LCR RIAA 600 ohm vs 7000 ohm???

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Tomwh
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#1 LCR RIAA 600 ohm vs 7000 ohm???

Post by Tomwh »

I posted this is different forums and read everything I could find on the net. There some very long threads with a lot of spice diagrams but not a lot of conclusions. As far as the curve goes I am not so concern with getting right in the computer, as most of the time it is going to have to be tested in the circuit.

So my questions are more in line with how did the low impedance units sound in comparison to the higher. If forced to choose a couple of tubes vs a bunch or transformer step down/ step up etc... I like the idea of the higher one for the the ability to roll alot of tubes in 1st position and of course the gain. But there is the camp that thinks the lower version sounds better.

So in a perfect world there would be someone who has tried alot of the different varibles and could comment of the sound. If they were not 500.00 a set I would try alot of different values.

Any input would be great.

Thanks Tom
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IslandPink
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#2

Post by IslandPink »

Hi Tom - nice to have you here .
As I hinted in the DIY Audio thread, I haven't got exactly the experience to answer your question - which is a very good one ! - but maybe I can get Nick or Andrew to comment . Not many people have got the specific knowledge of how two different impedance RIAA's built within the same sort of circuit , sound, in comparison !
One point that Andrew has highlighted ( not obvious ) is that the 600R units, with the 600R teminating resistor to ground , represent a 300R load to the driver valve :shock:
"Once you find out ... the Circumstances ; then you can go out"
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Nick
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#3

Post by Nick »

IMHO, there are at least two things that are effected by the network.

Lower impedance

Easier to wind coils that are constant inductance with frequency
Harder to drive

Higher impedance

Harder to wind coils that are constant inductance with frequency
Easier to drive.

It all depends on the circuit you are going to put around them and how accurate you want the RIAA to be. I have ended up (Like Andrew) at 1k5, but driving that is still not trivial. And of course the caps matter as well.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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