SUT, Cartridge and Phono Preamp

oracle1974

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Hello FMs,

Can you tell me when is a SUT required to be introduced in a set-up?

The manufacturer is suggesting that I use a SUT with the cartridge that I am using.

Would not the specifications of the phono-preamp also have a bearing on whether a SUT is required ?

When should I be looking to introduce a SUT?

Look forward to your answers.

Thanks.
 

arj

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An SUT is needed when your phono is an MM and you want to use a MC cart.
But it is not as simple.you need the SUT to present a load of 47K Ohms to the Phono and that's where the no of turns becomes important..and as per many experts this is more important than the voltage gain.
For most 100ohm cartridges, 20-22 turns is enough .

Formula is square root of 47k/output impedance. Eg for a dl103 with 100ohms output impedance it around 22 turns.

Best to ask the manufacturer
 

malvai

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I follow the below article... and it has worked out for me in spades... I have copied the text and pasted it here .... I believe Tin Pavacini used to believe the same principles, which is why his phonos are legendary...

Beginning of article:
"Cartridge loading and its efficacy can be a contentious issue among vinylphiles. So, I asked Icon Audio’s designer/owner David Shaw about his decision to hard set 100Ω for his MC option. Was it a philosophical, financial, or design choice? Here is Shaw’s very detailed and informative response:

Hi Anthony

I start my story with a visit to Ortofon’s factories and offices in Denmark some years ago. An amazing company dedicated to phono cartridges, they have tremendous knowledge and expertise. I learned a lot.

Behind closed doors they said two things I have never forgotten.

1. They only really make MM cartridges because the market demands it and MC is superior in just about every way.

2. If you are using MC you will only get the best results with a step up transformer. A $2 chip with 10x gain on the front of MM phono stage is just not the same.

At least part of the reason lies in the fact that the normal loading for an MM cartridge is a resistor, 47,000 Ohms and by convention a passive unchanging load.

Whereas a transformer is reactive load who’s impedance is constantly changing with frequency and amplitude. Therefore, any measurements must be qualified by stating whether it’s a DC measurement or AC and then things like frequency and level come into play. (For example a so called “8 Ohm speaker” (which usually measure 6 Ohms DC) will vary its impedance often between 2 Ohms and 30 Ohms, depending upon how easy it do that frequency).

For example the spec for Ortofon’s superb Cadenza Bronze says:

Recommended Load Impedance: 50 - 200Ω

A pretty wide tolerance don’t you think?

And the £4,000 “Expression” model says “greater than 10 Ohms”, they do not even specify an upper limit! The reason why is that it simply does not matter very much, the impact on the sonics will be small.

So, loading the cartridge with a minimum of 10 Ohms resistor will deliver the correct voltage to the next stage.

But loading the cartridge with a step-up transformer gives coil to coil transfer, then something magical happens! The energy transfer happens with all the micro detail that gives the flavour and emotion of the original recording. It’s “organic”.

So, that is why IMHO (and Ortofon + others) a good quality 10x step-up transformer is all you need. (at about 100 ohms).

I should also add that again IMHO a “pure” tube phono stage is always preferable.

Why? Because when in 1957 RCA/CBS/Decca/HMV agreed on the LP stereo format and agreed on the RIAA EQ as standard, they did this with tubes in mind as transistors were not advanced enough at that time. So, for a high quality accurate reproduction of the RIAA curve with a MM cartridge requires just two medium gain tubes. Doing this with transistors is actually not that easy and requires a lot more complexity. Of course, these days, the use of very high quality, low noise chips is the norm. Technically superb!

But (and this is a very big BUT!), as we know chips contain a huge number of junctions inside so the signal becomes highly processed though possibly hundreds of junctions, micro resistors, micro capacitors. Whereas the simplicity of just two triode valves (plus one for output) gives a much more “open” and “honest” presentation.

This is the basic idea, let me know if you need more.

Regards

David Shaw

Icon Audio (UK) Ltd"


-End of Article
 

arj

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I follow the below article... and it has worked out for me in spades... I have copied the text and pasted it here .... I believe Tin Pavacini used to believe the same principles, which is why his phonos are legendary...

Beginning of article:
"Cartridge loading and its efficacy can be a contentious issue among vinylphiles. So, I asked Icon Audio’s designer/owner David Shaw about his decision to hard set 100Ω for his MC option. Was it a philosophical, financial, or design choice? Here is Shaw’s very detailed and informative response:

Hi Anthony

I start my story with a visit to Ortofon’s factories and offices in Denmark some years ago. An amazing company dedicated to phono cartridges, they have tremendous knowledge and expertise. I learned a lot.

Behind closed doors they said two things I have never forgotten.

1. They only really make MM cartridges because the market demands it and MC is superior in just about every way.

2. If you are using MC you will only get the best results with a step up transformer. A $2 chip with 10x gain on the front of MM phono stage is just not the same.

At least part of the reason lies in the fact that the normal loading for an MM cartridge is a resistor, 47,000 Ohms and by convention a passive unchanging load.

Whereas a transformer is reactive load who’s impedance is constantly changing with frequency and amplitude. Therefore, any measurements must be qualified by stating whether it’s a DC measurement or AC and then things like frequency and level come into play. (For example a so called “8 Ohm speaker” (which usually measure 6 Ohms DC) will vary its impedance often between 2 Ohms and 30 Ohms, depending upon how easy it do that frequency).

For example the spec for Ortofon’s superb Cadenza Bronze says:

Recommended Load Impedance: 50 - 200Ω

A pretty wide tolerance don’t you think?

And the £4,000 “Expression” model says “greater than 10 Ohms”, they do not even specify an upper limit! The reason why is that it simply does not matter very much, the impact on the sonics will be small.

So, loading the cartridge with a minimum of 10 Ohms resistor will deliver the correct voltage to the next stage.

But loading the cartridge with a step-up transformer gives coil to coil transfer, then something magical happens! The energy transfer happens with all the micro detail that gives the flavour and emotion of the original recording. It’s “organic”.

So, that is why IMHO (and Ortofon + others) a good quality 10x step-up transformer is all you need. (at about 100 ohms).

I should also add that again IMHO a “pure” tube phono stage is always preferable.

Why? Because when in 1957 RCA/CBS/Decca/HMV agreed on the LP stereo format and agreed on the RIAA EQ as standard, they did this with tubes in mind as transistors were not advanced enough at that time. So, for a high quality accurate reproduction of the RIAA curve with a MM cartridge requires just two medium gain tubes. Doing this with transistors is actually not that easy and requires a lot more complexity. Of course, these days, the use of very high quality, low noise chips is the norm. Technically superb!

But (and this is a very big BUT!), as we know chips contain a huge number of junctions inside so the signal becomes highly processed though possibly hundreds of junctions, micro resistors, micro capacitors. Whereas the simplicity of just two triode valves (plus one for output) gives a much more “open” and “honest” presentation.

This is the basic idea, let me know if you need more.

Regards

David Shaw

Icon Audio (UK) Ltd"


-End of Article
Good one Manav. I had a lot of lengthy mails exchanged on this with Dave Slagle as well and his view was also a SUT is a far better option and even in that the secret is to match impedance rather than gain .
 

oracle1974

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You will either need a step up for .3mV cart output or a dedicated MC phonostage. I can help you in a DIY one if you are interested.

Regards
Sachin
Thanks for the offer. I am trying to understand these things better and will revert back to you .
 

newlash09

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I follow the below article... and it has worked out for me in spades... I have copied the text and pasted it here .... I believe Tin Pavacini used to believe the same principles, which is why his phonos are legendary...

Beginning of article:
"Cartridge loading and its efficacy can be a contentious issue among vinylphiles. So, I asked Icon Audio’s designer/owner David Shaw about his decision to hard set 100Ω for his MC option. Was it a philosophical, financial, or design choice? Here is Shaw’s very detailed and informative response:

Hi Anthony

I start my story with a visit to Ortofon’s factories and offices in Denmark some years ago. An amazing company dedicated to phono cartridges, they have tremendous knowledge and expertise. I learned a lot.

Behind closed doors they said two things I have never forgotten.

1. They only really make MM cartridges because the market demands it and MC is superior in just about every way.

2. If you are using MC you will only get the best results with a step up transformer. A $2 chip with 10x gain on the front of MM phono stage is just not the same.

At least part of the reason lies in the fact that the normal loading for an MM cartridge is a resistor, 47,000 Ohms and by convention a passive unchanging load.

Whereas a transformer is reactive load who’s impedance is constantly changing with frequency and amplitude. Therefore, any measurements must be qualified by stating whether it’s a DC measurement or AC and then things like frequency and level come into play. (For example a so called “8 Ohm speaker” (which usually measure 6 Ohms DC) will vary its impedance often between 2 Ohms and 30 Ohms, depending upon how easy it do that frequency).

For example the spec for Ortofon’s superb Cadenza Bronze says:

Recommended Load Impedance: 50 - 200Ω

A pretty wide tolerance don’t you think?

And the £4,000 “Expression” model says “greater than 10 Ohms”, they do not even specify an upper limit! The reason why is that it simply does not matter very much, the impact on the sonics will be small.

So, loading the cartridge with a minimum of 10 Ohms resistor will deliver the correct voltage to the next stage.

But loading the cartridge with a step-up transformer gives coil to coil transfer, then something magical happens! The energy transfer happens with all the micro detail that gives the flavour and emotion of the original recording. It’s “organic”.

So, that is why IMHO (and Ortofon + others) a good quality 10x step-up transformer is all you need. (at about 100 ohms).

I should also add that again IMHO a “pure” tube phono stage is always preferable.

Why? Because when in 1957 RCA/CBS/Decca/HMV agreed on the LP stereo format and agreed on the RIAA EQ as standard, they did this with tubes in mind as transistors were not advanced enough at that time. So, for a high quality accurate reproduction of the RIAA curve with a MM cartridge requires just two medium gain tubes. Doing this with transistors is actually not that easy and requires a lot more complexity. Of course, these days, the use of very high quality, low noise chips is the norm. Technically superb!

But (and this is a very big BUT!), as we know chips contain a huge number of junctions inside so the signal becomes highly processed though possibly hundreds of junctions, micro resistors, micro capacitors. Whereas the simplicity of just two triode valves (plus one for output) gives a much more “open” and “honest” presentation.

This is the basic idea, let me know if you need more.

Regards

David Shaw

Icon Audio (UK) Ltd"


-End of Article
Excellent @malvai ...thanks for sharing. Iam new to vinyl. But the gentleman in UK, who built the bigbottle mk3 phono stage, asked about my MC cart, and threw in a free pair of 100 ohm loading plugs with it. Reading your post today explains why :)
 

Beast_of_burden

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You will either need a step up for .3mV cart output or a dedicated MC phonostage. I can help you in a DIY one if you are interested.

Regards
Sachin
Hi Sachin,

I am running a DL103 into Lehman Black CUbe Statement. Loading is set to 100 ohm on the black cube. The sound quality is much better than the Schiit Mani. I am intrigued about the SUT, please tell me about DIY options. Everyone is advocating 20 turns for DL103R.
 

stevieboy

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Have gone transfórmeless. I have a SUT lying around if you’d like one. Cinemag 3440 wired up in a box. Should fit the denon. I know it fits the denon regular 103. Not sure of the R. Might fit on the other tap. Pm me if interested.
 

sachu888

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Hi Sachin,

I am running a DL103 into Lehman Black CUbe Statement. Loading is set to 100 ohm on the black cube. The sound quality is much better than the Schiit Mani. I am intrigued about the SUT, please tell me about DIY options. Everyone is advocating 20 turns for DL103R.
I can provide you AD797 based MC phonostage. It can work with any LOMC, gain and impedance can be set using onboard trimmers. You can read more here https://audiokarma.org/forums/index.php?threads/ad797-phono-stage-build-and-help-desk-thread.501186/
Many builds on hifivision https://www.hifivision.com/threads/ht-mc-phono-stage-ad797.43653/

Regards
Sachin
 

Sushant Sharma

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I can provide you AD797 based MC phonostage. It can work with any LOMC, gain and impedance can be set using onboard trimmers. You can read more here https://audiokarma.org/forums/index.php?threads/ad797-phono-stage-build-and-help-desk-thread.501186/
Many builds on hifivision https://www.hifivision.com/threads/ht-mc-phono-stage-ad797.43653/

Regards
Sachin
have been playing mine since earlier this week after giving it a rest for a few months. very happy with it.
 

stevieboy

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Hello FMs,

Can you tell me when is a SUT required to be introduced in a set-up?

The manufacturer is suggesting that I use a SUT with the cartridge that I am using.

Would not the specifications of the phono-preamp also have a bearing on whether a SUT is required ?

When should I be looking to introduce a SUT?

Look forward to your answers.

Thanks.
Hi Oracle,

Answering in order of questions you have posted.

A SUT is required when you have a low output cartridge (which you do). Normal Moving Magnet cartridges output a highish voltage 2-5mV which a regular phono stage requires. MCs output 0.2 to 2mv which require to be stepped up to the voltage levels your phono stage can handle and work with. ie 2-8ish.

The manufacturer (I'm assuming you mean of your cart) probably doesn't know your phono stage and that it can handle pretty much any cart with its gain and impedance settings that are built in.

Yes the specs of your phono preamp would have a bearing. If your phono stage already has gain switch options and circuitry to handle a low output MC (which yours has) then you don't need a SUT. However your phono stage will also have a standard Moving Magnet input 47kOhm and you can connect a step up into this input.

You should be looking to introduce a SUT if you want to see what sound flavour a SUT brings to the table inspite of your phono stage having the required gain options or assuming that (theoretically in your case) your phono stage is only an MM that takes inputs of 2mv and higher that typical moving magnet carts output.

The advantages are that a SUT is a passive device and generates less noise than an active stage and also the distortion is benign, being higher at lower frequencies and dropping as the frequency rises, unlike solid state amplification. Which translates to better sound. The thing to watch out for is hum, highly dependent on physical placement, interconnect type, shielding and length and grounding schemes which vary wildly by system and local power supply connections.

When choosing a SUT, ideally go for the lower gain ones. Multiply the stated SUT gain ratio into your cart's output voltage to see if it falls within the 2-6ish range and you're set. Then loading can be done with parallel loading plugs. There are online calculators to enter your cart output, SUT figures to see if resulting impedance matches manufacturer recommendation.

Regards
 

stevieboy

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An SUT is needed when your phono is an MM and you want to use a MC cart.
But it is not as simple.you need the SUT to present a load of 47K Ohms to the Phono and that's where the no of turns becomes important..and as per many experts this is more important than the voltage gain.
For most 100ohm cartridges, 20-22 turns is enough .

Formula is square root of 47k/output impedance. Eg for a dl103 with 100ohms output impedance it around 22 turns.

Best to ask the manufacturer

Hi Arj,

If I may correct the statement I've highlighted in bold. A SUT can never present a load of 47k to a phono stage. It's not what needed at all and in fact its electrically incorrect since the phono already has a 47kOhm internal impedance as standard for the MM input. What happens in reality is simple electrical/impedance interactions between components.

All devices have an internal impedance. A phono cartridge has an internal impedance. For Ortofon SPUs I think its 2 or 6 ohms. In order for optimum signal transfer to happen this internal impedance needs to be connected to a component with an internal impedance of around 10 times higher, ie around 60 ohm. When this happens, the signal from the cartridge flows on to the next stage with minimal loss. (In practice 100 ohm works for most MC carts). Now a cartridge is connected to the next component which is a stepup transformer which has its own internal impedance of lets say, I think its 37.5 or 150 ohms for the two optional taps of the Cinemag step up transformer. However the step up transformer is also connected to the phono stage which has its own internal impedance of 47kOhm. Now electrical rules state that two impedances interact to combine and present a new single lower impedance value. So lets take one impedance value of the step up 150ohm. This interacts with the phono stage's 47kOhm impedance to present a lets say 4000 ohm impedance value to the cart. (One can figure out the exact value through formulas that are freely available online). Now we've established that the cart needs to see a value of around 60 ohm. But its seeing 4000 ohm which is way too high. Again taking the electrical rule that two impedances in parallel result in a lower impedance value, the solution is simple - cartridge loading via resistors where you put a resistor in parallel with the phono stage's 47kOhm to achieve a new impedance lower than the original reflected 4000 ohm and closer to 60 ohm. It's really as simple as that. I hope more new vinyl enthusiasts understand that there's no mystery to selecting a step up transformer and are able to select one that's right for them.

A first step however as I've mentioned in the post above would be to multiple the turns ratio eg if its 1:15 then multiply 15 into your cart's output Voltage, lets say around 0.3mV and the resulting number (4.5mV) should be between 2.5-10 mV which your phono stage works at. Higher would overload the phono stage and lower it would not produce enough output. Once the output is assured next step would be making sure impedances line up for optimal signal transfer. Both are equally important, just like two hands are needed to clap, it's just that impedance is more widely misunderstood and hence has acquired an aura of 'criticality' and mystery. At least that's what I feel.

Then there are custom step up transformers that are electrically matched to one particular cartridge, ruling out the need for resistor loading.

Regards
 

arj

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Hi stevieboy,

Not sure I understood the above and also not sure if you are saying the same thing ! when I said SUT it was the cartridge + SUT ie external impedance of cartridge x square of no of turns =47K

My understanding was based on a discussion I had with Dave Slagle as thats how he makes custom SUTs . As per him the voltage ratio is flawed and you need to do it via resistance ratios since the V out of the SUT is not a direct ratio due to the internal impedance of the cartridge which grounds a percentage of the signal.
I had a discussion with him on AA Here and Lew actually mentions that ( yes I am Gravetones :) here )

I did get a custom one built for the DL103R by slagle but when I got the ortofon, just went by the manufacturer recommendation to ensure synergy
 
Last edited:

stevieboy

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Hi stevieboy,

Not sure I understood the above and also not sure if you are saying the same thing ! when I said SUT it was the cartridge + SUT ie external impedance of cartridge x square of no of turns =47K

My understanding was based on a discussion I had with Dave Slagle as thats how he makes custom SUTs . As per him the voltage ratio is flawed and you need to do it via resistance ratios since the V out of the SUT is not a direct ratio due to the internal impedance of the cartridge which grounds a percentage of the signal.
I had a discussion with him on AA Here and Lew actually mentions that ( yes I am Gravetones :) here )

I did get a custom one built for the DL103R by slagle but when I got the ortofon, just went by the manufacturer recommendation to ensure synergy


cart + step up ah. Will read up on the link you've posted!
 

stevieboy

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Hi Arj,

I went through the link you posted. Did not find an explanation of the above calculation you mentioned. But found it in one of the sites I have referred to to understand the subject, apart of course from the standard analog dept site.


Basically it says that multiplying the cart's impedance by the square of the turns ratio = 47kohm, this ensures maximum signal transfer but it also says that's misguided and not really the goal, the goal is stepping up the signal to a number that's usable by the phonostage ie around 5mV which is middle of the range and a transfer that ensures fidelity. Viren also had advice on one point that mirrors that site ie its preferable to use the lower turns ratio rather than the higher turns ratio on a step up if I remember right it's cos the lower turns uses all the windings whereas the higher one uses only half and that leads to issues which I've quite forgotten.

So basically it seems we have two step up designers who have contradictory advice. Unless Slagle's advice applies only to transformers like his wound for one particular cart and not to off the shelf ones? I dunno. I'm not too well versed with electronics so I'll park it here cos its purely academic for me I don't use them anymore anyway. Those who need to buy a step up can do their own reading and come to their own conclusions :)

Regards
 
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