The mysteries of the Cairn Boost phono stage and adjustable capacitance


Does anyone have a manual for this lovely phono stage?

Everything seems quite straight forward apart from the (DIN?) switches at the bottom which adjusts the capacitance and is a bit confusing to my simple mind.

There are various MM settings suitable for my Goldring E3 cart which has a load capacitance of 100 - 200pf (according to the website). The phono stage offers either 100 or 147pf in that range and then many more both higher or lower.

Which of these settings do you think is better and if I was to go for a higher / lower capacitance on the phone stage, what would the effects (sonically or otherwise)be?

Hope you can help?
Thanks (again)! So what I don't get is that there are 2 sets of Din switches and the grid says '2'.

Does that mean I have to put both switches to 2? Is one for each channel or something else (and why would you need to be able to have each channel set differently anyway?!)

Nice one.


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Joined 2011
Yes, there's one column of switches per channel.
So try switching on either 47pF (1) or 100pF (2) in each channel,
using whichever setting you prefer the sound of.

Unless you have a capacitance meter to measure the turntable leads,
just adjust by listening preference.

These small switches are only made as SPST types, which can only make or break one contact.
So you need one switch per channel.

Back again! I can't seem to ground my turntable to the cairn without attaching the GND to one of the phono inputs. It massively reduces the hum but it doesn't entirely get rid of it (hum is only audible when there's no music and I turn it up a bit but it's still there in the background).

Any idea why the original GND isn't working? I've opened it up and the connection from the terminal to the board is fine.

Could it be that there is no earth wire on the kettle lead I'm using? It's not the original one as I bought it second hand and the lead is moulded so I can't check without cutting the wire.

Also is there any danger of damage to anything by connecting to the phono?

If I connect it to the GND on my old tuner it's similar to attaching it to the phono, perhaps a tiny bit less hum...could it be an issue with the deck itself?

Thanks in advance.