Guild Quantum head

[brained26]

been trying to find out what a fair price for one is. Anyone got any idea? And what exactly they are good for. A guy contacted me about selling me his but doesn't know what they are worth and neither do I. Not trying to rip him off

[capnjuan]

Hi brained26: I believe this is the Guild Quantum head amp you're referring to:





It is physically / cosmetically similar to other Guild bass heads of the period but distinguishable by the small, rectangular label at the bottom-center of the faceplate. 3X12AX7, 1X7247, 1X6GF7 (screen voltage regulator), 6L6, 8417, or 7591 outs.

They only infrequently show up on eBay; much rarer than the other Thunderbass models which, in average condition / no fresh caps run high $100s to mid $200s. If your Quantum is in similar condition, say, high $200s to middish $300s?

If you are a DIY person, you may already know or have noticed in the pic that all three pre-amp and driver tubes and passives for each stage are mounted on phenolic pc boards. The under-chassis wiring is P-T-P but if trouble-shooting or tweaking, reading plate and other voltages on the pc boards or replacing/upgrading parts is more awkward with this configuration. IIRC, the original multi-section cap is 4X40uf/+/-500vdc; a cap no longer in production; Weber will fab a 3X40uf/450vdc but, if you re-cap, you'll have to find a home for the other section.

Good luck w/ your Quantum. John