Tweeter Capacitor Upgrade (Coincident PREs)


Hi all, looking to upgrade the Solen 4.7uF 100V caps that filter the low frequencies out of the Accuton tweeters on my Coincident PREs.  Started by looking at Duelund's, but PartsConnection doesn't even list prices for a lot of the models (or is out of stock) at that value... that motivated me to try and collect some impressions from the group.

Apparently Isreal is using Mundorfs in that position at this point.

As always, thanks for the input.
128x128cal3713

Showing 20 responses by erik_squires

Hey cal,
Mundorf Supreme has a particular house sound. Scintillating to over-saturated color. Magico uses them extensively, as does the top end B&W.

Otherwise, if you want something more natural and open, Clarity CMR to Jupiter Copper foil is the range I normally recommend.

Try the Clarity CMR with a small (0.1) Audyn TruCopper or Jupiter copper film as a really great low cost compromise.

The best way to find caps right now at Parts Connexion is to type the value into the search window:
4.7uF
and you'll find everything they have.

Best,
E


@cal3713
Right. You could probably even go lower, but hard to find a film cap any less. :)

Of course, higher voltage = higher cost, so watch out!
Here is my thinking:

4.7uF :
Clarity CMR : $54
Jupiter CF: $265

0.1uF:
Jupiter CF: $63

Audyn : $20 (Parts Express)

So somewhere in there I think the OP can find a fine solution. :)



Do not willy nilly change coils!

You have to match the DCR or you can make fundamental changes to the tone, and not in a good way.

For the woofer coil DCR sets the bass level, as well as helps with baffle step. Meaning, you must measure the DCR and only replace with equivalents (within reasonable tolerances).

In parallel to the driver, changing DCR without adding R can really muck with the impedance curve and have unintended consequences.
Hey @beetlemania
The CMR are excellent caps as mains, but above 4.7uF or so they need bypass caps. Below this, I can’t hear any benefit at all. The CMRs are really excellent caps.


My main speakers use a 3rd order hi-pass filter. To my ears, bypassing the larger cap (~ 10uF) they sound less compressed and more natural. I’m afraid it’s been about 2 years since I did this experiment.


@cal3713 Be aware that the CMR caps are physically huge! You don’t want to mount a 20uF directly to a speaker tab.

May be worth it to get some Duelund jumper cable too.


hi @bache,

Sorry, I meant to say the Audyn TC 0.1 uF was $20, and I was recommending it as a bypass.
How much a quality of the second order LP filter capacitor does influence on sound quality?

@alexberger

Based on my reading, this can be more important than the coil, even though it is in parallel. Especially if the original is an electrolytic, replacing them with even a modest film cap like a cheap Axon or Solen or Mundorf bipolar is going to be a bigger improvement than changing the coil.

Also, changing these caps is a little dicey, especially if replacing 1980's or earlier speakers, the ESR was pretty high and changes need to be compensated for. If you have relatively recent speakers (2000+) you should be fine.
Best,
E

Old capacitors ESR shouldn't be an issue, because I can adjust HPF cutoff frequency by potentiometer.



In shunt caps this can have really bizarre effects, so I doubt it. :) Depends very much on your amp.
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
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.
Hey Cal,

Did you try 0.1uF Audyn True Copper?

I feel 0.01uF is way to little. I've had 4x that and had no effect at all, also Duelund silvers.

I suggest you try the Audyn's because the value is right (0.1uF) and relatively cheap ($20  / each) 
If you hear no useful improvement, and you are on the border, then I'd give up on anything else.
I  meant:

4uF is the border for Clarity CMR. Above that, bypassing helps, below that it does not. 
4.7 uF ..... is right close. So it's worth trying but in the end you may find it's not worth it.
Hey @Cal3713
Glad to hear you are so happy. :)

Listen, can you tell me what your experience is comparing the Clarity with the Jupiters?

Best,

E
@cal3713
Thanks!

Color is what I thought the Audyn TC bypass caps added. :) I haven't noticed better imaging, but now I have a new amp so maybe I should do that experiment again?

I need about a total of 13 or 14uF in tweeter caps per speaker, so around $1,400 total. Not something I can afford for a while.

Best,

E