I am looking for advice on buying a second-hand TLM103 on ebay. Is there ever any appreciable deterioration in sound quality compared to new? And what are the key things to look for when buying through ebay? I'm a bit hesitant, as the only experience I have of ebay was my girlfriend getting stung selling a set of PA bass bins. But, there's a couple of great deals right now on ebay, and I've read a lot of the recent (discussions about mics, TLM102s and U87s) and older (e.g., poster asking about the NT1a Joly mod) threads, in which there have been some very happy second-hand mic buyers.

I've had good and not-so-good experiences of buying mics (including TLM103s) on eBay. I'd say there is normally no deterioration of quality on these mics over time, but it is always worth asking a few pertinent questions to help avoid a nasty and costly mistake.

Try to ascertain that the person selling it knows that it is a thing of delicacy and has looked after it carefully. Ask about the box it comes in (TLM103s came in wooden padded boxes as new, really this is what it should have been kept in for its whole life, and should be sold in it).

Ask if there are any bumps or scraches on the mic's body or grille - this should give you an indication if it's ever been dropped or been knocked over on its mic stand.

Ask if it's in full as-new working order, if this isn't explicitly stated in the eBay ad.

Ask if it has been kept and used in a smoke-free environment - cigarette smoke deposits can seriously affect the capsule surface as well as the foam in the pop-shield, although the foam can be washed. Cleaning the capsule is a specialised task that I wouldn't recommend trying yourself, so this could rule out the purchase unless it's very cheap and you'd consider getting the mic professionally serviced.

Check if it comes with the suspension shock-mount, or just the clip. The price should be a lot lower if it's just the clip.

If possible, see if you can try out the mic before committing to buy, which would probably have to be at the seller's house, unless you confirm that you can take it back after purchase if there's anything amiss. Of course you can always do that if the item has been in any way mis-sold on eBay.

There were two models of TLM103, and I'm not sure when they switched over, somewhere between serial numbers 10,000 and 50,000. The newer models seem to have a slightly different design of circuit board & capsule mounting, and include two tiny internal switches for -10dB and a hi-pass filter. These aren't officially supported modifications, and aren't externally accessible, which is all a bit bizarre!

I've used an old model as a stereo pair with the newer model with fine results, so it may make no significant difference anyway!

Hope all that's of some help!

Billum,
That's awesome. Thanks so much for this great response and advice. Yes, I'd read about the two versions, so I need to check this as well. I think I might tread carefully before buying sight-unseen.
Thanks again.
TIM