Some vinyl users use a SUT to enhance the signal of the MC cartridge so that it can be used in the MM input of a phono stage. Although I don't understand the theory behind it, I realize that a SUT should be matched individually to a particular cartridge, depending on the internal impedance of the MC, among other things.
Assuming an appropriately / ideally matched SUT and MC, What are the inherent advantages or disadvantages of inserting a SUT after the MC in the audio chain? Does the SUT theoretically enhance or degrade the sound quality? What does the SUT actually do to the sound quality?
I had a chance to listen to EM/IA SUT in my stereo yesterday. It was a 1:10 Cu version made for my friends combination of a Lyra Atlas and Marantz 7C preamp. Cable was a .6 meter Nordost Quatrofil. On my turntable yesterday was a SoundSmith Hyperion MKII/Kuzma4p9 going into my Pass Labs XP-27 phono pre. I usually have the pre set on high gain and 500Ohm resistance. So for the SUT, I switched to low gain and 47k resistance.
This experience supports a lot of what has been discussed on this thread. The addition of the SUT made things sound a touch more crystalline and at the same time a touch more dynamic. Bass definition and soundstage depth suffered just a little as did overall transparency. Clearly this SUT works better for the tube MM stage that my friend uses. Not that it sounded bad in my setup. Just different and a little farther away from my preferences. I didn’t have time to swap in a Lyra Etna SL or my Koetsu RSP. I bet that may have identified a better match with the SUT.
One of the things I love about the Pass is that I can use a wide variety of cartridges and find the optimal setting with the front panel switches.
Your XP 27 Phono Pre, has quite a value attached to it.
'Hats Off ', to you for trying out something new in conjunction with it. I'm glad you found value in the encounter and the experience.
With a short duration demonstration, especially as a comparison, usually the most noticeable differences are detected and not usually the subtle ones. The subtle differences, when detected can be perceived as a betterment or slightly lesser/different to the other device/devices in use during a comparison.
Discovering a variation in the perception of Transparency between a SS MC Stage and SS or Valve MM > SUT Stage is in keeping with my experiences. Additionally, a Valve MM > Head Amp is noticeably able to be perceived as Transparent in comparison to a SUT in use, for the same role.
I have two SUT's retained for my use, one is seemingly without a Colouration when compared to other SUT's I have used. The other sits about 3/4's around the dial to being perceived as Transparent, when compared to other SUT's I have used. I like a little noticeable colouration with my Chicago Blues Music.
I can declare, I have a colour in my music, even though generally not detectable and easily overlooked. A SS Device has proved its value at showing where there is Colour to be detected in the SUT's I have chosen to retain.
Your report, making it known the Transparency suffered just a little, would suggest to me, the EMIA is a SUT that can be referred to as Transparent in comparison to other SUT's and will only reveal it has a Hue of Colouration, when compared to a SS Designs MC Stage.
It would have been good feedback, if the other Cart's could have been used, as said previously, the permutations on offer by using an off board ancillary can be quite vast.
A brief internet search pulled up this basic, but informative article:
Audio Transformers are electromagnetic devices that transmit and modify input electromagnetic signals into output signals via inductive coupling. They isolate an input circuit from an output circuit and filter signals; operating on the audible band of the frequency spectrum (20Hz to 20kHz). As such they can have applications in the input stage (microphones), output stage (loudspeakers), as well as coupling and impedance matching of amplifiers. In all cases, the frequency response, primary and secondary impedances and power capabilities all need to be considered.
Materials and Structure
A transformer is an electrical device which allows an input signal (such as an audio signal or voltage) to produce an output signal or voltage without the input side and output side being physically connected to each other. This coupling is achieved by having two (or more) wire coils (called windings) of insulated copper wire wound around a soft magnetic iron core. Audio transformers are typically composed of copper wire windings around a steel or nickel-iron alloy core. Each core material transmits electromagnetic signals differently. Steel has a higher degree of hysteresis (magnetic signal lag), making it better for lower frequency transfer. The higher permeability of nickel makes it ideal for transmitting higher frequencies. The windings around the core determine the impedance level, which increases, decreases, or maintains the signal level as it passes through the transformer.
Figure 1: Audio Transformer Structure
When the signal enters the transformer via the input (primary winding), it then gets transferred to the output secondary winding due to the inductive coupling of the soft iron core. The ratio between the number of coil turns on the primary winding (NP) to the number of coil turns on the secondary winding (NS) is called the “turns ratio”. The turns ratio between the input and output wire coils provides either an increase or a decrease of the applied signal as it passes through the transformer. More windings around the core correspond with a higher impedance, so if the primary winding has more than the secondary, the signal will decrease (step down). Conversely, if the secondary winding impedance is greater than the primary, the signal will increase (step up).
The number of turns on each winding determines whether the transformer provides a gain or loss of the signal:
If there are more turns on the input winding, the signal will decrease or step down.
More turns on the output winding will result in a step up.
Audio transformers are produced for a range of specific audio functions; many are similar in construction to power transformers and they often perform several functions at once. They can be considered as either a step-up or step-down type, but rather than being wound to produce a specific voltage output, audio transformers are mainly designed for impedance matching, isolation, and a variety of applications (see Data/Voice Coupling Transformers).
Impedance Matching
Transformers can step impedance up or down in the same way they do with voltage and current. Whereas they change voltage by the turns ratio and current by the inverse of the turns ratio, audio transformers change impedance by the square of the turns ratio. The same amount of voltage is induced within each single coil turn of both windings. The primary to secondary voltage ratio (VP/VS) will therefore be the same value as the turns ratio (NP/NS). Impedance matching audio transformers always give their impedance ratio value from one winding to another by the square of their turns ratio. That is, their impedance ratio is equal to its turns ratio squared and also its primary to secondary voltage ratio squared:
Impedance is determined by the efficiency of the conversion from voltage into magnetic flux. Audio transformers are ideal for balancing amplifiers and loads together that have different input/output impedances in order to achieve optimal power transfer, as in the case of a transformer at the amplifier input to match the impedance between microphones, connecting cables and the amplifier input. The input and output impedance levels are matched to create efficient power transfer without distortion or signal overload. Impedance matching transformers are similar in design to low frequency voltage and power transformers, but they operate over a much wider range of frequencies (for example, 20Hz to 20kHz voice range).
Isolation or Unity Transformer
Transformers have another very useful property, isolation. Since there is no direct electrical connection between their primary and secondary windings, transformers provide complete electrical isolation between their input and output circuits and this isolation property can also be used between amplifiers and speakers. A transformer with a turns ratio of 1:1 does not change the voltage or current levels but instead isolates the primary circuit from the secondary side. This type of transformer is commonly known as an isolation transformer.
Figure 3: Isolation Transformer
As the impedance is identical for the primary and secondary, the signal level does not change. The transformer allows an audio signal to pass unmodified from the primary to the secondary while blocking DC voltage and radio frequency interference (RFI). Since the primary and secondary circuits are insulated from each other, the transformer will electrically isolate different pieces of equipment. This can solve hum problems by isolating or "lifting" the grounds of different devices. Other unity transformer applications include providing multiple outputs from a single mic input by using multiple secondary windings, and changing balanced signals to unbalanced signals or vice-versa.
Audio transformers are designed to operate over the audio frequency range, or much higher for radio-frequency (RF) transformers. Due to this wide frequency band, one of the main disadvantages of audio transformers is that they can be somewhat bulky and expensive. This is because a transformer's core size increases as the supply frequency decreases. Smaller designs can be achieved by using special core materials. Audio transformers have played an important role since the birth of audio electronics. When compared to modern miniaturized electronics, transformers seem large and heavy but they continue to be the most effective solution in many audio applications. The usefulness of a transformer lies in the fact that electrical energy can be transferred from one circuit to another without direct connection, and in the process the energy can be readily changed from one voltage level to another.
Perhaps this blurb from a manufacturer sums it up more concisely: they say the signal is tranferred "via electromagnetic induction" and creates "power transfer without distortion"
Audio transformers are typically composed of copper wire windings around a steel or nickel-iron alloy core. Each core material transmits electromagnetic signals differently. Steel has a higher degree of hysteresis (magnetic signal lag), making it better for lower frequency transfer. The higher permeability of nickel makes it ideal for transmitting higher frequencies.
The windings around the core determine the impedance level, which increases, decreases, or maintains the signal level as it passes through the transformer. When the signal enters the transformer via the input (primary winding), it then gets transferred to the secondary winding via electromagnetic induction. More windings around the core correspond with a higher impedance, so if the primary winding has more than the secondary, the signal will decrease (step down). Conversely, if the secondary winding’s impedance is greater than the primary, the signal will increase (step up).
Impedance matching is one of the primary uses of audio transformers. Impedance is determined by the efficiency of the conversion from voltage into magnetic flux. In addition to stepping signals up or down, audio transformers can match the input and output impedance levels to create efficient power transfer without distortion or signal overload. Impedance-matching transformers will not necessarily boost or attenuate the signal but will create balance for an optimal energy transfer.
Dear @karl_desch Your XP27 is very good design and something that made the differences on what you listened vs the SUT came for the XP27 bass range that not only gives you that depth in soundstage.
I think no SUT can touch the overall bass range management by a good active high gain SS design and one with the niquel core less.
I read this comments from a XP27 owner:
" XP27:
1. Lower noise
2. Lower distortion
3. Deeper bass, more articulate bass, less fat, more impact/punch
4. Better transient attack, fine, more precise leading edge
5. Cleaner, clearer sound, more resolution
6. Deeper stage, better hall information
7. dynamic, explosive
After dinner, I played the Sheffield Drum Track. Wow. It was explosive and loud with very little distortion. There was incredible nuance between the different types of drums and it had huge impact and dynamics. The different drum characteristics and his technique has never been more discernible.
I am still listening with the Burley Wire IC because it sounds so good, but I plan to send my Transparent Audio cable back for recalibration to see if it will sound even better. The XP-27 has continued to improve over time. It seems that the complete break in period was about ten days. I have now had it in my system for sixteen days, powered on the whole time.
Since Al heard it on the fifth day, the resolution has continued to improve. Low level information is even more clear. Micro and macro dynamics are better. The soundstage is about the same, but the depth has increased. Presence, an attribute of my system about which I am very pleased, is even more pronounced. I have not heard this level of 3-D palpability before. Timbral accuracy has never sounded more real in my system. The overall impression is one of improved clarity and a more natural sound. Everything just sounds more real to me. """"
Btw, could be interesting that your friends can ask to EMIA its measured FR due that even that exist audiophiles that just do not care about that kind of measure is really of critical importance and the manufacturer just " dead silence about " and I wonder why because other SUT manufacturers gives that kind of measure.
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