I jumped at this Ebay bargain knowing that Gibbs reverbs of this size are about US$50 or more, and then there are the import fees. I expected this old one to sound as nice due to its size.
A few things I want to document for future regarding the input and output sides of different spring reverbs.
I found out with the old Ashdown amp that had a Belton (now Accutronics) shorter, 3 spring type, and the Carlsbro CS60 head that had the nice large Gibbs in it (same length as this one, which turned me on to these things initially when I compared it to the cheaper, shorter ones) that the mini input and output transformers are usually quite close in DC resistance values, so do work even plugged the other way round.
With this vintage Laney tank, the same is true as seen in the DC values – 350 and 355 ohms, below:
However – with this one I found that the output transformer has one wire (blue) connected to the spring floated chamber, and so the chassis, but NOT the input side, which I didn’t notice with the others.
Why, I don’t know because the connections had been ripped off, so the connector may have grounded the input side anyway before the messy removal from its original amp…
In the CS60 schematic I had to repair the ground braid in the phono cable to make it work, as there was corrosion between phono grounds and a ground on one side only which I replaced – remember the Post?
Just something to be aware of if having sound issues – maybe a weak or no reverb signal etc. In most amps – whether a valve or a transistor reverb stage – the return signal AND the send signal would normally share a common ground which may be the tank chassis so dirty or corroded phono grounds there may be the problem with a simple solution, before assuming anything worse.
This Laney tank works as the chassis grounds are good, as I just screwed and soldered phonos to the wires AND the chassis each side, that I salvaged from an old audio unit, so I could plug it into the new TC60 to compare it to the stock tank that came in that:
What would be interesting from a tech view point is how greater spring tension affects the tone – I assume it would shorten delay and favour higher frequencies – losing the nicer, richer larger tank sound.
It would also be harder for the lever to twist the spring so a larger signal input would be required for it to work.
I have already put up some sound files of this played through the TC60, but here they are again anyway, recorded with the BR80 cap mics: