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.
Phono stage w/automatic Load-Impedanance.
Yes, automatic load impedance! The WLM PHONATA offers very high dynamics as a result of its very special design (see below)
A few years ago i purchased a slightly used demo unit from Australia. It was reasonable priced (mint- condition) WLM PHONATA reference MM/MC phono stage from respected WLM Acoustic brand (made in Europe). I use it since that day in my system.
a picture of the wlm phonata linked below:
http://audioaddiction.net.au/wp-content/uploads/2012/05/Phonata_3XL.jpg
http://audioaddiction.net.au/wp-content/uploads/2012/05/Phonata_4XL.jpg
When i bought mine demo it was newly released and totally different for previous WLM model (which was a smaller tube stage). The reference WLM Photana is not a tube stage. I'm not sure what's happened after, but probably it was not widely distributed, maybe they made first run and stop the production of this nice unit. They never updates their own website with info about this new unit. It's impossibe to find any reviews online and i assumed there are not so many users.
I wonder if anyone on AudioGon aware of this ice nproduct. I'm sure most of you familiar with amazing range of WLM speakers and different Tube Amps.
But do you know anything about WLM Photana Referense Phono Stage MM/MC ? It has some interesting features such as AUTOMATIC LOAD IMPEDANCE and 2 RIAA CURVES. It comprises pinnacle circuitry and design features that have never been realized before.
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.
The PHONATA offers utterly precise RIAA equalization:
• RIAA equalization is implemented across two amplification stages (within current amplification), providing a frequency expansion from 10Hz to 50kHz (Subsonic cut below 10Hz). Selected components (1% tolerance) are used.
• RIAA equalization can be selected from two positions with a switch at the back of the unit:
- Position “high” for records produced before 1965 or to improve the performance of somewhat “darker” sounding cartridges at higher frequencies. This position provides +3dB equalization as from 5kHz and +6dB as from 10kHz.
- Position “low” for all other records The PHONATA offers automatic adjustment of Load-Impedance:
• 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.
A few years ago i purchased a slightly used demo unit from Australia. It was reasonable priced (mint- condition) WLM PHONATA reference MM/MC phono stage from respected WLM Acoustic brand (made in Europe). I use it since that day in my system.
a picture of the wlm phonata linked below:
http://audioaddiction.net.au/wp-content/uploads/2012/05/Phonata_3XL.jpg
http://audioaddiction.net.au/wp-content/uploads/2012/05/Phonata_4XL.jpg
When i bought mine demo it was newly released and totally different for previous WLM model (which was a smaller tube stage). The reference WLM Photana is not a tube stage. I'm not sure what's happened after, but probably it was not widely distributed, maybe they made first run and stop the production of this nice unit. They never updates their own website with info about this new unit. It's impossibe to find any reviews online and i assumed there are not so many users.
I wonder if anyone on AudioGon aware of this ice nproduct. I'm sure most of you familiar with amazing range of WLM speakers and different Tube Amps.
But do you know anything about WLM Photana Referense Phono Stage MM/MC ? It has some interesting features such as AUTOMATIC LOAD IMPEDANCE and 2 RIAA CURVES. It comprises pinnacle circuitry and design features that have never been realized before.
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.
The PHONATA offers utterly precise RIAA equalization:
• RIAA equalization is implemented across two amplification stages (within current amplification), providing a frequency expansion from 10Hz to 50kHz (Subsonic cut below 10Hz). Selected components (1% tolerance) are used.
• RIAA equalization can be selected from two positions with a switch at the back of the unit:
- Position “high” for records produced before 1965 or to improve the performance of somewhat “darker” sounding cartridges at higher frequencies. This position provides +3dB equalization as from 5kHz and +6dB as from 10kHz.
- Position “low” for all other records The PHONATA offers automatic adjustment of Load-Impedance:
• 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.
Showing 11 responses by atmasphere
Cartridge loading of low output moving coils is almost of no consequence unless the preamp is unstable or unhappy with ultrasonic or Radio Frequency bursts at its input. If you find that loading is making a difference with your setup, its an indication that the preamp has stability problems. This is because the cartridge is entirely unaffected by load at audio frequencies. You hear a difference because the load resistance is detuning the resonant circuit created by the cartridge inductance and the cable capacitance. So if the preamp is unaffected by this the loading will have no effect. |
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. |
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! |
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. |
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. |
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. |
^^ 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. |
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. |
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. |