classic pre partner for Quad 405?

Thanks for that - if I've understood correctly then changing the voltage x3 (ie. 0.5 to 1.5V) does indeed give a shift of between 9.5 and 10 dB

the other thing I had come across on the dada site was this passage relating to resistor values for 405 gain reduction:

There are three time constants at work in the input circuit. R3C1, R6C4 and R4C2. The gain is changed by replacing R6, so C4 nust be changed to keep the time constants of the input filter and the opa feedbackloop equal. In this way the frequency respone will be flat. But if the gain is changed, the time constant of the DC feedbackloop must also be changed, otherwise ther will be a mild LF 'hump' in the frequency response. So C2 has a given value, R4 is changed to keep the timeconstant ok.

Joost Plugge
Click to expand...

It's stuff like this that makes me hesitant to simply buy a kit of parts on ebay. Does it also vary from one set of boards to another?
 
The cap does need changing along with the resistors in order to maintain the low high pass filter characteristic.

Same for all boards.

PS: PM sent.
 
realise the quote is slightly odd out of context, the question which prompted it was:

I notice in the new Quad 405 upgrade kit you have changed the cvalue of the resistor R4 to either 6K8 or 15K instead of the 9K1 in earlier versions. What is the significance of this?
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from: dada forum here
 
Been working through various sources over the past week and the drop to 1.5v does seem to have been the right choice.

LDR passive now slotted back in and depending on medium and time of day am generally between 1 & 12 of 24 steps so still plenty of scope to go louder.

Many thanks for your time Rob.
 

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