Intact Audio

no changes... Inductance is in the 200Hy range.

dave

sd

jk

I was asked about how the load seen by the cartridge effects the frequency response so I made some quick crude measurements of a shelter 501 and a denon 103R. The test record was the CBS STR-120. The sound card was a Focusrite Scarlett 2i2. captures were made with audiotester. The tonearm cable fed ...

nn

Hey Daniel, The first thing that comes to mind is if the iRiaa filter you are using has the 50kHz time constant. Here is a LCR filter with the 50kHz Neuman time constant into a LCR filter with and without it. Screenshot 2023-09-06 at 7.27.40 AM.png I suspect if you add the resistor R6 you might be a...

V1 / V2 are voltage sources and serve as an easy way to set the tube bias. I have used LED's in this position and they work well. I simply put the expected voltage drop of the LED as a voltage source under the cathode rather than trying to find or model the exact LED I use.

dave

no... I typically build the circuit, measure and then adjust the parasitics until spice matches the measured response.

dave

those numbers all look good.

Actually.... since the device being high passed typically also needs attenuation the "Rf" can also be part of the pad and then a shunt inductor added as the filter element. Assuming around 6dB here is a LR compared to a typical capacitor + autoformer. The big difference between the two wil...

Not that I can come up with for this situation. The RL filter requires a series resistance and a shunt inductor and the closest I can come is using the output impedance of the amplifier as the source Z and a shunt inductor but that will unduly load down the source at low frequencies. If say 6dB of H...

You would have to sim it but this should work... you may need a shunt resistor across the entire choke to get things stable since the impedance curve can get wonky with the stepup from the tapped choke.

dave

This comes down to the applied voltage and crossover frequency. 80% nickel has a saturation of 1/2 that of the supplied 49% which is the difference between 500Hz and 1000Hz or 2W and 8W.

dave

pp

pj

mnb

since these are simple input transformers the autoformer size would be fine. you should get 1:2 My first thought would be bifilar but I think the ground shift would "get you" at high frequencies.

dave

I do not follow.

The original $200 AVC's will not fit on the module PCB that has the integrated switches.

dave

tt

I cannot think of anything within the AVC that could cause this.... The apparent short between 12 & 13 should not be there and it is highly unlikely that the problem is internal to the autoformer

dave

it sure seems somehow pins 12 & 13 are shorted to each other. carefully retrace your wiring looking for an error. I am assuming it was functioning properly and then "broke at some point"? The fact that it is happening the same in both channels points to some external cause since it is ...

can you re-check you numbers?

the source impedance (867,2354 ohms) number does not make sense unless it rounds down to 867Ω

the measurements between steps 12 & 13 are the same which should not be the case. what is the DCR between 12&13 (at the switch and at the autoformer.

dave

it is not possible to get a balanced output from a single ended circuit but two units per channel can attenuate a balanced to balanced line.


dave

Hey, There really isn't any possibility of the AVC to become magnetized or break. The two things that come to mind are a leaky cap putting DC on the core and a possible shorted turn (two pins shorted to each other). A DVM should help diagnose the first and a visual search might point to the second. ...

this is a "loaded" question. My answer for myself is I always simply use a DVM to measure the resistance. HOWEVER! I am not going to ever suggest that to anyone else due to the small chance that something goes wrong in the process with a multi-thousand dollar cartridge. and I get blamed. T...

interesting.

My two questions on the situations:

Was the shunt resistor the same in both cases?

What was the nature of the crossover driving each autoformer?

dave

It seems odd that the change in the gap would effect the level in the measurements and it really needs to be driven from a ~1Ω source for reasonable results. My guess on the sonic results have to do with the lower inductance value of the 3X3 creating a high pass for information beyond what the speak...

The difference between 12 and 15 on the step up is only 2dB so for the most part I would consider them interchangeable.

dave

right.... and from the perspective of the SUT it is being driven from a 2Ω source or 3X the published 0.6Ω. I used to do SUT's specific to the sub 1Ω carts until I realized that the tonearm DCR has a dominant effect on the situation.
dave

The achilles heel of a 0.6Ω cartridge is the tonearm wiring is often double that value effectively turning it into a 2Ω cartridge.

I would confirm the tonearm DCR prior to committing to a design.

dave