Tron Seven Phono

Pierre,

A friend of mine had a HP200 preamplifier. That is a very good unit. My only "issue" with it was the course steps for the attenuator (the ideal volume always seemed to be between two steps).

Once you are familiar with the sound of the Hovland, I would suggest looking into trying different 12AX7s in the phonostage. The "right" choice would be a matter of taste and system matching. The one that came with the unit might be ideal for you, but, you may find something else works a lot better. My friend ended up swapping the one that came with the Hovland for Amperex Bugle Boy 12AX7s--a lot more expensive, but worth it in a good sounding unit like the Hovland.

A friend has the Tron 7. I've heard it in his system and in another friend's system. It is a very nice phonostage.

The manufacturer insists that it has been tuned specifically for the tubes that come with the unit and that alternatives will not sound better. I think that what sounds "better" is a matter of taste/system matching and it is actually unlikely that what Tron supplied will be "optimal."

In both friend's system, all three listeners, myself included, preferred different 12AX7 tubes than what came with the Tron. The owner ended up going with Amperex Bugle Boy 12AX7s (the other friend has a VAST selection of alternatives). I would suggest at least trying some alternatives.

We did not mess around with loading. The sound happened to be decent at the manufacturer's preset loading (I believe the cartridges in the two systems were a Lyra Helikon and an Ortofon Per Winfield.

I too wonder about manufaturer's that don't make it easy to try different loading. From experience, most cartridges sound acceptable with loading of 100-150, so one can get away with fixed loading somewhere in that range. Still, with some setups, I actually like very little loading for a more wide open sound (e.g., 47k loading).

You could at least experiment with loading by either soldering in additional resistors yourself. If the Tron 7 has a step up transformer at the input (I believe it does), you will have to decide where to experiment with loading. My own phonostage (Viva fono), has a step up transformer and fixed loading. I found (by opening it up) that the manufacturer had placed loading resistors across the back of the input jack. In other words, the loading was on the primary side. The alternative would be resistors after the transformer (secondary loading). I disconnected one leg of the resistor so I could experiment with differnt loading. I then bought Radio Shack RCA jacks and adaptors, and a variety pack of resistors to make plug in loading jacks with different values. Interestingly, I ended up going with the value that came with from the manufacturer (actually not that surprising since, I found out later, the unit was optimized for the Transfiguration Orpheus, the same cartridge I use). With step up transformers, you can drive yourself crazy with experimenting with loading because, as mentioned above, you can try loading before or after the transformer, or a combination of both.

If you are not that technically inclined, don't mess with loading with a unit with fixed loading. If you have the itch to experiment, start with changing the tubes.

Resistive loading is really NOT a big issue when it comes to step up transformers. The bigger concern is the appropriate turn ratio and the amount of gain provided by the step up transformer. If your Tron has the right gain for the Delos, you really shouldn't have to be too concerned about resistive loading. Tron offers several gain options for their built-in step up transformer. For the Delos, as would be the case with MOST MC cartridges other than high output cartridges or very low output cartridges, the appropriate gas is 20 db. If yours is so outfitted, I would not worry at all.

A very good paper to read about gain and loading of step up transforms can be found here:

http://rothwellaudioproducts.co.uk/html/mc_step-up_transformers_explai.html

Mullard longplates are good tubes too. We tried those in my friend's HP200. They sounded much better than what came with the HP200, though the three of us who were doing the comparison favored the Bugle Boys. The Mullards have a slightly phasey sound in the HP200 (and also in the Tron 7). The Telefunkens we tried were a bit too lean sounding.

I have not heard the Psvane tubes myself. They have a good reputation, so they are certainly worth trying. We really need current production tubes to shine, otherwise, the supply situation will just grow progressively worse.