Has anyone upgraded their preamp with V-caps?

We've been using the V-Cap as an option for about the last year or year and a half. The Teflon part is one of the best coupling caps out there with no reservations.

If you don't like what you hear with this cap its because it is revealing a weakness! Frankly, the part has very little break-in (despite claims to the contrary, although you *do* hear the breaking-in and resettling of wiring disturbed during updates and newly-built pieces quite easily).

The part is very relaxed like a good paper and oil, but more detailed, with better bass and without the shelved highs that are paper and oil hallmarks. Overall very neutral and in a very good way. They are well worth the cost of admission (more so than fancy NOS tubes and a variety of tweaks).

Our preamp has a patented direct-coupled output balanced output and so avoids the classic issue of the output coupling cap (big cap=bad sound). So my comments are based on smaller parts, the biggest being 0.47 that we use in the phono section.

Just a note to those thinking of making the change (which we think is very worthwhile)

Its a good idea not to change the value. Increasing the value to get more bass may cause the low frequency cutoff to go too low- lower than the power supply low frequency pole for example. This can result in low frequency instability or maybe just flabby bass.

Your 2nd best bet so far is the Mundorf, but if you are using the cap in an output section, consider that in due time most paper and oil parts will develop a small amount of electrical leakage, which can have disastrous effects on the bias of power tubes!

The following applies to all Teflon caps:

Don't try to cut it close on the voltage ratings. Our experiences with several Teflon types is that is asking for the cap to short! Leave plenty of leeway for the voltage rating, and don't forget that during warmup the voltages across the cap will be equal to the voltage of the unloaded power supply!

Finally, do not give the part a lot of handling. Teflon does not 'cure' like polystyrene and polypropylene, so handling the part can cause the dielectric to pull away from the ends of the parts, changing its value or even shorting it. Once in circuit they are fine.

Sherod, the output of the MP-1 is direct-coupled; the pair of 0.1uf caps (the unit is also differential) are between the voltage amplifier and the vacuum-tube output buffer.

Sherod, IMO if you are going thru the trouble and expense of replacing the coupling caps, do yourself a favor and put the good stuff in. Its not that much more!