Saturday, 15 August 2020

RETRO-MEASURE: Pioneer SX-880 receiver (1978). And the amplifier "THD Wars" of the '70s?


Back in the 1970's, Pioneer among various Japanese brands like Sansui, Sony, Yamaha, and Technics brought popular, budget-conscious audio gear to the masses. With the prices of solid state components dropping, these amplifiers powered many college parties and brought music into the homes of many audiophiles of that generation.

Check out this ad from back in the day featuring the Pioneer SX-780 (45Wpc):


Nice to see that the idea of "high-fidelity" featured prominently rather than some nebulous idea of "high end" audio. Today, let's measure and discuss the sound of the last in the Pioneer SX-800 series of receivers, the Pioneer SX-880 featuring up to 60Wpc into 8Ω. The SX-880 came out in 1978 with a retail price around US$425. Thanks to a large part to central government mismanagement... err... inflation, this would be about US$1700 2020 dollars which would buy a rather advanced multichannel receiver like the Denon AVR-X4500H these days.


It's a great looking ~27lb/12kg unit that's very well built. It's got the classic look with silver knobs and switches, power meters, AM/FM signal strength meter, and an FM tuning meter to help with precise radio channel reception. Of course, all this is made even more classic with the amber illumination and the wood veneer up top and sides.

There is a nice selection of functions available including the "loudness" switch for when you're listening at low levels to emphasize bass and treble, separate bass and treble EQ knobs, and of course a balance control. I noticed that the knobs were a little noisy due to age but otherwise the functions all worked and the FM receiver sounded great.

After wiping a bit of dust off, this particular unit literally looks "mint" on the outside. The wood grain veneer appears immaculate. It was originally bought in the late 1970's (~1979) by a previous owner from Inner Sound in Portland, Oregon with a label on the back I presume of the store's previous address and phone number (here's their current website).


There is a normal assortment of RCA inputs including of course phono in. I'll be using the AUX input for my testing today since I'm mostly interested in the quality of the amplification.

Notice back in the '70-'80s before ubiquitous remote controls, many receivers also had convenience AC outlets, typically switched with the main unit so you can plug in your turntable for example and everything turns on when the receiver is activated. Speaker cable terminals are the spring compression variety for bare wires with a convenient push release button. I suppose 12AWG thick wires were not popular back then, at best I was able to comfortably squeeze 14AWG wire into those holes without fraying the strands. I'm glad that most decent amps these days use universal binding posts with the convenience of banana plugs.

Since I didn't want to open this up to poke around (borrowed after all), visual inspection from the outside looks good. The components I can see appear to be clean with no evidence of bulging capacitors or any unsightly burn marks.

Based on the information on HiFiEngine and Pioneer's manual, this is a 60Wpc power amp continuous into 8Ω "with no more than 0.05% total harmonic distortion", is capable of driving 4Ω loads, and has an advertised damping factor of 30. The detailed specs in the manual also lists THD at 1W into 8Ω as 0.03%.

I. Basic Characteristics

Okay, let's start with the usual basic parameters. At full volume the voltage gain from this integrated amp is up around the +43-44dB range:

Voltage gain: Left   = +43.5dB
                       Right = +44.1dB

As you can see, there's an imbalance between the channels of 0.6dB which is higher than what I'd like to see. I actually noticed this when listening to the receiver before it got on my test bench with the stereo image a little shifted to the right side; thankfully with the channel balance knob, I was able to subjectively get the balance mid-line. We'll talk more about the listening down below.

Given the age of this machine, let's jump ahead to look at the square wave to compare the 2 channels at 2V into 4Ω to see if there are issues:


Hmmm, looks like indeed the left channel is weaker than the right by 0.67dB at around 2V (varies between 0.4-0.7dB depending on how high I turn the gain up). Furthermore, it looks like the left channel is symmetrically "tilted" down suggesting some mild low frequency attenuation or phase shift. Given what I see here then, I'll focus on measurements of the right channel which is likely representative of the true performance of this receiver back in the day.

Given how good the right channel square wave looks, the device should have a well extended frequency response.

Next, let's look at the damping factor:


Remember that I'm measuring this into 4Ω. Overall it looks good with a 7-point average damping factor of 18.4 from 20Hz to 20kHz (remember, into 8Ω the specs say 30).

As alluded to above with the square wave, I am expecting a well extended frequency response and with the damping factor at around 20 into 4Ω, control of the Sony SS-H1600 (8Ω nominal) bookshelf I use as my comparison speaker should be quite good:


As you can see, there is indeed a channel imbalance between the left and right with the right one louder (this is with 1V into 4Ω).

With a decent damping factor (compared to something like the Pass ACA 1.1 with damping factor of only 3), frequency response into the Sony's reactive load is well controlled.

Here's a peek at the phase curve - nice and flat, nothing surprising...


Since this is a stereo receiver, I checked the cross-talk using a simple 300Hz/4kHz tone in either the right or left channel and found an average of -63dB channel separation at 1W into 4Ω; certainly this is good enough for music playback. Remember, back in the '70s to early '80s you had vinyl, cassette tapes, reel-to-reel, and FM radio as stereo sources so even approaching 50dB separation would be excellent already in the home using the best gear and best recordings.

II. Single-Tone Harmonic Distortion and Noise

As usual, let's start with a look at harmonic distortion vs. frequency at 2V/1W into 4Ω using REW's frequency step function. I'm using the right channel:


The cursor is at 1kHz and we can see that THD+N is around -71dB/0.028% at that point. This would be in line with the Pioneer spec of <0.03% at 1W into 8Ω (we're using a more challenging 4Ω load here of course). The harmonic distortion does show some frequency dependence with a gradual increase in the higher frequencies which is not uncommon. Notice that below 600Hz, the 3rd harmonic is highest and above that, the 2nd harmonic dominates although not leading by a huge amount.

Noise floor (brown) looks good hovering around -100dB below fundamental.

Let's have a peek then at 1kHz harmonic distortion across various power levels to see the FFT details with both channels driven (again, we'll look at the better-performing right channel):


If we scan the results in that matrix of FFTs, we see that the receiver is very well behaved. THD+N remains better than -60dB (<0.1%) all the way to 20V/100W into 4Ω. Clearly by 23V/132W, the device has started clipping with a large jump in distortions and noise.

If we graph those numbers as THD+N vs. voltage output for our distortion-power curve with both channels driven:


That's very good, it looks like the amp is able to deliver good quality <0.1% THD+N reproduction up until it starts clipping (very quickly I might add!) at just over 22V or 121W. Remember, it's rated as 60Wpc into 8Ω, so it's great to see that the power supply is able to indeed deliver twice the watts into half the load.

III. Multi-Tone Testing: Intermodulation Distortion and Triple-Tone TD+N

Alright, let's now have a look at some of the intermodulation tones at 2V and 10V into 4Ω of the right channel, again, both channels driven with the caveat that the left seems to be sub-optimal:


Overall, not bad at all. IMD results were excellent at the 2V level around -80dB across the various IMD signals, and at 10V we're seeing a larger variation from -80 to -60dB, depending on the test variant used.

Here's the "transient intermodulation" (TIM) distortion test result for this vintage receiver; again both channels driven:


Again, very good. At a 2V output level, there are essentially no distortion sidebands on either side of the 12kHz sine tone. By 10V, we start seeing the anomalies but at low levels around -89dB which is not bad, but not as good as the 2011 Onkyo TX-NR1009 receiver as a more modern consumer-level product. Remember, these are late '70s-era transistors.

Finally, here's the Triple-Tone Total Distortion and Noise graph at my standard 2Vrms level into 4Ω:


I used the channel balance control so they're both ~2V output into 4Ω. As noted before, the left channel is not functioning at the same quality as the right. Based on what I have seen through these measurements, I suspect what I'm finding with the right channel is likely representative of the receiver's true performance (about -74dB) and that the left channel has deteriorated over the years (TD+N reduced to -64dB).

IV. Wideband Noise

Typically, I show the 1kHz square wave tracing here but given my concern with channel imbalance, I've already demonstrated the anomaly above (I).

The wideband FFT is not of high resolution but good enough to make sure we don't see any major issue with excess noise in frequencies >100kHz.


Looks fine up to 600kHz as one would expect with good Class AB amplifiers, no significant noise components unlike Class D amps discussed before.

V. Impressions and Conclusions

From an objective performance perspective, the results are certainly very respectable after all these decades!

Remember that this device is 42 years old. I was in grade 1 when this machine was built. As such, I suppose it's forgivable that the owner of this receiver did not notice the <1dB channel imbalance and higher distortion of the left side. For years, this receiver has been used as an amplifier/FM radio for casual music and TV playback in an asymmetrical living room.

Using the data from the right channel which I believe is representative of the true quality of this device back in the day, here's my summary AMOAR Score:


If we look at each component of the score, we don't see any major issues. In fact, if you compare this to the 2011 Onkyo TX-NR1009 receiver, you'll see that in fact many of the results are similar. This old Pioneer has slightly higher damping factor than the Onkyo. The triple-tone distortion factor are within 1dB of each other. The much newer Onkyo is capable of more power before hitting 0.1%THD+N and of course has all kinds of digital features, capable of multichannel playback, various surround decoding, and DSP capabilities. While features have been added, objectively it would be hard to argue that sound quality as an amplifier has changed substantially between these two consumer-oriented receivers.

Over the years, there has been talk about Slew-Induced Distortion (SID), specifically the type we call Transient Intermodulation Distortion (TIM/TID) also known as Dynamic Intermodulation Distortion (DIM). This was said to be a problem in the past with slow transistors. However, by 1978 with this amplifier, I'm not seeing any problems with the TIM test signal (similar to a 1975 Tektronix recipe using digital signal generation but more challenging with 1kHz square, 12kHz sine and 96kHz bandwidth). In fact, the amplifier I've seen showing the highest TIM was the Pass ACA 1.1 compared to other devices at 2V into 4Ω. We know that the ACA utilizes low feedback and has a commensurate low damping factor. There has been discussion recently by Bruno Putzeys that TIM is reduced by negative feedback - not the other way around as per audiophile lore about feedback being "bad" for TIM. As usual, be careful with all kinds of audiophile myths out there unless "fact checked".

Subjective listening of this old Pioneer I felt was consistent with the objective results. On my system playing music off Roon to the Oppo UDP-205 as network DAC to Emotiva XSP-1 preamp to the Pioneer SX-880 amp to the Paradigm Signature S8 v.3 speakers (I turned the subs and DSP off), I was able to hear the slight channel imbalance as noted in Part I above before putting this on the test bench. This was remedied with a ~15° turn of the balance knob to bias the left channel. By the way, the "mono" switch is convenient for this - just flick it to "mono" and turn the balance knob to center the sonic image.

While I know from the objective results after testing that the left channel had more distortion than the right, I honestly was not able to hear a difference while enjoying music (other than the channel imbalance). Remember, when we listen to music at normal levels at home, most of the time the amplifier doesn't need to produce more than 1W unless you have extremely inefficient speakers.

Perhaps it's just the bias of knowing that this machine hails from the '70s, I could not help but have the thought run through my mind that what I was hearing was basically the epitome of the "solid state hi-fi sound". Tube-amp lovers will call this "clinical", and "lean" sounding (like most solid state, right?). Not exactly a great match for '80s recordings like the first press of OMD's The Best of OMD (1988) with synth tracks like "Enola Gay" or "Souvenir" sounding a bit more sizzly than I prefer. I think some dramatic audiophiles may suggest that this kind of sound would "have me running out the room". No need to be so histrionic, my friends! :-)

"Regular Pleasures" from Patricia Barber's Verse demonstrated that this amplifier has no issues with the low end. Subjectively I thought the bass wasn't as tight as my reference Hypex NC252MP with volume pushed up; it's hard to know unless I have the other amp running in parallel with A/B switching. With the balance control tuned in, soundstage was excellent and Ms. Barber sounded like she was singing in the room seemingly a bit deeper than the 10' sitting position from my couch to the plane of the speakers. Natural instruments like the muted trumpet on the track sounded realistic and "popped" out nicely with a sense of space around it.

More classic female vocals like Sheila Jordan's "I'm a Fool to Want You" (Portrait of Sheila Jordan) extended that impression of this being a "hi-fi" amplifier playing what it's fed without adding its own editorialized "color". Wonderful details on this sparsely recorded 1963 track rendered cleanly although one can easily tell that this was not a modern digital recording (certainly no need for hi-res!). In particular, I appreciated the lack of any excess sibilance in Ms. Jordan's voice. Likewise, the unforgettable Louis Armstrong's "St. James Infirmary" (Satchmo Plays King Oliver) was simply divine - a track like that just subjectively sounded "right" played through vintage gear. :-)

Modern recordings like Ramin Djawadi's Westworld: Music from the HBO Series, Season 1 (2016) came through nicely as well. Expansive soundstage on "Nitro Heist", appropriate bass "weight" and balance with the highs.

Very enjoyable 3 evenings of listening to this amp; I didn't experience any fatigue listening for 2-3 hours each time.

Bottom line: The vintage Pioneer SX-880 appears to be a good performer - a reminder of the high-fidelity one can get from gear at least dating back to the late 1970s. While objectively I can measure that the left channel is not as clean on this unit, at normal listening levels provided that I compensate for the channel imbalance, I didn't think the sound was significantly compromised. Overall, the sound was clean and akin to the previously-measured Onkyo TX-NR1009. Honestly, I would hate to blind-test this against something like the objectively better Hypex NC252MP that I use as reference! I bet it would be very difficult at normal playback volumes; perhaps the only thing I would notice is if I pushed the volume up, the higher noise level with the Pioneer might be evident.

I will suggest to the owner that he tracks down the cause of the left channel imbalance (audible) and distortion (much less audible). It's worth cleaning out the innards a bit, use some Deoxit on the knobs and switches, inspect the old electrolytic capacitors closely. I think it goes without saying that when a machine is as old as I am, it would not be surprising to find some wear-and-tear compared to when it was young :-).

Unless you're buying used at a real bargain, make sure to get things checked out thoroughly.

BTW I think it's good to take the opportunity to have a listen to some of the vintage gear once awhile. Just like my "retro-measures" of the 1994 Sony LasterDisc as CD player or the old 2002 Lynx PCI audio card, it helps us maintain perspective on subjective sound quality correlated to objective results. Certainly digital/computer technology has changed the way we access audio in very substantial ways. However, despite all the dramatic "Best sound ever!" headlines every few months on the front covers of magazines, one might be surprised at actually how little difference there has been over the decades with mature products like the sound of power amplifiers at normal listening levels.

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Every once awhile on discussion forums, I run into comments like this one referring to stories from the past used to suggest that measurements / specifications are somehow of little use when it comes to sound quality:
"It is about much more than distortion. The lowest-distortion-possible race of the '70s created many amplifiers with vanishing levels of distortion, which nonetheless sounded like crap."
To be honest, I don't remember much of the '70s because I was only a kid back then. Stereophile talked about "The THD Wars" of the "1960s and early 1970s" for example. Interestingly, it's hard to find much information about such a "war" on distortion when I dug around. While it has been documented that the consumer receiver brands were battling over market share, I'm just not sure "THD" specs were a major selling point. In fact, looking at a few ads from the 1970s through the archives of Stereo Review, there did seem to be the "power wars" with devices like the 160Wpc Pioneer SX-1250 among other receivers like the 120Wpc Kenwood KR-9400. However the lowest THD measurement used in advertising I saw from the era was this one from Yamaha in 1979:


Okay, 0.02% THD (-74dB) is pretty low but certainly not unrealistic for what they consider the "leading" number. I don't know how good this receiver is and even if there is a bit of an exaggeration in the spec, it can't be all that off the mark, right? Many receivers over the decades would achieve this without great fanfare. As expected, I see significantly better results from my Emotiva monoblock and Hypex Class D amps. So where are numbers like "0.0001% distortion" in the 1970's I was led to believe existed? It appears the answer is nowhere.

I do remember the 1980's and later with false claims like grossly exaggerated advertised power numbers such as "1000W PMPO" from little boomboxes as I was "coming of age". Stuff like this still quite common to see:


But that's not serious hi-fi gear though.

It wasn't actually until the 1980's that we saw amps like the Yamaha MX-10000 with advertised "0.0005%" THD (-106dB) released in 1987. Or the Onkyo M-510 Grand Integra with "0.005%" THD (-86dB) released around 1984. IMO these amps still look fantastic and I think the meticulous construction of those devices remains enviable. Whether those THD numbers hold up to modern scrutiny is unclear as the numbers lack context. Is that "0.0005%" THD at 1kHz? At what output power/voltage? Into what load (for all we know it could be a 16Ω resistor)? Up to what harmonic did they measure (typically I report up to the standard 9th harmonic)? Remember that it's nice to also know the noise level, so even with pristine THD results posted, the THD+N might be significantly higher.

From what I've seen, perhaps there's no need to complain so much about the '70s and the supposed "THD Wars". It all seems rather tame from what I can tell, and nothing like snake oil hype with ridiculous cables, fuses, audiophile ethernet switches, unsubstantiated USB tweaks and such in the "high end" today and in the last few decades...

I agree with the forum comment quoted above though that sound quality is indeed "more than distortion". There certainly are perceptual preferences as well which are psychological and idiosyncratic to each of us as alluded to in the Pass ACA post a few weeks back.

Having said this, I have yet to find a component that genuinely measured well but "sounds like crap"! I've asked Internet audiophile denizens about such a beast for years. But like the Loch Ness Monster, Yeti and Sasquatch, I have yet to see plausible evidence of these creatures. Recently, there was a claimed sighting regarding the Topping D30 which was refuted by Greg Dunn.

Such is the nature of many (even most) audiophile claims and beliefs. The moment you ask for clarification, look for concrete examples, or test something for yourself, you quickly realize that much of it had either been poorly remembered at best, or worse... mythical yet dogmatically embedded into the subjectivist audiophile "culture".

Safety and health to you and yours. Enjoy the music as we enter the latter half of August.

PS: I just saw this video from Paul McGowan of PS Audio as I was finishing off the write-up... I'm a bit concerned about his generalization that today's amps sound significantly better, and calling brands like Pioneer, Kenwood "trash" and "dreadful sounding things" (~2:20). Nonsense! IMO, he's very wrong if he's applying this generalization to higher-fidelity products and likely just speaking as a salesman perpetuating the typical beliefs, promoting the idea of "sounding musical" - whatever that is.

24 comments:

  1. Hey Arch,
    Nice change from the endless march of new products.
    By some small coincidence, I recently refurbished my Dynaco SCA80Q amp for my daughter's new digs (along with an aging Rega 2). I am still not set up to measure power amp distortion, but after finding a replacement volume control and powering it up, it sounded very good through my LS50s and the Paradigm Atoms I gave her to match. Not clinical at all, but rather dark or warm sounding... might be a problem, I really can't say, as the highs seemed to be there, if somewhat recessed.
    Ridiculously high gain. She's over the moon (but now has to learn to take better care of her LPs.)
    Makes me wonder why I ever upgraded.
    But to me, these are the kinds of activities that make this hobby fun: spending a lot of money on the latest S'phile-hyped piece of gear always seems to lead to disappointment, buyer's remorse, or a domino-chain of upgrades.
    Keep up the good work; I (for one) would love to see more vintage measurements/reviews.
    Phil

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    1. Hey Phil,
      Great hearing from you and your daughter's a lucky girl to be listening to a Dynaco at her place :-).

      Awhile back, I saw this announcement for an upgrade kit:
      https://audioxpress.com/news/dynaco-sca80q-gets-improved-power-amplifier-section-upgrade-kit

      Looks like a nice kit to try out if I ever get my hands on one of these to play with - might change that dark/warm sound.

      I'll need to double check but I know a friend has a vintage Dynaco in his collection I might have to borrow for a bit, don't remember which model that was.

      I agree... It's nice looking back once awhile and remember to not get stuck on that rat-race of perpetual upgrades especially if much of what's new is fast becoming a lateral "upgrade" (if even that) including the latest digital gear now that the technology is well into maturity in the service of human hearing.

      Best regards...

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    2. Hi Arch,
      I saw those PS and other modules from Update my Dynaco and initially thought I'd probably have to buy them, even maybe do a complete rebuild. The little beast is OK for now, but I have those in mind if/when something goes wrong, or the owner gets more critical :)
      BTW, recording genius Kavi Alexander had a similar surprise a while back with the ST120 (same family as SCA80): https://www.facebook.com/kavi.alexander/posts/10213399171947139 - it was this post that made me consider reanimating mine rather than looking for a cheap integrated for the kid.
      Best,
      Phil

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    3. Ha! I'm a total pest today, but coincidentally received this text right after posting the above:
      << I’m listening to their satanic majesties request by the stones on vinyl and it sounds SO GOOD on this system. Their production really seems to be a cut above >>
      Another audiophile in the making... just get them off the MP3s and buds.
      Cheers

      Delete
    4. Cool Phil,
      Wow, getting into the Stones eh? ;-)

      Yeah, definitely off the buds and crappy low-bitrate MP3! That stuff will destroy hearing, man... Hmmm, can't seem to access Kavi A's Facebook post at the moment but will try again a little later.

      Delete
    5. Arch, it's the kid who was enthusing over the Stones on vinyl, although I do indulge in those bad boys occasionally... my favourite LP of theirs is a pristine Japanese pressing of Black and Blue from ~1980 that always drops jaws here. I've ordered the vinyl reissue of Let it Bleed to see if it's any better than the 88K download (choir always sounds terrible.) I've found some LPs really do sound better subjectively.
      Here's the text of Kavi's post (need to find out about those mods):
      <<
      Gentelmen, fellow seekers and travellers on the road to audio bliss, I place before you, for your thoughts and insights, the dreaded Dynaco ST 120. The very first solind state offering by David and his crew, consisting of him, Ed Laurent and Erno Borberly, of Mosfet fame. Formidable talent, experience and expertise, to say the least! A man named Bender, a builder of SE Triode amps, had a post on the web about this amp, which is I can to know about the ST 120. Bender maintained that after some mods, the ST 120 sounded close his Triode amps, which got me interested... A Jim Rogers in Florida was offering moded ST 120s on eBay for under 400$ and I got one... Low and behold, it sounded fantastic, driving my electrostatics, via 25 feet of speaker cables! There are only TWO transistors in the outputsatge and the power supply is regulated. Original Dynaco brochures show excellent square waves and state that the amp will drive electrostatics. In an interview with David, he maintained that ALL Dynaco Amps were tested on dynamic and electrostatic speakers. KLH 9s we're mentioned by name... Your input would be much appreciated... Thank you... Blessings... Kavi.
      >>

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    6. Thanks for the repost of the message from Kavi.

      Cool, will need to pop over and have a look at what Dynaco my friend has to see which model and whether I can borrow the beast for a listen and measure.

      Yeah, I figured you were referring to your daughter with The Stones. I have some of their ABKCO SACDs from around 2002; probably your 88kHz downloads based on those remasters. Okay, but not exactly mind-blowing sound...

      Yeah, the vinyl pressings could sound superior. Hope you're pleased with the Let It Bleed vinyl when it arrives!

      Delete
    7. The Rolling Stones have a huge and great catalogue to listen to. Awesome band, in my opinion. Just avoid 2009 remasters by Marcussen/Universal, original releases or Virgin/Bob Ludwig remasters are the best you can get. Enjoy.

      Delete
  2. If I had one of those, I'd get it professionally cleaned up and have the capacitors replaced. Get the knobs to function without noise, too. It would cost some money, but you'd probably end up with a fine piece of very useful and good sounding equipment.

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    Replies
    1. I agree Unknown,
      Like many cities, I know there are places in town here in Vancouver catering to used/vintage gear so will nudge my friend to consider bringing it down there to be worked on.

      I must say that having borrowed the unit for 2 weeks, I just adore how it looks! Makes much of the utilitarian design of modern gear appear bland. And it's certainly not "form over function" either given all the tone, balance, mono/stereo, loudness controls, etc. that's available for the user. I also love those power meters and FM tuning/controls.

      Beautiful stuff.

      Delete
    2. If I bought an old piece of gear like this then replacing caps would be the first thing I’d do. That square wave response is practically pathognomic of a electrolytic that’s leaked. Luckily it’s easy to find the service manual online, here’s one source:
      http://www.kallhovde.com/pioneer/sx-880sm.pdf
      It includes a full circuit diagram, and there are indeed electrolytics sitting in the tone control circuit, which are probably the source of the problem. I’d have a close look at the large power caps as well, purely with an eye on safety. Replacing all the caps (including the large ones) should cost less than £25 for the parts. Obviously the biggest cost is labour. I remember fixing up an old receiver like this many years ago, and my advice is to stay the heck away from the fiddly winding-string tuning drum if at all possible.

      Delete
    3. Excellent Charles,
      Thanks for the link. I'll forward it to the owner to have a peek. I agree. The great thing about these vintage products is that they can be serviced often without huge expense and certainly save from otherwise good gear from going in the trash!

      Delete
  3. I went through a kit Dynaco series and built a PAT5 and prior owned a Fisher 500TX with Dynaco A-25s that we enjoyed. My best wasa Yamaha M-80 amp and a C series preamp. The amp suffered a 2nd floor shower drain leak which fried and and could not be repaired. I have since used an old Pioneer Elite VSX 21 mostly in two channel mode and since I've spend most money on my recording studios never upgraded. I still use my 40 year old AR-58s and my Large Advents, but did buy a pair of 3-way JBL A-20s and a pair of JBL P 305 powered monitors for the studio, but did ad the Project S2 dac to the Pioneer set up. I did have to replace the volume encoder for the VSX as it died, but that is all that I have done to it.

    Much of the channel imbalance issues of the old gear was due to bad resistance pot imbalance. I don't think the Blue Alps were around then and no one worried about pot matching to 1% in those days I doubt.

    I also did own a Marantz receiver and really liked it. I think one of my boys ended up with it years ago. The gyroscope tuning was very nice on the tuner.

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    Replies
    1. Hi Jim,
      Great stuff man, I bet lots of good memories with the gear ;-).

      Good point about the possibility that channel imbalance might just be because of the old low-precision pots.

      Wondering if you've used the Pioneer Elite VSX-21 in multichannel? That's gotta be one of the first generation home theater units with Dolby Digital/DTS. My old Denon AVR-3802 would be around that vintage and is still going strong.

      Hmmm, come to think of it, it might be fun to measure the amplifier on that unit as a look at the mid-priced home consumer gear (I think I paid something like CDN$2000) from the early years of Y2K when SACD/DVD-A was introduced and many of these featured analogue inputs for multichannel since lossless copy-protected hi-res digital wasn't available as outputs yet.

      Take care Jim...

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    2. Yes I have done MC with it and it is great. Sad that it does not have HDMI, but we did not have that word back in the 80's lol. I run the 5 analog outs of my Yamaha S-1800 cd/DVD. SACD player and enjoy all of that. SASCD are great and the CDs through the Project S2 are now excellent. I removed the Sony as it is just not the equal of the Yamaha. I sure do miss that seperate Yamaha combo as that amp was effortless. I could run Class A for 20 watts PC. A side note was that my PAT5 had severe channel imbalance until my 3rd pot from then, just as did my early NAD preamp.

      I have never been a fan of statistical sampling where things come down the production line and we check every 50th or 100th and if they are good the "line" continues. Buying parts from the lowest bidder does not work either in cars (we sure know that one), bridges, elevators, brake work on your car, or heart or brain surgery. Quality needs to be paid for properly.

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    3. I hear ya Jim,
      Parts from the lowest bidder especially these days in the age of obsolescence by design, fast fashion, and the never-ending product cycle that requires folks maintain interest in upgrades is generally a bad recipe for mature technologies.

      The way I see it, unless an audiophile is interested in new features, at some point, there is no need to upgrade for the sake of "sound quality". The threshold's reached, and our ears will not get better with age :-(.

      As audiophiles, the hobby is not one that tends to chase new features; in fact audio folks tend to be the opposite with a more conservative take on things, preferring "pure" signal paths and the like. DSP room correction for example for me has made the biggest difference in what I hear, yet I suspect it's a hard sell for many.

      Without significant qualitative differences, new products often are just lateral moves with maybe esthetic differences or when it comes to DACs and power amps, you might actually see supposed "better" products have lower measured fidelity but in reality have little audibility. For example the hype around "multibit" and NOS DACs represent some of this IMO. Other times, some people will just like that something "sounds different" but it's not necessarily improved fidelity. The desire to "upgrade" also entices the snake oil salesmen who take advantage of the disposable funds probably knowing full well that what they sell have no benefits.

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  4. My Yamaha RX-700U receiver that I bought new in 1987 ($488) has an honest rating of .009% THD - 65W per channel into 8 ohms from 20Hz to 20kHz. And I absolutely remember there being a lot of THD talk at the time, with my friends not being overly impressed with that figure. Still using the receiver today and still think it sounds good.

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    1. Nice one Joe,
      Looking at the manual:
      http://www.usersmanualguide.com/manuals/yamaha-audio/RX700U.pdf

      Looks like it's a 75W amp using 1kHz into 8Ω at 0.009%. Assuming it's nice and quiet, I imagine this sounds fantastic. Yamaha has certainly produced lots of good products over the years.

      Yeah, I'm just not sure about the claims of a "THD War" back in the day. There was however an FTC ruling in May 1974 on wild amplifier power claims as discussed in this article:
      https://www.audioholics.com/audio-amplifier/ftc-consumer-audio

      Could some in the audiophile world be conflating the two? I suppose they are related to a certain extent...

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  5. I don't remember so much the THD war, but I do remember the WATT war as it seemed that many were trying to break the 200 watts per channel barrier.

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  6. Once again a Objectivist at his best!!!! Great work. I was a Marantz guy, bought a pair of M300 mono blocks and sold them for a new 2325 125/watts into 8 ohms a side. My rival to this day was the Pioneer guy with a 125/ matching combo. I got asked to leave the residence after the 1st year for many reasons and moved across the street into a Co-op. We put the two stereo's together for a Hootenanny, and had Pete Delean a guitarist with a 100 watt Marshall top and two bottoms in the middle for our opening house party. They still talk about it at the Co-0p 40 years later. LOL Great work. keep it coming.

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    1. Now we both have Onkyo receivers his the top of the line because he needs it more power. Myself Klipshorns. Shelved my Carver, I have a great 5.1 system but use All stereo most of the time. Because it sounds better. My B&W Bud 804D Diamond tweeters he has shattered two times. B&W canada replaced them for $1200 each twice. Now he is on his own He powers the B&W's with a Bryston Cubed amp 300 a side. sound great but still sounds like a Stereo. He has a small B&W sub in the middle and a pair of DB1's on each side. Amazing bass in his $2 million dollar home. IN the usa it would be 3 times that amount. He snobilly comes to my place and says Big sound! I say ya, like the band is in the room. I go to his place where he is still listening to a Sonos? His entire play list is mostly only available in CD redbook at best. He has more $$ than God and refused to get a higher end DAC?? mp3 his sonos, and his Sonos 5 all sound good. Real 24/96 music would make his system sing. You put a shit signal into Klipsch Heritage speakers and it sounds like someone is strangling the CAt. don't tell my bud, "The Cat" that cuz they will be sorry. cheers everyone

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    2. Great stuff Glen,
      Love the story about the legendary co-op party man! ;-) Sounds like good times!

      Wow. A guy with "more money than God" and only had Sonos? Ya gotta set the guy straight man.

      As for the B&W diamond tweeter shattering, that's pretty nasty. I've managed to kill one of my Paradigm beryllium tweeters a couple years back but that my user error unfortunately ;-(. Wondering what's the guy doing to cause such a problem!?

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  7. Hehe, (evil me) would love to (mis-)use some of the more "self-righteous" reviewers of some of the renowned hifi mags to be subjects to a blind test with this amp and a modern equivalent counterpart amp. My guess is over 50% would flunk...

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  8. As I recall, there was no THD war going on in the 70'es, and very few even knew about it. On the other hand, the power war was raging between brands to gain market leadership. I think you're right in concluding that THD, TIM, slew rate and such parameters weren't used much, or talked about much until the 80'es, in some cases well into the 80'es. That's the time when things started to become serious, as the prices came down to a level that decent stereo systems became available to common folks. The main reason I believe was that the power war became obsolete, as every brand could boast as much power as any listener might be able to make use of, and even more in most cases.

    But I am old enough to remember the DIN 45500 norm. This was in the 1960'es as I recall, and already back then hifi sounded pretty good, not that different from hifi of the 70'es or 80'es. I even have recordings (not remastered) from the 60'es that still sound absolutely great today. The overall performance of amplifiers haven't changed much since then, because there hasn't been many real revolutionary innovations with a few exceptions, Class D amps as an example, which until now has had issues, but slowly are gaining territory these years. The same could be claimed of cartridges and turntables. It's a whole other story with speakers, but the only really obvious thing IMO that has changed, is the price.

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