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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.
chakster
thekong
203 posts
 
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-
intactaudio
303 posts
 
Can someone please tell me how this resonance in the MHz range is being excited?

dave
fleib
1,124 posts
 
*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,
hdm
1,072 posts
 
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?
atmasphere's avatar
atmasphere
12,088 posts
 
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.
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