Quartet rebuild questions

[itsikhefez]

Hi all,

First post here! I'm more active over at AK and posted there but have not gotten any responses so will try here.

I have a DIY 300B amp and have been looking for speakers for a long time... finally picked up a pair of Quartets from CL.

 

I'll be doing most of the usual "upgrades" but have 2 particular questions:

1) Electrolytic cap value -- In the schematic it seems to be 50 or 60uf (can't really tell which), but currently there is 80uf there. I was wondering how crucial the number is here actually? Do I need to put a 80-82uf cap in there, or will a 68uf or 100uf work as well? Asking since I have preferred choices in those values

 

2) Any recommendations for gasket, particularly the 12" passive radiator? After removing it to do XO work, it appears to be very thin and may tear.

 

Thanks in advance!

Edited October 24, 2019 by itsikhefez

[MeloManiac]

Welcome!

I' m curious about this too. I think the closest you remain to the original specs, the closest they will sound to when they left the factory. 

[001]

the woofer cap in the quartet is definitely a 50uf according to the schematic posted here.  can you post a pic of the x-over?  unless there was a revision to the quartet x-over, it should not be 80uf... maybe a previous owner changed it out & misread the value or tried to experiment with changing it?

 

i agree you should keep the values the same as stock.  the quartets are great speakers & i see no benefit to change the x-over unless you are doing other major mods.

 

   

[itsikhefez]

Thanks for the response @EpicKlipschFan

 

I bought them from the original owner, and based on our short conversation I'm pretty confident they did not do any modifications to the crossover.

Attached is a pic of the crossover and the cap that I removed... they all look original Klispch parts.

I have not opened up the other speaker, I should probably do that to compare.

 

[MechEngVic]

Changes to the values of Crossover components will make significant changes in sound. Stick to stock values. 

[itsikhefez]

Right.. so should I believe the schematic or the current part in the crossover? I'm sure other Quartet owners can confirm...

[MechEngVic]

 

Looks like the schematic is wrong. 

 

[itsikhefez]

Thanks for confirming that.

 

9 hours ago, MechEngVic said:

Changes to the values of Crossover components will make significant changes in sound. Stick to stock values. 

I'm sticking to the original values pretty close but not exact.

I am replacing the 40R resistor (which measured 41.5R) with Mills MRA-5 39.2R resistors.

The 80uf cap (which measured 83uf) will be replaced with a 82uf cap. (all measurements done with Fluke 87-V DMM)

I am assuming these small differences are fine since the original parts are atleast 10% tolerance anyhow (unless someone at Klipsch sorted them out and picked exact values, but based on what I measured that doesnt seem to be the case)

[MechEngVic]

3 hours ago, itsikhefez said:

Thanks for confirming that.

 

I'm sticking to the original values pretty close but not exact.

I am replacing the 40R resistor (which measured 41.5R) with Mills MRA-5 39.2R resistors.

The 80uf cap (which measured 83uf) will be replaced with a 82uf cap. (all measurements done with Fluke 87-V DMM)

I am assuming these small differences are fine since the original parts are atleast 10% tolerance anyhow (unless someone at Klipsch sorted them out and picked exact values, but based on what I measured that doesnt seem to be the case)

At those high capacitance ratings, a couple of uf's one way or another won't be audible.

[MeloManiac]

6 hours ago, itsikhefez said:

The 80uf cap (which measured 83uf) will be replaced with a 82uf cap.

... All your crossover components fall within specs... So why replacing them, then? They are just fine and will likely be for years to come... 

[001]

On 10/26/2019 at 12:07 PM, itsikhefez said:

Thanks for the response @EpicKlipschFan

 

I bought them from the original owner, and based on our short conversation I'm pretty confident they did not do any modifications to the crossover.

Attached is a pic of the crossover and the cap that I removed... they all look original Klispch parts.

I have not opened up the other speaker, I should probably do that to compare.

 

 

thats definitely an 80uf cap,  maybe the schematic is wrong, or the crappy printing that looks like a 5 is really an 8.  anyone else with quartets able to look at yours to verify?  

 

i agree a couple numbers wont be a big deal but some would say otherwise.  also, maybe the caps have changed over the years & originally were closer to or at spec.  the benefit to changing old caps is they are usually replaced with better quality caps than the cheap ones klipsch used.  so even if they are within spec, some like to "upgrade" to better caps... even entry level poly caps like daytons are better than the mylar(?) stock klipsch caps. 

 

& another FYI:  according to Bob Crites, the resistors do not have any affect the sound, so changing them may not do anything,  at least not at this level.  high dollar x-over builds are a different story & may benefit from better resistors.  

 

i would stick to the factory specs if you can get the right values,  no reason to change them based on readings from 25+ year old caps.