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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.
128x128chakster
atmasphere's avatar
atmasphere
11,942 posts
 
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!
bpoletti
1,556 posts
 
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.
fleib
1,124 posts
 
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.

chakster's avatar
chakster OP
6,144 posts
 
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."
atmasphere's avatar
atmasphere
11,942 posts
 
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.
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