Help appreciated. Thin sounding V72, with audio example.

[SamuelPepys]

Hi! I bought two pristine looking Siemens v72's from a Deutche Grammophon console with very closesly matched serials, and while one sounds heavenly, the other has absolutely zero bottom end. Does anyone who has worked with these before know what could be causing this thin sound? They were used in a professional studio up until 10 years ago, and after that has been stored in dry conditions and completely unused for a decade.
I'm hoping it's capacitors, tubes or something that can realistically be changed, and not unobtainium transformers or something like that. I've attached a sound file in case someone has heard a similar sound from these and can make an educated guess as to what could be the problem.
Also, the one that has no bottom end also has a weak "on" light compared to the one that works fine, if that makes any difference.

soundcloud.com/michaelcaplin/v72-test

Thanks!

 

[Khron]

"Prehistoric" capacitors have been known to lose capacity after decades, so it's not unreasonable to think that a DC-blocking electrolytic may have degraded that much.

 

[SamuelPepys]

Thank you for the reply. I can hear from the recording that there is techanically full bandwidth-ish, there is just so much loss in the low end compared to the top end, but it for sure doesn't sound like cutting low and mid frequencies completely in an EQ. Again, hoping that it could be the capacitors (although it's weird that one would lose so much compared to zero loss on the other, considering that they were made probably during the same week or so. Would a bad transformer sound anything like this?

 

[JohnRoberts]

+1 old capacitors can lose low bass response.

JR

 

[panman]

Check out, if the input trafo has been bypassed. I have encountered that a few times. That`s done, because the transformer is shot. The filter-caps should be replaced anyway. The decoupling-caps should also be checked, but they usually still work after so many years, but for how long?

 

[mjrippe]

I hate to be "that guy" but I had the same frequency response from a unit with a bad input transformer. Measure the dcr of the windings and compare it to the docs I posted in the Technical Documents section. (Or to the good unit!)