Quad "Pull Deep" on chan 2

[dax2112rush]

Hello,

I bought a Mesa Quad a couple of years ago used off ebay and never was satisfied with it's sound. I felt something was wrong with it but I never heard it new so I was not sure. I was quite busy, and I could afford some time tinkering with my quad lately. I noticed the lead master control was affecting the Rythm 1 channel. I then proceeded to replace all LDR in the preamp (19). Now the Lead 1 and Rythm 1 feel better, but I still have an issue with the Pull Deep switch on channel 2. It really seems connected to nothing. I can't hear any difference in sound.

I tried looking at the schematics from www.tubefreak.com and I can't find the "Pull Deep" switch on the schematics. Where is it$ Are there any alternative schematics$ Should it make a noticeable difference in sound (I hope so)$ Any ideal what might be the problem$.

Also, my friend has a Mark IV and in my Quad's current state, he really seems to think my Quad doesn't sound great. Is there any online sound clip with associated settings I could compare my Quad with$

Thanks
Ric

PS: Keyboard is defective so I replaced all question mark by $

 

[stephen sawall]

Welcome to the forum.
Sorry no help.

 

[daveyboogie]

Welcome to the forum...

I'll check my Quad this weekend to see if I get a similar issue: I don't use L2 too much on my Quad but I'm sure the Pull Deep responds to R2, although it may be subtle.

Incidentally; how much were your LDRs and where did you get them$
I payed 9euros each for the last lot I changed but I could do with some more.

 

[dax2112rush]

Bought them Allied Electronics (www.alliedelec.com).I payed a lot less than 9 euros each:

VTL5C1 EA $5.30 USD
VTL5C4 EA $6.15 USD

And I am almost certain that I tried the pull deep switch on both L2 and R2. I'll double-check to make sure
thanks!

 

[daveyboogie]

thanks for the info on the opto-switches!

Not sure how to help with the 'Pull Deep' thing... I had a good play around with my Quad this weekend and there is a noticable (although subtle) difference when I engage the pull deep on R2 and L2. It basically adds a little more bottom end: just a little more thump when palm-muting on L2 or slightly deeper hum on R2. Not huge, though. More noticable with low bass eq settings and lower treble settings. That's when playing through a 4X12.

The Quad instructions say that the Pull Deep circuit is located between the Preamp and effects return section of the Quad although I couldn't find it on the schematic either. It may be located something like in the MkIIC+ circuit? I'll have a lookthe next time I'm changing some more LDRs.

 

[dax2112rush]

Thanks for the infos.

As far as me and my roommate can tell, there is no difference at all. I'll try with a low bass and treb;e settings and palm mutes to make sure. And if I can figure how to make a cheap reamp box I'll post soundclips (anybody has schematics for simple reamp boxes?).

You had a great idea to check other schematics, the pull deep switch is clearly identified on Mark III preamp schematics! I should have thought about that!

Thanks a lot!
Ric

 

[dax2112rush]

I found the answer to my problem on another older thread. It turns out that the "Pull deep" were on the last preamp stage on both MKIIC and MKIII. To share the same reverb and effect send/return circuit, I suppose, on the Quad it is located next to V22 in circuit (the 2 triodes after the effect returns). So instead of affecting Channel 1 and Channel 2, it will affect Output A and Output B respectively. As I was wired in mono with Output A only, only the upper "Deep switch" did something.

I now need to figure out why my reverb doesn't work at all (I don't even get some noise when I hit the tank.)

Thanks for your help!