Quad 34 volume

  • No one logged in.

08-Jul-2018 04:37 PM

Willy Van Win

Willy Van Win

Posts: 9

Have the kit installed and is working perfect.

When turning the volume it looks like a bad pot between the clicks. When not turning all is ok... Bad attentuator ?


  Reply

09-Jul-2018 02:37 AM

EJP

EJP

Posts: 1511

What do you mean by 'looks like a bad pot'?
  Reply

09-Jul-2018 09:14 AM

Willy Van Win

Willy Van Win

Posts: 9

When turning on the attentuator, you hear it on the speakers between the clicks. When you stop turning, all is normal.
  Reply

09-Jul-2018 09:33 AM

EJP

EJP

Posts: 1511

You hear what on the speakers? Little clicks? This could be due to hardwiring links instead of C30/31. Replace with 100uF bipolar, any voltage from 6.3V upwards.
  Reply

10-Jul-2018 04:54 PM

The Quadfather

The Quadfather

Posts: 110

I have also experienced the same clicks after DaDa upgrades on 3 Quad 34s. Pressing the input buttons can also create a minor click noise too.

Putting C30 & C31 back in didn’t cure it for me when I last tried. Possibly they need to go after the volume control instead?

These (very) minor clicks do not bother me, but I feel strongly that DaDa should mention this side effect in the upgrade manual. I prefer a few clicks, but a cleaner signal path. But others might prefer being given the option?

- John

  Reply

10-Jul-2018 07:14 PM

Willy Van Win

Willy Van Win

Posts: 9

I even don't bother that much, but when I have to do the modification for somebody else, I think they will be asking me whats wrong after this upgrade...They will possibly think that i have not done my job properly!

 

  Reply

11-Jul-2018 01:49 AM

EJP

EJP

Posts: 1511

There is already a 220nF  capacitor after the volume control, so restoring C30/31 should be sufficient. I haven't experienced these clicks myself.
  Reply

11-Jul-2018 02:43 AM

The Quadfather

The Quadfather

Posts: 110

As I said above, I tried reinstalling C30, 31 and the slight clicks remained. So I assume more of the couplers would need reinstalling if one wished to eliminate this side-effect altgerher - but which caps?...


I live happily with it, but I can see Willy Van Win’s issue. In fact I’ve just gone and installed the Q34 DaDa kit for a friend too, and whilst it sounds great the clicking when turning the volume control, or pressing selector switches is on his unit now too. Hopefully he won’t mind. But it should really be addressed in the Dada upgrade manual.

  Reply

14-Jul-2018 12:07 AM

Ton

Ton

Posts: 30

Just wondering why in the first place we should replace C30/C31 with a link.
 
After readingKeith Snook’s 34 modification the only reason seems to be “less is more”.
 
And reading his warning “…….beware with C30 and C31 bypassed op–amps IC9 and IC10 can have +ve or –ve outputs which if different could affect the sound signature….” I wonder if you should not just leave C30/C31/C48/C54 in place ?

 
  Reply

14-Jul-2018 05:27 AM

EJP

EJP

Posts: 1511

I'm not sure what exactly Keith means here, at least not with modern op-amps like LME49710 which have essentially zero offset voltage. (The page you cited was written 6 years ago.) The general idea was indeed 'less is more' but I have no objection to the circuit as Quad designed it ;-) especially in the cases you mention, which all lead to potentiometers, which should never have any DC across them.

EJP

  Reply

14-Jul-2018 09:02 PM

The Quadfather

The Quadfather

Posts: 110

Perhaps just a little note (whenever the next version is updated) in the upgrade pdf to say it’s up to the user whether to install C30/31 or add bypass wires. Clearest sound for perfectionists add the wire link, for any units that may experience the minor clicking, install C30/31. That way everything is covered in the upgrade manual, everyone’s (hopefully) happy :) 

  Reply

24-Jul-2018 08:10 PM

Nigel

Nigel

Posts: 2

There must be a slight offset voltage on the volume control. The easy option would be to refit C30 and C31 in place of the wire links.

Alternatively, a resistor of (say) 47 KΩ could be wired from either junction of R45 and C32 (and R46 C33) to ground to discharge any slight voltage.

 

  Reply