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

I recently tried a friend's Sound Traditions Hashimoto hm7 transformer-based sut and overall the sound was substantially more Dynamic and alive and generally better than my current Berning preamp MC section. The problem was the images were just so large and the presentation a little too forward for my tastes. I am thinking a different Sut such as the EAR MC- 4 or an Intact Audio (Slagle) Step Up Transformer, copper.

Has anyone used these Sut's and could advise about whether they might do what I'm looking for? I'm hoping to add more dynamics and life but I do prefer a slightly laid-back presentation to a forward one and I don't want giant instruments in the soundstage. I listen to mostly old Jazz and Blues with some rock and classical mixed in. I am not looking for the last word in in treble detail or "air" and my biggest sonic priorities are organic , rich mids, good sounstaging, and a realistic tonal balance that does not accentuate the top end as so many components seem to do (IMHO). So I guess I am looking for a sut with a reputation for musicality and richness, without javing a forward sound. But I would love somethng as amazing sounding as the Hashimoto HM-7 based SUT.

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.

Thanks for any thoughts.


montaldo
atmasphere's avatar
atmasphere
11,781 posts
 
My largest concern here is that it sounds like it is the optimal to build the sut to suit one cartridge so when/ if you do the cartridge square dance ideally you would need change sut too?
No. You simply have to load it correctly for that cartridge.

I still don't believe you :-)

That's a bit of a surprise- your response on AudioAsylum lead me to believe otherwise. I can point you to a number of other examples should you need more proof.

A SUT or line level transformer driving a gate/grid of an active device is a different situation where any load or network required is a function of a compromised transformer design and not part of the transformers "job description"
SUT's typically drive the input of a phono section, where the input standard is 47Kohms. In this situation, the inductance of the cartridge and the capacitance of the interconnect cable form a resonant circuit. This resonance might have to be snubbed else it can cause troubles for the preamp, if the preamp has poor RFI immunity. That's what the loading resistor is for. However, driving a SUT with its additional inductance this peak is a bit different.  If you don't deal with it it might cause the transformer's response to not be flat- depends on if the transformer is designed specifically for a certain cartridge, but if the transformer is mounted in the preamp as is the case with this thread where the transformer is expected to work with *any* cartridge then loading should be set up. 

  I have found that when operating as balanced care must be taken with the cable layout to adhere to the balanced standard and simply attaching an XLR connector to an existing tonearm wire is hit or miss when it comes to hum pickup.  
Actually you treat it like any other balanced source. The '+' and '-' outputs of the cartridge travel in a shielded twisted pair, the shield is the tone arm ground (pin 3 on DIN connections, pin 1 on XLR connections). If you set it up this way (assuming that the arm itself is actually connected to the ground) there will be no hum whatsoever. 

chakster's avatar
chakster
6,144 posts
 
@intactaudio 

 47K is a silly value for the input of a phono stage when considering a SUT. Selecting a turns ratio on the reflected load of that 47K is misguided.

I install a 300K at the input of my LR phono and I believe shindo used 100K so no everyone adheres to that antiquated 47K value.

Very Interesting.
I can confirm that higher load resistor value in MM input for SUT is harmless, at least to for my ears. I was concerned about it simply because most of my MM phono stages already upgraded with 100k Ohm Vishay instead of some cheap stock 47k Ohm resistors manufacturers installed by default in MM input. But i was a bit afraid to use SUT since 47k Ohm recommended, not 100k Ohm. However, i tried and it was OK. 

Actually it's a good news. 
Luckily my favorite JLTi phono stage was upgraded by the manufacturer upon my request too (internal resistors is 500k Ohm), so i can use parallel RCA plug resistors of 47k Ohm (or 100k Ohm), i can go even higher if needed. The only problem is that i don't have higher than 100k at the moment, but i could buy to try. The reason why i like this JLTi phono stage so much is the flexibility and convenience.





intactaudio
300 posts
 
That's a bit of a surprise- your response on AudioAsylum lead me to believe otherwise. I can point you to a number of other examples should you need more proof.
I think we are missing each other on a few of these things.  I have no doubt that assuming enough inductance and a reasonably competent transformer design that for a given cartridge an acceptable network can be found to give flat response.  My contention is those networks put in place to account for a mismatch also do some sincere damage to the sound quality.

We agree that SUT's can never be "universal plug and play" and while you say issues can be fixed by loading, I contend while that is technically true, this imparts a rather large sonic compromise.  

While on this topic I will add that in a perfect world I would install the "ideally matched" SUT into the front end of the phono stage but then what happens when you want to compare a Lyra Atlas to a Van Den Hul Colibri?  In my world you would need a new SUT and in Ralph's world you would need to hope that there is enough inductance to support the VDH and then adjust the load accordingly. In either case with an internal SUT this becomes a difficult task which is why i advocate for using external devices as the best option for this situation.


uberwaltz's avatar
uberwaltz
13,381 posts
 
Which the above answers my thoughts that in the ideal world the SUT would be built and tailored exactly to the cartridge in question.
Makes it a bit of a pain if you swap carts a lot though......
chakster's avatar
chakster
6,144 posts
 
Which the above answers my thoughts that in the ideal world the SUT would be built and tailored exactly to the cartridge in question.
Makes it a bit of a pain if you swap carts a lot though......


I can just swap SUTs for almost any LOMC because smart manufacturers like Luxman made at least 3 different toroidal silver plug-in SUTs for one base connected to the arm and phono stage, very easy to swap in 5 seconds. On that page you see 2 of them, but there was actually one more in the middle (8025 for 3-40 Ohm). There is a SUT for any situation, for carts under 3 Ohm, for carts over 3 Ohm til 40 Ohm, for carts over 40 Ohm. But most of my favorite LOMC are all low impedance, anything from 0.17 mV works fine. 

Any modern manufacturer can offer something like that ?
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