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In Reply to: The Importance of Audio Measurements posted by Phil Tower on November 19, 2002 at 15:13:35:
Everything I've seen indicates Rowland equipment is very fine."The measurement criteria usually involve flat frequency response, insignificant static and dynamic nonlinearities, high input impedances, low output impedances, low noise and crosstalk levels, etc."
I notice from the Rowland site that the specifications and reviews indicate excellent performance in those respects, and that the amplifiers can deliver substantial power into low impedance loads, too.
Well, one thing we agree on is that many of the usual measurements of electronics don't tell us much useful for choosing between them. Many of the measurements are so good that they do not indicate an audible difference in normal operation. It is always possible that something else may cause an audible difference, but I would like to some some good evidence.
No question either that electronics should filter out hum and RF from the power lines. I think most good equipment does.
As to the multi-tone measurements and cable microphonics, it would be nice to see some quantified results, and of course, DBTs. But you already know that. I have no objection to choosing equipment because it does well on such measurements or others, BWT. My equipment is overkill in many respects. But it would be nice to establish whether the difference is audible under normal circumstances.
I would point out that Rowland does seek to correlate measurements with sonic characteristics. Does that make him an objectivist in principle?
____________________________________________________________
"Nature loves to hide."
---Heraclitus of Ephesus (trans. Wheelwright)
Follow Ups:
On the subject of overkill, I once heard someone say that anyone with an unlimited budget ought to be able to build the best. It's the engineer who has to design to a real world budget that has the real challenge. Rowland is not the most expensive gear in the world, but Jeff certainly has a lot of lattitude within his budget constraints that others don't. Whether my Model Twelves at $14,000 retail can out perform John Curl's JC-1s at $6,000 I don't know, but I'll be comparing them soon.As to the multi-tone measurements and cable microphonics, it would be nice to see some quantified results, and of course, DBTs. But you already know that.
Yes, I certainly agree. One reason I picked this particular quote is because it seemed to have a little more engineering detail than most high end websites. Nonetheless, it raises more questions than it answers, and obviously has its share of hype-factor.
I would point out that Rowland does seek to correlate measurements with sonic characteristics. Does that make him an objectivist in principle?
Probably, but we don't know where he stands on blind testing, and, despite some of the doubts and questions I've raised regarding blind testing, I still maintain that blind listening tests will be the only way that true objectivity can every be achieved in audio (and I understand that for some that is not necessarily their objective). It always has seemed a little strange to me that not a single manufacturer of high end electronics can, to the best of my knowledge, claim that the effectiveness of their various theories of technological superiority has been subjected and validated through blind testing. Of course, I know to many objectivists this doesn't seem strange at all, since they strongly suspect those claims cannot be validated.
Too bad more designers don't or won't participate here. For all the grief I and others have given John Curl, while he may have deserved some of it for his abrupt responses, I give a lot of credit to him for being willing to open himself up to all of us and for being extremely honest and blunt in expressing his own personal beliefs. I wish more designers would show the willingness he does to participate. For example, wouldn't it be interesting to press Jeff Rowland a little on some of the statements he made in that article?
Quoting two levels: Level 1: As to the multi-tone measurements and cable microphonics, it would be nice to see some quantified results, and of course, DBTs. But you already know that.and 2: Yes, I certainly agree. One reason I picked this particular quote is because it seemed to have a little more engineering detail than most high end websites. Nonetheless, it raises more questions than it answers, and obviously has its share of hype-factor.
If you still have an LP table, just try tapping the side of one of your low-level phono cables. Just to make sure it isn't the cart being microphonic, hold that end (not an absolute test, of course).
You may be surprised. You may have to turn up the gain, but then you'll be surprised, too, maybe.
You'd be surprised what can be a microphone under the wrong conditions :)
JJ - Philalethist and Annoyer of Bullies
Setup a PA system for touring the magnet division factory last summer. Found that balanced mike runs, when they hit the floor, produced exact replica's of the cable to floor impact through the speakers. Not noise, but perfect microphonics. With the mikes off. And every cord I tried. Six in all.I do suspect, however, that it was a combination of the plus to minus wires in the cable bouncing w/r to each other, and the stray magnetic fields present in the concrete rebar, on the order of tens of gauss.
The braid shielding of course, doesn't stop the external magnetic field from penetrating to the conductors.50 ohm cables are microphonic also. Take a scope, plug in a cable, and hit the cable end on the floor. There will be an interesting waveform on the scope.
TTFN, John
Well, I just tried it. I put the preamp on Disc, turned the preamp gain all the way up (in steps, just to be safe; of course, there was some broadband hiss at full volume), and tapped the phono cables. Couldn't hear any result from the tapping out of the speakers.I also tried my headphones through the headphone jack of a tape deck (my preamp has no headphone jack), and could hear nothing from the tapping, but the gain isn't really very high in that case, though more than adequate for music.
I imagine the effect would be measureable, but in this case, I couldn't hear it.
____________________________________________________________
"Nature loves to hide."
---Heraclitus of Ephesus (trans. Wheelwright)
Wow, even I would have expected it from the Phono cables, but certainly not the regular interconnects - impedance is too low.I've done this on an oscilloscope numerous times, especially with unterminated teflon cables, it's easy to see the results - until you put a low impedance(resistance) load on them, then it's gone.
Isn't the standard phono input impedance 47 kilohms?
____________________________________________________________
"Nature loves to hide."
---Heraclitus of Ephesus (trans. Wheelwright)
Yep, 47k is it.
Some call for 47K input. Some don't. Some call for rather orders of magnitude less.And a few (does anyone know if any of those old ceramic THINGS are still out there) expected something like 2.2 meg.
JJ - Philalethist and Annoyer of Bullies
I have a Grace F9E.The Quad preamp is spec'd for a phono input impedance of 47K, with a choice of adding in 180 pF capacitance, which would be in addition to whatever the phono cables had. The extra capacitance introduces a roll off in the FR, about 5-6 dB at 16K if I recall, which generally sounds way too dark. In any case, the phono cable I tapped on is on the outside the TT, a Denon DP-60L, which Dougman says is fine, BWT. If I tap the cartridge or tone arm, of course I can hear something.
Now, if I had a low output moving coil, which requires more gain, perhaps I would hear something. Quad used to have different input modules available for moving coils, and they may still be available.
2.2 meg? Gee, my Radio input is only 1 meg; CD input .5 meg; the rest are about 100,000 ohms (varies somewhat with the input sensitivity, which is adjustable). I really don't know anything about the availability of ceramic cartridges or replacement needles.
____________________________________________________________
"Nature loves to hide."
---Heraclitus of Ephesus (trans. Wheelwright)
The lowest of the two impedances the cable see, is normally the source impedance, say 1kOhm for MM, down to 2 Ohm for MC.The source impedance load down the cable's generator, which is a high impedance generator.
Microphones often have 600 Ohm source impedance and low levels, making this cable microphonic effect audible.
Preamps and CD players have from a few Ohms to 2kOhm source impedance, but much higher levels, and thus relative less audible effect of microphonic cables.
I have no idea what the source impedance of a Grace cartridge is.What sort of magnitude are cable microphonics?
____________________________________________________________
"Nature loves to hide."
---Heraclitus of Ephesus (trans. Wheelwright)
Ole is correct. The Grado cartridge is low Z.
Well, I do own a Grado cartridge, but I no longer use it. They are supposed to maintain their FR pretty well into various capacitances, as I recall.I currently use a Grace F9E. Is it low impedance, too?
____________________________________________________________
"Nature loves to hide."
---Heraclitus of Ephesus (trans. Wheelwright)
I don't think so.
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