Cartridge Loading- Low output M/C

By the way, I still have no idea what you mean by energy of the cartridge itself etc.

I didn’t say "energy of the cartridge itself." I said energy "generated by the cartridge itself," and I was referring to energy "generated by the cartridge itself" at RF frequencies. Which I was distinguishing from Radio Frequency Interference, which appeared to be the focus of your analyses.

Surely it must be more than obvious to you that a cartridge generates an electrical signal when it is playing a record, and electrical signals contain energy, and:

Energy = Power x Time

And for a resistive load:

Power = Voltage x Current = Voltage Squared / Resistance = Current Squared x Resistance

Not sure why what I meant by energy "generated by the cartridge itself" would not have been clear.

Regards,
-- Al

OK. Thanks for defining what you mean. So lets look at power.
I ran a simulation and calculated the power dissipated in the cartridge series R and the load R and plotted what happened to the total power as the load cap is varied.
The voltage and current must be in phase for a resistor so power remains V^2/R. We know that the voltage across the load R is reduced as the cap is increased- after all, that’s the objective- so the load power must fall- but what about the series R? I calculated this and added it to the load power to get the total power.
So, back to the "real" case with a 11.8uH winding inductance , 16 ohm Rcart, 85pF load and 100 ohms. I set the input to 1v rms and calculated the total power in the two resistors =10*log(((voltageacrossRcart^2/16) +(voltageacrossloadr^2/100))
The power plot starts at -20.6dB at LF then falls by 3dB at 1.7MHz and by 18dB at 10MHz. No peak is present.
I then changed the cap to 0.1uF.
The power at 1kHz was -20.6dB, it peaks at -13dB at 150kHz , is 3dB off the peak at 87kHz and 320kHz, then falls monotonically by 25dB at 10MHz.
So we’re measuring 1/7 the bandwidth and a bit less than 6x the power in that bandwidth- which is, again, hardly surprising, so the power is more or less constant, but the total power at 10MHz is reduced and the load power at RF is hugely reduced, so isn’t that better?
Is the increase in power dissipation in the cartridge at supersonic but not RF frequencies problematic?
Darn! I wish I had some way of showing plots.

Wyn, I'm not claiming anything original here, except perhaps my anal-retentive dedication to costly devices!

Speaking of which - direct drive ESL. I have new generation Quads, which I opened up as soon as the warranty expired. I found a step-up transformer for each stator, cheap WW resistors and ceramic caps with their high dielectric constant. Obviously, all of these had to change.

As you seem to be an owner of ESL's, obviously you know that the step-up transformer tends to ring unless the input is coupled through a resistor. I changed the step-ups to a toroidal device which drove both stators, requiring an input resistor of about an ohm, which is a natural place for nichrome wire. Since I needed speaker cables anyway, I thought,"Why not use the nichrome wire for both purposes?"

Now I am thinking of high potential amps driving the stators directly, without any step-up device. I was wondering if you knew about HV transistors, and if you could save me some time and some angst with awful prototypes. That's all.

Well, I once was the proud owner of a couple of quads- the original ESL-57 and a pair of ESL-63s that I also pulled apart- their delay line/filter design to drive the annular segments was quite neat. However, I had serious reliability problems and I switched to Martin Logans and I've stayed with them ever since. I have Montis in the main audio room and a pair of venerable Prodigies in the home theater room and I've never had a problem with either of them.
Yes, I am aware of the fundamentals of their operation, but alas not the details so I really cannot help you out in this. Frankly, I'd be pretty leary about shipping the needed HV to the speaker from an external amp. Visions of lethally shocked dogs, maids, and kids spring into my mind. Having said that I believe that at one time Acoustat built ESLs without the transformer, instead using built in output transformer free tube amps

Your cautions are accepted. I've been thinking mil spec circular connectors and cables encased in grounded shields, or mono blocks bolted to the back of the speaker bases.

Interesting parallelism. I went from Magnepan to ESL-57's to Prodigies to 2905's. That's been an 'absorbing state' for 15 years now.