AirTight ATM-300 - new Coupling Caps

@rubjel The Copper V-Cap (CuTF model) is an excellent coupling cap in tube electronics, and this applies to any coupling application—-input, interstage and output.  I haven’t used it in a bypass position or in a power supply application so I limit my recommendation to coupling applications.  I also have never used a V-Cap with solid state gear.

CuTF caps have strong bass with excellent dynamics and excellent detail.  The only other caps I would consider as signal couplers in tube electronics are Audio Note copper foil and silver foil and possibly Jupiter copper foil.  I say “possibly” because I haven’t used Jupiters in my own equipment although I have heard them in other preamps and DACs.

@rauliruegas Crossover caps are a very different application.  I understand you preferred FKP over CuTF in your amps, and that’s fine.  Everyone has their own tastes.  No capacitors is perfect.

@rauliruegas 

I generally agree with your points, and I'm no speaker designer, but I wonder how crossover caps could always be totally neutral.

For instance, if you replace a factory electrolytic with an equivalent film cap, won't the film cap's lower ESR by definition give the frequency band it's in a slight boost?

Dear @salectric  " No capacitors is perfect. "

YES, the best cap is no cap in the same way that the best fuse is no fuse and that's why I take out all the fuses input electrical power in my electronics. Yes, it makes a change for the better.

R.

Dear @devinplombier  : I'm with you. No cap is totally neutral and electrolitic cap behavior is diffirent that the film ones.

In the case offf my speakers that are really old/vintge ADS L2030 ( fantastic silk dome drivers in the tweeters and mid ranges,. ADS made its own drivers in all its speakers but the 2030 that were made in exculive for ADS by a Germany manufacturer. ) ) the crossover original caps for the woofers were an electrolitic ones ( 100uf. ) There are several alternatives coming from Sprague, Vishay, Kemet and the like . Instead I choosed film caps Wima MKP10 wired in parallel to achieve 100uf and performs better than ever but we have to consider that I'm talking of the bass frequency  range where what you said you just can't be aware of it ..

R.

@rubjel , Tinned copper Duelands. 

The othere cap that is very organic but no longer made is the Jensen copper foil caps. Very organic sounding cap. Jensen was bought out by a conglomerate who discontinued these caps. 

As long as you are in there you can also take a look at the plate resistors on the input tubes. Most are either carbon or flame proof metal oxide used for reliability. 

I replaced them with higher wattage MiLLs wire wound audio grade. You will lower the noise floor a few db as well.