What Makes a Good RIAA or Line Stage?


Hi Doug,

In a currently running thread on a certain RIAA / Line stage beginning with the letter "E", some very provocative comments were made that are of a general nature.

I fear that this conversation will be lost on the many individuals who have soured on the direction which that particular thread has taken. For the purpose of future searches of this archive, those interested in the "E" thread can click this link.

For the rest of us who are interested in some of the meta concepts involved in RIAA and Line Level circuits, I've kicked this thread off - rather than to hijack that other one. In that thread, you (Doug) mused about the differences between your Alap and Dan's Rhea/Calypso:

... the Alaap has the best power supplies I've heard in any tube preamp. This is (in my admittedly unqualified opinion) a major reason why it outplayed Dan's Rhea/Calypso, which sounded starved at dynamic peaks by comparison.

Knowing only a bit more than you, Doug, I too would bet the farm on Nick's p-s design being "better", but know here that "better" is a very open ended term. I'd love to hear Nick's comments (or Jim Hagerman's - who surfs this forum) on this topic, so I'll instigate a bit with some thoughts of my own. Perhaps we can gain some insight.

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Power supplies are a lot like automobile engines - you have two basic categories:

1. The low revving, high torque variety, characteristic of the American muscle car and espoused by many s-s designers in the world of audio.

2. The high revving, low torque variety characteristic of double overhead cam, 4 valves per cylinder - typically espoused by the single-ended / horn crowd.

Now, just as in autos, each architecture has its own particular advantage, and we truly have a continuum from one extreme to the other..

Large, high-capacitance supplies (category 1) tend to go on forever, but when they run out of gas, it's a sorry sight. Smaller capacitance supplies (category 2) recharge more quickly - being more responsive to musical transients, but will run out of steam during extended, peak demands.

In my humble opinion, your Alap convinced Dan to get out his checkbook in part because of the balance that Nick struck between these two competing goals (an elegant balance), but also because of a design philosophy that actually took music into account.

Too many engineers lose sight of music.

Take this as one man's opinion and nothing more, but when I opened the lid on the dual mono p-s chassis of my friend's Aesthetix Io, my eyes popped out. I could scarcely believe the site of all of those 12AX7 tubes serving as voltage regulators - each one of them having their own 3-pin regulators (e.g. LM317, etc.) to run their filaments.

Please understand that my mention of the Aesthetix is anecdotal, as there are quite a few designs highly regarded designs which embody this approach. It's not my intent to single them out, but is rather a data point in the matrix of my experience.

I was fairly much an electronics design newbie at the time, and I was still piecing my reality together - specifically that design challenges become exponentially more difficult when you introduce too many variables (parts). Another thing I was in the process of learning is that you can over-filter a power supply.

Too much "muscle" in a power supply (as with people), means too little grace, speed, and flexibility.

If I had the skill that Jim Hagerman, Nick Doshi, or John Atwood have, then my design goal would be the athletic equivalent of a Bruce Lee - nimble, lightning quick and unfazed by any musical passage you could throw at it.

In contrast, many of the designs from the big boys remind me of offensive linemen in the National Football League. They do fine with heavy loads, and that's about it.

One has to wonder why someone would complicate matters to such an extent. Surely, they consider the results to be worth it, and many people whom I like and respect consider the results of designs espousing this philosophy of complexity to be an effort that achieves musical goals.

I would be the last person to dictate tastes in hi-fi - other than ask them to focus on the following two considerations:

1. Does this component give me insight into the musical intent of the performer? Does it help me make more "sense" out of things?

2. Will this component help me to enjoy EVERY SINGLE ONE of my recordings, and not just my audiophile recordings?

All other considerations are about sound effects and not music.

Cheers,
Thom @ Galibier
128x128thom_at_galibier_design
Quite so, Mothra. I've been at recording sessions where I was able to physically put my ears where the microphones were, and then listen to the electrical feed from microphones. In the majority of cases, there is a substantial difference between what the ear and microphone hears, even from the same location. And in most modern recordings, a variety of microphones are used, and each modifies the sound in distinctive ways.

Also, the location and angle of the microphones will in most cases be quite different from what you would hear if you were at a performance of the same event. Most microphones are located far closer to the instrument than any audience seat, and the angles will be quite different, too.

If you have a friend who plays the violin (for example), it is very instructive to listen to it being played at a distance (like you would hear from an audience seat), then listen to it from a distance of under one meter to get the microphones' perspective, and also listen to the instrument from above (again to get the microphones' perspective).

Now put all of the above together and think about the implications for a home audio reproduction system. Since the recording likely does not sound like what you would have heard live from a seat in the audience, if you have set up your audio system to sound like what you'd hear live, it is almost certain that your audio system is modifying what's on the recording, and not in a small way, either!

However, there are recordings that include a list of the equipment used, and also microphone placement drawings. If you know what the recording gear sounds like, and also study the placement drawings, you can form a closer guesstimate of what these recordings should probably sound like, and this can be a somewhat better guide to setting up your system (although you still won't know what the mixing contributed, as Mothra pointed out).
yes, and some of those "you are there" recordings like roy dunan's Rollins "way out west" are all u-47's and c-12's. very colored mics with a lot of proximity effect in cardioid pattern. I'm do this for a living and I can't make a record sound that good (nor have i ever had players of that caliber), so i'm not knocking it. But you're right that the live sound and the mic feed is often very different. Sometimes good, sometimes bad.

I have great respect for your ability to make cartidges that bring out those colored sounds with an even hand though!
And my hat goes off to you, and all recording engineers who capture those great performances which justify our having audio systems!
It is really helpful to work with live recording sessions and master tapes, especially if they find their way to LP!

I've done a lot of recording and after a while you get used to the way your mics 'hear' and place them where they will get the effect you are after- not always where you would put your ears.

Hagtech is quite correct that the device does not have to be inductive; IOW a balanced source is certainly not limited to inductive devices (like microphones, transformers and cartridges). You can even get ceramic devices to be balanced, but who would want to- like frying an egg on the sidewalk :)

IMO, careful design of differential balanced circuits includes the use of properly designed constant current sources and you will want to have a properly regulated power supply too. A proper CCS will dramatically increase the differential amplifier's ability to reject power supply noise, and again if done right seems to reduce the overall noise floor of the differential amplifier as well.

I my case where this took me was less stages of gain overall. Figuring out what the tubes needed to be quiet was the key.
I my case where this took me was less stages of gain overall. Figuring out what the tubes needed to be quiet was the key.
Ralph, It sounds like you and my friend Mr. Doshi are working from similar briefs, and from experience I know that's a good thing. I haven't heard your preamps but I think I'd like them.

Mothra,
It's great to see you posting here. Thom's thread has collected an impressive group of designers, plus some lucky listeners like you and me.

Your comments on cohesiveness vs. transparency nicely outlined the divide between the majority of rock listeners (I think) and a minority - like you and me - who prefer transparency to the source even for that genre. For better or worse, my ears usually won't let me enjoy a less transparent component once I've heard a more transparent one. I can't stop hearing temporal smear or overhang as an artifact, even if it blends some music or recordings into the appearance of a more seamless whole.

I recognize I'm in the minority on this, at least among rock listeners. It has occasionally gotten me into trouble with them, since we hear or respond so differently. Even Paul, whose ears are faster than mine, prefers a more cohesive sound for rock.

BTW, which B&W's do you have? I recently tried something on my N803's that I hadn't bothered trying for a couple of years - removing the tweeter screens. We've always listened without the mid/bass grilles, but when I removed the tweeter screens two years ago the sound did not improve. IIRC it sounded more shrill. That didn't make sense to me at the time, but I now understand I had HF problems (including smearing) with upstream components and wire. Removing the screens was letting me hear those more clearly.

Our upstream components are now *much* better, including Nick's preamp, amp and nearly everything else. Removing the tweeter screens now provides a large improvement. HF's are clearer and less edgy, imaging/soundstaging are much improved, just what you'd expect from removing all that diffracting wire mesh. Bass clarity has improved too, which I find weird. People report that supertweeters give a surprising boost to bass quality and removing our tweeter screens has had a similar effect. Try it if you haven't.

Sorry for the digression folks. Back to the preamp-a-thon.
Doug