Quad Mod - please help me to solve the mystery!

[Wolfster]

Hi Guys,

I'm a new member, and a (proud) new owner of a Quad. I gave it to my tech pretty much instantly to give it a once over, and as well as discovering a couple of faults, he noticed that some modifications had been made to channel one. He said that it would lower the gain by a large amount, and that it might also have other effects on the tone. I'd very much appreciate any help in working out what the point in this mod is, and also how to put it right. Thanks a lot in advance ! Here are his brief comments about has been modfied:

'2nd stage, valve V21B: pin 8, 'C231' removed; 4.7kohm cathode resistor
fitted.

Lead Drive potentiometer: 100kohm resistor added in parallel to input.'

Here are some photos he took of the affect areas:

Thanks in advance,

Nik

 

[Wolfster]

Anyone?

 

[ando]

Well, since you are getting no replies...

Unfortunately I know nothing about the Quad, but my question to you is, Why does it matter what the mod is for? Your tech knows enough to recognize that mods have been made, so he should know enough to restore the unit to its original schematic. Then if you want any mods done in future, at least you'll know what you are changing and why.

 

[Wolfster]

Thanks for the reply.

thats a good point and one which I am leaning towards. My tech guy said the mods seems to basically reduce the gain quite considerably, and I am curious to know why some one would do such a thing if they could just turn down the drive. This is why Im looking for more info about the mod; in case anyone else has had an experience of it, and if anyone knows exactly what it does - the person may have done the mod to improve the tone.