Jmcgrogan2,
Thank you very much for the info; it is greatly appreciated.
Dover,
I concur. |
I'm also looking at the Chinook as a potential upgrade to my current phono stage. It's got everything I'm looking for, except one thing: a relatively low gain of 60 dB for MC. This would suggest that it's not adequate for MC cartridges with an output below 0.5 mV, which eliminates a lot of great cartridges. This is almost as frustrating as John Curl's JC-3 phono preamp offering only one impedance setting of 100 Ohms for MC. That one I'll never understand. |
Lewm
Dear Actusreus, If what you say is true about the JC3 load resistor for MC, I share your chagrin, but one might always open the chassis, find said 100R load resistor, remove it, and replace it with a resistor of the desired value. I do agree that the task is tedious, if one wants to play with a variety of cartridges and/or experiment with different load values. I'm usually reluctant to mess with a product that is designed in a specific way. I always think there was a reason why a designer made his choices the way he did. I'd think that someone like John Curl knew exactly what he was doing when he fixed the impedance at 100 ohms, even though it is rather curious given other phono preamps in this price range. Atmasphere
This is almost as frustrating as John Curl's JC-3 phono preamp offering only one impedance setting of 100 Ohms for MC. That one I'll never understand.
The reason is if the preamp is resistant to RF at its input, the load on the LOMC is not critical. Its only there to reduce RF caused by the inductance of the cartridge interacting with the capacitance of the interconnect cable, which can form a tuned RF circuit. The resistor destroys the 'Q' of the circuit. IOW if the preamp works right, the value of the resistor is not important since it only works at RF frequencies. Atmasphere, I have to admit I don't fully understand your explanation as I don't have a technical background and my understanding of technical intricacies involved in designing playback equipment is rather limited. This particular aspect of the JC-3's design baffled me as the great majority of phono preamps in this price range (and certainly above) offer adjustable impedance settings for MC cartridges. It was also my understanding that it is so because impedance always mattered with MC carts, just like capacitance with MM carts; a mismatch can result in a less than optimal sound that the cartridge is capable of (usually expressed as too harsh on top or too mushy at the bottom). Admittedly, I played with load impedance settings in my friend's setup once with his remotely controlled Aesthetix phono preamp so any effect should have been immediately audible, but the differences were very subtle, if any. However, we both preferred his Dyna XV-1s at about the same setting, and we reached that conclusion independently. Fluke? Perhaps. Jmcgrogan2
Actusreus, I would think that 60 db of gain from a phono stage would be enough for any cartridge, unless possibly if you are considering running through a passive controller instead of an active preamp. Most will run the Chinook through an active line stage preamp (as the OP is here) which will add more than enough gain for any cartridge. If you use the KAB calculator, 60 dB of gain is optimal for MC cartridges with an output of 0.4 mV or higher. If that's true, the Chinook does not have enough gain for most Dynavectors, just to mention one popular manufacturer. The KAB calculator does not seem to take the gain of the line stage into consideration. From my experience, I certainly had phono preamps that simply did not have enough gain to produce a sufficient volume level with the cartridge I used (in this particular case a MM), even though the same amplification produced more than adequate volume levels for CDs. Doing the math, the KAB calculator seemed to be pretty spot on. My current phono stage has 55 dB of gain in the MC setting and I feel anything less would not be sufficient for my Lyra Delos's 0.6 mV despite the fact that my line stage has a variable gain. It appears that having the optimal gain at the phono stage level is more crucial than having enough gain downstream. At least in my less than expert opinion... |
Al, Thank you for linking to this article. I believe I actually have seen it before as it looks familiar. Interestingly, the author posits that a loading value of 100 ohms might indeed be suitable for MC cartridges in general. If so, are audiophiles unnecessarily obsessed about resistive loading, and manufacturers simply cater to that obsession? As always, I am sure the answer is more complicated than that.
Great point about the noise issue that's tied to increased gain. My line preamp has five gain settings and definitely noise increases as the gain is increased, so I try to find a setting that will provide an optimal balance of (low) noise and the weight, presence, and immediacy of the sound. It is still unclear to me why, but increasing the volume at a certain gain level will not render the same results as upping the gain at a given volume level. IOW, the sound is much better at a higher gain setting and lower volume, than lower gain and higher volume. The sound just lacks the heft and presence that it has at a higher gain. Perhaps that is why I am so focused on gain when it comes to phono stages... |
Thank you Al. I've always been interested in the interplay, for lack of a better word, between volume and gain. I understand they are obviously not the same thing, but certainly more gain at a given volume = louder sound. So with variable gain settings gain can also be used as volume control, even though in a more dramatic way.
As a correction to my post regarding resistive loading in the JC-3, it actually has two settings, not one, for MC cartridges: 100 Ohm and 47k Ohm. |
Jmcgrogan2,
I'm not sure, but as I mentioned in one of my posts above, my preamp has five gain settings so it certainly does have gain. I might be wrong, but I believe the KAB calculator only considers the gain of the phono stage. It's possible that an assumption is made as to the base line preamp gain. You can read more about this at www.kabusa.com
Btw, for a cart with an output of 0.24 mV, you apparently need 63 dB of gain so it makes sense that you found 66 dB to be more than enough. I just experienced the opposite a few times, so I am always very careful about matching the phono preamp gain with the cartridge output. |
Jmcgrogan2,
That has certainly not been my experience. My current phono preamp came with a factory preset gain of 29 dB for MM cartridges and it was not enough to drive my temporary Shure M97-xE that outputs 4 mV. It simply didn't have enough volume even though I could not go past 12 o'clock when I played CDs. I then had the manufacturer up the gain to 39 dB and it solved the problem. As an experiment, I also ran the cartridge using the built-in phono stage in my then-amp, Rogue Cronus Magnum, that had a gain of 35 dB in the phono stage before the line preamplification and the difference was tremendous. According to the KAB calculator, an optimal gain for the Shure was 38 dB...
I experienced a similar problem with my original cartridge, Soundsmith Aida, which had an output of 2.12 mV, when I used it with the built-in phono stage in the Cronus. When I switched to a separate phono preamp (Soundsmith MMP3) with 43 dB of gain, the volume was much higher and just sufficient, which obviously points to the low gain in the phono stage as the problem. Well, the KAB calc is 44 dB for an output of 2.1 mV so, in my opinion and experience, it provides a pretty good estimate of an optimal gain for a given cartridge in the phono stage independent of the line stage. How differences in line stages would affect that calculation, I frankly do not know. |
Thank you, Atmasphere. This does help with understanding the issue. I don't want to keep dragging this topic, but I must ask: if Fremer (or anyone else for that matter) hears clearly definable differences in the quality of the sound, not the noise, with different resistive loads when using an MC cartridge, is he full of it?
Jtwrace,
The Andros is a beauty and everyone raves about it, but it is also nearly twice the price of the Chinook, so they are really not in the same league. If you can afford the Andros, it seems it's an easy choice, at least on paper. elast |
So we have support for loading at 100 ohms and 47k ohms, and possibly everything in between. So to summarize, it depends... :-) |
Syntax,
That's a pretty bold statement that only those four phono preamps got it right given the many reputable brands out there. How many different units have your actually heard to make such a definitive finding? I'm by no means being critical of your statement, but simply curious how you reached it.
Speaking of the preamps you mentioned, do you know who distributes Klyne or how one can get more information about where you can audition one? The Klyne website has no contact or dealer information, which I find rather disappointing and unprofessional considering the target market.
Regarding the Atma-Sphere preamp, it appears there is no a stand-alone phono unit, but it's a built-in phono stage in one of the preamplifiers. Is that correct?
I'm also curious whether you heard the JC-3 preamp, which was compared favorably to the Vendetta by I believe Art Dudley in Stereophile not a long while ago. Your (and others') comments regarding the 47k ohm load also compel me to ask if this is purely a function of how good the preamp is, why do designers refer to the cartridge's design as the determinative factor, or flat out state something diametrically different? Here is a quote from the JC-3's description:
"MM 47 k ohm, MC 100 ohm or MC 47 k ohm; (MC 47 k ohm is ideal for high-end Grado moving iron cartridges)."
From the $26,000 Boulder 2008's manual:
"In the MC position, the maximum input resistance is 1,000Ω without additional components installed on the card. All four of the cards are shipped with a resistor to bring the impedance down to 100Ω, which is recommended for MC."
Are you saying Boulder claims their unit runs best at 100Ω because "they can't do it better"? |
Sorry, the Boulder's retail price is actually $36,000, not $26,000. Chump change. |
