Cathode Follower

[bikerhifinut]

My sixpence worth...…….

Using a CF or transformer output preamplifier circuit, (Or for that matter a simple op amp buffer or emitter follower in silicon) will give you a nice low output resistance which more or less means cable capacitance hasn't got the effect, if any, that it would if connecting things up off the wiper of a pot or switch in a passive volume control ( you can't really call it a preamplifier to my mind).
So That's one concern out of the way.
I'm 100% with Bob on the relative merits of expensive connecting wires. And Bob and I don't see eye to eye on everything but here we do.
For a while in the old listening room I was using a 10m length of cable from preamp to power amps due to the layout I was using. I first had some fairly basic single core screened cable (it claimed to be OFC copper but who knows). That seemed perfectly satisfactory to me and I couldn't detect much if any difference to my usual 1.5m of the silver plated soniqs branded stuff from Matthew. Incidentally if making your own wires up that's a good value product and looks quite sexy...…….
Then I tried some bandridge "professional" microphone cable. It was cheap from maplins at the time in one of their regular stock clearances, wish I'd bought the drum of it when they closed down for a tenner! Again it was excellent, I wired it up "semi balanced" i.e the screen only earthed at one end and the inner wires completing the circuit. I had a Hum loop issue at the time, I never really got to the bottom of it and since then I have moved to a new listening space and also rebuilt the power amp, reverting to a stereo rather than the 2 monoblocs. And also the WD KT88 amp now is set up as an integrated with the relay board and a home fitted Hi Fi Collective remote volume control.
Anyway I found the "Cooking" pro grade mic cable to be every bit as good as any fancy stuff I have odd examples of.
As Greg says...…… your mileage may vary.

I also have the Aikido CF board in a pre3 case. It's about as good as any CF gets, again I think you'll find very little to choose between that, the current WD CF kit which will be excellent value as a kit of parts, and a standard "Bootstrapped" CF circuit.
Confession time now...….. my preferred preamp these days is a solid state Rega Cursa3 which I really like, its very neutral and has the advantage for me of having an easily adjusted gain setting in 3 steps from unity to enough to drive a pair of quad11s that need 1.4 Volts on them.

here's a good explanation and practical example of a Bootstrapped CF
http://www.valvewizard.co.uk/accf.html

Andy

[emollusc]

Originally Posted by John Caswell

Hi Brian,
Last question first - You would require all the bits for a Pre3 CF plus a PSU of some sort and the necessary interconnecting cables.
Advantages - A relatively low impedance output enabling you to use longer leads, simplicity itself. Can keep existing Vol control/input selector
Disadvantages - loss of gain -0.9dB, Large capacitor to isolate output DC, power supply and all attendant bits, cables etc.
As to how it would sound, I will pass on that, suffice to say I work on the Dr Lanchester principle "if it sounds right it is right" He quoted the maxim "If it looks right it is right" which applied to aeronautics
I know that this is going to create howls of protest here, but the only real criteria are your ears, equipment and listening room, and even music. I have had people say "I don't like the sound" when they really didn't like the music being played

John

Hi John,

completely agree with regards to the sound... Like a lot of people I'm always open to improving the sound, but understand that a lot of changes are a bit of a punt as you don't know if you like the change until you've spent the cash.

As I see it all I'll need is the electronics + power cable as I already have a PSU2, and a passive pre2 case with connections etc. Not sure, but I might even have a spare power cord kicking around.

Loss of gain should not be a problem as I'm currently at around about 1/4 turn from minimum volume.


Brian