Audible Illusions Modulus 3A troubles


Just purchased a used Audible Illusions Modulus 3A preamp for my system but only getting very very faint sound when turned all the way up.  Plus the very very faint sound is very fuzzy as well. 

I popped off the top & re-seated the 4 tubes but that was no help.

My 2 amps are both rated at 50k ohms input sensitivity, so this is the right preamp for them at around 1.2k ohms output sensitivity, running a biamp configuration.  AI documentations confirms this.

I've tried each amp on its own, using both output RCAs on the preamp, to no avail.

How to tell what is wrong...looking into the return policy, but at least the shipment was insured.

Any ideas?

Thanks-Kevin

kevinshunt

Tubes in this AI unit may need to be replaced. AI designs push the biasing of these 4x6922 tubes to their limit. So potential lifetime of tubes is much shorter compared to those from preamp circuit designs from other manufacturers such as Audio Research, VTL, etc. You can buy 4 JJ 6299 tubes for $29/each from Amazon. You can get this to work without breaking the bank.

@pwerahera +1 Good suggestion! Buy and try a new set of 6922's before returning the preamp. The joys of tube gear ownership!

The tube filaments are powered continuously even when the power switch is in the off position. Even though the amount of electricity to the filaments is at a lower level, the tubes don’t last as long.
 

I bought a used Audible Illusions L3 linestage. When I replaced the tubes with new ones I was amazed at how much better it sounded. It had much more gain since the setting on the volume knob was at a lower point for the same loudness. Try new tubes before you return it. Good luck.

Agree. If you otherwise are pleased with the condition of the unit, spend some money on a set of tubes instead of return shipping. You probably would have ended up buying tubes in short order anyway.