Step Up Transformers Into an Adjustable Phono Pre?

Wondering if there would be any improvement in sound quality using a step up transformer plugging into an adjustable gain phono preamp that is MC and MM capable.
For example, I want to keep my phono preamp which is low output moving coil capable and wonder if using a SUT and the lowest gain setting would sound better than using only the preamp at the highest gain setting.

I have heard good and bad about SUTs, mainly low noise at the expense of dynamic energy.

 

If you could reach the proper numbers required, you give up gain distortion for trannie distortion, it will sound different. Couldn't say one is better. Too many variables and is subjective perhaps. Many people do prefer transformer distortion.

 

I you could bypass the MC stage in your preamp, then using a SUT should work fine. Otherwise, you run the risk of overloading the phono stage during dynamic peaks.

jeff

 

I think the improvement in sound quality would depend on the MC cartridge involved. If it is particularly low output, you may benefit from the SUT into the lower gain setup.

 

Long before I started representing Music First Audio and Audio Note I gave up on fully active amplification of the tiny signal from a MC cartridge. I have compared many, many preamps, phono preamps and step-ups. Most step-up transformers do indeed sound compressed. Most fully active MC phono preamps do indeed sound "electronic". But the best transformer step-ups into a MM phono stage have sounded much better, to me, in every way compared to the best active head-amps or MC capable phono preamps.

Now that I carry transformer step-ups from both Music First Audio and Audio Note (and MM-only phono preamps from both), it has been very easy for me to demonstrate this. I have a very nice MC-capable Krell preamp, that sounds better with any of these step-up transformers into its 47000-Ohm MM input. And, I encourage anyone who is interested to borrow one of my demo step-ups, to try in their own home, and find out for themselves.

The answer to your question, in my opinion, is yes. Listen to your MC cartridge, into the MM input with a good step-up transformer that is matched properly to the cartridge. If you tell me what cartridge you have, its output impedance (or coil resistance), and output mV, I can tell you what range of step-up ratio will work well for you.

 

Interesting, thank you.
I have a Dynavector 20X2 Low Output cartridge, 0.3mv output.

 

I am fully in agreement with Warren Jarrett. A very good SUT, and eliminating at least one active stage of amplification, is the way to go. I have heard enough solid state and tube phono stages with active amplification of the low level signal from MC and there was almost always something I did not like--excessive noise, grainy quality or lifelessness--much of which was cured with a SUT. The problems I have encountered with outboard SUTs involved sensitivity to hum--you have to find the right location and orientation to prevent this from being a problem. Fortunately for me, my phonostage has a built in SUT that has never given me problems in that regard. I once tried the top of the line Audionote SUT and it sounded good, but, there was always a slight hum. My dealer, who has custom gear built for his exclusive sales, put the very best Audionote SUT into one of his phonostages and that stage was VERY good and dead silent. I bet there are some significant advantages to building the SUT into the phonostage (much shorter wiring path, elimination of two junctions).

While some people fret about matching impedance characteristics and the requirements for dampening ringing, I am with those that find that almost any good SUT will work well with a broad range of setups--the only matching requirement is the right amount of gain (turn ratio) so one does not get too low a signal level which would increase problems with noise, or too high a level, which could overload the phonostage. I tried fiddling around with both primary and secondary side loading of the built-in SUT of my phonostage, but found that what the manufacturer hardwired on the primary side worked well with both of my cartridges and so I left that alone.

 

Raferx and I went through the specs in detail for this cartridge, as well as the math to determine optimum loading. Basically we decided that for its 5 Ohm coil resistance, the manufacturer's recommendation for a 100 Ohm load is just about right, as a starting point. A 1:20 transformer step-up will provide 117 Ohms, which is close enough. Since every transformer sounds a little different, and every audio system needs a little bit different balance to sound just right, I must emphasize that is only a starting point, to listen and tweek, if necessary. Its nice to have a step-up which is easy to lower the impedance from there, by the addition of resistors. If at 117, you don't hear anything bright or aggressive, I would accept that loading as just right. But, if you would prefer smoother highs, then you will want a lower input loading. Try about 70 to 80 Ohms, and about 50 to 60 Ohms, listening for a loading that sounds compressed or dull. Then you will know what to go back to, as a perfect compromise.

A 1:30 transformer will give you 52 Ohms load on the cartridge, which is probably as low as you will ever want to go with this cartridge.

So the most versatile approach is to try a 1:20 transformer which has a provision for adding loading resistors, or is adjustable with built-in resistors. The next best solution is to compare more than one transformer, within a step-up ratio range between 1:30 and 1:20.

 

Since I recently purchased a Decware SE34i.4 and it's input sensitivity is approx. 2.5 volts, I'm not getting enough gain from my P5 turntable loaded with a Dynavector 20x2-L cart going into a Musical Surroundings Phonomena II set at a gain of 60db. I calculated that I would need a gain of about 78dB to match the input sensitivity of the Decware.
My OPPO BD-105 provides a good amount of gain into the amplifier, but when I switch to the turntable it becomes a letdown.

My interest in now piqued into pursuing a SUT, and looking at Music First's webpage there is a low cost option, the MC stepup 632. I suppose with the calculations that Warren posted above, this device would be appropriate? Am I moving in the right direction with this?

 

Whether or not you'd hear an improvement would really depend on the whole system. That said, I've found a good SUT to perform better to my tastes than most of the high-gain input stages in most relatively affordable preamps. There are exceptions, but not many.

I've never heard this purported loss of dynamic energy. I'd say that a well mated SUT usually excels at dynamics compared to most of the high-gain phono stages I've heard. There are good reasons to avoid a SUT (easier loading, avoiding phase shifts at the frequency extremes, avoiding hum problems in some cases), but a lack of dynamics isn't on the list. Flesh'n'blood bombast is the usual reason people switch to a SUT.

Seriously, though, the front end in the Pro Ject is a a little noisy at high gain. A SUT can help with that. The bigger problem is that a decent SUT is probably going to cost a great deal more than your phono preamp.

 

Hi Warren, I stumbled across your post in my effort to try to understand whether or not I could connect a SUT (Parks Audio Budgie CM1254) to a Cambridge Audio Azur 551P MM Phono Preamp in order to sufficiently "power" a Dynavector Karat 17D3 which gets fed into a PrimaLuna DiaLogue Premium Preamplifier. I think that your answer is, yes? But I don't fully understand how I match the various outputs/inputs of the three devices to reach an acceptable level. Can you help me understand this? Thanks in advance!

 

As many of us in this hobby may need to (re)learn old knowledge on our path to sonic ecstasy, because the science of it really hasn't changed... see if this article may find some utility.

Step-Ups and MC Cartridges - The Secrets of a Successful Marriage - Vinyl Engine »

 

Another interesting resource on step up transformer matching, although it can be somewhat technical, is this:

mc step-up transformers explained »

 

Maybe. As some others have stated, it depends upon what you have and what you choose going forward. Just being a transformer doesn't automatically make it superior sonically to an active circuit. That said, the better cartridge and phono stage pairings that I have heard have used the lowest active gain setting allowable on the units. More active gain generally gets a bit more brittle and perhaps over-dynamic. A poor transformer can make things too soft and compressed. A really nice transformer in front of a really nice phono stage with just enough gain is exceptional but can also be expensive.
-Bill

 

I am not sure what you are asking, so I will start with the basics, then describe how to best load your cartridge, by choosing the correct corresponding step-up ratio. Your tonearm cable will go to the step-up (set to the correct step-up ratio for your cartridge), then from the step-up to the phono preamp (47000 Ohms MM input), and from the phono preamp to any line-level input of your Primaluna preamp (such as a CD or AUX input). Once these are interconnected, you may hear hum while playing a record, or with no record playing and the volume turned-up to a higher than normal setting. Making sure the tonearm is grounded to the step-up's ground lug is the first step to solve this problem. Then, trying another ground cable betweeen that ground lug and a ground on the Primaluna, may provide further reduction in that noise level.

The CM 1254 has two choices of step-up ratio, 1:20 or 1:40. The 1:40 setting is TOTALLY wrong for your 17D3 cartridge. The 1:20 setting will provide very close to the cartridges manufacturer's minimum recommended loading, although for my taste still not best for the sound of your cartridge. Dynavector recommends "greater than 100 Ohms". The 1:20 will provide 117 Ohms.

117 Ohms is an acceptable value to start enjoying the cartridge. But, the 17D3 is really a very nice sounding cartridge, very revealing, and will sound best if loaded by just the right step-up ratio.

In my opinion, your cartridge will sound a bit compressed and rolled-off into 117 Ohms. Also, noise level will be higher than optimum. The 17D3 has a coil resistance of 38 ohms. I recommend a loading, for best sound, of somewhere between 400 and 700 ohms. At 1:40 your step-up would provide 29 Ohms, which is WAY too low. At 1:20, the 117 Ohms is still a little low. My recommendation is to find a 1:10 step-up to use with this cartridge. Then, the resulting load on the cartridge would be a PERFECT 470 Ohms.