Newbe Question: ESL bias power supply

[CharlieM]

Hi Jerry,

I willl be posting the new bias supply and updated parts & price lists on my blogpage within the next couple of days. As for stretching the film. I use only 6 micron film exclusively, stetched to 1.5% elongation (which may not be appropriate for films thinner or thicker than 6-micron). I use a caliper to measure-- first place reference marks exactly 6.000" apart and then stretch the film until the marks are 6.090" apart for 1.5% elongation. If using a scale, you could place refrence marks 12" apart and stretch until the marks read 12 & 3/16" apart to achieve approximately 1.5% elongation.

Jazz

[dochungwell]

Thanks again Chalie for this info, and as I mentioned earlier in this post I intended to complete reading all the post revelent to my build and feeling more confident about my up comming build, that is until I wandered into several post from 2001. Several post surfaced with regards to the amplifier which should be used for ESL's. While today I have an inexpensive Denon 200 watts amp I ultimately want to purchase an inexpensive Yaqin amp rated between 40-65 wpc. Does tube amps/Trannys prove to be a challenge for ESL's to handle, or are silicon based finals a better match, or has this problem been solved with the current design utlizing toridals on the ESLs?

I knew I went back too far in the archives when I heard Rod Steiger narrating the post!

Thanks,
Jerry

[CharlieM]

Originally Posted by dochungwell

Thanks again Chalie for this info, and as I mentioned earlier in this post I intended to complete reading all the post revelent to my build and feeling more confident about my up comming build, that is until I wandered into several post from 2001. Several post surfaced with regards to the amplifier which should be used for ESL's. While today I have an inexpensive Denon 200 watts amp I ultimately want to purchase an inexpensive Yaqin amp rated between 40-65 wpc. Does tube amps/Trannys prove to be a challenge for ESL's to handle, or are silicon based finals a better match, or has this problem been solved with the current design utlizing toridals on the ESLs?

I knew I went back too far in the archives when I heard Rod Steiger narrating the post!

Thanks,
Jerry

Actually, toroidal trannys are a harder load on amps than the IE core trannys but I like the sound and good treble output of the toroids much better. There are differing opinions on tubes versus solid state amps for driving esl's. For example, Sheldon Stokes' website says he uses modest powered tube amps to drive his ESL 1.0's to high sound levels with ease. Whereas, Roger Sanders recommends high powered solid state amps with high damping factors (exclusively).... depends on who you ask, I suppose.

My old Carver TFM-25's hardly break a sweat driving my ESL's to ear-bleed levels.

[cocolino]

Originally Posted by EUVL

I also have a newbee question :

How do you test the output voltage ?
I tried even with a 10M high voltage probe.
It still overloads the circuit too much, that I get nowhere near the 2kV i expected.
Thx,
Patrick

Originally Posted by Calvin

Hi,

10Meg is the typical impedance of a multimeter and way too low to measure HV of a Bias supply. The currents are too large and the load forces the voltage down. For measuring HV think of impedance values in the Giga-range. Simplest is to solder a chain of 100 pcs of 10Meg resistors and measure the voltage over one or a couple of the ´lowest´ resistors and calculate the voltage after the resistor-divider-formula Vmes=Vbias*Rmes/Rcomplete (with Rmes beeing the parallel from the resistor measured over and the multimeters internal impedance).
This method doesn´t give exact values, but You are close enough.

jauu
Calvin

If I think High-Voltage and imagine a DIY construction from 100pcs. of resistors, I`d say the "simplest" (and safer and more handy) way is to simply buy ... something like this: FLUKE 80K-40 High Voltage Probe

The 80K-40 will achieve rated accuracy when used with a voltmeter (ac or dc) having an input impedance of 10 MΩ ±1.0%.

Specifications for the probe are as follows:

• Voltage Range: 1 kV to 40 kV dc or peak ac, 28 kV rms ac
• Input Resistance: 1000 MΩ
• Division Ratio: 1000: 1 (1000X attenuator)
• Accuracy DC: 20 kV to 35 kV: ±1% at 20°C to 30°C; add 1% at 10°C <20°C and >30°C to 45°C. (For total measurement accuracy add accuracy specification of voltmeter being used.)
  0 kV to <20 kV and >35 kV to 40 kV: ±2%.
• Accuracy AC: 60 Hz, ±5%.

Okay, it`s not DIY and it`s not cheap but it must not necessarily be an expensive FLUKE or You can also buy one used from e.... You know where, where such things pop up once in while (I bought mine second-hand years ago for about 40€).

[geraldfryjr]

A side from this beeing about bias supply's ,I like to chime in about using the ole' power torid.
They have a great bandwidth and are readly available and works in a pinch with great results.
BUT,they do have a very large self capacitance and this has nothing to do its shape or form.
It is about how they are constructed and if one were to take it apart and rewind it properly all of those issues would go away.
In this case the IE core looks inviting.
But you must consider the efficiency of the core itself.
As all coils are a PIA to wind no matter what.
Yes it is easy to just slip on a bobbin with a new winding ,But what are the chances of getting the same results from the core after you reassemble all of those I-E peices and have to seal them so that they don't vibrate and make noise.
Even the slightest airgap in the material changes the charcteristics of the core and Hence performance.

jer