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Were Renaissance 90s the best Infinity?

i opened the speaker and measured the coils dcr.

the 12.7mh and 18mh coils are 0.300ohms.

the 6.5mh which is 0.200ohms

after that i think that i should not change

them since they are the same dcr as the erse.

what do you guys think?
 
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With my crossovers, L1-5 all tested precisely to spec, so they were not replaced.

L-6 and above were all at least 20-30% under their specs, so they were replaced with new Erse (I believe Super Q) inductors which were individually unwound to match them to the exact spec.

If I recall, the DCR on the new Erse coils was a good match for the originals.
Click to expand...

The above is from a posting of mine from earlier in this thread. When I rebuilt the crossovers on my 90's, I went ahead and invested in an LCR meter so that I could adjust the windings on the coils and match the capacitors, and was surprised to find the inductors to test so far off of spec.

I think the T.I. Industries inductors that are in there were pretty good as far as DCR, but I will have to leave it to more knowledgeable folks to suggest whether an inductance 30% under spec is a real concern, but I did replace mine since I was doing a full rebuild anyway. YMMV.

I've got the tested values written down somewhere- I'll try to find them tomorrow.

Herb
 
i don`t have an lcr meter.i only measured the dcr and it was very low.
i don`t about out of spec and how important it is.
let`s see what others will say.
 
i borrowed an lcr meter and measured all the coils.

i think something is wrong here.

the 18mh is 12mh

the 12mh is 8mh

and the 6.1mh is 3.9mh

i don`t think this is by accident.

maybe infinity wanted to keep secret

how this woofer works.

besides they don`t give the crossover schematic.

the one available is reverse engineered.
 
so you pulled the inductors out of the circuit (at least on one side) to do those measurements?

curious indeed that they each measure almost exactly 2/3 of the spec'd value. is each inductor labeled or are you getting the expected value from the position in the circuit compared to the handwritten schematic?
 
cdfac said:
so you pulled the inductors out of the circuit (at least on one side) to do those measurements?

curious indeed that they each measure almost exactly 2/3 of the spec'd value. is each inductor labeled or are you getting the expected value from the position in the circuit compared to the handwritten schematic?
Click to expand...

of course i pulled out one side.

this 2/3 of the spec`d value gave me second thoughts.

the values at the schematic agree with the values written on the coils.(small white self stuck paper) and propably the guy that draw the schematic used
them.
 
cdfac said:
very strange. did you measure coils from both speakers or just one?
Click to expand...

i only measured one but i will measure and the other.if both have the same values i will be sure this is not a mistake.probably they will because hdjr808 found them to be smaller too.
 
i finished recaping the one speaker without changing any coils.seems good but i will wait and the other speaker and then i will wright impressions
 
i measured the other speakers coils.
almost same values with the first speakers.
something must be wrong with the labels.
 
probably they will because hdjr808 found them to be smaller too.
Click to expand...

I've tried to find where I noted the original values of the inductors in mine, but no luck. They did consistently read low however. And I'm pretty sure this was not a testing error, since the new inductors (prior to fine tuning) read spot-on to their stated values.

The labels on the original T.I. inductors matched the values in the schematic, so I'm not sure how the discrepancy could come about.

Possibly consistently high current being drawn through them heating the coils and causing internal shorts? I don't know, just conjecture.

Herb
 
it would be a pretty big a coincidence to be a heating issue with that much consistency. that being said, i don't really have a better explanation. is there any way that Infinity could have partially unwound them by hand at the factory?

i'd like to see some in-room frequency response plot comparisons between a "fixed" speaker and stock speaker. has someone done a plot for either? does anyone with 90s have the equipment for that?
 
i finished and the second speaker and the results are stunning.
infinity can`t unwound the coils.
they are fixed like EI transformers.
i believe the labels are wrong on purpose or not i don`t know.
besides the schematic is hand writen so propably the values was taken from the labels.
measuring 90`s in different rooms won`t give comparable results.
i wonder if timpani have the old coils to tell us the values.
 
back said:
i finished and the second speaker and the results are stunning.
infinity can`t unwound the coils.
they are fixed like EI transformers.
i believe the labels are wrong on purpose or not i don`t know.
besides the schematic is hand writen so propably the values was taken from the labels.
measuring 90`s in different rooms won`t give comparable results.
i wonder if timpani have the old coils to tell us the values.
Click to expand...

When I have some time next weekend I will test all of the old inductors - at the correct frequency of operation. This requires a function generator and an oscilloscope - along with several 2% capacitors of correct value.
This should answer all questions.
 
back said:
anybody remember which coils are air core?
i didn`t touch the mid high crossover yet.
Click to expand...

Only the MB coupler xo uses iron core inductors. The EMIM / EMIT use air core - as you would want.

Iron core inductors do suffer from ageing - and it increases with temperature. However, the problem is less at low frequencies - where eddy current loss is lowest.
 

Attachments

cdfac said:
it would be a pretty big a coincidence to be a heating issue with that much consistency. that being said, i don't really have a better explanation. is there any way that Infinity could have partially unwound them by hand at the factory?
Click to expand...

The IC inductors need to be measured at a frequency within their designed operating range and ideally at real world operating voltage and current - to avoid spurious results.
 
timpani said:
When I have some time next weekend I will test all of the old inductors - at the correct frequency of operation. This requires a function generator and an oscilloscope - along with several 2% capacitors of correct value.
This should answer all questions.
Click to expand...

hello timpani.
long time no see:)
what do you meen by that?
an lcr meter gives wrong values?
 
back said:
hello timpani.
long time no see:)
what do you meen by that?
an lcr meter gives wrong values?
Click to expand...

Do you know what frequency your LCR uses for testing L & C? It might be too high to give you a valid result.
Most modern LCR meters use a tone gen (eg. 1KHz) and then measure the amplitude and phase across the load (inductor). The measured quantity is converted from polar to rectangular form to obtain the value of XL - which is then used to find 'L'. The best meters allow you to test at several frequencies - to take into account the type of inductor or capacitor. For the Ren iron core inductors you should be testing at about 300Hz and 100Hz for MBC and woofer inductors.

cheers, t
 
aha this must be an explanation for my 40% lower values.
on the other hand when you buy a replacement inductor
where is the stated value refered to?
i believe at 1khz and not at the frequency you need.
so the result is the same.
am i right?
 
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