@lewm Yeah, i know you like Ralph prefer 47k for LOMC I can do that too with my Gold Note PH-10 or with JLTi phono stages, but this is another story. I have separate vintaage Luxman toroidal silver SUT for carts with 3 Ω (DC Resistance) or less. But for that god damn WLM Phonata i have to choose an appropriate Lundahl SUTs to replace stock SUTs on PCB. I have no idea about parameters of the stock SUTs i have in it. That "Automatic impedance" confusing me. I’ve checked the article here and there to understand. I know that 1:10 is safe, but my cartridges are lower in output than 0.3mV: 0.050 mV (Ortofon MC2000) / DC resistance 3Ω 0.15mV (FR PMC-3) / DC resistance 8.6Ω 0.2 (Klipsch MCZ Ruby) / DC resistance 2Ω 0.24mV (FR-7fz) / DC resistance 5Ω Which step-up ratio of the SUT would you choose for example for your Ortofon MC2000 ? 1:32 or more ? I’ve checked K&K Audio for which Lundahl SUTs installed in their kit. There are two kits (basic and premium). Basic with LL9226 http://www.lundahl.se/wp-content/uploads/datasheets/9226.pdfPremium with LL1931 http://www.lundahl.se/wp-content/uploads/datasheets/1931.pdf Maybe i have to choose one of these SUTs from Lundahl to soldeg them in my WLM instead of the cheap stock SUTs i got there now. |
I want to make sure we are talking about the same thing. Cartridges have a fixed DC resistance (DCR) if you measure the resistance between hot and ground connectors for each channel using a simple ohmmeter. Cartridges also have an output impedance, which would be the DCR + any changes in impedance with frequency of the audio signal. However, we are typically not told much about the frequency-dependent resistance, except usually we get a figure for "inductance", which is very low for most LOMCs. Anyway, I usually would go by the internal resistance (DCR) in order to choose a load resistance on the phono stage side or in thinking about an SUT. Rule of thumb says you want the ratio of the output impedance (in this case, the DCR) to the input impedance to be at least 1:10 or thereabouts. Also, in choosing an SUT, we need a certain minimum turns ratio to guarantee that the signal at the secondaries of the SUT will be sufficient to drive the downstream phono circuit. The turns ratio then has to interact with the load resistor at the phono circuit input, usually 47K ohms. As you know, the impedance "seen" by the cartridge will be equal to the phono load (e.g., 47K ohms) divided by the square of the turns ratio. So, if the turns ratio is 1:10, affording a voltage gain of 10, then the impedance/resistance seen by the cartridge would be 470 ohms (47K divided by 10^2 or 100). Any typical LOMC can drive the 470 ohm load, because any typical LOMC has a DCR <47 ohms, which exceeds the desired 1:10 ratio of output to input impedance. If your LOMC cartridge makes at least 0.3mV, the net signal voltage after the SUT would be 3 mV, enough to drive most MM phono circuits with at least 40db of gain. (This also depends upon the input sensitivity of downstream components and the efficiency of your speakers.)
I have two very different phono stages, but both have sufficient inherent gain for any LOMC that I can imagine. I now find that I prefer to listen to most LOMCs with "wide open" loading, setting the load R at 47K. That cannot be done with an SUT, because of the obligatory effect on impedance, in relation to the square of the turns ratio, that is a property of any SUT. |
@lewm You are right, i thought it was a current-driven because of the "Automatic Load Impedance" feture advertized by the manufacturer, and because of the comments in the beginning of my post (from 2015). But never too late to learn. As we noticed now the real current-driven phono stage works best with cartridge with very low impedance. But based on a comment from one of the WLM owner (from 2015): "The Phonata works very well between 25 - 100 ohm cartridges". And base on info from the manual: " MC-Input Impedance Range: < 100 Ohm to 50kOhm". This is definitely opposite to the current-driven phono stages. In the beginning of this thread two people made two different comments: @hdm The Phonata operates in current mode with MC cartridges. Not anything really new here. I’ve been using an Aqvox for about 7 years now which operates similarly. @larryi It may be the case that "automatic" really means "fixed." There are some manufacturers that don’t think that any sort of precise setting of loading is important and so they go with a reasonable fixed value, typically somewhere around 125-150 ohms (e.g., Linn).
With the phonostages I have worked with, I like relatively little loading (high value resistor such as 47k) or no loading at all. Over a huge range of values, I don’t hear that much change except for an undesirable loss of top end "air" with values lower than 125 ohms. So i think Larry was right. The question is which SUTs step-up ratio i have to choose now when i will replace WLMs internal SUTs if my cartridges are all low impedance (under 8 Ω estimate ) and low output (under 0.25 estimate) ? |
So the Phonata is not, in fact, a current-driven phono in the way that the Aqvox and BMC MMCI and several others are. Somewhere I thought you said it was.
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So the Phonata is not, in fact, a current-driven phono in the way that the Aqvox and BMC MMCI and several others are. Somewhere I thought you said it was.
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@sksos1 Well, thanks, but i think you missed the point, i have an external SUTs and headamps, but this topic is about WLM phono stage with internal SUTs, they are small and mounted on the motherboard inside my phono stage. I don’t need another external sut. Also i trust SUTs manufacturers like swedish Lundahl more than to a local DIYers. Lundahl made SUTs since 1958. All i need is to solder two better SUTs directly to the motherboard of my existing phono stage. |
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To summarize it from the manual: WLM is An inductive VOLTAGE AMPLIFICATION (SUTs) + A solid state CURRENT AMPLIFICATION stage (MOS-FET) There is a separate MM phono stage inside and i’m happy about the quality of it with 100k Vishay load resistors. My upgrade now is all about separate MC part of Phonata, so i think i will replace SUTs and i will also replace stock 47k Ohm resistors in MC path with better qulity 47k Vishay. I wish i could just measure step-up ratio of the stock SUTs to replace them with similar, but better quality SUTs from Lundahl catalog. Actually recommended by Lundahl SUT (as safe alternative) is very small LL9226: http://www.lundahl.se/wp-content/uploads/datasheets/9226.pdf Turns ratio and possible use at different termination alternatives for this SUT: A Turns ratio: 1:5 Copper Resistance: 20Ω / 260Ω Suggested use for best frequency response: MC cartridge < 100Ω C Turns ratio: 1:10, Copper Resistance: 5Ω / 260Ω Suggested use for best frequency response: MC cartridge < 50Ω E Turns ratio: 1:20, Copper Resistance: 1Ω / 260Ω Suggested use for best frequency response: MC cartridge < 25Ω ------------------------------------------------ Actually most of my MC cartridges have a fairly low impedance such as 2Ω, 3Ω , 5Ω, 8Ω ... only one of my MC has 20Ω impedance. So maybe i need another SUT from their catalog with step-up ratio ? |
There is another thread of much more recent origin around current-driven phono stages. But in any case, by definition, a current-driven phono stage with so-called automatic impedance loading would not require an SUT. As I think I wrote elsewhere, these stages try to offer zero input impedance to the cartridge, and they only work really well with very LOMC cartridges that have very low internal resistance, less than 10 ohms. (This is based on my own understanding of what I can find on the internet. I am not an EE; I only pretend to be one on Audiogon.) So, the first tube or transistor of the phono stage itself acts like an I/V converter to drive the downstream phono circuit with voltage output. It’s really not so complex. This circuit would work but less well with LOMCs that have internal resistances above 10 ohms, would not be recommended at all for HOMCs or MMs. But I guess the Phonata has separate dedicated MM inputs. I am curious to try one myself. Which is to say that I am curious to try a current-drive phono stage, not necessarily the Phonata. I've had my eye on the BMC MCCI.
Conversely to my description, if the Phonata does incorporate an SUT in its LOMC circuitry, it probably is not a current-driven phono stage in the technical sense, although I suppose you could say correctly that a SUT converts current to voltage too. |
@lewm we’re talking about internal SUTs on the motherboard inside WLM phono stage. WLM Phonata has "Automatic Load Impedance for MC" as its unique feature or a simple marketing? I wish to know, the unit is long time out of production, company went out of business and returned re-branded with different owners, strange story. No tech support from WLM for old products. As our Fleib pointed out it can be just a "fixed impedance", other users pointed out it can be a "current type phono stage". I had no idea what is a "current type phono" back in 2015 when i started this thread, simply a lack of knowledge. It’s an old post as you can see, last year i have opened up this phono stage to replace 47k Ohm resistors for MM input (for a Vishay 100k Ohm). I’ve noticed the SUTs inside (you see one between the caps) does not looks like Lundahl SUTs, now i decided to upgrade the caps with higher grade Audyn Reference (ordered this week). I want to replace the internal SUTs with Lundahl LL9226 ( here is the whole catalog). Last night i have re-read the whole thread again. Maybe it’s not a current type phono stage? --------------------------------------- FROM THE MANUAL: The PHONATA works with two-stage amplification: • An inductive VOLTAGE AMPLIFICATION stage (for MC cartridges) using high performance professional audio step-up transformers. • A solid state CURRENT AMPLIFICATION stage, using specific MOS-FET transistors with tube-typical harmonic distortion characteristics. • You don’t have to adjust the load-Impedance of your cartridge (plus the interconnect-cable between cartridge and Phono-Preamplifier). It goes automatically thanks to one ingenious piece of circuitry. • You don’t have to adjust the source voltage of your cartridge as well. • There are no micro-switches or any other mechanical contacts in the signal-path. Technical Data: MC-Input Impedance Range: < 100 Ohm to 50kOhm MM-Input Capacity: 100pF THD (Total Harmonic Distortion) @ 1kHz: 0.01% SNR (Signal to Noise Ratio) MC: >72dB SNR (Signal to Noise Ratio) MM: >85dB Max. Input Voltage for MC-cartridges (theoretical value): 1200mV @ <1% THD High Performance, Professional Type Step-Up Transformers. |
Dear Chakster, maybe I should read more of this thread before writing this, but I am confused. If the phonata is a current type design, why would you even be using any SUT? An LOMC cartridge with low internal resistance should plug right into the MC inputs. I am sure I am missing some point you must’ve made back there in 2015.
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Thanks @atmasphere Well, sadly the SUTs in my WLM are not Lundahl, i’ve noticed that, but today i got an email from Lundahl support to make sure. The SUTs are what’s WLM called professional step-up transformers. Actually the WLM Phonata model with Lundahl SUTs in 2009 catalog, but probably never was released! http://www.6moons.com/audioreviews/wlm8/retailprices.pdfAnyway, it’s the right signal for me to replace them with a proper Swedish Lundahl high quality SUTs. First recommendation by Lundahl support is this one (LL9226 / 1:10): http://www.lundahl.se/wp-content/uploads/datasheets/9226.pdf " LL9226 is an MC transformer based on (and pin compatible with) our classic LL9206, but with reduced copper resistance and level capability. The new design has resulted in an even better frequency response but still with enough no load impedance to maintain the LF bandwidth. The transformer is built up from two coils, each coil with one secondary winding surrounded by two primary windings. Advantages with this structure are excellent frequency response and high immunity to surrounding magnetic fields. All winding ends are available on the pins. Thus, the transformer can be used with a set of different turns ratios. The LL9226 core is our cobalt based uncut amorphous strip core. The transformer is housed in a mu metal can." I hope experienced users can review this to help me with a best choice |
But which step-up ratio to choose? The least amount of stepup that gives you the gain you need. That will minimize the sonic fingerprint that all SUTs have. Also pay attention to proper loading of the SUT to minimize coloration. Talk to Luhdahl about that. |
Dear all, after quite some time of using different phono stages from cheap Grado PH-1, iPhono2, to the great JLTi and finally Gold Note PH-1 i have to say the old WLM Phonata is really good. For some reason the WLM bass is addictive and none of my phono stages can do the same. Input resistors for MM carts has been upgraded to 100k Ohm Vishay Naked Foil last year. It was a huge upgrade and some of my favorite vintage MM cartridges are really really good with this phono stage. Well, i decided to upgrade Capacitors in my WLM Phonata Reference. Last year i took some pics of the circuit and realized the original stock caps are all German made Audyn. Constant upgrade is rule number one. Time to replace these Intertechnik Audyn MKT (Axial Metalized Polyester-foil) capacitors. Intertechnik manufacture High End Audio capacitors in Germany since 1983. As you can see my caps are 6.8 C/µF (160v) and 1.0 C/µF (250v) with 5% tolerance, they are very cheap. Right now Audyn offers much better audiophile grade caps. In the biggest capasitors test review i found that Audyn Reference, True Copper, True Copper Max and True Silver received the best verdict! I just bought Audin Reference caps, 4 of them cost me 170 euro with shipping. I’m thinking to upgrade stock built-in SUTs on the motherboard too. Looking for the right one from Swedish Lundahl (they made then since 1958). Actually my stock SUTs claimed to be Lundahl too, but they does not looks like any Lundahl i can see on the official website now. Here is a picture of the motherboard with stock SUT and stock caps that i want to upgrade ASAP. But which step-up ratio to choose? |
I have found that is true as well. If for example if that 50KHz step was really employed (and if I understand correctly, meaning that it goes to flat response at 50Khz), the ear will interpret the resulting phase shift in the audio band as brightness.
The old MFA Magus preamp used to do this and it also sounded bright. I found that by restoring the RIAA curve at 50KHz eliminated the brightness. |
All good points. Nevertheless, he wrote in favor of very extended bandwidth. I will try to find the quote; perhaps I mis-remembered. He might have been referring either to the linestage section of the RTP or to one of his amplifier designs. Anyway, his point was that although the roll-off was occurring at frequencies impossibly high by any rational analysis as regards any effect on the audio bandwidth, there was in fact an audible (to him) "trickle down" effect, because the roll-off created distortions down in the audio range. |
Allen was a big proponent of using the "Neumann" time constant in his designs which shelves the response with a corner at 50Khz. Using a "normal" riaa puts the info at 750Khz about 32dB below the value at 20Khz but including the "neuman" drops that to 8dB difference.
dave |
I don't know how you would get bandwidth that high given that the RIAA curve is rolling off the circuit at 6db per octave, so he must have been referring to the bandwidth of the gain stages rather than the overall bandwidth of the entire phono circuit. |
Allen Wright wrote in his Preamp Cookbook that he could hear the difference when his RTP phono stage was "rolled off" at 750,000 Hz, vs when he fixed the problem allowing it to go much higher in frequency. Of course, that kind of subjective statement is impossible to dispute, but I am dubious that what he might have been hearing was due to bandwidth and not something else. On the other hand, he was smarter than I, in this area for sure. |
On 6/3 and 6/4 it might look like I was clarifying Atmosphere's response. My posts were delayed for 4 or 5 hours on those days. When I wrote them, there was nothing to clarify. They hadn't yet appeared.
I'm not saying this to be contentious, but the explanation of resonance in the MHz range, came from J Carr, and seems plausible. This is somewhere on Raul's MM/MI thread, around p.200?
Of course a cantilever can't wiggle fast enough to output in MHz and I think this is completely a function of the tank circuit and not a harmonic of 30K (or whatever) noise. Two separate, but related issues or two aspects of the same issue is moot. In a voltage amplifier front end, both the stability and bandwidth of the device come into play.
Some think (Goldmund) a power amp needs bandwidth at least to 200K to make speakers play accurately. What about a preamp? Some might not share this opinion, but if wide bandwidth is a positive attribute of analog where's the cutoff point?
Are some phono preamps flawed by having too much bandwidth? Maybe it's a bad cartridge design with a tiny output and relatively high inductance/impedance? Just a bad matchup?
Are any of these current amplifiers considered top rated?
Seems worth pursuing.
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hey The cartridge is not physically generating at these frequencies. Agreed.... It's an electrical resonance at a particular frequency which can cause overload or oscillation. doesn't this contradict your first statement? In order to excite a resonance you need an electrical signal at the frequency in question. I can see a cart generating signals up to say 100Khz but the resonances in question are a decade above that which is why I asked for the source of the excitation signal. dave |
No contradiction. Bottom line is how it sounds. No sense in defeating the sound by compromising the components or defeating good components in the chain. |
Bpoletti wrote: There's ONLY one parameter that counts.
So, how does it sound? Bpoletti wrote: Czarivey - I'm with you. No SUT, just a silent high-gain mc input stage. Bpoletti, just look at the contradiction. First, the OP proposes a new phonostage in the market with a lot of enthusiasm but instead of a thumbs up, all you have to say is "I dont care about the design and all that, the only thing matters is the sound". And then when he tells you that it sounds good, your reaction is "hey, I dont care how it sounds because it has an SUT"!! You dont even stop there, then you write: Chakster - Are you in any way associated with the company or designer that produces this unit? Seriously ? Thats the first thing that occurs? Just because the OP is talking about phonostage which is not a Herron VTPH, you have all kinds of problems. Then you even write this: How can a cartridge be autoloaded when the manufacturer specifies a particular load to voice a cartridge? (Sounds like more audio hooey and snake oil to me.) Extremely well respected phonostages like the 47 Labs phonocube have been designed on this concept but probably the Herron VTPH does not fall into this category so it is snake oil ? I am sorry that I am derailing the thread and bringing this out but this has been a prolonged observation that for you everything starts and stops at a Herron VTPH. It is okay as long as you do not treat other member's opinion about their phonostages with a condescending attitude (illustrated here). |
^^ The cartridge itself provides the excitation and it does not have to do so at its rated output by any means (that is the nature of resonance- it does not take a lot of excitation to get it going). Harmonics of signals on the LP or noise in the LP surface is all it takes.
I think many people don't realize that one of the reasons the LP sounds better than digital is that it has a lot more bandwidth.
We run an LP mastering operation; we can record a 30KHz tone on a lacquer and play it back on a modest stereo (Technics SL1200, Grado Gold and H/K 430 receiver from the 1970s) with no worries at all. Cartridge manufacturers only show 20-20KHz response on their spec sheets but the cartridge always goes much higher than that. There is also noise that appears in the grooves of many LPs that is ultrasonic, caused by the pressing process itself.
So its pretty well guaranteed that the resonant peak is going to contain some energy. |
Dave,
The cartridge is not physically generating at these frequencies. It's an electrical resonance at a particular frequency which can cause overload or oscillation. This occurrence will also intermodulate and affect the mid/high frequency range with an overtone coloration.
A common example of this occurring is with the DL-S1 MC going straight into a phono stage with extended bandwidth. The cart has very low output (0.15mV) due to the coreless design, but its impedance is 33 ohms. This low output requires extraordinary gain and makes the problem more likely to occur.
To deal with this, a prominent poster on Asylum loads his DL-S1 below the impedance value of the cart (22 ohms I believe). Apparently his phono stage has enough gain to compensate and he's happy with results.
Not all phono stages will be thus affected. If a design is more bandwidth limited, then this overload is less likely to occur. If phono preamp response rolls off at 100K, it probably is immune to resonance in the MHz range.
I've read about tonearm cables for MC's with very high capacitance. More capacitance will lower the frequency of electrical resonance and might be a bad idea.
A phono cart generates output with magnets and coils. The internal cart resistance reflects the size of the coils. Some coreless designs have stronger magnets inside the cart and lower impedance/inductance. The AT 50ANV and ART7 are such designs. Output is still extremely low, but so is inductance.
Regards, |
I have simulated it using J_carrs model and indeed considering the simple ideal model a MC cartridge can in theory resonate with cabling capacitance in the Mhz range. However in spice, you are feeding a signal from a generator that has no problem creating a 0.2mv (or whatever) signal at the resonant frequency in order to excite it. I want to know is how a physical cartridge is generating its full rated output at these high frequencies in order to cause these issues.
dave |
But I think for many audiophiles using MC cartridges it is difficult to get their head wrapped around not being able to "load" the cartridge-I think this is perceived very negatively. Hence this type of phono preamp is probably a harder sell in the marketplace. Yes, the importance of loading the cartridge and how that all works is one of the more prevalent myths about LOMC cartridges. Once you get what is really happening though, you see that being able to load the cartridge or not really isn't a problem- so long as the phono section has either a very low input impedance or is stable with ultrasonic noise or RFI at its input. The advantage of balanced operation is that the interconnect between the arm and cartridge will not have any sonic artifact. This is really helpful as the cable is at the very source of the signal path- if it messes things up, there is little you can do about it downstream. So insuring that it works right is important and balanced operation can do that. |
" Intactaudio
Can someone please tell me how this resonance in the MHz range is being excited?"
The output of a cartridge has inductance as a property of that output. If you draw the circuit, the voltage of the cart has its self resistance and inductance in series with it (voltage).
The capacitance of the preamp + cables is in parallel with preamp input impedance (resistance), and they go to ground.
This creates a resonance tank circuit, the frequency of which depends on the value of component parts. Because a LO cart has low inductance (reflected in its impedance), the electrical resonance will be at a very high frequency.
It's commonly thought that capacitance doesn't matter with a MC. It does or might. Higher capacitance will lower the frequency of electrical resonance. This electrical resonance effectively gives the cart output (noise) at a frequency where there is no mechanical output.
You can calculate the frequency at the Hagerman link.
Amplifying current avoids this potential problem, with low input impedance. The BMC MCCI has MC input impedance of 3 ohms. The Aqvox 2Ci is 10 ohms.
Regards, |
Thanks Ralph. So in theory, at least, there are some technical advantages to this approach.
I'm only guessing that it has not become a bit more popular as a result of being "off the beaten path". That perhaps and the fact that the advantage is only realized in the MC domain.
My Aqvox, for example, tries to be a bit of a "jack of all trades" in that it offers typical voltage amplification, and both MM and MC compatability including adjustments for both capacitance and load, through its single ended inputs. While it's adequate I suppose through those inputs, that's about all I could say for it; I would not have purchased it based on its performance as a voltage amplifier.
In the current mode (fully balanced) its performance is very impressive though and I've been more than satisfied with it. But I think for many audiophiles using MC cartridges it is difficult to get their head wrapped around not being able to "load" the cartridge-I think this is perceived very negatively. Hence this type of phono preamp is probably a harder sell in the marketplace. |
Hdm, current gain designs often tend to work with a slightly different principle. In tubes, one means is called 'grounded grid' as the cathode of the tube is used as an input. With transistors, the emitter device of the semiconductor becomes the input. In any event the input impedance is quite a bit lower. This prevents any chance of resonance from the cartridge/cable circuit from occurring.
While LOMC cartridges don't make a lot of voltage, they do qualify as a low impedance source as they have no troubles whatsoever driving a 100-ohm load, unlike most preamps, which would have difficulty doing the same thing.
So its the inherent low impedance input that is why loading isn't an issue. Many preamps do have provisions for very low impedance loads, but if you are working in the voltage domain, bypassing the cartridge output with a very low impedance will simply serve to reduce the output of the cartridge. |
A lot of back and forth going on here but I'm not sure it's related at all to what the OP posted on.
I've used the Aqvox happily for about 7 years now. I had a chance to audition it and there was clearly something pretty special going on (at least to me and relative to the phono stage I was using previously) in the fully balanced current mode.
I'm not really a technical guy, and because current mode phono preamps are relatively rare, there is not much discussion on them.
Manufacturers of them claim there are advantages in presenting this "short circuit" type of interface with the cartridge and perhaps the discussion should be more on the technical merits (or lack thereof) of this type of interface relative to loading the cartridge on a voltage input. I've never really seen that type of discussion before.
I won't be changing phono preamps any time soon but would still be open to hearing that kind of discussion. As I said earlier, there's been a generalization out there that current mode inputs do tend to work better with low impedance designs (at least from reviewers-not all but some, the TNT review on the Aqvox for example suggested a number of higher impedance moving coils also worked quite well with it).
As the impedance at the current input seems to be quite low in these designs I always wondered whether the supposed working better with low impedance MC's was more a result of most phono stages with fixed or even adjustable loading simply not having settings low enough to really maximize performance with very low impedance cartridges or if there is something more at work here technically? |
*The above comment was from jcarr, which seems to agree with what Atmasphere is talking about.*
Even if you agree with JCarr and Atmasphere about Lyra, does this apply to all carts? What about those which are underdamped?
Once again, this thread is about Phonata and I don't recall a Lyra being mentioned other than JCarr being used as an authority. He uses some kind of double damping system. Is this common to all MC's?
Atmasphere,
You seem to horn in on multiple threads seeking a free advertisement. Aren't you supposed to identify yourself as a manufacturer? I noticed the Liberty Audio guy took some flack about this.
Beside theoretical objections to wide open ALWAYS being better, there are plenty of real-world examples of that being untrue even with the MP1 or Herron phono stage. Don't some people load other than 47K ? Don't you offer a loading modification? I've read about Herron users preferring other loads.
Now you're implying benefits with consequences based on generalizations which may or may not be true. Elitist minded scare tactics? You ought to have an ad saying, You're Cartridge Working Too Hard? Tearing Up The Grooves?
Regards, |
Can someone please tell me how this resonance in the MHz range is being excited?
dave |
My comments are based on an objective understanding (measurements, calculations, and simulations) of what a low-impedance cartridge generator is, what an interconnect is, what happens when the two are combined, what happens when resistors of various values are added to the mix, and what happens when extra capacitance is added. A low-impedance cartridge has an inductive generator, while a phono cable has significant capacitance. Put the two together and you get a huge spike at ultrasonic frequencies. These frequencies are much too high for any human to hear directly, but fall in a band that is likely to impair the linearity of the phono stage in much the same manner as excessive RF. When we "load down the cartridge", for the most part we don't affect what the cartridge does at all (unless the value of the load approaches or drops below the internal impedance of the cartridge). What adding resistive loading at the phono stage input accomplishes is to dampen the resonant energy of the ultrasonic spike, and give the phono stage an operating environment isn't so likely to trigger any latent non-linearity tendencies that the phono stage circuitry may have.
For the reasons given, the phrase "cartridge load" is misleading. "Phono stage input terminator" is a better description of what really happens. The above comment was from jcarr, which seems to agree with what Atmasphere is talking about. http://www.whatsbestforum.com/showthread.php?15077-Cartridge- |
Atmasphere, From this thread:
*In the absence of noise one might prefer to load down a MC because of preference. Damping a cantilever/generator might improve focus and detail, while wide open might increase stage and size.*
*A phono cart is an electro mechanical transducer on the source end, but no electrical damping isn't necessarily better. Mechanical performance is the overwhelming determinant of cart performance, something that many EE's don't get. Loading, electrical damping can be a way to balance factors other than amplitude response and noise.*
Why does Jonathan Carr recommend for Kleos: *Recommended load directly into MC phono input: 95.3ohm ~ 816ohm* ?
http://www.lyraconnoisseur.com/Products/Products_Analog/kleos/kleos3.html
If you say that's because of inferior phono preamps, I say it doesn't matter or it's an inappropriate response. It doesn't matter because this isn't about you, it's about the Phonata. It's an inappropriate response because your examples and consequences are misleading at best.
Do you really think Kleos will start tearing up grooves if loaded at 100 ohms rather than 47K ? That's what you imply. Is every cantilever optimally damped? A MC cantilever is usually damped just enough to suppress mechanical high frequency resonance to between +3 to +7dB @ 20KHz. Of course usual isn't always and there are exceptions, like no cantilever or short ones. This is way outside the scope of this thread, but no-load always being better is a wrong assumption IMO. It's not right for any preamp all the time, and certainly not all MC's.
Regards,
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Many cartridges that make 0.2mV into 100 ohms can do so into 50 ohms as well. Its a small amount of wattage, but you can see in this example that in the latter case it would be making twice as much power as the former. This has to come from somewhere (the groove walls) and as such means that the stylus has become slightly harder to move. I know that's what you're talking about. I made it clear that tonality change is NOT what I was talking about. What don't you understand? Fleib, maybe you could outline what you *are* talking about as it is not clear from your posts so far. |
*the lower the impedance of the load the more work is being asked of the cartridge.*
What do you mean by "more work"? Are you talking about the cantilever/rubber suspension interface being stressed more?
I enjoy you posts. |
**I am talking about the fact that if you hear tonality change with a LOMC seemingly due to loading, its on account of the behaviour of the preamp and not the signal from the cartridge.**
I know that's what you're talking about. I made it clear that tonality change is NOT what I was talking about. What don't you understand? |
Apparently you think this is the only reason to load down a cartridge. If so, you're wrong. I've already explained that wide open is not always better. Maybe it is in your preamp, I wouldn't know, but we're not talking about your preamp. I am not talking about MM, where achieving the critical damping value is important for best performance. I am talking about the fact that if you hear tonality change with a LOMC seemingly due to loading, its on account of the behaviour of the preamp and not the signal from the cartridge. I had a conversation with Jonathan Carr at the recent Munich show. He mentioned the same phenomena that I did in a prior post- that when you load a cartridge with a lower impedance, you are asking it to do more work. Since the cartridge is a magnetic transducer, the lower the impedance of the load the more work is being asked of the cartridge. For this reason he was very interested in developing a phono stage that had a high impedance input so as to minimize the work that the cartridge is doing. This would leave it more free to follow the modulations in the groove. Re. current gain inputs: due to their inherently low input impedance, the mechanical loading issue as pertains to the above paragraph is likely not optimal, however you certainly would not have to worry about what the load impedance actually is since the electricalresonance would be well-damped. |
Yes, no updates on WLM website for a very long time :(
no reviews on new Phonata Reference which was the neхt model and released after their tube phono stage.
This is a google doc link to MANUAL of Phonata Reference:
https://drive.google.com/file/d/0B7SnhzDV__cCc2lfQ0NYRnVuRlE/view?usp=sharing (anyone with this link can download .pdf file) |
If you go to WLM Acoustics they only show the tube phono available in 3 different configurations with SUT for MC gain. Specs to be announced.
http://www.wlm-acoustics.com/
Fremer reviewed the BMC MCCI phono stage on 8/13. This uses current amplification on the MC front end. The unit looks remarkably similar to Chakster's link for the solid state Phonata.
http://www.stereophile.com/content/bmc-phono-mcci-phono-preamplifier
Results seem different from what Chakster said, especially concerning cart impedance, and it's unclear if these are the same.
A couple of guys who post on the MM/MI thread own Atma-Sphere MP1 preamp. They each have high end systems in the extreme and think highly of the MP1 phono section.
Our disagreement is mostly one of appropriateness and in no way is a reflection on the product.
http://www.atma-sphere.com/Products/#MP-1 |
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Atmosphere,
You should have quit while you were behind. I've read Hagerman's article and I could point out some erroneous assumptions, but they pertain mostly to MM's. If you're interested you should read the VE thread, Cartridge Loading Explained.
But we're talking MC's here and one HOMC with a solid state phono stage, and I still fail to see where your comments pertain. I know about the tank circuit on the output. I'm also familiar with high frequency overload or oscillation and the possible need to load down the preamp shunt resistance.
Apparently you think this is the only reason to load down a cartridge. If so, you're wrong. I've already explained that wide open is not always better. Maybe it is in your preamp, I wouldn't know, but we're not talking about your preamp.
If you have something to say about current amplification on the front end, that might be helpful.
Regards, |
Atmasphere, thanks for the link and your comments.
This is amazing! |
Fleib, with all due respect, rather than calling my comments BS, why don't you look into the matter? I suggest you look at the comments of JCarr (Jonathan Carr of Lyra, who is active on this forum) about the effects of cartridge loading. Or how about reading this article? http://www.hagtech.com/loading.html(the closing summery of which is that 'Load resistance tunes damping'...) In a nutshell you will see that I am correct. Loading of LOMC cartridges is one of the more prevalent myths in high end audio LP reproduction; I was under the same illusion until years ago I tried to make a box that would determine the correct loading for any LOMC cartridge. It was during that research that I discovered that loading of the cartridge itself had no effect at all on the output waveform at audio frequencies. The reason is simple enough: the inductance of the cartridge is rather slight. Its impossible for a load to have much effect other than reduce the cartridge's output at audio frequencies in extreme cases. What is happening is that the inductance of the cartridge, in parallel with the capacitance of the tone arm cable, forms a resonant circuit, as Hagerman's article outlines. This can be simply ultrasonic but might be at several MHz. If the phono preamp is unhappy with this sort of signal at its input, you will hear effects, effects of which are easily controlled with a 'loading resistor' which damps the oscillation by detuning the resonant circuit. IMO/IME it is better if the phono section is stable and therefore immune to such things in the first place- it sounds better that way and its a lot less trouble. |
I just emailed to Herr Frick of WLM (Austria) with a link to this thread.
Really hope he can join' discussion and explain more about his product.
It's getting hot.
i just want to remind to everybody in this discussion that WLM released TWO phono stage:
1) PHONATA TUBE is their old model was available in 3 different versions such as MM ONLY, MM/MC or MM/MC with Lundahl step-up transformers.
2) the latest model is PHONATA REFERENCE (MM/MC) in a bigger cabinet. "This unique preamp has automatic impedance matching so that the input impedance for the cartridge is perfect each and every time."
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Free advertisement over?
This thread isn't about tubes or the viability thereof. The Phonata is solid state and the discussion is now about current vs. voltage amplification.
**The answer is that no manufacturer 'voices' a cartridge in the way you are suggesting! The load is there to sort out an unstable phono section, not the cartridge.**
This is BS. All phono stages where one might prefer a load other than wide open, is unstable? Suggested loads are usually a minimum value or for SUT impedance matching.
We've been through this before. In the absence of noise one might prefer to load down a MC because of preference. Damping a cantilever/generator might improve focus and detail, while wide open might increase stage and size.
The analogy to amplifier damping is a bad one. The goal is to make the speaker play accurately with a high damping factor. A phono cart is an electro mechanical transducer on the source end, but no electrical damping isn't necessarily better. Mechanical performance is the overwhelming determinant of cart performance, something that many EE's don't get. Loading, electrical damping can be a way to balance factors other than amplitude response and noise.
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Atmasphere is correct. A tube circuit can be designed to be low noise, components can be specifically for their low noise. Noise is NOT a drawback to tube design.
And Atmasphere's last paragraph and last sentence speaks volumes! Dead center on the facts. |
Tubes are inappropriate for a high gain stage. They're too noisy, so they employ either a SUT or a solid state high gain stage. This statement is incorrect. We have been using all-tube phono sections for LOMC cartridges for about 25 years and they work fine with 0.2mV with no SUT, only 2 gain stages and passive EQ. The trick to getting silence out of tubes is very similar to how you do it with transistors- fully balanced differential with 2-stage constant current sources to get the proper differential effect with high Common Mode Rejection Ratio (CMRR) values. How can a cartridge be autoloaded when the manufacturer specifies a particular load to voice a cartridge? The answer is that no manufacturer 'voices' a cartridge in the way you are suggesting! The load is there to sort out an unstable phono section, not the cartridge. One aspect of loading that is not discussed so far is that fact that in order to drive a load, energy is required. So the more you load down a cartridge, the more energy it has to produce the drive the load. This **has** to have an effect on the cantilever, which is in motion to drive the transducer. Think 'damping factor' as in an amplifier and loudspeaker and you've got the right idea. The implication is that low impedance loading will affect the performance of the cartridge somewhat; that it will be better able to follow the groove modulation if not so damped. This is a profound argument for a stable phono section that does not require loading! |
Just a clarification. The Aqvox was NOT designed for the MC 20 Super. Aqvox only started marketing cartridges a number of years after they had introduced their phono preamp and it is only speculation on my part that their cartridges are based on the MC 20 Super.
I pointed out the use of the MC 20 Super only in light of its lower internal impedance (5 ohms) as many have suggested that current mode phono preamps tend to give their best with low impedance cartridges (say in the 1-10 ohm range).
In any event it is my experience that phono stages like this can offer up pretty good performance (there are also multiple positive reviews on the Aqvox and BMC, some of which probably delve more into the technical aspects of the current mode and the "non-need" for adjustable loading as a result of this design). I don't really miss or feel the need for adjustable loading under the circumstances.
Others with more technical knowledge than I can make the case for adjustable loading being necessary but the designers/manufacturers of current mode stages (as non-standard and as quirky as they are) obviously feel there are some legitimate technical reasons to take this track.
I was just putting the info out there to shed a bit more light on this as, for the most part, it seemed that most involved in this thread were not really aware of this type of design. |
