SUT Inductance

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Neal
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#1 SUT Inductance

Post by Neal »

Prompted by a post Mark made on AoS about SUT primary inductance I'm curious how inductance affects the response when used with a low and high impedance cartridge....IE: the DL103 is 40 Ohm and I've read a lot of SUT don't have sufficient inductance to get good LF performance. Is this simply a case of the inductance forming a HPF with the cartridge? I suspect it's more complicated but if anybody know the details I'd be interested.... Thanks!
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Nick
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#2 Re: SUT Inductance

Post by Nick »

In essence yes. I think of it in terms of the inductive reactance of the primary in parallel with the inductive reactance of of the secondary in parallel with the load resistance divided by the square of the step up ratio. With some brackets in there that I am sure you can add. That is the load that the cartridge is driving into, so that is where the HPF comes into the equation. Given the secondary inductance is going to be a lot more than the primary, you can probably ignore that. So Zload = 2.Pi.f.L || reflected load.

You can do the same sort of thing with the primary and secondary leakage inductance, load capacitance (including cable) to workout the LPF side of it,
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Neal
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#3 Re: SUT Inductance

Post by Neal »

Cheers Nick!
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IslandPink
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#4 Re: SUT Inductance

Post by IslandPink »

Good detail from Nick thanks - had forgotten about the secondary, but as you say, less of a problem than the primary .
The plain 103 is a bit of a headache really . If you want low bass and any bass timing with them, I'd be inclined to use a SS head amp or something like a jFet input to a valve phono like I tried a while back on mine - I was amazed how good and extended the bass was on the 103 then - nothing wrong with the cart - it's just a simple first-order technical problem due to the internal impedance .
The other alternative is to experiement with direct MC input to a valve phono which can be done but difficult to get it quiet . 6C45Pi's have been mentioned as one of the best options to try, also Nick's phono will take direct MC input into the pentode front-end, with the tricks he employs in there and good earthing.
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