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Trafomatic Audio Luna LCR phonostage

These days I am looking into tube phono stages a lot. Especially phonostages which are within $5-6k and that can serve in a serious high end system. While I know that solid state phonostages have traditionally been known for their low noise and high dynamic presentation, I still believe that harmonics that tubes preserve (and SS throw away) can be a great asset to the end result i.e music. And if well designed tubes can do low noise and high dynamic range too.

I know that an all-tube 70db phono gain is a steep challenge and while there are manufacturers who have attempted it (e.g Aesthetix, NVO), the response from the users have been mixed. I am more for the conventional approach of using a top quality tube MM stage with a top quality SUT (matched to the cartridge) or FET stage. In this realm there are not many serious options in the $5k range if I look around. The few that I have looked at are:

Allnic H1500 II SE
Luxman EQ-500
EAR 88PB
Herron VTPH-2 
Leben RS-30EQ

Then there are some full function tube preamps which do have very competitive in-built phonostages like the Shindo Masseto, Manley Steelhead, CAT Ultimate etc.

Here is another one that looks like very good contender for a top quality tube phonostage in this budget:
http://www.trafomaticaudio.com/products/luna/

An LCR design using an all-out tube design with interstage transformers and output transformers, so absolutely no capacitor in the path. MC stage is handled by Lundahl 1941 amorphous cobalt core SUTs. This looks like a no compromise assault for this price category. I have not yet heard it but whenever I have heard Trafomatic products I have always come back with a smile. They have been consistently balanced and musical without any typical voicing artifacts. They never sounded like a product that has been hastily put together or built out of a garage. For a tube amp I have never heard them having any hum or noise issues. In fact I have always found his amps to have a very matured sound. In that regards this is a phono stage I am excited about. If anyone gets an opportunity to hear them, do share your thoughts here.
pani
pani OP
1,219 posts
 
Lewm, loading a phono cartridge is a phenomena that is primarily for active MC stages. All this HF ringing and damping comes into picture when an active circuitry is amplifying the MC signal. It is more or less a band-aid in that context. When it comes to SUT, the primary job of an SUT is not exactly loading the cartridge but to convert the low-voltage-high-current cartridge signal into high-voltage-low-current one and feed the following MM stage with sufficient voltage gain to work on. In this process there is some loading due to the turns ratio in the SUT. But this is a much more of a natural thing which is not a band-aid. SUT matching is critical form the point of view of providing the right amount of voltage gain, not so much the loading aspect. That is also the reason cartridges behave very differently when "loaded" via resistors vs an SUT. So your concern about experimentation with loading while using SUT may not be that significant a concern actually. It will most probably just fall into place if the SUT is chosen to match the cartridge output to the requirements of the MM stage.

Regarding the Herron phonostage, I have heard it. It is nice for its asking price of $3.5k but I would not pay much more than that for it. I would not go into the details of how it sounded etc, it will probably drift the thread into a different discussion.

For the record, I do not have any DIY exposure into building equipments so I per se do not know how an interstage transformer would sound but I have noted that the best tube equipments are either pure OTL or loaded with high quality Iron wherever suitable. Trafomatic Audio uses all their transformers and chokes made by the designer (Sasa Cokic) himself. He is actually known to be a transformer Guru in the Europe. Whether his transformers are better than Slagle or not I cannot comment but whenever I have heard his amps I have always felt I am listening to a very good product.
tomwh
150 posts
 
Pani 

Loading a cartridge has to be done regardless of sut.  Most people add one on a mm phono which normally has a 47k load.  So the transformer is now loaded on the secondary.  So now the load on the cart is affected by the turn ratio of the transformer.

So with out getting into the math or theory let's just say most carts sound different when you change the loading. If the phono stage does not have a adjustment for this I would find out what it is and see if the cartridges you use match up pretty close. 

Enjoy the ride
Tom
goheelz's avatar
goheelz
297 posts
 
@pani Have a look at the ModWright PH-150 reference tube phono stage. It’s a contender fairly close to your price range and definitely works superbly with my Dynavector LOMC cartridge. I chose this unit over the Herron and Manley.

As a low-tech guy, I appreciate the convenience of ModWright’s front-panel adjustment of loading parameters. It’s built to a high standard, looks fantastic, and sounds great.
lewm
13,124 posts
 
Tom, I think I said this before, but judging from your follow-up post, you did not "receive" my message.  I keep an open mind on transformers in audio.  I don't necessarily think interstage transformers are "bad", but perhaps that is the audio transformer function of which I am most skeptical.  In my response, I was merely pointing out that some who know more about the advantages and disadvantages of IS transformers than I do have written about the disadvantages, and I was influenced by what I have read.  But this hasn't caused me to dismiss the idea. t would be eager to hear your phono stage any time.

Pani, I know what a SUT does. However, the SUT will affect the impedance seen by the cartridge according to the square of the turns ratio.  So, if your SUT is providing a 1:10 voltage step-up, then the impedance seen by the cartridge running into a SUT in series with a typical MM phono stage will be 470R (47,000 ohms divided by 100).  My point was that lately I have been finding that I like to run my LOMC cartridges into more like a 47K ohm load (i.e., unloaded).  To achieve that with a 1:10 SUT, I would need a 4.7M resistor across the secondaries.  Since that resistor also serves as the grid resistor of the input tube, problems with grid current might be created by using such a large value grid resistance.  (It would probably work OK with certain tubes, but not all.) Also, I do not agree that using a SUT necessarily avoids problems related to "ringing" that might otherwise be encountered if using an active gain stage with an LOMC (unless that gain stage is intrinsically flawed in design).  There's a nice white paper on using Zobel networks to tame the response with SUTs, on the Jensen website.

I was interested to read your thoughts on the Herron. I've never heard one, but as you know, there are many devoted users here.

john_tracy
341 posts
 
Lynn Olson did a study of the harmonic spectrum of different coupling techniques. His results might be of interest to those curious about IT transformers.
The smooth fall-off of harmonics is especially noteworthy in the transformer-coupled circuit - the reason for the excitement about the naturalness and "directness" of transformer coupling is obvious when looking at the spectral data. This is the best distribution of harmonics I've seen — looking almost exactly like an RCA "textbook" distribution of spectral content.
http://http//www.nutshellhifi.com/library/FindingCG.html

Disclaimer: My phono pre., line stage, and power amps are all transformer coupled - input and output.
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