Step Up Transformers - SUT Thread

displayname

displayname

Well-Known Member
Per usual I'm finding myself distracted, away from my stereo and wondering about various system possibilities. I've started to give more thought to the world of Step Up Transformers, aka an SUT. I know I've seen posts from @SnowmaNick @Joe Mac and @HiFi Guy discussing SUTs at various points. As I started to dig around, I couldn't find an SUT thread and figured this might be the place to go.

I plan to do some more learning and hopefully hear some options in few weeks at Southwest Audio Fest, but in the mean time if anyone wants to share their learnings, experiences, favorite SUTs, etc - I'd love to continue to be distracted by the topic! I'm not sure if I'll go that direction, but I'm officially curious at this point.
 
displayname said:
Per usual I'm finding myself distracted, away from my stereo and wondering about various system possibilities. I've started to give more thought to the world of Step Up Transformers, aka an SUT. I know I've seen posts from @SnowmaNick @Joe Mac and @HiFi Guy discussing SUTs at various points. As I started to dig around, I couldn't find an SUT thread and figured this might be the place to go.

I plan to do some more learning and hopefully hear some options in few weeks at Southwest Audio Fest, but in the mean time if anyone wants to share their learnings, experiences, favorite SUTs, etc - I'd love to continue to be distracted by the topic! I'm not sure if I'll go that direction, but I'm officially curious at this point.
Click to expand...

I’ve had one for 3 months to connect to a new MM only tube phono stage which is horribly delayed. It should, touch wood, be dispatched week of 10/3 so hopefully I’ll be able to contribute a bit more after that!
 
Here's my biggest initial question: deciding on gain/loading ratios?

I understand that it's generally thought that one should match their SUT to their cart, but I'm curious how things work if you have a less than ideal match, but also a flexible phonostage. For example, let's say I decide the right fit for me is an SUT with a 1:10 step. But later down the line I change carts and really need 1:30 now. Could I use the step up to bring the signal up a little, and then use the phono gain to bring it up the rest of the way? Or would I really need to hunt down an SUT with a better ratio for the new cart?

I saw some formulas for this, and I was pretty instantly confused. Figured maybe others here might have more insights.
 
displayname said:
Here's my biggest initial question: deciding on gain/loading ratios?

I understand that it's generally thought that one should match their SUT to their cart, but I'm curious how things work if you have a less than ideal match, but also a flexible phonostage. For example, let's say I decide the right fit for me is an SUT with a 1:10 step. But later down the line I change carts and really need 1:30 now. Could I use the step up to bring the signal up a little, and then use the phono gain to bring it up the rest of the way? Or would I really need to hunt down an SUT with a better ratio for the new cart?

I saw some formulas for this, and I was pretty instantly confused. Figured maybe others here might have more insights.
Click to expand...

It’s not an exact science from what I can gather, a bit like cartridge loading itself in the first instance. From what I gather for something like a Sutherland MI for LOMC or Hana SL that quotes aeound 400ojms a 1:10 is a good match but for something like my AT OC9-XML or a Hana ML or SL MK2 that quotes 100ohm around 1:20 is better, I think the guy that built mine gave me a 1:16 option for those carts thst he felt was ideal.
 
Joe Mac said:
It’s not an exact science from what I can gather, a bit like cartridge loading itself in the first instance. From what I gather for something like a Sutherland MI for LOMC or Hana SL that quotes aeound 400ojms a 1:10 is a good match but for something like my AT OC9-XML or a Hana ML or SL MK2 that quotes 100ohm around 1:20 is better, I think the guy that built mine gave me a 1:16 option for those carts thst he felt was ideal.
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That's kind of what I was thinking. I just thought it would be such a shame to have an SUT that becomes bricked effectively because you decided to change carts. Especially if you went to a lower output. But if you could use the lower output cart, the SUT you have on hand, and just up your gain to 45-50db in the your phono... well then that's not all bad.
 
displayname said:
That's kind of what I was thinking. I just thought it would be such a shame to have an SUT that becomes bricked effectively because you decided to change carts. Especially if you went to a lower output. But if you could use the lower output cart, the SUT you have on hand, and just up your gain to 45-50db in the your phono... well then that's not all bad.
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Totally and my SUT even has two gain settings. I know importing to the states is probably a ball ache but these guys made me a really flexible SUT for a great price. They used higher up the line lundahl transformers than some named audio companies, offered more flexibility in the SUT and charged less.

Orso Audio - Official UK Lundahl Transformer Distributor

Orso Audio make high wuality moving coil step up transformer preamps. We are also an official distributor for Lundahl transformers in the UK, in particular for DIY HIFI valve amplifiers.
www.orso-audio.com
 
Some SUTs, like @Joe Mac mentioned have different settings. My Fonolab EQVES has an option for 1:10 and 1:36 for example. Some others have multiple taps so you can add a parallel resistor. My “Dream Sut” the Consolidated Audio Monster Can goes that route. So there are ways that make them more flexible. Best bet though is to target your most used carts and see if a custom one like Orso Audio could cover them, or Bob’s Devices already has something that would. Or, look at keeping your cartridges in a certain range, impedance wise.

Consolidated Audio has a handy calculator you can use to see how various turn options and Zoebel networks would give you.

In the end though, it’s like loading. It doesn’t have to be perfectly matched, but within a range (~5x-20x the internal impedance generally).
 
This article from Hagerman Technology discusses how to calculate impedance in a SUT:

Hagerman Technology LLC: Cartridge Loading

The key message: "Simply put, the impedance differs by the square of the turns ratio. For a 1:10 (20dB) step-up, the impedance is transformed by a factor of 100. That is, with the secondary loaded by 47k ohms, the primary reflects what appears to be 470 ohms to the cartridge."

Fun fact: This is why the original Sutherland Insight had a 10,000 ohm loading. When used with a 20dB SUT, it produces a loading of 100 ohms to the cartridge which is perfect for many LOMC carts.

This other article has way too much info but is for those who like the rabbit hole of SUT utilization.


All said and done, I think SUTs are the best reason why HOMC carts exist. That being said, I own a SUT and two phonos with embedded SUTs.
 
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displayname said:
Here's my biggest initial question: deciding on gain/loading ratios?

I understand that it's generally thought that one should match their SUT to their cart, but I'm curious how things work if you have a less than ideal match, but also a flexible phonostage. For example, let's say I decide the right fit for me is an SUT with a 1:10 step. But later down the line I change carts and really need 1:30 now. Could I use the step up to bring the signal up a little, and then use the phono gain to bring it up the rest of the way? Or would I really need to hunt down an SUT with a better ratio for the new cart?

I saw some formulas for this, and I was pretty instantly confused. Figured maybe others here might have more insights.
Click to expand...
The short answer for your gain question is "yes". You can make up a shortfall of SUT gain with additional gain in your 20/20. But, realize that the whole reason for getting the SUT probably was to reduce phono gain noise.
 
displayname said:
That's kind of what I was thinking. I just thought it would be such a shame to have an SUT that becomes bricked effectively because you decided to change carts. Especially if you went to a lower output. But if you could use the lower output cart, the SUT you have on hand, and just up your gain to 45-50db in the your phono... well then that's not all bad.
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You can't brick a passive analog device.

SUTs ratios are very much like tonearm compliance.

Don't overthink the ratios. The change from my 1:15 switch to 1:30 is not night and day.

It's pretty subtle like turning the impedance up and down on a phono amp.
 
displayname said:
Here's my biggest initial question: deciding on gain/loading ratios?

I understand that it's generally thought that one should match their SUT to their cart, but I'm curious how things work if you have a less than ideal match, but also a flexible phonostage. For example, let's say I decide the right fit for me is an SUT with a 1:10 step. But later down the line I change carts and really need 1:30 now. Could I use the step up to bring the signal up a little, and then use the phono gain to bring it up the rest of the way? Or would I really need to hunt down an SUT with a better ratio for the new cart?

I saw some formulas for this, and I was pretty instantly confused. Figured maybe others here might have more insights.
Click to expand...
Everything you wanted to know in one place with references via hyperlinks.


I have used SUT’s previously and the gain, along with a RC network across the secondary to eliminate ringing, is the key to success. My Lyra Parnassus, .25 mv output, came to life with a 28 db Ortofon SUT (25X gain). My Denon 103, .35 mv output, liked the 23 db Quicksilver Audio SUT (14X gain). My Hana SL, .5 mv output, worked well with a DIY Jensen 20 db SUT (10X gain). As long as the SUT is properly shielded with mu metal, they are relatively noise free and work great with tube or solid state MM phono preamps. However, they can seriously drain your bank account if you buy into some of the “hype” surrounding certain “brands”.

I now use a Parks Audio Waxwing which allows precise gain adjustments along with a host of other tweaks to the response - to match any cartridge. It is very quiet with regards to background noise. As a result, my SUT’s occupy space in my “spare components” drawer…..

The thing about this hobby is that it is always tempting to “try something new” not realizing we are already “there”. I like my current setup but if I am honest about cost/performance I should have stopped making changes sooner than I did.
 
Bob from Florida said:
Everything you wanted to know in one place with references via hyperlinks.


I have used SUT’s previously and the gain, along with a RC network across the secondary to eliminate ringing, is the key to success. My Lyra Parnassus, .25 mv output, came to life with a 28 db Ortofon SUT (25X gain). My Denon 103, .35 mv output, liked the 23 db Quicksilver Audio SUT (14X gain). My Hana SL, .5 mv output, worked well with a DIY Jensen 20 db SUT (10X gain). As long as the SUT is properly shielded with mu metal, they are relatively noise free and work great with tube or solid state MM phono preamps. However, they can seriously drain your bank account if you buy into some of the “hype” surrounding certain “brands”.

I now use a Parks Audio Waxwing which allows precise gain adjustments along with a host of other tweaks to the response - to match any cartridge. It is very quiet with regards to background noise. As a result, my SUT’s occupy space in my “spare components” drawer…..

The thing about this hobby is that it is always tempting to “try something new” not realizing we are already “there”. I like my current setup but if I am honest about cost/performance I should have stopped making changes sooner than I did.
Click to expand...
I have read the Rothwell article before.
Just to point out how conflicting the recommended ratios can be, Bob's recommends 1:40 and the Rothwell recommends 1:24 on the same Denon 103R.
That's an example of why I just say try it and listen for yourself.
As I said earlier, the differences are not so significant to my ears but closer to subtle.
 
Bob from Florida said:
I like my current setup but if I am honest about cost/performance I should have stopped making changes sooner than I did.
Click to expand...
Truth.

I purchased a standalone SUT before I purchased my two additional phonos that have embedded SUTs.

In reflection, I would have been better served (in my price range of cartridges) exploring high output MC carts into a high quality MM phono.

I purchased the SUTs and phonos because I was enamored with the idea that a LOMC was the “true” MC sound versus HOMC. Bogus notion that was built on lore versus listening experience. Ask the owners of the SAE 1000LT how they feel. 😂
 
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