SUT for Ortofon Verismo?

[AudioHR]

No, CH doesn't have a SUT inside. I mentioned in order to answer @Delkat question. CH P1 is a solid state phono based on current amplification (also has voltage amplification option) and is not related with any SUT or tube MM phono. As a response to @Delkat question, I meant I haven't listened Channel D (perhaps I did listen but I don't remember) but I don't think it's better than CH P1 and CH P1 is not better than best SUT+tube MM phono IMHO.


I don't know, cause it's hard to describe quality, especially quality that translates into good sound but they usually can go very low on cartridge impedance.

Thank you! I wasn't trying to be confrontational just questioning to gain from your experience.

I agree it is hard to describe quality other than you know when you hear it! Unfortunately that difficulty often leads us to trying things that are more expensive because they must be better !

Have you posted your system somewhere? I don't see it in your signature. Just wondering what you are using presently.

 

[Delkat]

IMHO/IME, it’s possible to use cartridges with internal impedances up to about one-third of the reflected load when using a high-quality SUT. For example, a SUT with a 1-ohm tap, a 1:63 turns ratio, and a 12-ohm reflected load can accept cartridges with internal impedances up to approximately 4-ohms.

@mtemur - Ok, I think I’m getting this now. The 10x or 20x rule of thumb referred to earlier is in reference to the internal impedance of the cart so, for the Verismo, that would be 70ohm and 140ohm as a “target” load that the cart sees reflected by the SUT based on the 47K ohm input impedance of the phono pre divided by the square of the turns ratio. You reference “a SUT with a 1-ohm tap”. Is this 1-ohm tap another characteristic of the SUT design that needs to be accounted for? I see in the EMAI SUTs they seem to have ways to add resistors externally to change this characteristic. Does this just add to the reflected impedance seen by the cart, i.e. another way to tweak impedance to maximize performance?

 

[mtemur]

@mtemur - Ok, I think I’m getting this now. The 10x or 20x rule of thumb referred to earlier is in reference to the internal impedance of the cart so, for the Verismo, that would be 70ohm and 140ohm as a “target” load that the cart sees reflected by the SUT based on the 47K ohm input impedance of the phono pre divided by the square of the turns ratio. You reference “a SUT with a 1-ohm tap”. Is this 1-ohm tap another characteristic of the SUT design that needs to be accounted for? I see in the EMAI SUTs they seem to have ways to add resistors externally to change this characteristic. Does this just add to the reflected impedance seen by the cart, i.e. another way to tweak impedance to maximize performance?

I think adding resistors to a SUT is causing new problems while solving others. Investing in a high quality SUT and not tweaking makes more sense to me. It’s not a rule but better SUTs usually have higher turns ratios (low impedance taps), just like higher end cartridges. Internal impedances of cartridges go lower while the sound quality increases. Again it’s not a rule. For example EMT silver SUT sounds very good to my ears and very high quality but it offers up to 1:10.

 

[Balle Clorin]

I believe there are SUTs in most phono stages

Most MC stages do not have a SUT, extra MC gain provided with transistors is the normal. But adding an external SUT is a fun experiment. When a SUT states 3 or 40 ohm on the input side that is the cartridge resistance that the SUT like to see for optimal behavior…

And then it is what load the cartridge like to see( reflected to the primary side) , and what load is optimal for the SUT in the RIAA side, and what input signal level is right( too high or to low is bad) for the MM input on the RIAA.

Someone mentioned Dave Slagle /Intact Audio, he will give good advice on this . Rothwell Audio also explain SUT matching very well on their website.

Here is a SUT with optimal cartridge resistance choice of 3 ohm for high gain(33x 30db) low MC signal, and 40ohm for low Gain/p(10x 20db)/High MC signal. Disregard the bump below 100hz it is a measuring artifact

If you do not have the optimal cartridge resistance for the SUT you may get a variation of the plot below..
A 10 ohm cartridge on the 40 ohm input gives the blue peak,
a 10 ohm cartridge on the 3 ohm input gives the magenta dashed line with early loss of high frequencies.

If you do not have the optimal cartridge resistance for the SUT the response can still be tweaked to an optimal result, but it requires some knowledge and measuring equipment to be sure to get it right.

So it is best to get a SUT that fits your cartridge or vise versa right away

 

[AudioHR]

Most MC stages do not have a SUT, extra MC gain provided with transistors is the normal. But adding an external SUT is a fun experiment. When a SUT states 3 or 40 ohm on the input side that is the cartridge resistance that the SUT like to see for optimal behavior…

And then it is what load the cartridge like to see( reflected to the primary side) , and what load is optimal for the SUT in the RIAA side, and what input signal level is right( too high or to low is bad) for the MM input on the RIAA.

Someone mentioned Dave Slagle /Intact Audio, he will give good advice on this . Rothwell Audio also explain SUT matching very well on their website.

Here is a SUT with optimal cartridge resistance choice of 3 ohm for high gain(33x 30db) low MC signal, and 40ohm for low Gain/p(10x 20db)/High MC signal. Disregard the bump below 100hz it is a measuring artifact

If you do not have the optimal cartridge resistance for the SUT you may get a variation of the plot below..
A 10 ohm cartridge on the 40 ohm input gives the blue peak,
a 10 ohm cartridge on the 3 ohm input gives the magenta dashed line with early loss of high frequencies.

If you do not have the optimal cartridge resistance for the SUT the response can still be tweaked to an optimal result, but it requires some knowledge and measuring equipment to be sure to get it right.

So it is best to get a SUT that fits your cartridge or vise versa right away

This looks very interesting.

I think I follow the basic premise but can you explain the specific nomenclature. For example although I can see the difference in the frequency responses I am not exactly sure I know what the terminology you are using means. In general terminology and specifications seem to be all over the place when looking at cartridges and SUTs which certainly adds to my confusion. Probably my basic lack of knowledge, lol.

So what does RS mean for example.

I believe what you are showing could be very useful but I don't think I understand it enough to apply it to my cartridge. It's a SPU with an internal impedance of 2 ohms and recommended load impedance of 10 ohms. The output voltage is .2mv.

The SUT I am using offers some choices as far as turn ratio and primary load at 47k ohms. Based on my limited knowledge I have chosen to try it at 1:40 with a primary load of 30 ohms. How does this align with what you are saying?

 

[Balle Clorin]

RS is source resistance=cartridge resistance.
With SPU at 2 ohm , 0.2mV and 1:40 you get 7.5mV to the RIAA and 29 ohm load for the 2ohm cartridge. 7.5mV is high but not too high. The ratio between load and source is 29:2=15 which is > 10 that gives minimal loss is signal level. It is also according to the recommendation you mention. Normally the recommended load is greater than , so that should be OK too , with 29>10 ohm. To get lower load the gain will become too high causing too little margin to clipping in the RIAA.

So I would expect you are good. What SUT is it? What is the input ohm?

 

[AudioHR]

RS is source resistance=cartridge resistance.
With SPU at 2 ohm , 0.2mV and 1:40 you get 7.5mV to the RIAA and 29 ohm load for the 2ohm cartridge. 7.5mV is high but not too high. The ratio between load and source is 29:2=15 which is > 10 that gives minimal loss is signal level. It is also according to the recommendation you mention. Normally the recommended load is greater than , so that should be OK too , with 29>10 ohm. To get lower load the gain will become too high causing too little margin to clipping in the RIAA.

So I would expect you are good. What SUT is it? What is the input ohm?

Thank you for the quick response and some excellent information.

How do you calculate the 7.5 mv output to the phono?

The SUT is an Ed Clayton Cinemag 1254 with 4 different winding ratio options. Another option would be 1:20 and load of 118 ohm. How does this fit? Less gain. The load would seem to be greater, what effect would this have on frequency response?

The input ohm is not specified on the SUT if that is what you are looking for. So not sure what this is.

I have a Shindo Monbrison preamp with a phono that is specified as Input sensitivity／Impedance：3mV／100KΩ. With a Phono Max. Input Voltage 1,200 mV. If this means anything?

 

[Balle Clorin]

7.5mV comes from:
0.2mV * 40 x gain is 8 mV, but the load reflected to the primary side is 47000/(40*40)=29,3 ohm, and that resistance is combined with the cartridge resistance of 2 ohm giving a total resistance of 31,3 ohm. The actual signal level out is then becoming lower by a factor of 29.3/31.3. (Load/(load+ source) this gives a real gain of 40*(29.3/31.3)=37.44.

Signal to RIAA becomes 37.44*0.2= 7.48mV. I have ignored the coil resistance on primary and secondary side for simplicity, the result is close enough I think.

You can now do the same for 20 gain ratio and see what you get.,, 3,9mV and a load to the cartridge of 117.5 ohm.
That 4mV mV is very suitable for the RIAA, and with a RIAA with a low overload margins that would maybe be better than 7.5mV, gives almost 6db lower level. But the SUT input may not be so happy with the 2 ohm cartridge on the 1:20 gain ( see the blue curve in my second plot posted above)

However , your RIAA seem to have a very good overload margin 1200mV ! It should be no problem using the 1:40 gain ( 7.5mV), I also suspect that SUT 40x tap will give the flattest high frequency response.

Your Shindo is to be on MM 47k ohm when using the SUT.

You may try both 20 and 40x and report back, just remember to adjust level +5,6dB when you got from 40 to 20x. 40 will sound much louder and punchier than 20 if volume is not adjusted. My guess is the your choice of 40x will sound best and be technically best in your system .

( cannot be 100% sure with out measuring it, but that involves much more than sending a sweep through the SUT, the source and load must be correct and they will not be if just an ordinary sound card is used)

 

[AudioHR]

7.5mV comes from:
0.2mV * 40 x gain is 8 mV, but the load reflected to the primary side is 47000/(40*40)=29,3 ohm, and that resistance is combined with the cartridge resistance of 2 ohm giving a total resistance of 31,3 ohm. The actual signal level out is then becoming lower by a factor of 29.3/31.3. (Load/(load+ source) this gives a real gain of 40*(29.3/31.3)=37.44.

Signal to RIAA becomes 37.44*0.2= 7.48mV. I have ignored the coil resistance on primary and secondary side for simplicity, the result is close enough I think.

You can now do the same for 20 gain ratio and see what you get.,, 3,9mV and a load to the cartridge of 117.5 ohm.
That 4mV mV is very suitable for the RIAA, and with a RIAA with a low overload margins that would maybe be better than 7.5mV, gives almost 6db lower level. But the SUT input may not be so happy with the 2 ohm cartridge on the 1:20 gain ( see the blue curve in my second plot posted above)

However , your RIAA seem to have a very good overload margin 1200mV ! It should be no problem using the 1:40 gain ( 7.5mV), I also suspect that SUT 40x tap will give the flattest high frequency response.

Your Shindo is to be on MM 47k ohm when using the SUT.

You may try both 20 and 40x and report back, just remember to adjust level +5,6dB when you got from 40 to 20x. 40 will sound much louder and punchier than 20 if volume is not adjusted. My guess is the your choice of 40x will sound best and be technically best in your system .

( cannot be 100% sure with out measuring it, but that involves much more than sending a sweep through the SUT, the source and load must be correct and they will not be if just an ordinary sound card is used)

A very informative series of posts. I think amongst the best information on SUTs that I have read. Well done!

The clarity of what you have explained is top notch. I think somewhere you noted that English is not your first language, but you certainly have no problem communicating!

I originally started out with the Icon Audio 1:10 SUT that I had been using successfully on another cartridge. It sounded pretty good with the Ortofon but I sensed based on my reading, some posts on WBF and well the sound that there was likely better performance to be unlocked.

The Ned Clayton SUT seemed a good choice to explore the performance with various settings. I actually have tried the Ortofon with a few settings now and found fairly quickly that the 1:40 setting seemed to bring out the best in it. Yes one must pay attention to the system gain as often louder initially sounds better. I will probably circle back to the other options at some point just to confirm but for now I am very happy to explore the sound of my SPU Classic GE Mk ii.

 

[Kinn]

Hi Delkat,

I had Ortofon A95, like you, found it lack of drive and thin sounding. It was until I spoke to Dave Slagle, bought a 1:20 copper SUT and I hear the cartridge performing at its best. Drive aplenty, meat on bones, quiet, I can go on…

Verismo has the same spec as A95, you’d written/spoken to Dave Slagle, go for the 1:20 unit. Set your phonostage to MM, use the lower gain setting(at 45db) and enjoy the music.

Have fun