2. analog
  3. 1432420024

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
fleib
1,124 posts
 
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,
pani
1,219 posts
 
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).
bpoletti
1,555 posts
 
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.
intactaudio
302 posts
 
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
fleib
1,124 posts
 
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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