arnoldc wrote: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