SUT for the DIYers

[Doc Jr 8156]

Here is an inexpensive SUT for the DIY crowd. Why an SUT transformer? Let’s look at the basics.

For us low output moving coil users, an SUT is essential. We have to remember that .2mv to .4mv range of cartridge output is not enough to present proper voltage for the phono head amp to drive. A regular MM phono stage needs at least 360mv. Ever wonder why sometimes when you compare your CD player’s output through your system to that of your vinyl, the CD sounded to be more dynamic and clearer, sort of? One of the reasons is that the CD player is putting out an output voltage of normally 2 volts. Compared to LOMC output, it is unthinkable to compare. One more thing to consider is that if you are using LOMC, the total gain of your vinyl playback (phono amp and SUT) should not be less than 62 db; this is excluding the preamp gain to get the most out of it.

As mentioned above, the phono head amp requires voltage to drive. The LOMC cartridge for that matter is a poor voltage source but a good current source, requiring an SUT to increase the gain (in db) and also transforming the current created by the cartridge into voltage required by the phono head amp.

For a whopping $96, the Cinemag is a best buy for the DIYers. Cost less than half of the most common alternative, the Lundahl 9206, but no pcb is required. Try this SUT and you will be surprised by the sound. Better yet, for those not using any SUT, here’s the solution, what are you waiting for. Cinemag is a mic input transformer developed for the pro audio industry. Remember, if the mic cannot record at its best, then the playback afterwards will be ruined. Enjoy. There is one other thing besides SUT and cartridge output to maximize your vinyl playback, you LOMC user you. Cartridge loading. That my friend, requires a whole new thread to discuss and very complicated to understand.

Good day…..Good luck……Godspeed.

[arnoldc]

Doc, couple of Qs-

Which version of Cinemag is this?

The CMQEE-3440A is specified at 37.5,150,600 : 50K which translates to 1:36.5, 1:18.3 and 1:9.1

The CM-75101A is specified at 150,600 : 15K which translates as 1:10 and 1:5

The CMQEE-3440APC is specified at 150,600 : 50K also translates to 1:18.3 and 1:9.1

The CMMI-10C 150 : 15K and translates to 1:10

What led you to this model of Cinemag?

Why 62dB min for low-output MC? At what cartridge output range? 0.2, 0.3, 0.4, 0.5, 0.6?

How did you go about the matching? Are you feeding a Cornet? Rather, what is your MM stage? What gain does it have? What is your linestage? What gain does it have?

Cheers!

ps.

You don't need PCBs (although they will look nice) for Lundahls. I've worked with them *without* a PCB.

[Doc Jr 8156]

Arnold,
I'll try to answer all your queries. It is the CMQ 3440A tranny. Those that have 1:10 and 1:5 ratios are useless if you are using a low output MC in the vicinity of .4mv. Try and compute for the gain using 1:5 and 1:10 ratio and they will not be enough. One thing to remember is that when you match the source impedance with the load impedance, the output of the cartridge is halved. In this case if you are using a .4 mv cart, when you match the load impedance you are only looking at a .2mv output. In the same token a .2mv cart will be a .1mv output cart. Using the common gain of mm phonostage of 44 to 46 db at 1:10 ratio will only give you 54db and so on. I cannot find the reference I read about the gain of at least 62 db but through experience too, this proved to be correct. Also, there is a formula to compute this but at 62 db of gain, the voltage developed approach much closer to that of the typical CD output of 2 volts as presented to the line stage after the phono stage, so they say. Typically. The recommendation is to achieve 60 db of gain for cartridges between .15 to .3mv output but this is without the loading scheme mentioned above. I do not understand the question regarding “matching. Matching of what? Source and load impedance? Well, you should look at the specified load for your cart and you have to match that with what the cartridge will see in the secondary of the transformer. Since the typical load for a phono stage is 47k, one should find the value a resistor when paralled to 47k will give you a value in the secondary divided by the ratio squared to be equaled that of the specified load. I would like to refer you to Bent Audio’s website for the actual theory and discussion. My phono stage is a K&K SE with 50db of gain for the MM stage. At the moment, I’m using a Bent NOH passive preamp, no gain. Hope I answered most of your questions.

Yes, with your DIY skills I will not be surprised that you can wire the Lundahls effectively without using the required pcb but I want to see how you did it and how neatly it was done. Godspeed.

[amandarae]

Doc, couple of Qs-

Which version of Cinemag is this?

The CMQEE-3440A is specified at 37.5,150,600 : 50K which translates to 1:36.5, 1:18.3 and 1:9.1

The CM-75101A is specified at 150,600 : 15K which translates as 1:10 and 1:5

The CMQEE-3440APC is specified at 150,600 : 50K also translates to 1:18.3 and 1:9.1

The CMMI-10C 150 : 15K and translates to 1:10

What led you to this model of Cinemag?

Why 62dB min for low-output MC? At what cartridge output range? 0.2, 0.3, 0.4, 0.5, 0.6?

How did you go about the matching? Are you feeding a Cornet? Rather, what is your MM stage? What gain does it have? What is your linestage? What gain does it have?

Cheers!

ps.

You don't need PCBs (although they will look nice) for Lundahls. I've worked with them *without* a PCB.

arnoldc,

Obviously, I am not Doc but please allow me to contribute here.

What led you to this model of Cinemag?

The obvious answer is that most MC cart with 0.4mV or lower output have an manufacturer impedance of 40 Ohms or lower. If you look at the spec for the Cinemag it is specified at 1:37.5 if the secondary is seeing 50K. Since the phono is 47k and very close, the net impedance when transformed by the xformer is about 36.5 ohms which is very close to the ~40 ohms or lower cart impedance Without loading. Maximum power transfer?

What led you to this model of Cinemag?

Probably the 1:36.5 gain and the reason stated above. To explain this, let me give an example. I am sure you heard that in order to load the cart properly, you should choose 5X or 10X its internal resistance right? IMHO, this is wrong! Assuming you have a 0.4 mV cart, 25 ohms, MC. So following the conventional wisdom, you will load it at 125 Ohms or 250 Ohms. I can assure you that if you load this by a net resistance lower than 50 ohms, you will hear that the presentation is "in your face", the highs are harsh, the soundstage shrunk, not to mention you have to crank the gain up. Why? Simple current divider formula tells you that any resistance value lower and in parallel to the 47K on the secondary side will produce a current to the phono input much smaller than that of the second resistor. For example, if 47k is 2 units, and you are trying to load the cart with a one unit resistance compared to the 47k, the current to this resistor is 2/3 of the total while the one going to the phono is 1/3!This is the reason why all the "anomalies" happens! The simple remedie is to load the cartridge 5X or 10X so that the current will increase 5 fold or 10 fold.

Take note, I said remedy, not solution! Because imho, this practice is wrong. Proof? Listen to any cartridge 0.4 mV or less with internal resistance less that 40 ohms with a gain of about 62 dB not inluding the linestage loaded at its specified resistance and you will hear the differece which is not subtle because it does two things right:

1.) Proper loading/matching of load (max power transfer)
2.) Sufficient gain so to avoid the phono preamp doing all the amplification (Noise figure!)

So, if you have a Denon 103 or 103R, try it and that will be the verdict.

How did you go about the matching? Are you feeding a Cornet? Rather, what is your MM stage? What gain does it have? What is your linestage? What gain does it have?

At 36.5 transformed impedance(1:36 at 47K), you can load the cart with 36 ohms(no load) or lower resistance by Y = (47k // X)/36 squared where X=the resistance value for loading and Y = target resistance


That is how I understand the principles of proper cart loading.

ps.

You don't need PCBs (although they will look nice) for Lundahls. I've worked with them *without* a PCB.

Yep, arnoldc is right! Doc, go here and click the data sheet of the LL9206 http://www.kandkaudio.com/datasheets.html

cheers

[arnoldc]

Doc, that's what I was looking for in your post. All the logic behind it, the matching, and the more important technical stuff which will help other analogistas who might be contemplating on going low output MC but does not have an MC head, such as troporobo Robert, how about an MC cart for you?

I can't post a picture yet of my Lundahl but I used teflon coated solid wire, nicely curved to fit to solder on the terminals. On one lazy day, I used perforated board to wire up the other Lundahl.

Abe, yup the reason I posted the 3440A first is that it is what seems to be a really good one. Even for my 50 ohm cart, it will be very close.

About loading 5x or more, which really drops down the resistance, I just don't get the picture so I've never really tried it. If we were talking about output transformers for tube amps, *maybe* for less distortion and much less power But that's a totally off-topic thing. He he he.

There's not a single issue about proper loading, and we all agree to this. But for some who has not explored it yet, may blame the table , the phonostage , the cart as the culprit for some nasty sound when in fact it's just a simple issue.

One thing I can say about those Cinemags is *they're cute!* And I like cute.

ps.

I'd like to add that if you haven't loaded your phonostage properly according to your cartridge, then you reallyt haven't heard your cart

[amandarae]

There's not a single issue about proper loading, and we all agree to this. But for some who has not explored it yet, may blame the table , the phonostage , the cart as the culprit for some nasty sound when in fact it's just a simple issue.

Absolutely right!

[Doc Jr 8156]

Arnold,
I agree wholeheartedly that those who are not loading their cartridge to the specified impedance by the manufacturer is missing a ton of what their cartridge can and designed to do. 50 ohms eh? What is the output?

If you love the looks of the Cinemags because they are cute, (they are) then you will even more adore them for how they sound. Let me put it this way, if you had the chance of hearing what a Tribute transformer sounds like, the Cinemags are very, very close but cost a lot less than the Tributes. I like my Lundahl 9206 as SUT too, but after hearing the Cinemags, now I have doubts. Have a nice day Arnold, may I visit your lair this coming December? If everything goes well, that is.

Good day......Good luck.......Godspeed.

[amandarae]

Dak-dak ako ng dakdak, wala namang pruweba! Eto na...









Enjoy!

[arnoldc]

Doc, my cart is 50ohm, 0.6mV output. My lair?? Baka my bodega Walang problema doc. Just let me know.

Abe, ayan naman pala eh. Same model of Cinemag? Di ba may hex nut yan for mounting?

[Doc Jr 8156]

Thanks Arnold. .6mv output is a lot, even the 1:18 tap of the Cinemag will be plenty.

Abe, ano iyung kulay blue sa mounting? Kabit na kaagad at makinig.

Godspeed.

[amandarae]

Doc, my cart is 50ohm, 0.6mV output. My lair?? Baka my bodega Walang problema doc. Just let me know.

Abe, ayan naman pala eh. Same model of Cinemag? Di ba may hex nut yan for mounting?

arnoldc,

Sama ko diyan! Anyways, it is the same model of Cinemag. It does not have a hexnut unlike the diagram on the mechanical drawing but it has two holes that fits #4 metal screw.

Abe, ano iyung kulay blue sa mounting? Kabit na kaagad at makinig.

Seeecreeet..... !

Teflon washer just enough to slide the trannie from the case. With it, even if you missed on the drilling of the holes for the screw to hold it, you have a leeway to slide the transformer a bit. But wait...there's more! It also floats the trannie so that its metal case does not come in contact with the metal box.

'Tol, nakikinig na ko. All I can say is that....I am looking forward for the endless nights of puyatan. This tranny is great! O ano, 'niwala ka na sa gain calculation?

peace

[garp]

Hi,
MC newbie here. Just have a question and I hope this is the proper forum. I have Cinemags enroute but my question is applicable to any SUT.

For the cinemags I'm looking at the 1:18 tap. With my MM input impedance set at 51.1K, the load seen by the catridge is about 158R.

But if I want to play around and want to bump that up to say 1K, it means I need my MM input impedance to be 324K (=1K x 18^2). Now I can't parallel a resistor to the 51.1K to get that figure which is usually the method if you want a lower load than the 'natural load' for this tap.

My question is, can I just replace the 51.1K resistor with a 324K (or close) resistor get my desired load? I haven't seen anyone do this or mentioned it before in other forums or tutorials on the subject so am asking here.

Thanks and thanks for the tip on cinemags.

[Jon Agner]

Hi,
MC newbie here. Just have a question and I hope this is the proper forum. I have Cinemags enroute but my question is applicable to any SUT.

For the cinemags I'm looking at the 1:18 tap. With my MM input impedance set at 51.1K, the load seen by the catridge is about 158R.

But if I want to play around and want to bump that up to say 1K, it means I need my MM input impedance to be 324K (=1K x 18^2). Now I can't parallel a resistor to the 51.1K to get that figure which is usually the method if you want a lower load than the 'natural load' for this tap.

My question is, can I just replace the 51.1K resistor with a 324K (or close) resistor get my desired load? I haven't seen anyone do this or mentioned it before in other forums or tutorials on the subject so am asking here.

Thanks and thanks for the tip on cinemags.

Garp,

While I haven't tried SUTs for my MC, I did add resistors to fine tune the load for both my MM and MC inputs. The way I understood cartridge loading, theoretically, replacing it with another resistor that will match the desired load would be correct. Problem lies when you decide to use another cartridge that requires a different load. You will again have to replace the resistor.

What I did with mine was to use dip switches for the resistors. That way, I can to use the preset 47K load or toy around with different loads when I install a different cart.

Hope this helps.

[amandarae]

Hi,
MC newbie here. Just have a question and I hope this is the proper forum. I have Cinemags enroute but my question is applicable to any SUT.

For the cinemags I'm looking at the 1:18 tap. With my MM input impedance set at 51.1K, the load seen by the catridge is about 158R.

But if I want to play around and want to bump that up to say 1K, it means I need my MM input impedance to be 324K (=1K x 18^2). Now I can't parallel a resistor to the 51.1K to get that figure which is usually the method if you want a lower load than the 'natural load' for this tap.

My question is, can I just replace the 51.1K resistor with a 324K (or close) resistor get my desired load? I haven't seen anyone do this or mentioned it before in other forums or tutorials on the subject so am asking here.

Thanks and thanks for the tip on cinemags.

Hmmm, I'll try to answer your queries the way I understood the subject matter.

The 47k, or 51.1k in your case is the input impedance of the phono preamp circuit as seen by the current wether its coming from a cart, transformer or other sources. The 47k, to make the discussion simplier, is a standard where the phono circuit will behave in predictable results based on the designed parameter of the circuit designer. The key word here is predictable. The impedance is a vector in electrical terms. It has a magnitude and direction and also varies in terms of frequecy. A source at changing freq (i.e. cart output) will feel the input impedance changing as the frequency changes and as a result will influence the reaction of the circuit in electrical terms.

Having said that, IMO, in your case of 51.1k and if you want to have a 1k input impedance the best way to do it is to have a step up with a turns ratio close to 1:7(results to 1042 ohms). Doing this will preserve the phono circuit parameters instead of changing the input Z with a parallel 324k resistor which you will not know what the results maybe.

For the CMQEE-3440A, the calculations was made at 50k input impedance and the highest you can get is when using the 1:9 taps at 600 ohms.

But is there a solution to your problem using the CMQEE-3440A at 51.1k load to get 1k impedance? Absolutely! But you need 4 transformers (tw0 for each channel)because the CMQEE is tapped and not individually wired at the primaries.

If you take the 1:9 ratio of one SUT and connect it in series to the 1:18 of the other SUT the result is 1:6! i.e (9x18)/ [9+18]

At 51.1k, 1:6 the resulting load will be 1419 and can then be loaded by 60 k ohm resistor on the secondary resulting to 1000.5 ohms as seen by the cart on the primary.

(51.1k * 60k)/(51.1k + 60k) = 27.847 x 36 (the square of the gain) = 1000.2

Oh well, that's how I understood it. I could be wrong of course!

[garp]

Amandarae, gee, thanks for taking the effort to explain. I sort of gleaned as much that increasing the value of my MM's input impedance is not a good idea though I couldn't get a definitive answer why. I've searched through many forums and I've yet to encounter a recommendation to do that. I thought the 47K was arbitrary as far as the MM circuit is concerned but is chosen primarily to match MM carts recommended load. After all, I thought, why is it ok to adjust it lower (via parallel resistors) but not higher? It's not as if its part of the EQ, right? I'm not sure, just thinking out loud.

I just read through the setup tutorial at VinylEngine and the bottomline is...as Jon Agner here suggests...to use an active stepup instead if I want 1K loading:-). I have my eyes on Hagtech's Piccolo if ever.

You're suggestion of using 4 transformers is a bit of a stretch for me moneywise. And at 1:6 ratio, assuming I can get full output from my cartridge at 0.3mv, that only comes up to about 16db at best, if I'm not mistaken. With my 40db gain MM stage, I think I won't have enough gain.

Lots of AA inmates praise the DL-103/Cinemag combi, a lot of them preferring the 1:36 at ~40ohm load to the 1:18 tap. Of course Ill try both configs but I just want to mess around with the loading to satisfy my curiousity.

[garp]

Hi,
MC newbie here. Just have a question and I hope this is the proper forum. I have Cinemags enroute but my question is applicable to any SUT.

For the cinemags I'm looking at the 1:18 tap. With my MM input impedance set at 51.1K, the load seen by the catridge is about 158R.

But if I want to play around and want to bump that up to say 1K, it means I need my MM input impedance to be 324K (=1K x 18^2). Now I can't parallel a resistor to the 51.1K to get that figure which is usually the method if you want a lower load than the 'natural load' for this tap.

My question is, can I just replace the 51.1K resistor with a 324K (or close) resistor get my desired load? I haven't seen anyone do this or mentioned it before in other forums or tutorials on the subject so am asking here.

Thanks and thanks for the tip on cinemags.

Garp,

While I haven't tried SUTs for my MC, I did add resistors to fine tune the load for both my MM and MC inputs. The way I understood cartridge loading, theoretically, replacing it with another resistor that will match the desired load would be correct. Problem lies when you decide to use another cartridge that requires a different load. You will again have to replace the resistor.

What I did with mine was to use dip switches for the resistors. That way, I can to use the preset 47K load or toy around with different loads when I install a different cart.

Hope this helps.

Hi Jon, thanks for the reply.

Yeah, for an MC headamp it just seems as easy as changing resistor or paralleling with the usual 47K input impedance to get your desired load.

But for SUTs its not as straightforward as the load is a function of the square of the turns ratio and the MM's input impedance. It seems for me to be able play with high loads, I'd have to get a headamp.

[amandarae]

Amandarae, gee, thanks for taking the effort to explain. I sort of gleaned as much that increasing the value of my MM's input impedance is not a good idea though I couldn't get a definitive answer why. I've searched through many forums and I've yet to encounter a recommendation to do that. I thought the 47K was arbitrary as far as the MM circuit is concerned but is chosen primarily to match MM carts recommended load. After all, I thought, why is it ok to adjust it lower (via parallel resistors) but not higher? It's not as if its part of the EQ, right? I'm not sure, just thinking out loud.

I just read through the setup tutorial at VinylEngine and the bottomline is...as Jon Agner here suggests...to use an active stepup instead if I want 1K loading:-). I have my eyes on Hagtech's Piccolo if ever.

You're suggestion of using 4 transformers is a bit of a stretch for me moneywise. And at 1:6 ratio, assuming I can get full output from my cartridge at 0.3mv, that only comes up to about 16db at best, if I'm not mistaken. With my 40db gain MM stage, I think I won't have enough gain.

Lots of AA inmates praise the DL-103/Cinemag combi, a lot of them preferring the 1:36 at ~40ohm load to the 1:18 tap. Of course Ill try both configs but I just want to mess around with the loading to satisfy my curiousity.

Hey garp,

No problem! I suggested the 4 tranny solution because that is the only way to do it if you stick with the Cinemag. FWIW, I am using my Cinemag at present on a Denon 304 (40ohms, 0.18mV) and the 1:18 is more than enough for the Cornet II (44 dB gain) phono preamp. I have 1 meter IC'c from SUT to phono and 1.5 meters from arm base to SUT and have plenty of signal.

Piccolo? I had been waiting for mine since third week of March. It seems that Jim is sorting out some stuff on the kit and said should be ready next month.

regards

[amandarae]

.... I thought, why is it ok to adjust it lower (via parallel resistors) but not higher? It's not as if its part of the EQ, right? I'm not sure, just thinking out loud..

Because if it becomes higher, then the gain of the transformer will change dramatically lower also making the current smaller and may not drive the load. Most SUT use for phono are wound so that the turns ratio produces a specific gain for a specified load (47k) so that it is easier to figure the resulting natural impedance from the impedance transformation. If you change two variables at the same time, it would be difficult to calculate one in relation to the other. It can be done of course but you need to wound your own transformer because intermediate values are not commonly available.

regards

[garp]

Just an update. Finally done with this although I'm waiting to get clamp to mount the transformers properly. Total cost is P6.4k, including suts, rca jacks, box and spray paint.

[amandarae]

Just an update. Finally done with this although I'm waiting to get clamp to mount the transformers properly. Total cost is P6.4k, including suts, rca jacks, box and spray paint.

hey Garp,

Apologies! I don't know why I missed this. Excellent work!

enjoy!

regards,

Abe