Tubes and Vinyl and An Understanding Spouse

For the three of you who will care about this, here’s the birdseye lowdown about my tentative journey back into the land of tubes and vinyl.



First, the ground rules. I will not be dragged into any arguments about the quality of experience of vinyl versus digital, tubes versus transistors, active versus passive, coaxial versus component. In each of these controversies I have held unshakeable convictions only to have them dashed to pieces in the harsh sunlight of experiment, and the only thing I can say for sure is that everything—from the choice of microphones, to whether the musicians had breakfast, to whether the balance engineer actually understood the emotional underpinnings of the music, to whether the listener had breakfast—affects how recorded music is perceived. I only offer my observations from a lifetime spent listening and mixing in a mostly vain attempt to coax the ghosts out of the hidden spaces.

Second, a disclaimer. Mine is not by any standard even a lower-mid-level audiophile playback system. Serious devotees and veterans of the high-fidelity wars will find both the gear and the observations quaint at best, laughable at worst. I can only say that each part of it carries historic baggage, and some of it is the stuff of legend.

Now, after writing around 3,000 words, I’m realizing the things people probably want to know first are, what are the components, and what does it sound like? So let's get that out of the way.

L-R Tannoy SGM-10B, McIntosh MC-40, iPad, Fluance RT-85, Schiit Audio SYS and Mani, MC-40, SGM-10B 

The components...

The system is very simple. The sources are an iPad with access to Apple Music (so that I can listen to pretty much anything I can think of) and a Fluance RT-85 turntable for the fifty or so LPs that have survived into 2020 from our once fairly large collections. The RT-85 feeds a Schiit Audio Mani preamp. The iPad and preamp feed a Schiit Audio SYS, which is nothing more than an extremely high-quality A/B switch and volume pot. The outputs of the SYS feed the inputs of a pair of McIntosh MC-40 amplifiers which power a pair of Tannoy SGM-10B monitors with Mastering Lab crossovers.

I need to especially thank Teresa here, as she has let me rearrange the furniture in the living room and put the gear out in plain sight. She simply asked me to help her with her Google Classroom content in return (which I would have done anyways), so I’m making out like a bandit on this.

The sound…

Well, sitting in the sweet spot there are some things that sound pretty magnificent. Anywhere else downstairs is not especially great. This is one of the tradeoffs when using studio monitors rather than standard high fidelity speakers: studio monitors are not intended to sound pretty, they are meant to be brutally accurate. One of the assumptions built into the design of studio monitors is that the listener will always be in the exact optimum position with relation to speaker placement. This allows the speaker designer to use directional tweeters to reproduce high end, which improves accuracy by reducing the amount of sonic reflections coming off nearby walls and tables reaching the listener’s ears. It also means that outside the pattern of the tweeters there is a dramatic drop-off in perceived high end. (Typical home speakers have a much wider dispersion in the high end.) So when I’m really listening, I stay on the couch.

And the term “sweet spot” isn’t terribly accurate. Because we still need to use the front door, the listening position on the couch is a least a foot too close to the speakers. It also seems to be right in a bass “suckout”—the place in a room where bass frequencies tend to cancel out rather than build up, a phenomenon fairly typical in most human-scale room sizes. And no, moving the listening position really isn’t a possibility right now.

It’s definitely a work in progress. Tube amplifiers like the MC-40 are largely dependent on the quality of the tubes for their sonic signatures, and while the current tubes aren’t anything special, they sound OK to me. I replaced all of them around six years ago, but in my ignorance of tube lore I didn’t know which ones were the best. I recently put the original power supply tubes back in as an experiment, and while they’re not the best either, I think they sound a bit better on the low end. I will be experimenting with different tubes for the next few years at least.

The very first thing I listened to when the RT-85 arrived was Prince’s 1999. I put the vinyl on and just for fun called up the tune on Apple Music as well, matched the volume between the two, started them both at the same time, and switched back and forth between them. The vinyl won by a significant amount—the high end was silkier and felt like it had an additional octave, the low end was more in-your-face, and the imaging (the placement of instruments across the stereo stage) was truer. Some of this can be laid aside as excitement over a new toy, and some of it has to do with the wild equalization curves LPs require for anything approaching linear reproduction, but some of it is definitely about the fact that the exact same song on vinyl sounds different from its digital cousin.

So with all that out of the way, here’s the story.

I grew up in a music home, and for that I’m forever grateful. The first piece of furniture my parents put in the Rossmoor house was a Baldwin baby grand piano (left the factory in 1922, Baldwin looked it up for me). I’m sitting across the room from said piano right now. When I crossed the threshold of that house as a two-year-old in 1959 there were no couches, chairs, or tables—the piano enjoyed primacy of placement. My earliest memories are listening to my mother wend her way though Chopin or Bach or Debussy or giving lessons to the neighborhood kids. Then at some point in the early sixties, my father decided my mother deserved the very best hi-fi he could lay his hands on. They were called hi-fi sets back then, the term stereo just then coming into vogue.

The Fisher 400 Receiver 

He did pretty well. He came back from the hi-fi store with a Fisher 400 FM receiver (in those days you differentiated between amplifiers and tuners, and a box with both was called a receiver), a Thorens TD-150 turntable (they’re worth about two grand now) and a pair of Altec-Lansing (yes, that was a real brand for a minute) Carmel 838 speakers. The Carmels deserve their own story—they were the home version of the A7 Altec Voice of the Theatre speaker that spent 50 years as the main component in most movie theater playback systems.

The legendary Thorens TD-150 

That system is forever etched in my head. It even smelled great—the tubes in the Fisher got hot enough to sear the surrounding air into ozone. My father loved it because the final timpani notes of the Shostakovich Fifth Symphony would make the house shake. My mother loved it because it made Alicia de Larrocha, Vladimir Horowitz, and Artur Rubinstein come alive in the living room. My siblings and I loved it because of the Doors and the Beatles. That sucker could move some air.

Altec-Lansing Carmel 838a. They were BIG. 

Times change, kids grow up, technology moves on. Tubes became antique as early solid-state devices came along with enhanced feature sets, lower prices, sexier lights, and in some cases unquestionably inferior sound quality. The Fisher developed severe problems with its few front-panel switches (which would have taken very little to fix, but what did we know?), the Thorens independent suspension system began to list to one side, and the cats peed on the speaker grills. I hung on to the speakers until well into the 2000s, but I never had a decent place to put them and they eventually went to speaker heaven.

The new system begins to accumulate...

Tannoy SGM-10B. I suppose I should take the picture again with the grill off. 

Some time in the late 80s my best friend and alter-ego Gary Van Pelt developed a crush on Tannoy SGM-10B speakers after he watched Doug Sax master an album at the Mastering Lab. I think it was a Bill Schnee mix, and I think Gary worked on it, but I have no way of knowing. 

 

Gary in his usual habitat, some time in the 90s 

Doug had futzed around for years trying to come up with a small box speaker system that lived up to his own exalted standards, and finally settled on the Tannoys. They had a concentric tweeter, a fairly exotic idea in driver design Tannoy…er…borrowed…from the UREI Time-Align designs. Doug liked the driver and the massy construction of the box but hated the Tannoy stock crossover, so he had the Mastering Lab maintenance techs fashion a wicked complicated passive crossover network to give him the sound signature he wanted. Those were the boxes Gary heard and fell in love with. Apparently other mixers in town loved them as well, because The Mastering Lab soon had a lucrative side-hustle going modding SGM-10Bs with Doug’s exotic crossover. I have often wondered what Tannoy thought of this—Doug was far too big a fish to ignore. (You can still find Mastering Lab SGM-10Bs today in a somewhat evolved format from Eveanna Manley.) Gary bought a pair, and sent them to Doug to get the mod done.

The Mastering Lab crossover plate

Some context: in 1990 John Meyer started making the HD-1 monitor. The HD-1s took the audio world by storm and were fixtures in most control rooms and OB trucks within five years. They were also the first commercially successful active monitors (amplifier and speaker in one box) on the planet. They used some lessons John had learned in the live audio world about using power feedback sensing loops to maximize speaker efficiency while minimizing distortion. Ed Greene loved them. (I always hated them—they gave me headaches.) The Meyer HD-1s started the whole active monitor explosion and relegated passive systems to, well, the past.

Meyer HD-1s. I used to balance on whatever else was in the control room and then check the HD-1s once really loud to make sure everything translated. More than that and I needed some Ibuprofen. 

But some of us still loved tubes. A year or two after buying the Tannoys, Gary came across a pair of McIntosh MC-40 monoblock tube amps. As I recall he didn’t pay much for them, but had very high hopes about how they might get along with the Tannoys. He was, unfortunately, disappointed. He had a much better set of ears than I ever did, and the combination never sounded right to him. The Macs ended up powering subwoofers in various systems until more powerful solid state amps became available, and then went into storage with the intent of restoring them at some point.

As we all know, some point never comes—it just keeps receding into the distance. Gary contracted a really nasty prostate cancer and got very sick. Before he went, I spent several long weekends working on his house to help his family out. On one of his better days we took a break (he couldn’t do much at the time but eat ice chips and tell us which walls to pull down and which to keep) and sat together in the man-cave he had cobbled together in his garage, listening to the LP of Bill Schnee’s direct-to-disc mix of Thelma Houston through the Macs and the Tannoys. I bought them from him that same day. He passed in 2011, and the hole he left in my life is still an open wound.

This album is still the shit. Live stereo mix by Bill Schnee. Jim Keltner, Michael Omartian, Jim Gordon, Lincoln Mayorga, Larry Carlton, Dean Parks, Tom Scott, Chuck Findley, Larry Knechtel. Good fucking grief.

About halfway through my time on the Lopez Tonight show, probably around 2013, I replaced the tubes and set the Macs and the Tannoys up in the music mix room alongside the JBLs production provided. They imaged great, but I never really trusted the combination—the low mids were strange and I always sensed some level-dependent input distortion. Like Gary, I resolved to have the Macs rebuilt “at some point” and into the garage they went.

Terrible shot of the music mix room at Lopez Tonight. MC-40s and SGM-10Bs with lava lamp. 

I finally crossed “some point” in October of 2019, and decided the Macs should be heard from again. I looked around on the web and found, in South Dakota of all places, Bruce Brown, a guy who loves tube amps and does audio-centric rebuilds of McIntosh products among others. I started an email conversation with him about the Macs, and he agreed to take on the project.

Bruce is a bit of a purist. There are some places he insists on using NOS (new old stock) replacement parts for things like tubes and power transformers. There are other places he will only use brand-new parts because there are some newer parts that sound better than NOS and match the original McIntosh specification more closely. Unless you really insist, Bruce won’t re-chrome the chassis, or put in gold-plated RCA connectors, but he will get the amp as close as humanly possible to sounding the way it did when it left the factory. And he’ll give the chassis a good polishing anyways because the things are so damn sexy.

The one thing Bruce can’t stand is haphazard modifications to original schematics. And both of these amps had been modified extensively. (I think this was how Gary got them relatively cheaply—there is actually no really cheap McIntosh product unless it has been abused somehow.) Bruce’s rebuild revealed two things: one, neither amp left the factory as a stock unit. Both had been subject to modifications, perhaps as part of some kind of contract build, but there’s no real way to know. (I intend to research the serial numbers with McIntosh at some point [and there's that damn phrase again], but the chance that a factory floor change order made it into the permanent paperwork is slim.) And two, both amps had been modded after leaving the factory, one of them extensively. This did not please Bruce, and he proceeded to remove all of the offending wiring (along with all the dodgy component choices) and started over with parts he trusted, the original schematic, and a deep and abiding knowledge of what he was doing.

* * *

Sidebar for the truly geeky: 

When I first started communicating with Bruce, I mistakenly told him I had a pair of MC-30 monoblocks I wanted rebuilt. He told me what his normal MC-30 rebuild consists of and how much it usually costs, and I ordered some shipping boxes made especially for MC-30s. When the shippers arrived, I took the amps out of the garage, removed their protective plastic bags, and discovered they were not indeed MC-30s but MC-40s. There are slight physical differences between the two models, but with a few modifications I was able to use the shippers to send the units to Bruce.

McIntosh MC-30 monoblock tube amplifier with tube rectifier 

There is a cachet and mystique surrounding MC-30s that makes them more desirable in the vintage market than MC-40s. In the late 1940’s, McIntosh came up with a revolutionary design concept: the problem, up to that point, was that while the invention of the vacuum tube made high-power amplifier design possible, the tubes ran so hot there was an audible distortion penalty. McIntosh solved it by winding their own output transformers, a process that added significant expense and weight but also allowed the tubes to work more efficiently at lower heat. The MC-30 was a culmination of that design, simple and robust with great sound. McIntosh built the MC-30 from 1954-1962 and then replaced it with the MC-40 from 1962-1979.

McIntosh MC-40 monoblock tube amplifier with silicon rectifier (and 10 more useable watts)

The only substantive difference between the two models is a thing called a voltage rectifier. Amplifiers require DC to make audio rather than the AC that magically comes out of the walls. I don’t pretend to understand why. The rectifier “straightens” out the AC turning it into useable DC. The MC-30 has a tube-based rectifier because the solid-state silicon rectifier had only just been invented (along with the transistor). The MC-40 has the newfangled silicon-based rectifier, which allowed McIntosh to up the power rating of the MC-30 from 30 watts to 40 watts without having to do any other major modifications, hence the name change.

There is, of course, a contingent of tubethusiasts (I suppose in the UK they would be “valvethusiasts”) who claim that the change in rectifiers irretrievably damaged the sound of the MC-40s. There is yet another cohort who believe the change fixed a noticeable problem in the bass response of the MC-30. To illustrate, after the rebuild I was remarking to Bruce how tight and fast the bass feels now, and he explains:

“Since bass is a function of transformers and power supply storage capacity you now have the best of both worlds. The huge difference in the speed and depth is due to the solid state rectification. Tube rectifiers have a sag when large current draws occur. They still sound good, they just aren't as solid.” 

McIntosh indeed offered an aftermarket “damping kit” for the MC-30 and -60 models to address the problem.

And here is what I’m getting at with this arcane side trip: given what I know of Gary’s personality and his fascination with esoteric audio gizmos, it is entirely possible he figured this out on his own and sought out a pair of MC-40s on purpose. If so, I am the beneficiary, since the bass response of these amps is tight and fast while still being musical. If such a combination of imprecise adjectives can be applied to something as subjective as music.

* * *

And in conclusion...

Bruce gave me a detailed summary of what he did to the amps. Reduced to terms I can understand, it amounts to completely rebuilding the power supply using Bruce-approved parts, replacing most of the resistors, and replacing all the electrolytic capacitors (which dry out and can become dangerous in high-voltage devices like power amplifiers after 10-15 years). He also noted one of the amps had a wiring error that significantly affected performance. He maintains the replacement of the big power supply capacitors (techs call them “cans”) had the biggest effect on the sound, and recommends replacing all of the tubes with premium product at some point (there’s that phrase again). The results obviously made him happy: one amp measured 57.8 watts with no clipping (400Hz sine wave) and the other 59.6 watts. He said with the right tubes they will probably top out over 60 watts with no clipping (shows how conservative McIntosh was with their power ratings, doesn’t it?) with distortion measured at 0.5% at full undistorted output.

After examining my vinyl collection I am reminded once again of the reason I rejoiced when CDs began replacing vinyl. Put simply, I’m a slob. I use things, and I may accidentally leave them out for a year or two. I am not and never have been terribly fastidious about taking care of vinyl (I’m looking at you, Michael Killen) or making sure the stylus is still sharp, or any of that jazz. Spending some $ on a decent cartridge has changed me, however. For the sake of the needle I’m trying to avoid putting any vinyl on that hasn’t been cleaned first. I actually spent several hours last weekend washing my collection in the Knox spin-washer using distilled water. This is something I would never have expected of myself. And I have to admit, it makes a difference in the surface noise of records that have been abused over the years, as mine have. I think most of the peanut butter is gone now.