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BillEpstein 29th January 2010 09:35 PM

Simple SE C11/C21 Question
Thinking of rolling some caps. What effect would halving the value to 0.1 have on the sound? I have many more choices of that value.

Further, would already having pretty good (Transcendar) OPTs make the cap rolling futile?

Ty_Bower 30th January 2010 12:14 AM

These are the coupling caps between the driver tube and the finals. Per design, they should offer response down to 0.3 Hz (Fo=10/2piCR). If you change these to a 0.1 uF cap, the corner will move to 0.7 Hz. I suspect the difference is irrelevant.

Within reason, the "quality" of these coupling caps probably matters more than the precise value.

Tubelab_com 30th January 2010 12:44 AM


Within reason, the "quality" of these coupling caps probably matters more than the precise value.
In theory a .1uF will move the point where phase shift begins up near 40 Hz. In practice the quality of the cap plays a bigger role than the value does. I have tried caps from .1 to 1 uF in my Simple SE. All work good for HiFi use. I did notice some rather obvious overload recovery issues with a 1 uF cap when I drove the amp about 10 db past clipping in guitar amp service. The .1uF (or even a .047) works best in a Simple SE based guitar amp.

Some users with better ears than me claim the superior sonics of teflon, or PIO, or beeswax, or even those German caps made with silver and gold that cost way too much. I can hear the difference between a cheap ($.15) mylar cap and an Auricap. I refuse to spend more than $10 for a capacitor, so that I have never tried any of the $pendy stuff. I am not sure that I could tell the difference between an Auricap and the $1.50 caps that I have been using lately, if I didn't know which was which.

rknize 30th January 2010 04:11 AM

When I initially bread-boarded the Simple SE, the only "good" caps I had on hand with high enough voltage rating were some of those Russian PIO caps from eBay. Those caps stayed in the board until final assembly. It was then that I did some "serious" listening and compared it to the TSE. One of the things that seemed to make a marginal improvement in the SSE's performance was replacing those PIO caps with Auricaps. It seemed to improve the detail when running the amp with EL34s.

I have liked Auricaps in every amp I have put them in.

rknize 30th January 2010 04:14 AM


Originally Posted by BillEpstein (
Further, would already having pretty good (Transcendar) OPTs make the cap rolling futile?

To that I would think the opposite is true. At least for me, the more subtle differences between components are masked when there is some other component holding you back. For a long time with me it was the speakers. Now my speakers are so revealing I've had to remove components from my stereo system because they sound awful.

It's funny how one thing leads to another.

BillEpstein 30th January 2010 11:05 AM

So I opened the case and discovered a nice streak of sticky brown goo on the bottom plate right under C12, 1500uF 50 volt. The case looks OK except for a very slight 'dome' to the top and a light coating of the goo.

Geez, 5000 hours at 105C. that shouldn't happen!

In other news, C11 and C21 are already .22 Obbligatos which I will leave alone being my fav caps.

rknize 30th January 2010 03:08 PM

Heh...well replacing that cap ought to improve the sound. :)

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