Crossover component

[miguelnoda]

atc 75-150

hello they sell me some atc sm 75-150 st and the measurements with the multimeter are 10 ohm is it feasible or are they already widely used?

 

[mbrennwa]

hello they sell me some atc sm 75-150 st and the measurements with the multimeter are 10 ohm is it feasible or are they already widely used?

Just ask them for a recone kit with 16 Ohm.

 

[EarlK]

hello they sell me some atc sm 75-150 st and the measurements with the multimeter are 10 ohm is it feasible or are they already widely used?

mbrennwa,

FYI, my interpretation of miguel's words is/are that he has purchased a pair of sm 75-150st from ATC and is now wondering why they measure out at 10 ohms ( dcr ).

- IOW, ( to paraphrase someone else's thought-balloons ) I believe he wants to know if the lower than expected dcr measurement implies that they sold him used goods?

That's my take // which ( looking behind the curtain ) all-in-all helps explain why it's taken 4 years to get to this point in a so called DIY forum.

 

[miguelnoda]

atc 75-150

the 16 ohm recone kit is almost like the new speakers.
They sell me some but they measure 10 ohm I think it's a little low value

 

[mbrennwa]

Unfortunately ATC does not seem to specify the RDC in their datasheets of the SM75-150, so we cannot compare the 10 Ohm reading with the ATC specs. However, here is an impedance curve I measured with a 16 Ohm SM75-150-STD: http://hifibau.ch/wp-content/uploads/2016/02/lowpass_atcSM75-150_hiba.png --> this is consistent with a DCR close to 10 Ohm. This might suggest that miguelnoda has 16 Ohm units.

miguelnoda: please check the markings on the back of your drivers. Maybe post some photos.

 

[mbrennwa]

the 16 ohm recone kit is almost like the new speakers.

You cannot buy these drivers "new". When I bought the recone kit, it was quite a bit cheaper than the typical ebay prices for second-hand drivers.

They sell me some but they measure 10 ohm I think it's a little low value

The DCR value is different from the "nominal impedance" value. The RDC can well be 10 Ohm for a "nominal 16 Ohm" driver.

 

[42476]

That sounds about right for a DCR. 8 Ohm drivers usually have a DCR around 6 Ohms; 4 Ohm drivers DCR around 3 Ohms...very generalized for sure. 10 Ohms DCR for a 16 Ohm driver is about what I would expect not knowing anything else about it.

 

[mbrennwa]

Ok, I double-checked my SM75-150-SUPER. They are 16 Ohm units (not 8 Ohm as stated before). The DCR is 9.8 Ohm.

miguelnoda: I am pretty sure you have the 16 Ohm version.

 

[miguelnoda]

Atc sm75-150 8ohm

How can I check you means to know if they are in perfect condition apart from the dcr resistance

 

[JMFahey]

Play some music through them and listen.

 

[mbrennwa]

How can I check you means to know if they are in perfect condition apart from the dcr resistance

Measure the impedance curve. Measure SPL response. Measure harmonic distortion.

 

[miguelnoda]

What inductor and capacitors can give an improvement to the treble part

 

[JMFahey]

What is the problem you are trying to solve?

Are you repairing an old speaker or building a new one?

If there are bad/dry components, fresh modern ones will improve sound.

If they are working properly, "Audiophile"/snake oil/NASA type etc. ones won´t improve anything.

Those are passive components and can´t add which was not there to begin with.