Cartridge loading explained

[JMCI]

Hello, if my Line/phono preamp has a choice of set up for MC cartrige which is : 30 Ohms, 160 Ohms, 200 Ohms, 825 Ohms, by changing internal switches with a ball point pen.
Can I Change the set up when listening to an LP or I 'd better switch the all system off before changing the capacitance ?
I suppose the best result will depend on the full system.
my (future) cartridge : Denon DL-304 ( recommanded capacitance >= 100 Ohms ), my Preamp : ML-10

thanks a lot

[Aerobat]

I never had a problem changing loading on the fly, but you may want to turn the volume down first just in case.

[JMCI]

Tks ! Next sunday I will have the new MC cartridge

[nezbleu]

Not to be pedantic, but capacitance is measured in Farads, resistance (or impedance) is measured in Ohms. You are changing the load resistance, not capacitance. It should be fine to change on the fly, but it is at the input of a very sensitive high gain amplifier, so yeah keep the volume down at least for first try. Any bit of charge on the resistors or DC on the phono input could cause a "pop" or "snap" which would be much louder than any signal from a cartridge. That said, especially on a low impedance MC stage, there should not be any DC current present nor charge on the resistors (which shunt to ground), so it should be fine.

[JMCI]

tks, it's not a huge pain to switch the amp+pre+phono off but I was just wondering because it is easier to quick notice some small differences

[jagermonster]

I have a Denon DL-103 feeding a Denon AU320 step-up transformer set to 40 ohm, going into a Clearaudio Nano v.2 moving magnet section, which has default loading of 47k.

Should I change the Clearaudio loading or keep it at the default, since the MC signal has already been stepped up? The Nano has jacks for adding resistors, so there's no limit to the adjustability.

[nezbleu]

Adding resistors in parallel will lower the net resistance, which will lower the impedance seen hy the cartridge (divided by the turns ratio of the transformer). I don't have 103, although I do have a Denon LOMC, but I would not load a 103 below 40 Ohms. In fact I would hesitate to go that low. How does it sound?

[andyr]

Adding resistors in parallel will lower the net resistance

Correct. :)

which will lower the impedance seen by the cartridge (divided by the turns ratio of the transformer).

Actually it's divided by the square of the transformer's turns ratio. So a 1:10 SUT feeding a MM phono stage which has the standard 47K input resistance ... makes it look like 470 ohms to the cart. And a 1:20 SUT would make the load 118 ohms, to the cart.

but I would not load a 103 below 40 Ohms. In fact I would hesitate to go that low.

Agreed. I don't know how the "Denon AU320 step-up transformer set to 40 ohm" actually works ... but I would suspect the DL103 will actually sound its best at several hundred ohms load.

Andy

PS: life is so much easier - in terms of loading - when you use a headamp, rather than a SUT. :D

[jagermonster]

The AU320 has two settings - 3 Ohm (1:20 winding) and 40 Ohm (1:10 winding). The 40 Ohm is meant specifically for the DL-103.

From what you described above, it sounds like the reason for that is when that signal is fed to a MM phono stage loaded at the stock 47K Ohm, the resulting impedance load is 470 Ohm, which seems like a good spot for the 103?

Of course, it is entirely possible that I didn't understand a word of the above posts.

[andyr]

The AU320 has two settings - 3 Ohm (1:20 winding) and 40 Ohm (1:10 winding). The 40 Ohm is meant specifically for the DL-103.

From what you described above, it sounds like the reason for that is when that signal is fed to a MM phono stage loaded at the stock 47K Ohm, the resulting impedance load is 470 Ohm, which seems like a good spot for the 103?

Of course, it is entirely possible that I didn't understand a word of the above posts.

Thanks - no, you have it right. It's just the peculiar way they have of specifying the 2 settings - the important fact is that one is 1:10 turns ratio ... and the other is 1:20. You use the former for a LOMC with an output of 0.3-0.5mV ... and the latter for a 0.2mV output cart.

The DL103 - at 0.25mV - is kindof in between - so you could try it with both; you'll just have to turn up your preamp volume control more with the 1:10 setting. Ignoring this minor volume issue, you need to decide which load the DL103 sounds better to you, at: 470 ohms (1:10) or 118 ohms (1:20).

Please let us know. :)

Andy

[jagermonster]

My particular 103 is particularly hot - I think the measurements that came with it showed L and R gain was both around 0.38.

The 40 Ohm tap definitely sounds better than the 3 Ohm, but I wasn't sure if perhaps i was loading it incorrectly.

[Sunwire]

The switch positions on the Denon AU-320 don't refer to the load presented to the cartridge. They refer to the impedance of the phono cartridge that should be matched to those switch positions.
So, the 3 ohm position is ideal for cartridges of 3 ohms internal impedance.
The 40 ohm position is ideal for cartridges, like the DL-103, that have an internal impedance of 40 ohms.

If you have the usual 47k ohm phono input resistance, the load presented to the cartridge will be 470 ohms in the 40 ohm position and 36 ohms in the 3 ohm position.

Manual is in the library here.

More info here:
https://www.vinylengine.com/step-ups-an ... dges.shtml

[jagermonster]

The switch positions on the Denon AU-320 don't refer to the load presented to the cartridge. They refer to the impedance of the phono cartridge that should be matched to those switch positions.
So, the 3 ohm position is ideal for cartridges of 3 ohms internal impedance.
The 40 ohm position is ideal for cartridges, like the DL-103, that have an internal impedance of 40 ohms.

If you have the usual 47k ohm phono input resistance, the load presented to the cartridge will be 470 ohms in the 40 ohm position and 36 ohms in the 3 ohm position.

Manual is in the library here.

More info here:
https://www.vinylengine.com/step-ups-an ... dges.shtml

Well, that sure makes a whole lot more sense. Thank you!

[andyr]

The switch positions on the Denon AU-320 don't refer to the load presented to the cartridge. They refer to the impedance of the phono cartridge that should be matched to those switch positions.
So, the 3 ohm position is ideal for cartridges of 3 ohms internal impedance.
The 40 ohm position is ideal for cartridges, like the DL-103, that have an internal impedance of 40 ohms.

If you have the usual 47k ohm phono input resistance, the load presented to the cartridge will be 470 ohms in the 40 ohm position and 36 ohms in the 3 ohm position.

Manual is in the library here.

More info here:
https://www.vinylengine.com/step-ups-an ... dges.shtml

Sorry, Sunwire, your maths is not quite right.

Previously, jagermonster posted that the '40 ohm' position selects a 1:10 gain ratio, whilst the '3 ohm' position selected the 1:20 gain ratio. The load presented to the cart is the MM phono stage Zin divided by the square of the turns ratio. So:
* yes, the load seen at the 1:10 gain ratio is 470 ohms
* but the load seen at the 1:20 gain ratio is 118 ohms (47,000 / 400).

Andy

[andyr]

The switch positions on the Denon AU-320 don't refer to the load presented to the cartridge. They refer to the impedance of the phono cartridge that should be matched to those switch positions.
So, the 3 ohm position is ideal for cartridges of 3 ohms internal impedance.
The 40 ohm position is ideal for cartridges, like the DL-103, that have an internal impedance of 40 ohms.

If you have the usual 47k ohm phono input resistance, the load presented to the cartridge will be 470 ohms in the 40 ohm position and 36 ohms in the 3 ohm position.

Manual is in the library here.

More info here:
https://www.vinylengine.com/step-ups-an ... dges.shtml

Well, that sure makes a whole lot more sense. Thank you!

Except, see my post above! (So hopefully, it didn't make all that much sense! :D )

Andy