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Lundahl LL 1933 MC-trafo - ENGLISH
Manufacturer: Lundahl Transformers, Sweden - .https://www.lundahltransformers.com/moving-coil-input/

Price: LL 1933 - pair 3.400,- DKR including Danish VAT. (460 Euro)
Price; LL 1933 Ag - pair 10,780, DKR including Danish VAT  (1,447 Euro) - review will come, when they arrive!

Latest update 3 September 2020


 

Swedish “top class” step up transformers

Lundahl transformers should be known by most. They build everything from output transformers (tubeamps) to interstage, line- and powertransformers. In their program there is also a very large selection of SUTs (MC step up  transformers) to be used between a MC cartridge and a normal RIAA input. For those who should have forgotten what it's all about - or who just want to know more about the technology - please take a closer look here: LINK - THE SUT .

 In the following I will also refer to the Excel spreadsheet that can be downloaded from the above page.

LL1933 frintLL 1933 internt10


Background and structure

It's been a while since I invested in two LL 1933 MC transformers. The selection at Lundahl is large with as many as 10 different versions, so it can be difficult to decide. There are e.g. also LL 1941, which offers a step up ratio of 1:18 and 1:32. The latter suitable for super low output MC pickups from e.g. Audio Note, Lyra and Ortofon. Four of the transformers are also available in an "Ag" version - ie with silver wire internally.

Lundahl LL 1933 is with mu-metal (nickel) core and the corresponding LL 1931 with an amorpheus cobalt core. Whether one is better than the other, I should not be able to say, but there are differences. Lundahl  describes LL 1933 as "A SUT for those who prefer a low distortion, and linear magnetic curve from a nickel laminate core" It should sound a little warmer and more pleasing, where the amorpheus cobalt core in 1931 is a bit smoother and a little more revealing. Furthermore, they write that the double coil construction (which is common to the almost all their MC transformers) improves the immunity to magnetic fields from power supplies, motors, etc. Internally, conductors of Cardas OFC copper are used. The transformer itself is mounted in a mu-metal housing. Both LL 1931 and 1933 are also available in versions with silverwindings. Here the price is a little more than 3 times higher. Whether the use of silver changes the sound, I cannot say, but in Thomas Meyer's blog VinylSavor: http://vinylsavor.blogspot.com/2011/12/lundahl-silver-mc-transformer-listening.html) he says, that the difference when using silver in transformers is far greater than what one experiences in cables. Maybe I should invest in a set of silver Lundahls, to experience the difference?

LL 1933 med DVLL-1933

Troubles from the beginning

As mentioned, I have had the two LL 1933 lying around for a few years. The connection of the terminals gave me a disproportionate number of problems. It does not help that Lundahl writes "connections seen from the component side" in their instruction. Which side? Should I flip it all over or should I look at the side where the terminals are? After many attempts and lots of hum, I almost gave up. But with more searching on various forums and a more targeted approach, the problem was solved. And yes, the drawings are seen from the terminal side - so it is quite simple!

I connected my transformers in the configuration parallel / serial, which gives a ratio of 1:18. In other words, a gain of 24 dB. It should be suitable for typical low-impedance MC pickups with approx. 0.2 to 0.5 mV out. It is also possible to couple the transformer to 1: 8, which gives 18 dB gain. This setting  is suitable for cartridges with somewhat higher output. In the end, it also depends on how much amplification there is in the connected RIAA, as well as how much output you actually need.

I mounted the transformers in a small aluminum box with a metal lid (magnetic and shielding). Not that it makes that big a difference. The transformers themselves are screened and in addition, the double construction makes it possible to work fine without additional screening. All internal connections in the box were made with Silver Sonic solid core silver cable.

Note that Lundahl in their specs  indicates a source impedance of 50 ohms as well as an open output. I know of no MC cartridges with such a high source impedance. Many of the newer ones have very low impedances around the 2-3 ohms, but the normal is probably closer to 6-8 ohms. Whether a typical load of 47 kohm at the output is the same as "open", one can discuss. Either way, it's impressive data which shows. that Lundahl knows how to make a good SUT.

 

Thorens in boxThe sound of the LL 1933 MC transformer

I have listened to (reviewed) many different step up transformers. The best were the Ikeda IST-201 with a ratio of 1:20 / 26 dB gain (DKK 29,900) and My Sonic Lab Stage 1030 (DKK 36,900) also with a turnover of 1:20 and gain at 26 dB. As can be seen, the prices are something completely different than Lundahl LL 1933, but whether the sound can be compared to these high end transformers is something completely different. However, I can say that LL 1933 is absolutely without hum, buzz or any other disturbing elements. If you have control of your ground and other connections, everything works flawlessly.

The first cartridge I tried was an Accuphase AC-3. With an output of only 0.2 mV and an internal impedance of 4 ohms, it must be said to have been ahead of its time (from 1984). It is more like specs you find in today's top MC’s. The sound is still excellent - yes with LL 1933 actually more than excellent. It is already a very dynamic and controlled cartridge, but here there is more body and power. You can clearly hear that the AC3 is doing well with this transformer coupled to the normal RIAA input on my Accuphase C-27. There is absolutely no noise and compared to the MC-input on the C-27, you can say that the sound is more physical and a bit more alive with a physical punch. There is, as I have experienced it before, a little more air and black background directly into the C-27, but the other way around, with the LL 1933 in the signal path it helps to make the experience a little more exciting and immediate.

Next cartridge  was my IKEDA 9Gss silver. Again low output 0.28 mv and an output impedance of approx. 2.8 ohms. Yes, it does well the little Lundahl transformer. However, it lacks just the last air and space that I know this top cartridge manage. But in the lower octaves there is a good fullness and control. As I remember Ikeda's own transformer, there was a larger open window and a nice air to the upper range. But at the same time it also played differently than the active solution via my Accuphase. At first glance, I would say that the LL 1933 is probably not intended to be used with a cartridge in this class, but in terms of gain, they fit well together. The impedances I will come back to later.

Then I tried with my Ortofon MC-3000. It is stated to be 0.125 mV out, so it almost requires a SUT. The output impedance is 6 ohms. Ortofon's own T-3000 transformer indicates a gain of 30 dB, which is 6 dB more than the 24 dB we achieve with LL 1933. However, I heard clearly. that the resulting output to the RIAA (approx. 2 mV) is somewhat lower than the other cartridges. In general, this combination has a somewhat more smooth and relaxed way of playing. The MC 3000 is still a revealing and smooth cartridge. These qualities are intact and in general one would probably be able to accept it all as a successful combination. Was it not because I have heard better with an active solution or e.g. the T-3000 transformer (with silver coils), then this would be absolutely acceptable.

Last cartridge was a Thorens MCH II. In fact, it is sources from EMT. It offers 0.25 mV output and 22 ohms internal impedance. Here it all fitted like hand in glove!  I have never heard this cartridge so dynamic and immediate with lots of punch and a solid bass. There was an infectious joy of playing with lots of dynamic range. At the same time the top from the VdH tip was smooth and detailed. I Played all three records in my "Ella & Lois / Classic Album Collection". This was music! I used this combination for a long time during this review and will probably do so in the future.

Calculations

With the help of the spreadsheet I linked to in the beginning, you can easily find gain and impedances with different SUTs.

LL 1933 has a gain ratio of 1:18. Looking into the typical 47kohm load from the RIAA, it will provide an input impedance of 184 ohms. A rule of thumb says that the optimum is a load of 10 times the internal impedance of the cartridge. Some say it must be 5 times and then again others say something completely different. For the four cartridges mentioned above, it will then only fit with Thorens MCH II and its 22 ohms impedance. By changing the RIAA load from 47K to 100K, the input impedance increases to 391 ohms. This was also tried and gave a little more air and details with this cartridge.

But why was the result with the Accuphase AC-3 positive? With the 4 ohm output impedance, it looks into the same 184 ohms. It is far higher than the immediately optimal 40 ohms. With a SUT it is possible to load the output with a parallel resistor (good low inductance quality). With 13k we get the approx. 40 ohms, which should fit better..

Likewise my Ikeda should have a load around 30 ohms - ie a load resistance of approx. 9k. Strangely enough, Ikeda's own transformer IST-201 results in a load of 118 ohms, so the “rule” with 10 times the internal impedance should probably be taken with a pinch of salt. Or has Ikeda loaded the transformer internally, without telling anyone about it?

Ikeda
Ikeda 9Gss silver via Lundahl LL 1933 - impedance corrected


The curiosity was too great. Two Takeman 10k resistors were soldered over the transformer output. This changes the input impedance to approx. 32 ohms. So much lower than the aforementioned 184 ohms. My favorite records were played agian. First Gerry Mulligan and Dire Straits' "Love over Gold" - Mobile Fidelity 45 RPM. Everything was fine and there was clearly the extra grunge and weight int bass region, but still it was as if the top was a little less detailed than directly into the C-27.
Finally, classical music came on the platter. Solti / Venice - a RCA Victor Living Stereo from 1959. Here it was immediately a little more obvious what happened. A thin layer of tapehiss from the old recording was somewhat muted. It seemed a bit more robust and direct - more body on the instruments. At times positive, but the soothing strings were clearly less detailed. The room in this excellent recording was toned down and it all moved a little closer into the living room. Still an excellent recording and reproduction, but just missing the last bits.
Overall, the conclusion must be that yes, the impedance correction probably makes a difference. But no miracles. The LL 1933 is still an excellent transformer, but it does not quite live up to the requirements I have with my Ikeda 9Gss cartridge.

I asked Per Lundhal about their opnion on impedance correction: "The use of a dampint resistance on the secondary side of the SUT is used to dampen the moving system of the cartridge. In my opinion it has little to do with the transformer. However the right load can be important for the system to sound good."


Read more about impedance correction in the link above /sorry, onli in Danish)

Conclusion

Lundahl LL 1933 delivers a very convincing reproduction. As Per Lundahl himself writes, "Where other companies stop, we start". You could say they believe in themselves and their products. Regardless of the qualities of the transformer, it must match the cartridge you want to use. In the four cases I tried here, it was my Accuphase AC-3 and even more so Thorens MCH II that gave the best results. The latter was almost a kind of symbiosis with LL 1933, so the result was super musical and with lots of presence, warmth and generally a naturally relaxing reproduction. I have heard better transformers with my IKEDA 9Gss and Ortofon’s MC 3000. The latter was immediately a little too reluctant with the LL 1933. In both cases I would think that other MC transformers from Lundahl will do better. Could be tempting to try the silver version LL 1933 Ag or maybe LL 1931 Ag. There is silver coils in my IKEDA, so there might be a good chance that silver in the SUT is what I need?

September 2020 - A set of LL 1933 Ag have been ordered from Lundahl. This page will be updated, when I have tried the out!-


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