quad overall volume on channel 2

[FF5]

since i've got my quad, i've had a minor problem with the volume on channel 2. it really doesn't bother me right now because i can level the volume on all the 4 modes, but i'm hoping to having it fixed sometime soon. the best way to describe the issue is that i have the masters on channel 1 at 2.5 and lead 5, but on channel 2 they're both at 10. the only problem that creates me this is that i have the quad connected in the line input of my pc, so i can record whenever i feel i want to with just the push of a button, but it sends a low signal to the pc, which forces me to raise the line level (even with the outputs of the quad at 10) and the recorded piece ends with a considerable amount of noise because every output and input level is at it's peak.

oh, boogie support is at the moment not an option because i'm not in the states, so shipping is somewhat expensive and i can't afford not to have my quad over 2 weeks.

edit: forgot to add, it's not tube related. i've changed suspicious tubes and remains the same.

5

 

[Blueracer]

Hi,

Like most of these problems this is a bit of a guessing game with incomplete information at best but here it goes. One thing to check is if your channel 2 front panel LED's are working. If they are either off or only dimley lit when you are in channel 2 it could be a switching issue. One thing you can try is to use a foot switch, like you would use for reverb control, to activate either of the channel 2 modes from the 1/4" jack inputs, which are labeled external/midi or something similar, on the back. If this increases the volume for either mode then it would indicate a switching issue. If this works at least you have a temporary work around until you locate the problem. Hope this is both clear and helpful. BTW I would try this even if the LED's are fully lit. I will check back and see if this either helped or not and see where to go from there. Good luck.

Gary

 

[maeshuggah]

Hi,

I recommend you have the filter caps replaced inside the quad. worked wonders for mine. for some reason quad's usually have issues with channel 2. But the installing new filter caps fixes the problem for me.

 

[4nkam]

That's how ch2 is so don't worry too much

mJ

 

[LUCRETIA]

Hi,

I recommend you have the filter caps replaced inside the quad. worked wonders for mine. for some reason quad's usually have issues with channel 2. But the installing new filter caps fixes the problem for me.

filter caps? the big blue one?

 

[maeshuggah]

There are 6 large filter caps in side the quad.

When I fixed mine I changed 8 of them.

 

[LUCRETIA]

i saw 6 large caps.Wheres the other 2 caps?

 

[maeshuggah]

the other 2 are small orange sprauge. 220uf 100v. they are perpendicular to the front of the quad. on the right hand side next to the "on" & standby switches. I replaced these with 220uf 350v untill I get the smaller ones.

Changing all these caps really improved my quad. the Main outs are not nearly are as harsh and the eq sounded generally better, plus no more ghost notes on certain octaves and chords.

Mine is an 1989' model with the fu-2 footswitch.


all of the four 33uf 500v Sprauge old caps I replaced with 47uf 500v caps.


If anyone cares I got my caps from here.

http://www.torresengineering.com/tubampar.html

 

[AdmiralB]

I realize this is an ancient topic, but I had the same problem with my Quad and dug this thread up in my research.

It's a design problem, the result of what I bet is a typo on the schematic. If you look at the main circuit diagram, the LDRs that feed the channel masters receive signal from the plates of V12A (channel 2) and V12B (channel 2). The blocking capacitor in both cases is .047uF; in the case of channel one, there is a ground reference resistor of 100K and a resistor in series with the channel master of 22K.

In channel two, there is no ground reference resistor, and the series resistor is 220K. This resistor forms a voltage divider with the master volume, and the net result is that at full volume channel 2 drops ten times the signal voltage here, compared to channel 1. It doesn't sound that severe because channel 2 has more gain available overall.

I'm certain that this resistor was supposed to be 22K also. I replaced the resistor in mine and the volumes are very similar now. R2 is a little bit louder than R1 at most given settings, and L2 is a little less loud than L1 - both the result of the overall higher gain in channel 2.

 

[Blueracer]

Good catch and I think you are absolutely right.