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.

----

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
Jose, or anyone else, have you correlated RIAA error to colorations? As in, error of x amount or of y type leads to a z coloration.

Dan, in my experience the term "coloration" involves 2 facets:

On one hand you have a measurable deviation of flat frequency response of X dB, sustained over Y Hertz of bandwidth, which will cause an identifiable sound similar to that produced by the bands of an equalizer. ABX tests have been conducted showing that the audibility threshold is lower as the bandwidth of the deviation is increased. This simply means that we are more sensible to this error when it spans several octaves. RIAA stages are particularly vulnerable to this kind of coloration, simply because the RIAA curve is made up of 3 turnover frequencies affecting big portions of the audible band.

On the other hand, coloration is also a characteristic sound caused by a circuit's more intrinsic factors that can't readily be measured with conventional frequency-domain analysis. Nevertheless it manifests itself as a "fingerprint" in the sound (punching bass for instance). This type of coloration, at times enjoyable, will reveal itself more with the passing of time. This is mainly the reason why ABX kind of tests commonly reveal the first type of coloration, but fail with the second.

Enjoyable or not, decreasing coloration is a good thing in order to preclude our ear from extrapolating the musical signal into a predictable sound.
Raul, give it a rest. You're making the same points over and over again.

The salesmanship is getting old.
Thom, a replay curve that deviates more from the RIAA standard can sound better on select recordings, but it will almost certainly also sound worse on other recordings, compared to a replay curve that deviates less. My experience is that a flat RIAA curve is likely to allow you to enjoy more of your LP collection, not less. If 0.1dB or better is possible, go for it, as I think that on the whole, you will be ahead. The one categorical exception is when an LP contains sampling noise (sometimes CRT monitor noise). There are albums by Kraftwerk and Lorie Anderson that have this which I find painful. Everything sounds find until the sampler kicks in, and then I look for a wad of cotton, or wish that I'd designed an RIAA playback network that shelved down the top end (grin).

As an aside, the other possible solution for an RIAA playback curve would be to implement an EQ trim control, like with the FM Acoustics designs, or maybe a Cello/Viola Pallette. I've listened to and played with both, and yes, I can see their point.

I also find that a theoretically "better" solution - better power supply, better regulators, better amplification circuitry etc. will nearly always improve the sound of nearly every LP that you own. I don't find that "more accurate" means that you become more picky about the LPs that you can find enjoyable. Yes, you may become more aware of recording, EQ or mastering issues, but the music and performance comes through even more strongly, more than enough to overwhelm trivial concerns about the recording. The better my designs become, the more I appreciate a greater number of musicians.

I do find, however, that when it comes to component selection, you have to use your ears and subjective taste, in addition to your head. I've picked components that on paper should have been the cat's meow, but in listening turned out to be a pig's kiss instead. The designer cannot know each minute particular of every component that he chooses, and as they say, the devil is often in the details. So unlike the case with overall topology or circuitry or layout, with components I find it necessary to have a "range of candidates" on hand and go with whatever sounds the best - in the context of the circuit being tested. Engaging in this is more like cooking or choosing clothes than it is intellectual design, and is the phase where the more artistic types can strut their stuff, and pull level with or even ahead of other designers who may be their intellectual superiors. That's the fun part about audio (designing it as well as using it) - there is a place for the sensibilities as well as the intellect.

regards, jonathan carr
Dear Thom: With this I'm finish:

+++++ " Your "it has to be perfect" mantra is really tiring me out " +++++, that's what I posted: we are different in this subject but I can asure you that we have more in common than differences about sound/music reproduction.

+++++ " I'm sorry, Raul but as good as the Essential is, it is as colored as many of the other fine RIAA/line stages I rank in the top tier (and the Essential is a fine piece). " +++++

Absolutely, I never speak that it is not only that we try to leave those distortions/bad colorations at minimum, that's all.

+++++ " Please get over it and realize that no one can be all things to all people " +++++

Absolutely, I don't think in other way: I agree.

+++++ " Regarding Audio Puritans, " +++++

No. I'm not: I'm only trying to be better.

+++++ " a very lean and modern sound. " +++++

No, it is not ( I don't know what means " modern sound " ): the sound perception depends on the whole system and my point of view about is that our design is very high revealing of what happen in all the audio chain because that design does not hide almost anything out there, of course that the Essential is part of that audio chain and puts its " grain of salt " about.

The diffrences is how you, other people and I perceive the sound reproduction in an audio system and how be related against the live event or at least near to the recording.

Our attitude/philosophy in the electronic audio design is: truer to the recording and you can't blaim me for that, it is only a way to think that is a little different from yours and other people but there are other people that think in the same way that us: our design goes for that people and we will wait that the other people could change ( a little ) in the future, no our design is not for all in the same manner that horns speakers are not for every one.

Thom, thanks to our differences we have some fun and we can learn a lot about those differences, don't you think?

Regards and enjoy the music.
Raul.
Raul:
Our attitude/philosophy in the electronic audio design is: truer to the recording and you can't blaim me for that
You probably mean "truer to the reference riaa de-emphasis curve". Whihc, hopefully, means closer to the recording. After all, the phono equaliser only equalises whatever is picked up by the TT setup and transfered through the wire & connectors...:)

BTW, Raul, do you have an added pole at 3,18us as well as 75us?