Quad 34 / Quad FM4 / Quad 306 Volume Adjustment

  • No one logged in.

24-Jul-2018 06:14 PM

Nigel

Nigel

Posts: 2

What is the correct and recognised method of attenuating the output from the Quad 34 / Quad FM4 / Quad 306 combination when using the FM4 on the Radio input?

My problem is that with resistors R135 and R136 removed, output from the Quad 34 / 306 is just about perfect when using a Logitech Bluetooth adaptor from my iPod, or a CD player. However, if I use the FM4 with the Q34 set on the Radio input the volume is far too loud even on the lowest setting. 

I therefore need to reduce the output from the FM4 OR reduce sensitivity of the Radio input on the Q34.

Reducing overall output from the Q34 or reducing input sensitivity of the Q306 will affect CD output, which I don't want.

Having studied the FM4 circuit diagram I am thinking about replacing the 4.7 K resistors R54 and R57 with 15 KΩ or even 22 KΩ resistors to reduce output by about 9 - 12 Decibels, but I am concerned that this would affect the de-emphasis circuit. 

Unfortunately there seems no easy way of reducing the input sensitivity of the Q34 Radio input as it feeds almost directly into the signal busses without any amplification.

I could use some attenuated Phono leads but that option seems a bit naff to me.

My Quad 34, Quad FM4 and Quad 306 are all 'late' models in grey with Phono sockets. I am currently using a pair of Celestion DL8 II loudspeakers which are fairly sensitive, but my Quad 12 L's are just as sensitive so this isn't a loudspeaker problem.

 

  Reply

27-Jul-2018 01:40 AM

EJP

EJP

Posts: 1537

The solution is to restore R135/6. They are there to match the CD input to the Radio input by attenuation. The 34 is designed around the Radio input level of 100mV, which is exactly what the FM4 produces. If all that produces inconvenient volume control settings (it doesn't on mine) then maybe someone has fiddled with the output level resistors R118/120 (2k2) and R119/121 (1k).

EJP

  Reply