I recently purchased a pair of Mu MC Step Up transformers by Bent Audio. Does anyone here know the break in process for these. I was able to find this by Thorsten Loesch but I don't understand it, doesn't quite make sense to me. Maybe a more simple explanation would be helpful.
From diyAudio; Break-In Instructions from Thorsten Loesch
This worked very well for me, so I recommend it highly. This is what Loesch wrote, with a little editing:
"(The TX-103)... will require a substantial period of "forced burn in" to give it's best, simply because the magnetic core is huge and will not see much magnetisation with normal MC signals. Please consider connecting a CD-Player to the secondary (Output) of the TX-103 and then terminate the input with a low resistance resistor (quality uncritical), I'd say 27 Ohm when connected for 14db gain, 6.8 Ohm when connected for 20db gain and 2.2 Ohm when connected for 26db gain. Leave with a highly dynamic, wide bandwidth signal CD to play for a week or two. I would use music, but I'd expect pink noise to work well too."
Chakster, With all due respect and meaning no offense, first you describe the input shunt resistors of the CPP-1, which is not a SUT but a pre-preamplifier designed to amplify the voltage of the signal generated from a cartridge, without adding RIAA correction. That is not anywhere near to what the OP needs to know. Then, you go on to recommend that he should buy a vintage SUT, but the point is that he is the new owner of a new SUT and only wants to know how or whether to break it in. Whether you or I or anyone else "believes" in the value of burn-in is irrelevant. The only question is whether such a break-in regimen enhances SQ, and that ultimately is a subjective judgement. So, if it pleases the OP to break in his new SUT, he only needs guidance in how to go about doing it. After all, it cannot hurt to try.
By the way, totally noise-free and zero inductance (or zero capacitance) resistors only exist in advertising brochures.
chakster, I think its an excellent device, it's as good or even a little better than the TX-103 SUT's. To answer your question, no I have not opened it up. But I have considered having SoraSound send it back to Japan as there is an upgrade for it. I am not familiar with the Luxman SUT.
I also have ZYX CPP-1 headamp and it's a nice device. Have you seen it inside ? Last year i opened it up to replace the batteries. It was a first time when i saw input resistors like that! Those resistors looks like an MC cartridge coil and made by winding the wire to a coil that has no inductance in a special process. Those resistors made by ZYX to transfer the output signals with no noise and no inductance at all. They are made of pure coil wire of MC cartridges, cryogenically purified. Signal from LOMC cartridge should go into ZYX CPP-1 Headamp’s resistor wihtout any influences from resistor noise and inductance. Nakatsuka-San decided to use his own resistors made of pure copper wire, same material as a copper wire of MC carts. In order to playback the sound info of LOMC carts in 100% fidelity, CPP-1 headamp has special circuit in the simplest amplification circuit. Great device to avoid Step-Up Transformers for LOMC
As for the SUT's burn-in the best option, in this case, is to buy a classic SUTs (used) made 40 years ago. There are some killer SUTs. My personal favorite is Luxman toroidal silver sut. With the set like on those pics any MC cartridge can be used with it.
I don't believe in burn-in process of the SUT, people overestimated the importance of it, you'd better just connect it to play music from your vinyl.
racamuti, I suppose it's possible that it was broken in, but I have my doubts. They should sound better than they do. I ordered the resisters today from partsconnexion and have the RCA's ready. I have a ZYX CPP-1 Pre-PreAmp to use while the SUT's are out of the system.
Interesting that you are not using them as their main benefit is to improve playback performance rather than provide gain, you can get the gain you need from your phono section as you are doing now.
When I bought My Bent audio mu's directly from John at Bent Audio, He asked if I wanted to have them broken in before he shipped. Of course I said yes as there was no charge just a longer wait. Your mu's just might be broken in from the factory. I'm sure most people who bought one would have said yes to his offer. I don't use mine anymore because I bought a phono pre that has all the gain I need. (Wright Sound Silver Top with 60db of gain).
Charliee, In one of your responses, you mentioned hooking the CDP to the INPUT of the SUT. I am guessing that was a momentary lapse; Loesch and all the others are talking about hooking the signal to the OUTPUTs of the SUT. Just to be certain.
While I do not necessarily share Robjerman's skepticism about the value of break-in, I do wonder at Loesch's comment suggesting that it is desirable to "magnetize" the core of the transformer in order to achieve proper break-in. I would have thought that magnetization is undesirable; you'd want to break in the wire coils without magnetizing the core. But I have never played with a SUT in my own system, so I don't have a validated opinion. And Loesch is no dummy.
Also, contrary to what Rob said in one post, a SUT has no "resistance" of its own. There is indeed resistance presented by the wire coil on the primary side, between hot and ground, and a second analogous resistance presented by the wire on the secondary side, but these have trivial effects. Transformers merely reflect the output and input impedances of the devices to which they are connected. So, if you have a SUT with a 1:10 voltage gain, that means the turns ratio of the SUT is also 1:10. (That's 20db, a little more gain than that of the SUT you own.) The impedance seen by the device on the primary side will be related to that on the secondary side (or vice-versa) by the square of the turns ratio, or in this case, 1:100. If you drive the secondaries of such a SUT, the device connected to the primary side will "see" an impedance equal to 100X the input impedance of the driven device. So, if it's just a 27 ohm resistor or whatever, the resistance/impedance seen by the CDP connected to the secondaries would be 2700 ohms. Most CDPs can drive that impedance, but I did wonder why he stipulated such relatively low values of R. Maybe so as to assure that everything heats up.
Thank you elizabeth, I appreciate your help. I will be ordering from partsconnexion tonight.
roberjerman, I did not take physics in college, so I guess I am screwed. But when it comes to SUT's I think I will be taking advice from folks like Thorsten Loesch, Arthur Salvatore, and my new friend here elizabeth. But thank you for trying to help.
If I desire to hear a different "flavor" of sound, I can select from any of the six. They all have dissimilar resistances and gain ratios. "Burn-in" is not, and has never been a consideration because I know electrical theory. I believe in SCIENCE - NOT "Magic"!
I bought my first mc SUT in 1978. A Verion P (designed by Mitch Cotter) and using Jensen transformers. Alas, I no longer have it! But I have on hand 6 others, including a Quicksilver (designed by Mike Sanders). So I can speak with some authority on the subject!
@charliee: I see from your second post here that you must have done poorly in your college physics course. Not knowing how a transformer works! Willing to believe in any old Mumbo-Jumbo!
Got it, thank you very much. Connect my CD player to the inputs on the SUT's, play an appropriate CD on repeat (Classical). On the resistor, does the value matter?
Thank you for responding. I'm pretty sure I am following what you said. What I don't understand is connecting the CD player to the output of the transformer, then connecting the RCA/resistor to the input. Isn't that backwards? How is the transformer receiving a signal if the CD player is connected to the output?
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