Advice on SUT for Koetsu Rosewood - EAR MC-4, Slagle/EMIA, other

Dear @montaldo  : """  I think our respective objectives in this Pursuit might be very different.  """ Could be you are rigth.

My overall room/system target ( main target. ) is that what I listening through it be stay nearer to the recording.
Then my quest is to acieve that target that puts me nearer to what the recording microphones pick-up that puts me nearer to the " real music " ( it's imposible to mimic live music experience in any room/system. ).

For that can happen the room/system must be a very high resolution one and at the same time with very low distortion levels at each singhle link in the room/system audio chain. That is true HiFi, not what refferd Tom.

Now, in " paper " those Jensen are very good transformers and for many years Jensen was and is a reference in audio, several high end manufacturers use it:

https://www.av-iq.com/avcat/ctl1642/index.cfm?manufacturer=jensen-transformers&product=jt-347-axt

I know that numbers does not say all but are important.

Hashimoto as other transformers are good too but in the case of the Hashimoto and due the way of thinking of the manufacturer amybe just maybe what you are listening trhough it more than a real an better " dynamic " characteristics against the Jensen in your Berning been only a different kind of distortions not only because the SUT but because the additional IC cables and connectors.
I think that way because you said the differences for the better is not a tiny one but something important.

In the other side, through the years you owned the Berning and after the burn-in time the quality level performance  of that unit changed in any way?

Because could be too that through the time something " degraded " the Jensen performance as " cold " wire solder down there ( with so many wires. ) or even one de-soldered.

It's imposible to figure out what is happening in your room/system because no one here already had your experiences betwwen the Berning and the external SUT.

Btw, @mulveling  the KRSP ( that I owned. ) is way different to the Koetsu OP model. The KRSP output level is 0.2mv and the OP is 0.4mv. As a fact both models only shares the Koetsu name because the quality level performance is way different in favor of the KRSP.

R.

 I have only owned the berning preamp I have only owned the berning preamp for 2 months so this is not a change that happened over time. I  I think I may have mentioned that my time with the Hashimoto sut was very limited but the impression of dynamics differencess was pretty stark.
 the interconnects I used with the sut were the exact same that I  using the rest of my system, so well every interconnect adds some sort of flavor or distortion, I don't see it dition of one more as possibly creating the difference I was hearing.

My system is a Koetsu Rosewood Signature (.4mv), Jelco 850M on a Sota Star Sapphire, Berning all-tube bespoke capacitance coupled preamp (46 dB gain on the MM stage, Jensen transformers on the moving coil stage), Quicksilver v4 monos, Verity Audio Pafisals.

Jensens are some of the very best SUTs made anywhere at any price.

They are Jensen JT-347-AXT Step Up transformers (1:12 ratio configured). Given these and overall MC gain of only 64dB, does this explain my lack of dynamics with the Koetsu Rosewood Signature (.4mv)?

@montaldo
-And that is one of the best that Jensen makes.

Now there are some things you should know about when you use an SUT and this applies to all of them: SUTs need to be loaded correctly in order to perform correctly. Not to go into it with too much depth but transformers have an input side (primary) and output side (secondary). If they are not loaded at all, the inter-winding capacitance comes into play and the transformer will not have proper bandwidth- it will look like a flattened bell curve. If the transformer is loaded too heavily, the output will be rolled off!


The cartridge itself doesn’t need any load if an SUT is employed! IOW **never** attempt to load the cartridge if a Step Up Transformer is in use!! Instead, you load the output of the transformer, and the correct loading values change depending on which cartridge you are using.


Again, this applies to all SUTs. BTW cartridge loading is a different topic but in a nutshell for this conversation the impedance of the cartridge is what is requiring the loading of the SUT to change depending on the cartridge.


Now in the case of Jensen, they’ve sorted out what the correct loading values for most cartridges actually are (including the Rosewood Signature). If you contact them they can advise you on the proper loading the JT347. You’ll have to talk to David about how to install the loading in the preamp.


Seriously, the Jensen is excellent! But to unlock its performance you **have** to pay attention to proper loading, and this will be true no matter what transformer you use!!

Thank you Atmasphere!  the Berning preamp has loading plugs for the moving coil section but if I understand what you're saying correctly those are for the INPUT side whereas you think the Jensen transformers themselves may need  loading on the output side. Is that correct?
If so it sounds like I should contact Jensen and ask what kind of loading should be added to mate with the koetsu Rosewood signature.
Since the consensus is that the Jensen Transformers are excellent and the 8:1 winding is not a huge mismatch, this output loading is a hypothesis that might explain what I was hearing with the Hashimoto transformers. So maybe the Hashimoto simply  had a better loading match and weren't necessarily superior sounding. Maybe is a road to fixing this.

I use a 1:20 step up with my Koetsu RSP and it is a perfect match.