Tweeter Capacitor Upgrade (Coincident PREs)

Let me add a little:
If you mess up the 2nd pole in the low pass filter, you can drop the impedance through the area above the crossover point, which actually doesn’t change your LP frequency response very much, but if your amp has very much output impedance at all, it will drop the output. Weird right? Seen it 2-3 times.

If you use a crossover simulator, you'll see this in the impedance graphs, but not the frequency response graphs, unless you have one that lets you simulate amplifier output impedance, then it's super obvious.

Best,
E

Hi @erik_squires ,

I get it. 

With bypass I noticed that vocals, saxophones and acoustic guitars sound not as smooth and tonaly reach as it was without bypass. It seems it cause a deep in lover mid range.

I think that vintage oil capacitors should be replaced by something that have a natural tone. I don't want to use cheap Solen capacitors. They sound too synthetic. I avoid to use them even for tube amp power supplies.

With bypass I noticed that vocals, saxophones and acoustic guitars sound not as smooth and tonaly reach as it was without bypass. It seems it cause a deep in lover mid range.

This can certainly be a symptom of what I'm describing. The amp used matters a lot, so this will be worse with tube gear.

You can measure ESR with Dayton DATS or a home grown jig using Room EQ Wizard. It can help you compensate accordingly.

https://www.roomeqwizard.com/help/help_en-GB/html/impedancemeasurement.html

So if you are bypassing old caps, measure the ESR, and then ensure that in parallel, your new caps don’t cut that more than 0.2 Ohms or so.

You can use something like the free XSim crossover simulator to examine the impedance plot and add the appropriate resistance with the bypass cap.

@d2girls Unfortunately I haven't had the chance to be around too many high end systems that might compete with the Coincident PREs (previous speakers were Thiel 1.6s, 2.4s, and Coicident Super Eclipse IIIs). 

As they should be, the PREs are in a different league from those other speakers.  It's been a real learning experience getting these set up, even coming from another Coincident system (I amplified the SEIIIs with their Franks).  It probably took me 6 months to really dial them in.  I had to replace my speaker cables, my 300bs & rectifier tubes, add new power cables, grounding wires, replace a "harsh" power strip, consolidate all my gear down onto one dedicated line, and am now adding new capacitors to the head units.  I've also tried four different amplifiers (the Franks, Atma-sphere M60s, the Pass XA25, and Lyngdorf TDAI 3400).   

At various points I've had almost no bass, harsh irritating high frequencies, and muddy imaging. Gradually, however, it's become clear that none of those problems were because of the speakers... just some other part of my system that had to be brought up.  Having persevered through all that I do think I'm committed to the speakers.  Obviously they're brutally revealing, but can also sound really warm and gentle once everything is setup correctly.  As I said, the process of getting them setup has been incredibly educational.  

That said, I believe your concerns about dealing with the company is also a real issue.  My speakers were damaged in shipping and so I had to interact a lot during the repair process.  I could go on and on, but do expect to be charged a premium fee for any parts or repairs.  And if there is ever any problems or conflict, do not expect Coincident to do anything to "make it right."