Rheostat for JansZen I-130 ESL arrays?

[centaurus3200]

dangit, bought all this stuff from mouser and partsexpress and forgot the rheostat for rebuilding the I-130U ESL arrays inside my JansZen Z-200 speakers.

anybody know what the specs are so i can get better quality ones?

there's a bunch of ALPS and other ones at mouser.com but i don't know what i'm looking for.

there's also a bunch of dayton ones at partsexpress.com.

any help would be greatly appreciated as there are no specs for it on the 130 schematic. they are currently wired out of circuit by a previous owner, so i assume they are shot being they do have a high failure rate from my understanding.

thanks,
Robby

 

[bear]

Shouldn't make a bit of difference as long as they handle the requisite wattage.

They ought to be found to be placed to adjust the bias voltage of the cells.
That's how all the JanZen's that I worked on years past were set up.
Lower the bias voltage, set the HF level...

If it's in the audio line, then you want a high power rheostat or an "L" pad. If it is, I'd set the level that way then sub in some fixed resistors for daily listening - soldered.

_-_-bear

 

[centaurus3200]

thanks bear, you are right. i opened them up, the rheostats are still connected. after doing some research, i found exactly what you are saying. they merely set the bias voltage, not the level. so, the difference in gain between twiddling the pot is subtle. so, i guess they do work as is.

thanks,
Robby

 

[bear]

Well no, the difference is not in gain so much as sensitivity of the ESLs... thus the level.

If the pot is operating properly, there is a pretty wide range of - let's call it - level adjustment of the ESLs. But it's not in the signal path. That's the key point.

_-_-bear

 

[centaurus3200]

the difference between cranking the rheostat from counter clockwise to clockwise is a subtle difference in audible output, but not much. according to people on audioasylum, this is their correct operation.

you turn the pots to "minimum" while the stats warm up for 24 hours, then slowly crank them up until you start hearing hissing from the stats, then back them off until the ESLs become dead silent. correct?

meaning the ESLs will still have decent output even with the pots set to minimum.

Robby

 

[bear]

Perhaps...

But yes, the max level is where it starts hissing.
That will vary somewhat with the relative humidity that day!

The proper level is the one that provides the best overall response from the speaker system, not the loudest one, unless that happens to be correct.

On pink noise, the tweeter should not be more noticeable than say the midbass or the midrange noise... often not the case for typical "hi-fi" speakers...

_-_-bear