Raul, are you thinking of the Goldpoint series attenuators for your and my Phonolinepreamp? Yes, you did advise me to replace the originals with those Goldpoints that use SMDs. Can you tell me what value, in terms of Kohms? One thing I noted is that Goldpoint claim they no longer need to sell ladder type attenuators (one resistor in circuit per position both in series and in parallel with the signal) because the SMD resistors raise the quality of the series type to that of a ladder type. (For others, series attenuator will have a string of resistors soldered end to end, with resistors added as you go increasingly attenuate the signal. This is usually inferior to a ladder type attenuator, if you are seeking Nirvana. Since there are so many solder joints in a series type attenuator circuit, it is no wonder at all that SMDs will work better.) I probably should look into doing the mod but when I did, I also considered using Khozmo shunt type attenuators and got stuck on the decision between the two. I use the Khozmo stereo balanced shunt attenuator in my MP1 and they are excellent. A shunt type places only one resistor in the circuit in parallel with the signal per setting. What I tried to convey to Mijostyn is that I would not choose between two components based ONLY on the fact that one uses SMDs and one does not or that one uses fiberglass PCBs and one does not.
Showing 17 responses by lewm
Fremer by and large has better equipment than most of us have, not necessarily better hearing. He's old, like we are. Like I said before, what is the big deal about SMD components? Good for op amps in circuits with very very wide bandwidth but not necessarily an audible upgrade with a phono stage. That said, the quality of construction of the Seta circuit does appear to be very high, judging only from photos. I've not seen the innards of a BMC. I'm not buying any time soon, or maybe ever. |
Without ever having heard or even seen any current drive phono stage, my current favorite just based on tech and reviews and cost, plus balanced operation, would be BMC MCCI. I suppose some aspects of SMD construction are beneficial, especially in a device centered around an op amp, but not all, and not when repair is needed. |
Here is the vdH website on their phono stages: https://www.vandenhul.com/product-category/electronics/ The way I read it, the SB offers balanced operation; the base model may only offer XLR inputs into an SE circuit. I don't know. The language is only a little less vague and confusing than what you find on the Channel D website. Clearthinker, I think you made the most cost-effective choice among the many Grail iterations, but it occurs to me that their statement about auto matching for cartridges in the 40-400 ohm range might mean that if the cartridge has an internal Z of 4 to 40 ohms, which covers just about all low output LOMC types, then the current drive stage will accommodate it. It's a bit confusing and suggests that voltage drive is an option. I cannot blame drbond for being confused. But you own one, so let us know. Most reviewers don't have a clue. |
Boothroyd, I found this in the Sussuro cartridge owners manual: "Please also note that some designs of “current amplifier” preamp circuits will not allow loading in the range required, causing the Sussurro MK II ES to sound very dull – caused by improper loading, resulting in loss of high frequencies." What I could not find was a spec for the inductance of the Sussuro, but if memory serves it is about 50 mH. This would give an impedance of 314 ohms at 1000Hz. Let's say it's only 10mH; then divide 314 by 5. Still high for a typical current driven phono. Add the impedance due to inductance to the coil resistance of only 10 ohms. I emphasize again that I love MI cartridges as a rule. This is more about the usefulness of most current driven phonos stages. |
Hi Ralph, You wrote, "This suggests that as the impedance of the cartridge goes up, the gain of the circuit goes down, which is probably good since the output of the cartridge will be higher." The linear relationship between voltage output and stylus velocity (higher at higher frequencies) is accounted for by the RIAA correction. Would you want the cartridge to alter that relationship by virtue of an upgoing internal impedance? Also, the paradigm for current drive is you want the cartridge to have a very low internal resistance/impedance to begin with, which makes it a decent current generator. Obviously, I am parroting ideas that are in the air without much depth of knowledge. But this question points out how consumers are a bit confused by "current drive" or a term like "transimpedance". I think there are an array of products that each may do it differently enough to defy generalization. |
Boothroyd, LOMC cartridges, like the Lyra cartridges you mention, will have inductance in the low micro-Henry range. The low output MI cartridges made and marketed by SS have an inductance in the low milli-Henry range. In other words, the inductance of their LOMI cartridges is about 1000X higher than that of a Lyra or other typical LOMC. (This is no attempt to critique the SS cartridges; I actually prefer MI cartridges over most other types, and I am grateful to SS for carrying the MI banner.) The point is that level of inductance might affect the cartridge's capacity to produce signal as current, especially at high frequencies. Thus I am curious about what happens when you mate a Sussuro, for example, with a current driven phono stage. |
"Suitable" = very low capacitance, I assume. My question was more about the effect of MI inductance on cartridge output impedance as frequency increases and how that affects the efficiency of current drive. It would be of interest to know which of the many "transimpedance" phono stages PL uses. Because my own investigation indicates they vary quite a bit in input impedance, some not so close to zero as one might like. |
Dover did not mention what current driven device he is using, so far as I can see. However, he did say he feeds its output to the phono section of a Marantz 7 preamplifier. That suggests he is using one of the very few available outboard devices that do the current to voltage conversion ahead of any conventional MM phono stage. I think Sutherland makes such a device and a few others. I think that's a great idea, as it does not require or may not require a major purchase cost for a whole new phono stage. I am using such a device that was custom made for me, not commercially available. I use it only with the Ortofon MC2000 cartridge. Output goes to a modified Silvaweld SWH550 phono stage in MM mode. I have two other voltage driven phono stages that both have enough intrinsic MC gain for any of my other MC cartridges. I did some reading on the van den Hul Grail. The basic unit seems to be SE only. The SB version costs nearly twice as much and provides balanced circuitry and some other unique features. Depending upon whose review you read, the RIAA correction is done using either only inductors and resistors (LR type) or using capacitors along with LR (LCR). Then there are the SE and SE+ versions that cost 3X as much as the base and include upgraded power supplies. I am not sure whether the base model (~$9000) has the fancy RIAA circuit or not. Fremer compared the base and the SE versions to the CH Precision with X1 PS. |
Ledoux, First, thanks for being one of the first among us to make a direct comparison and to report on your result. You wrote, "The tube/ voltage mode phono sounds more vivid, the SS current mode sounds more warm and relaxing." It's a matter of semantics but the words "vivid" and "warm and relazing" convey (to me, anyway) very similar feelings about how the two stages sound side by side. But perhaps you chose those adjectives to show how close they are. Especially since you describe the voltage amplifier as also being more "dynamic"; to me that also goes with vivid. I guess the main point is that you prefer the voltage mode phono stage, adjectives notwithstanding. On the Channel D Lino, did you choose a version that does RIAA in the digital domain, or is it all analog? Both of your cartridges ought to be very good at producing current, based on dividing their output voltages by their respective internal resistances (V/R = I). I totally agree on your opinion that one technology is not necessarily superior to the other, given one uses either with an appropriate LOMC. Current drive is just a la mode at this moment. We also have LCR and LR types of RIAA correction that have drawn attention in the last 5-10 years. |
See above. For current drive the phono stage input impedance needs to be as near zero as possible so as to “see” the cartridge as a current source. It also has be amplified by current and to put out amplified voltage in response to current. That’s why I called it an I/V converter. Ultimately the stage has to put out amplified voltage just like a conventional stage. It’s basically as simple as Ohm’s Law. Conversely a conventional voltage driven stage has to have an input impedance that is a multiple of the cartridge internal resistance, in order to amplify its output voltage. |
Just to embellish what Dover wrote, the upshot of his analysis is that for LOMC cartridges with very low internal resistance (10 ohms or less?), all other things being equal, a current drive phono stage makes a lot of sense (because the capacity to produce signal as current is inversely proportional to the internal resistance). But you will not want to use such a phono stage with MM or MI cartridges and even not so much with some LOMCs that have a relatively high internal resistance, e.g., >20 ohms, although that is far from a hard cut-off. From what I can tell, most current drive phono stages consist of an input stage that converts current to voltage. Downstream from the I/V converter is pretty much like any other high gain phono stage. |