SOLOS II need more bottom end oomph, electronics ideas?

[quickbird]

So I finally got my old Peavey Renown 112 back from the factory repair and set it up against the SOLOS II and ran my guitar processor left-right channels to each respectively.
The Peavey was kicking the Sunn's ass with one speaker at the bottom end. 
Input to the second normal channel and the bass all the way up, I had to back the Peavey to 7 from 10 to equalize the bass output. and that was one speaker against two.

What region of the amp should I pay attention to if I want to boost the bass, pre or post?
Capacitor age a problem or is there just a dynamic range difference in the designs that I will never get the full bottom end from the Sunn?

Thanks in advance.
rm

[loudthud]

First you need to verify that the speakers in the Sunn aren't the problem. Try comparing the amps one at a time into another speaker or into each other's speakers.

[quickbird]

Impedance matching problem there.  1 each 4 ohm speaker Peavey 2 parallel 16 ohm speakers on Sunn.
But I think I have another solution by using some old Fisher speakers.  I expected the two HH speakers to have more umph but I realize that is not a good assumption.
Actually I think I can take the pre out of one and put into post in the other and vice versa. 
More fun.

I did notice that the other standard input channel on the Solos does give off more bass than the effects side. That channel only offers tone control where the second channel supports the reverb, trem, and distortion effects.

Found a possible mod that changes the .22 mfd cap on the bass control to .47 mfd to open up more bottom end.  May experiment with that once I eliminate speaker affects.
thanks
r

[quickbird]

So using the Peavey pre-out to drive the Sunn pwr amp-in, the Sunn cabinet is capable of some serious low end output with the twin HH 12"ers.

Two things I found. 
When plugged into the Sunn I found that if I roll off the treble and midrange the bass suffers.
I usually play with the bass 10, mid 5, treble 5.  This really kills the bass response.
I presume this is part of the way the tone is managed in a cascading fashion.

The other was that the shear output of both amps running flat out will strip the paint off the walls.
 

I ran all of this clean into the amps so that no effects were included in the equation. 

[loudthud]

Here's a thread where I posted the schematic and layouts:

http://sunn.ampage.org/sdp/index.php/topic,4781.0.html

Because you reported that the normal channel seemed to have more bass, we'll make the assumption that there is something wrong with the effects channel. Any electrolytic caps in the signal path could have drifted in value so they are suspect. You could simply solder a new cap in parallel with the existing cap to see if you can find one that is restricting the bass or just replace them all.

There is a 1.6uF 25V cap, C339 that works in conjunction with the Distort switch. Increasing the value might make the distortion too woofy. Experiment with the value. If the reverb gets too much bass, we can fix that later.