock. I was very surprised at how good that Onkyo was. I had it until we were burglarized in 84'. I was always happy with that unit and I think Onkyo was very conservative with the power ratings.

 

[arbilab]

Your 4311s were what much of rock history was mixed on. They are near-field ear-level, don't do well on the floor and whatever you do don't lay them on their sides. Just like, don't ever stand L-100s--exact same components--on their ends.

Agree, late 70s was the perigee of fidelity. Don't get me started on germanium or what happened in the 80s and beyond. It becomes very difficult to name/find a design of any integrity beyond 1978. It was easier ten years earlier.

Today you've got 3 choices. Refurbishing Ebay/Craigslist classics from Macintosh/Dyna/Eico/select Marantz or Pioneer; audiophool stuff starting in 4 figures and isn't that good anyway, and throwaway junk from major brands that used to be good like Sony.

And what are you going to play on it? CDs? MP3s? Ugh.

 

[electron1100]

Vintage hi-fi

I generally agree with the comments on here about 70s Japanese hi-fi, I too run a vintage system from the 70s apart from a modern moving coil Denon cartridge and an 80s Nakamichi tape deck.
Build quality was superb as was sound on some of the equipment.
I agree that you can still get superb sounding hi-fi today but it is very expensive.
And also any product from the 70s will need checking over thoroughly, capacitors being the main items likely to give trouble plus the odd leaky transistor plus general servicing of the controls.
And the same for glorious valve gear if you can get it cheap enough definitely a worth getting hold of and pleasure to listen too.
Good Luck
Gary

 

[yogitunes]

when it comes to stereos of any type....when you get ones from the 60's and back, you have the concern of tubes, and finding replacements.....from the 70's transistors are far better, but may need replacement here and there as well....this also goes for anything newer....and like our machines, the vintage plays and sounds so much better than todays stuff, and of course lasting much longer.....

although I like component systems to mix and match.....nothing can take the place of traditional home stereos in console cabinets or combined with TV's.....that was always a rich sound.....nothing can take you back to childhood memories than my sister playing her Motown albums as we cleaned house when the parents were away....

I found this one at a thrift store for $20.00....and plays and sounds like a dream...although I have come across a few for an outrageous price too....

ths one also has many RCA jacks on the back to add in, or output, to other components...a nice addition to keep an eye out for....

 

[michaelman2]

All,

Thanks for the education regarding the audio. Thanks also for the private messages ....all of this information has been truly valuable!

 

[firedome]

finding tubes...

is not a problem thanks to the guitar amp market, which is about 80% of world tube production: 12ax7, el34, el84, 6v6gt, 6l6gc etc are all readily available as new production. Yes, any amp over 20 yrs old should be recapped as a matter of course, they are either failed or about to. The superiority of tubes over any solid state is due to the difference in prevalence of odd vs. even order harmonic overtones, vacuum tubes are natural high frequency producers even at very high power, which is why in Radar and radio transmission they are still used... bit of a science lecture here, but there it is, the reason most high end studios doing mixing & production and virtually all top guitar players have gone back to tube amplification. The fact that most tube amps and radio receivers have discrete components and point-to-point wiring is sheer icing on the cake, making them easy to repair. You can still get vintage Fisher, Scott et all for $3-600 range, if new they would be more like $3000 in today's mooolah. A McIntosh tube amp (made right here in Binghamton NY, and I've had almost every amp they ever made over the 40 years I've been into this stuff) sells for 5 to 10 times what their SS stuff does... there is a reason!

 

[kb0nes]

No doubt there has been a resurgence in vacuum tube audio which has made all the components easier to find, tubes, transformers and high voltage capacitors etc. I first started dabbling with tubes in the mid 80's and there was a time there where even common tubes were scarce!

No doubt there is truth about the harmonic distortions raised by tubes, generally they are musically related and more pleasing to the ear. But provided the transistor design is run in a linear condition the argument is muted to a degree. I do TRULY love my Marshall 2204 guitar amp though as the EL34's sound so good when they start to saturate the output transformer. I have a handful of tube amplifiers I use in my hifi that I enjoy a lot, but most of the time I run some form of solid state power amp. The tube amps do have some warm and fuzzy agreeable distortions though if I am in the mood for that. To each their own and the only thing that matters in the end is to enjoy your music!

The use of vacuum tubes in radio or TV applications is actually becoming rare in new transmitters below 1000Mhz. LDMOS transistors have become so rugged and linear that they have replaced tubes in most all applications over the past few years. For a long time I have stated that anything over 100w RF needs a filament, but that just isn't true today. Efficiency, linearity and ruggedness are on a par and there is no need for a high voltage supply and its inherent problems. Note I still use a 1.5kw HF amp based around a pair of 3-500Z tubes though. The tube amps are a bit cheaper per watt still for ham radio use.

I'd gladly help anyone wishing to enter into vacuum tube hifi nirvana, but I have to stop short of recommending them as daily drivers to people that don't want the hassles. I have mentored a few friends into becoming their own tube technicians, but a lot of us just want a hifi that works without the need os a soldering iron and a DMM.

 

[tolivac]

Tubes for transmission----Still used today-esp in Short Wave broadcast transmitters.The driver stages in them are solid state-but the power amplifiers are still tubes-VERY large ones at that.These tubes can dissapate up to 1MW!!Some digital TV transmitters still use tubes,too-Klystrode tubes-these have both the advantages of klystrons and tetrode tubes.They can handle the digital peak pulses best.For the short wave transmitters-modulator stages are solid state pulse step--you have 32-48 of these stages in series to develop both the plate voltage for the power tube in the final PA and the modulation for it.One of our transnmitters has the first pulse step modulator built.They can work great if all is well-but DIFFICULT to service-Ours has been doing well now-all of the modules have been rebuilt.A module in this is time consuming to replace-they are water cooled-new PSM's have air cooled modulator modules-this is easier.The traditional tubed push pull modulator is still easiest to service.A modulator tube can be replaced only in a matter of minutes-even having to use the tube puller cranes.
The agency I work in has solid state MW tranmsitters overseas that are up to 1 Mw.They do take up a lot of space-actually more than the tubed transmitter of equal power.Its just as we put it--You can have a lot of ants pulling the load or say two elephants pulling the load.The tubes are still much easier to service in the high power stuff.
For Hi-Fi some folks insist on the tubes just as the muscians do.If you have a good vintage name brand amp such as Dynaco,MiIntosh,Scott,Marantz,Fisher,Magnavox and so on you really won't have difficulties if you just understand that tubes have to be replaced so often as light bulbs are---remember a tube is still a light bulb with the extra electrodes in it around the filament! And for those vintage amps-caps will need to be replaced-so you will need to weild the soldering iron.Some caps may be hard to find-I am still looking for electrolytic caps over 525V rating for my MI 60 monoblock amps.So want to recap them.Tubes for audio-for G-amps or Hi-Fi-there is a market still for them are they will be around--more are actually made TODAY than 50 yrs ago!!Most are built in China or Russia.The Russian ones are best.A few tube factories are still in use in the US.Esp Burl Electronics(used to make tubes for RCA) that makes transmitting tubes as Eimac does and Econco(Rebuilt transmtter tubes)Large tubes can be green-when old they can be rebuilt and work like new!

 

[firedome]

new tubes...

Richardson still makes quite a few audio as well as Eimac, think they bought the name and prod equip for them quite a few years ago, they make the majority of the tubes for commercial & Military in the US. They even made a special run for McIntosh a few years ago for the KT-88s in the Mc275 re-issue.

My uncle here (ex- IBM EE) built the first prototype MacKit MK-30 when his EE buddy over at Mc asked him to put it together and tell him how it went, he still has it in a closet along with a regular MC30 and a C-20.

The Mc MI-series amps were mostly silver-painted commercial versions of the Mc30, Mc60, Mc75 etc, but I once had a MI-200 2 chassis 200 watt tube monster that was mainly built for lab and research use in vibration analysis, shaker tables and the like, however a few were sold as mega-Hi-Fi amps by places like Harvey Radio in NYC. It used 2 x 8005 big transmitting tubes in the output stage, and that thing was just amazing, talk about headroom! With the right speakers like big Altec VOTs or Acoustat Electrostatics the sound-stage was galactic in proportion! The Grateful Dead used MI-200s for their first 15 years of live concertizing. That's one of the few amps I wish I'd hung onto. The Marantz M2, M5 & C-7 are the only others.

Good SS amps/receivers are for sure less work to maintain, but certain blown output transistors can be harder to find than some tubes!

 

[firedome]

Oh and...

yes, most new production tubes are made in Russia and China, along with some Eastern Europeans like JJ (formerly Tesla), and there's Westrex in the US who still makes a few of the classic Western Electric tubes under license like the 300B (pricey!. The Russian/Chinese tubes have improved hugely in recent years, but due to lack of some rare-earth metal alloys and specialized production equipment no longer made, they have yet to reach the quality of some of the best vintage tubes circa 1940s-70s.

 

[ovrphil]

weighing in late...

Michaelman2(Mike): audiokarma.org is a good resource..people there are helpful, knowledgeable, and you can get an idea on anything you're looking at or haven't considered. Thrifting, I found a Kenwood KR-4070 and Sherwood S-7250. While not high end, these are respectful systems that have very good build quality.

I like your now r.i.p. Marantz -so who knows, you might find one again, if that's your interest. Yogitunes mentioned the old stereo consoles; worth considering, too, even if not components - if you have room!

PS -not really related to the thread, but with firedome, tolivac and kb0nes talking about tubes, I thought I'd present my biggest tube...given to me my buddy/neighbor via his dad ...when a Detroit TV station, I think, was upgrading their transmitters in the mid 1960's. If I could just get it to power some speakers. it weighs a ton. Specs: http://www.rossrevenge.co.uk/tx/5762.jpg

 

[2packs4sure]

The system i put together in the early 90's

Here's the system i put together in the early 90's and it's still going strong after THOUSANDS of hours.

All this stuff is getable on ebay...

KENWOOD Basic C1 Pre-Amp the C1 has tons of tone settings, a great phono section with settings for cartriges and etc.

ADCOM GFA-535 strong yet compact amp.

TECHNICS SH-GE70 GRAPHIC EQUALIZER between the pre-amp and the equalizer you can make almost anything sound great.

Originally i had Boston Acoustics towers but in the mid 90's i got a deal on a pair of ADS M9 towers which i still have and they are just better.

I love classic 60's tube gear but at this point when that stuff is 50 years old there always is something needing repair and no one to repair it.

 

[tolivac]

Ovrphil:The tube you have is an RCA 5762/7C24 power triode.During the fifties and 60's even into the 70's these tubes were WORKHORSES in the broadcast industry.The 5762 is a realitivly low gain forced air cooled triode with 3Kw plate disapation.I have encountered these tubes in mostly RCA transmitters-AM,Older FM and RCA VHF TV transmitters both high band and Lo band analog.For the TV transmitters these were used in the Visual driver stages-and several in parallel-in what was called the "Afterburner"-"Incinerator"25Kw and 50Kw linear power amp stages.7 were used in the 25Kw-for 50Kw (High band) two 25Kw power amps were used feeding a hybrid combiner.Tuning these things was a real challange-for TV--phase shifts in the tuning caused "ghosting" in the visual image-and color shifts for color programs-once the amps and combiner was tuned-it was pretty stable and fine.For AM transmitters-these tubes were used in RCA 5Kw and 10Kw AM tranmsitters in both the RF power amp and the modulator-for modulator duty-two were used in push-pull.Since it was low gain stage-high drive power was needed-this was commonly done by triode connected 813 tubes as cathode followers feeding a special 4winding primary driver transformer.These are now unobtanium!!!if you have an RCA AM transmitter whose mod driver transformer is blown-you can get one from a junker transmitter.The mod transformers are still available thru Peter Dahl and other rebuilders.The mod transformer is push pull primary-and often two secondary windings-one for the RF driver stage-the other for the PA-they are capacitance coupled by oil filled blocker caps-if these are old-you can pep up an old transmitter by replacing them-Just like a NEW transmitter-esp if the mod chain tubes are replaced,too-same with blocker caps in low level audio stages-these often use 807 tubes or common audio tubes like 6L6,6V6,EL34,KT88,6550 and so one.Those mentioned tubes can even drive the grids of tetrode modulator tubes that have high gain-some later triodes,too.
Those Westrex tubes are loved by the high end Hi-Fi folks who can afford the GROSSLY overpriced SA amps for them and the GROSSLY overpricved 300 tubes-remember at a surplus store years ago-they had BINS full of JAN 300's at something like 50 cents each--now I am kicking myself for not buying some of them-they were WE tubes,too.Just made to mil Joint Army-Navy specs.Bet these would go for more than 50 cents each today!!!
Anothwer tube maker I haven't heard from was "Action-TUNGSEGRAM!!" as stated on the tube package-they made a lot of 5762/7C24 tubes as shown in OverPhils picture.Have several of the Tungsegram ones in my collection-problem-when they burnt out-rebuilders such as Econco could not accept them for rebuild.So off to the trash they went-didn't save the stations money after all-NO DUD VALUE!!The RCA and other maker 5762 tubes could get you up to $50 each for dud value.
Oh sorry-on my Amp designation meant to say MC60-the non industrial version-yet these often showed up in some radio stations and recording studios as monitor amps.Just wish I was around when they replaced them-and got the old "MACS"These aren't that hard for the electronics guy to redo.You jst have to be able to get electrolytics for the rectifier section that are rated at 525V and above.And for older amps--the bias rectifier diode will need replacing,too-these were selenium diodes and get weak as they age-bias voltage can't be set for the output stage and the output tubes overheat--GLOWING PLATES--NOT GOOD!!!And the blocker caps from the driver-phase inverter get leaky-causing false positive bias on the output stage tubes-and more stress on the bias diode-I just replace them with 1N4006 silicone rect diodes-then just fine-same with the bias cap the diode is connnected to-then get set for YEARS of operation!Then doesn't matter what brand amp it is.
Yes,agree on the SS parts-most are "house" numbers or ones made for that applicationyears after the amp was made--these are Unobtanium!!!So you have to try to find subs-and these don't always work-esp for Sony parts-esp in their TV sets.Thats what I like about tubes-you can get them and subs can be made without problems for the most part.And the circuits are easier to work on-more straightforward.I do have some McIntosh MI75 amps-these new recapping,too.I would like to build a full wave rectifier stage to replace the voltage doubler stage these have-the voltage doublers are CRAP compared to a full wave 5U4,5AR4,5R4 and so on.Replace the voltage doubler power supply and the amp takes on a NEW and BETTER sound personality!

 

[tolivac]

More things on 5762 tubes--the large radiator part is the plate terminal.The ring in the middle is grid.Since this tube has a direct heated cathode-the cathode return is the filament center tap.-In the transmitter thru the filament transformer center tap term.Filament is 12V AC or DC-DC is used for TV visual RF appliation to avoid filament hum bars in the picture.The plate vltage for these is 5Kv and up to 2A cathode current.Grid current is 200 Ma.When used in RCA TT25LB they have a real beauty-all of those 5762's running with their filaments glowing-the rectifier cabinet with all the mercury vapor rectifiers glowing light blue on light picture-dark picture-max modulation-they glow bright blue.The 5762 currents go up.In AM transmitters RCA 5H,10H the mercury vapor thyratron power-supply rect tubes flash to the modulation beleive they were 5563A mercury vapor thyratron-handles up to 10Kv 3A per tube.For its day this was a good system-the regulation was solid and if there is a fault-the thyratrons were bias off and the supply shut down.Faster than overload relays.The power transformer was 200-240V 3Ph and 2200V Scott connected 4 ph out going to four thyratron 5563.The Scott transformer was made by Mahoney Electric-they made a lot of transformers for RCA's transmitters.They were easily rebuilt when they went bad.These tubes were from the what radio guys called the "Chrome&Glass" era-transmitters had chrome framed veiwing windows so you could see the tubes and other parts.Very helpful!Transmtters today are just monolithic boxes-no beauty at all.In those early days transmitters were made to be seen as well as heard.They always fascinated me-and still do.Remember without transmitters--your radio just receives static!Same with digital things,too.

 

[firedome]

That IN4006 substtution

is commonly done on the zillions of Fisher 400/500/800 receivers, along with many many other '60s tube amps and receivers, that use selenium rectifiers for another important reason as well - selenium is HIGHLY poisonous and a rectifier that starts smoking in failure mode can be highly dangerous to one's health! We outlined the procedure along with dropping resistor mods required in our "Fisher Receiver" issue of Vacuum Tube Valley Magazine: "The Classic Electronics Reference Journal" published 1995-2004" RIP. Units with slow turn-on 5AR4/GZ34 rectifers seem to be the best functionally.

Tungsram of Hungary made some excellent audio tubes, their 12ax7s are now very sought after, I think I still have 4 somewhere. They also made light bulbs and that division was bought by GE in the 90s. The tube arm is defunct, afaik.

Tolivac if you need info on the caps needed to restore your MI-75s you may wish to consult "Audio Classics" here in Binghamton, you can Google them...they do all of McIntosh's service work on vintage units and are the largest Authorized McIntosh Service station in the world. I've had several MC-75s and several pairs of MC-60s, Mc225s, along with many others over the years, they are well built units and very easy to repair or restore, as long as the trannies ore OK...you don't want to know what it costs to rewind/rebuild one of those!