Hans, it seems that some of the caps are actually 20nF.
Does that change your sim results as far as 100M loaded output is concerned?
Jan
For the past 5-8 years there was no US distributor in the states, This was because the previous distributor gave up - panels were failing within a year and Quad had NO panel warranty. Believe they are still being made in China BUT doing it correctly now.
Wanted to go to ETF but apparently wasn't on the notification list. Thought that there wasn't going to be one. By the time I found out (October) that it was actually on, had made plans to go to the Capital Audiofest instead (same weekend). Had a great time there - may bypass ETF in the future. EXCEPT I missed guys like you and the other European crazies.
Is MoFi still their distributor? In the latest 28(9)12 models, they finally changed the stator glue after 4 decades. So maybe the stator bonds won't fail so much. But they were having serious issues with the diaphragms splitting to the point that MoFi wasn't importing them for a while. I've heard repeatedly over the years that the problems are "all fixed". I'll believe it when I see it. I have a set of 2912's that I paid $1000 for that were full of broken "all fixed" panels.
Sheldon
I have several electrostatic voltmeters. For this stuff there are NO substitutes. However the Classic HV probe for a CRT HV is close at typically 1000 Megs. At least you will be in 10-20% of the voltage and can validate the HV supplies function. I have seen enough in this discussion to validate the electronic supply + 100M to each panel we did 30 years ago.
I just noticed that I already used 20nF caps for all 8 eight capacitors in my sims, see #576.
This resulted in the 1.1Volt pk-pk on the bias.
Going to six 20nF and two 10nF as in #612 and like Jan reported, did not change a bit to the 1.1Volt ripple.
But making all caps 10nF, doubled the ripple to 2.2Volt.
The two versions with resp. one and two VDR's have different output impedances, and also having 8*10nF or 6*20nF+2*10nF makes a difference, as shown in the Bias voltage table below for two different loads, all versions starting with 5K25 with just the diaphragm's load.
So, the best performing version is with one VDR and 6*20nF+2*10nF.
Hans
This resulted in the 1.1Volt pk-pk on the bias.
Going to six 20nF and two 10nF as in #612 and like Jan reported, did not change a bit to the 1.1Volt ripple.
But making all caps 10nF, doubled the ripple to 2.2Volt.
The two versions with resp. one and two VDR's have different output impedances, and also having 8*10nF or 6*20nF+2*10nF makes a difference, as shown in the Bias voltage table below for two different loads, all versions starting with 5K25 with just the diaphragm's load.
So, the best performing version is with one VDR and 6*20nF+2*10nF.
Hans
Nice idea, but I guess this makes not much sense. For two reasons:
1. Make an estimation for what to expect, with very gross rounding: As from my measurement of the loading step with the neon bulb, let's assume a step of 25V (V_ignit-V_off) for the loading V_delta which accounts for a SPL intensity delta of 0.05dB. So a HV delta of 2.5V bias would produce a 0.005dB SPL delta. And the ripple of my measurements was at approx. 0.01dB, certainly also containing some (rectfied) AC line hum. This seems to be a too bad SN Ratio right from the beginning.
2. My panels are isolated from the HV supply by the neon and the parallelled capacitor. How much of the supply ripple would then finally show up as an AM modulation? Therefore in the end I would expect even less than 0.005dB ripple.
As said, before, it's just guessing. Maybe I am wrong.
Agreed. At an assumed R of lowish 1GOhms for the panels Ft would be at 0.0034Hz. This should indeed make pass most of the ripple. Shame on me
So you wiped away my objection No. 2 against measuring. Anyone objecting my 1st objection? If so, I will try measure ...
Seen that on FB. Nothing new in the promises IAG makes on build quality and technical changes for this X series.
All the items Kent quotes were also there for the xx05 and xx12 series.
There is nothing to be found about this release anywhere on the web ore on the official Quad UK site.
I only saw the picture of the manual with the X behind the model number to prove it's existence.
I'm very anxious to find out more about what, if anything, really changed. Until that point I'm very sceptic
It's not the neon bulb relaxation that I expect to make any trouble, but it's the ripple on the Bias voltage with a rather wide spectrum.
I'll make a simulation in LTSpice with the real signals.
But if it not too much trouble, receiving a 1 sec 1Khz .wav recording would be nice to compare.
When it brings nothing, a stabilized Bias voltage doesn't seem to make sense.
Hans
The original ESL originally has very high resistance Nylon coating 10^12
The LE1 uses the same panels licenced by Quad, the step-up transformers and electronics however are designed and made by Braun.