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Old 9th September 2011, 09:28 PM   #1
5544 is offline 5544  Russian Federation
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Default STAX ESS-4A Help!

I have 3-band STAX ESS4A but regrettably without conecting cable which contain power and signal. I managed to feed the power but still having difficulties with signal: 2 pais of wires red-black and white-blue are joins input socket and tranformer. Transformers inputs are black-blue shows 0.9 Ohm and red-white shows 0.9 Ohm. They are plaing while signal fed to black-blue and red-white but very quiet. Probably I have to make a parrallel connection of any circuits? I'm afraid to make it wrong. Share your wise, guys, please. - How to feed signal the corredt way.
Photos:
Cables: http://i058.radikal.ru/1108/0f/8a71434d7e78.jpg
http://s50.radikal.ru/i127/1108/cf/f15aa8f51118.jpg
Commutation box: http://i039.radikal.ru/1108/fb/622883131d8b.jpg
Commutation box in: http://s59.radikal.ru/i163/1108/d8/3f3de45e8c61.jpg
Transformer: http://s51.radikal.ru/i134/1108/1c/c3b0d0b88fe0.jpg
Speakers inside: http://i075.radikal.ru/1108/ae/329dc95e2a57.jpg
Midrange unit: http://i047.radikal.ru/1108/ce/6e57bdddadf3.jpg
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Old 9th September 2011, 10:40 PM   #2
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It's pretty straight forward.

Bias voltage - high voltage is applied to the connection that goes to the center/diaphragm.
Signal is applied to the stators.

Looks like the unit is encapsulated with wax. So you can melt it out, if you have to in order to see what is connected to what.

Have it lifted by some metal rods (or whatever) above a pan in an oven set low, like 150deg F (whatever that is C - less than 100 C...) the wax will melt down and out...

This assumes you have no test gear and can not just measure the HV to see where it is and look at the signal with a scope...

The unit may or may not have a problem with the HV bias supply...

So you have to determine the HV and then a pair of signal carrying leads... presumably they are paired coming off your "transformer"... so you hook them up one at time, and try to determine which is for the bass, mid and highs - do it at a low level and you are unlikely to damage any cells...

Others may have other info and ideas...

If you have it hooked up 100% right and it doesn't play, likely you have a bad HV supply.

_-_- bear
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Old 10th September 2011, 06:36 AM   #3
5544 is offline 5544  Russian Federation
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Who has STAX ESS-4A? I want to get a response from the owners: what kind of cable design?
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Old 12th September 2011, 12:11 AM   #4
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Are you asking about the wire used or the connectors?

For the wire you would likely need something with very high voltage breakdown rating...
if they used something with less than HV rated wire, then they were asking for a breakdown... usually the "interface box" - the one with the xfrmrs and the HV bias supply is placed very close to the cells so that it can be wired directly...

It's unclear to me what the box with the pot (volume control) on it does, or where it goes WRT the other larger (black) box and where all that mounts WRT the cells... and/or where the cable runs too and from...

Of course I do not have a STAX ESS-4A... but these things can be figured out with the proper information...

_-_-bear
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Old 12th September 2011, 12:19 AM   #5
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Ok, the cable is for the AC mains input:

STAX@ESS-4A@Œ‘1-3

It looks like the end of this cable has been connected to some EUROPEAN AC mains plug.

This one is a USA type plug:

http://earsp.web.fc2.com/kakosp/ess-...3_jpg_view.htm

Should be easy enough to determine what the wiring is... the wire needs only to be rated above the AC mains voltage (whatever is standard for your country).

... the speaker input is the black and red binding posts.

_-_-bear
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Last edited by bear; 12th September 2011 at 12:23 AM.
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Old 12th September 2011, 04:33 AM   #6
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Quote:
Originally Posted by 5544 View Post
I have 3-band STAX ESS4A but regrettably without connecting cable which contain power and signal. I managed to feed the power but still having difficulties with signal: 2 pais of wires red-black and white-blue are joins input socket and transformer. Transformers inputs are black-blue shows 0.9 Ohm and red-white shows 0.9 Ohm. They are playing while signal fed to black-blue and red-white but very quiet. Probably I have to make a parallel connection of any circuits?
Hello,

I don't own a pair of STAX ESS-4A, but have read about them.


HV power
You say you have the power applied to the speaker. This should be 120Vac through the two white wires shown in the attached figure. You can use the knob on the outside of the box to adjust the level of the HV(bias voltage). The output should increase as the HV level is increased. You want to adjust it as high as possible without hearing hissing or crackling from the panels. There are separate levels of voltage fed to the bass panels( HV1) and the midrange/tweeter panels(HV2).

As Bear already mentioned, if you can't get much output from the speaker, the HV supply is most likely the problem.
You will need to verify the HV1 and HV2 outputs.


Audio Signal
The "A" version of the model 4 was designed to have 2 modes of connection:
1) low impedance mode for use with solid state amplifiers
2) high impedance mode for use with OTL tube amplifiers

This is done by winding the step-up transformer with 2 primaries windings.
Hook the two windings in series to get a high impedance load for OTL tube amplifiers.
Hook the two windings in parallel to get a low impedance load for transistor amplifiers.

You say you measured 0.9 ohm between the black and blue wires.
You say you measured 0.9 ohm between the red and white wires.
These will be the two primary windings.

If you are using a transistor amplifier, you should hook the two windings in parallel.
I would guess hook red and blue together for the (+)audio input, and hook black and white together for the (-)audio input.
The output should be about the same as hooking audio signal to just (red-white) or (black-blue) separately.
The difference will be the high frequencies will be better with both windings hooked in parallel.

If hooking the two windings in parallel as described above produces less output than one primary winding alone, reverse the connections to one winding. No damage will come to the amplifier or ESL by connecting the two primaries incorrectly.
Attached Images
File Type: jpg Com_box_labels.jpg (111.7 KB, 80 views)

Last edited by bolserst; 12th September 2011 at 04:35 AM.
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