pre-CF4 ccs circuit change over switching

[colin.hepburn]

Hi all
This post is more directed to Richard and or Dr john as the schematic will be required to answering this one

On the pre-CF4 ccs circuit is there a way to switch both LK1 And LK2 VER A Switch instead of having to reconnect the wire links in a different order to put the ccs in or out of circuit?
Looking for a toggle switch that’s capable of switching both LK1 And LK2 together just by adding a single toggle type switch on the back panel of my old pre-2 CF case. Something like a 4PDT if there is such a thing in switch land any ideas on this
Thanks’
Colin

[bob orbell]

Sorry to butt in Colin, but, I think the CCS would be the best bet, otherwise it will be just like your CF you had from me, I doubt you will hear the difference, but it will be measurable and I think the output resistance will be a bit lower. Bob

[Richard]

Hi Col and Bob,

Bob, anyone, always feel free to join in.

Here's a good site with drawings etc for switches,

https://www.watelectronics.com/types...-applications/

About 2/3 way down is the DPDT drawing which should do what Col asks.

The 2 sections of the DPDT switch are separate circuits and both actuators move together (Double Pole Double Throw).

I've attached it with LK1 and LK2 numbering and shown it in CCS "OFF" position.

I haven't checked re voltages and other switch specs for a suitable one. The site shows a rocker but you will be able to get toggles and rotaries. John may well have done this already or have a reason why not to do it other than switch off before changing over.

[colin.hepburn]

Hi Bob/Richard/all
Bob your input is appreciated as always and Richard thanks for the link and graphic

Sorry wasn’t trying to cut members out of his thread I was just trying to figure out how to ask my question relating to LK1/LK2 of the ccs without showing the schematics which I knew Richard and john have unless you already have the CF4 kit of course.

Bob my thinking behind the switch was the idea of a simpler way to reconfigure it if I use long leads it may sound better with the ccs switched in regardless anyway

The following in red Pasted from the WD Adds

The Pre4 CF can be configured by the user to use a cathode load resistor or a Constant
Current Sink (CCS). The CCS provides an improvement in technical performance when driving long leads between the pre and power
Amplifiers

colin

[Richard]

Just thinking, a rotary with a small knob might be neater and less likely to get switched on by accident.

You may have a Lorlin 2 pole 6 way in the spares box already - the one most WAD kits used for input selector (fit the range stop in hole 2 on the front).

It shouldn't matter whether it's a shorting MBB type (usual for a selector) if you power down first. Otherwise the non-shorting BBM version is cheap enough.

Drawing attached.

[John Caswell]

Hi Colin et al,
Just picked up on this, I have both a 4 pole CO toggle switch and also a 4 pole 3 Way rotary switch which I have just re-configured to 4 pole 2 way CO switch by moving the stop pin.
I have your address Colin so will stick them in a Jiffy bag in the post to you Monday.
You can then choose which type you want to use configure the changeover. No need to return the surplus switch

John

[colin.hepburn]

Hi Richard /john/all
Thanks for the suggestion Richard and john for sending me the switches
Will have to put an order into RS or somewhere I thought I had some MJE340 or their Equivalent nope sod's law I do have a shed load of the BC549s though
just a thought Is it necessary for the transistors to be matched
colin

[John Caswell]

Hi Colin,
Don't bother with RS I have just sorted a pair of MJE340 for you as well.

John

[colin.hepburn]

Originally Posted by John Caswell

Hi Colin,
Don't bother with RS I have just sorted a pair of MJE340 for you as well.

John

Brilliant john thank you
colin

[Richard]

A 4 Pole switch
Sorry guys, I was just reading the circuit and not thinking we needed 2 channels
Found the Lorlin data sheet and have re-done the drawing attached. Colin is fixed up but it may help someone having got this far. RS keep them for a few pounds.

So... has anyone here compared CCS to cathode resistor on this Pre3/4CF and what switching if any did you use or was it connected on tags/pins? Was the sound difference noticeable?

What's the consensus on shorting vs non shorting switches - would either allow hot switching to compare or is it always safer to power off first etc?