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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
chakster's avatar
chakster OP
2,482 posts
 
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.pdf

Anyway, 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

lewm
6,770 posts
 
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.
chakster's avatar
chakster OP
2,482 posts
 
@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.
lewm
6,770 posts
 
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.
chakster's avatar
chakster OP
2,482 posts
 
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 ?


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