Capacitor size for SEX kit, stock and with new iron

[dobbykins]

I'm going to be buying a set of Obbligato premium gold caps for the signal path of my SEX amp.  I'm curious if you guys could suggest the best size to use - I've heard the larger caps should be upped to 2 uF when the iron is upgraded.  However, I'm stock for now, with intent to upgrade later.

So, given the sizes available, which would be best for now and later?  The reasonable options would be 1.5 or 2.2 uF.  I'm sure either would be acceptable, but I'd like to make sure it's ideal.

Thanks,
Guy

[Jim R.]

Either one will be fine for either configuration.  It's ok to use a 2 uF with the stock iron, and you'll get it broken in while waiting for your iron upgrade.  If you upgrade to the c4s evenwithout the iron, I believe the 2 uF is recommended for that too.

-- Jim

[Maxwell_E]

I have a 2.2 and a .33uF on my SEX with the stock iron and C4S boards and I couldn't be happier. Also nice to know that these values should work if I ever pony up for the MQ iron.

[Paul Joppa]

There is no real "ideal" value; it does depend a bit on the speaker being used. Even if the speaker were a pure resistance in the bass (they are not!), there are some tradeoffs between distortion (small cap is good) and extension (large cap is good) which depend on how loud you want to listen.

My best compromise, based on simulations with pure resistive loads of exactly 8 ohms, is 0.94uF stock and 1.56uF with the MQ iron. But based on those simulations, anything from half to twice those values is not greatly different; also the larger inductance of the MQ iron allows a greater compromise towards extension, so I have suggested 2.0uF for that case.

OK, enough techno-babble! If you expect to be pushing the power capability, I'd go for the 1.5uF. If you won't need to push the power limits, use the 2.2uF.

[dobbykins]

Thanks a bunch for all the responses, guys!  I presumed there would be little difference between the two values, but, based on PJ's response, I went ahead with the 2.2 uF.  I don't often go higher than 50% on the volume dial, with my Heresies.

When they're burnt in and installed, I'll be sure and give my impressions of the Obbligato Golds.

Take care,
Guy

[dobbykins]

I just wanted to quickly share my experience with the Obbligato golds I installed.  The change by doing the 2.2 uF caps was about equivalent to the change I got by then doing the 0.1 uF's, about a week apart.

The only other cap swap I have done has been putting Russian teflon FT-3's in my Seduction.  The FT-3's gave an immediate impression of warmth and smoothness, making the entire sound substantially more mellow and liquid.

The Obbligatos were quite different.  The first feeling I had about them was that they were very clean.  They're noticeably more neutral than the FT-3's, seeming to avoid influencing any frequency regime over another.  The biggest changes were in resolution and very low level distortion/muddiness - everything seemed cleaned up and more true in timbre and texture.

As the only two amplifying components in my system, the SEX and Seduction with these very different capacitors seem to complement each other very well.  I feel if I had gone for all FT-3's or all Golds, I would feel my system would be either too mellow or too neutral to be as enjoyable as it is - the combination is very pleasant.

[InfernoSTi]

Thank you for the write up and the observations on the synergy of the two different caps.  Great work! 

John