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A question of loading...

I have just replaced my aging tube preamp with a new model. When I was using my older model with tube phono stage, I would run my Lyra Kleos and other MC cartridges with a load of 750 ohms. So, I assumed that with my new tube phono stage, which also utilizes a transformer in the phono stage and is also built into my new preamp, that the same cartridge loading would apply. I listened to the Kleos for about a week with this loading, and frankly, while it was fine, I wasn’t bowled over. Tonight I decided to experiment, so the first thing I did was to run the cartridge straight in, with no loading plugs. WOW, the increase in overall musicality and soundstage width was eye opening! Lesson learned is that not all gear is going to react the same when it comes to cartridge loading, particularly if there is a transformer involved and even if you are using the same cartridge from one phono stage to the next! An eye opener, anyone else experience something like this?
128x128daveyf
atmasphere's avatar
atmasphere
11,574 posts
 
Ken uses a SUT that doesn't really have a lot of boost because I think he believes that as the step up increases, the loss is SQ is too great.
That's been our experience too. The more stepup you use the less bandwidth you get.


We regularly run cartridges that are 0.2mV. If you have an SUT you should be able to get in that same range quite easily. The only thing you would have to work on is the loading of the SUT, with which Ken might be able to help you. We use Jensen Transformers when we use an SUT; they have published a pdf file of all the loading values for a great deal of different cartridges including Lyras.


Keep in mind that 0.25mV is 6dB less than 0.5mV; that means you'll have to run the volume control up a few notches to get the same sound pressure. I don't think you'll have any problems doing that :)
daveyf's avatar
daveyf OP
2,835 posts
 
Indeed, the CAT has plenty of gain available, almost too much. With Ken's new 47 step volume control, luckily there is plenty of control and there should be no issue running up a few steps.
fsonicsmith's avatar
fsonicsmith
931 posts
 
With Ken’s new 47 step volume control, luckily there is plenty of control and there should be no issue running up a few steps.
47 steps in attenuators seems to be another inexplicable industry standard.
dover
2,177 posts
 
@daveyf 
@atmasphere 
I suspect Ken got tired of people calling about noisy tubes and SUTs are a way to get around that.
Yep, I know from experience that customers were complaining about their Koetsu's with the CAT - not enough gain & too much noise.
The problem was that you only needed a transformer with about 10db ( turns ratio 1:5 ). Most off the shelf audio SUT's are up around 20/26db - which resulted in too much gain. I think this is why he has addressed the gain issue in the way he has.
Daveyf, the gain is also impacted by the system gain - how sensitive is your power amp input - so there are always exceptions.

daveyf's avatar
daveyf OP
2,835 posts
 
@dover   Good point about the overall gain in the system. However, my ancillary gear is exactly the same, with the exception of the old preamp vs the new preamp. So. I would have to believe the overall gain should be the same. My amps ( i use both a ss stereo amp and a tube mono block..(not at the same time) do have similar gain structures ( the ss amp has a gain switch to switch between two settings- a very useful feature that I wish more amps featured)) .
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