2006 vintage upgrade?

faudrei wrote: I do not know electronics. Therefore I can not and will not argue any given technical argument.

It is difficult for me to explain without being technical.

Edited by Graham Slee - 24 Jul 2009 at 1:26am

I guess if I were one of my competitors I would be saying "James, you really need one of these!", but you all know me better than that. It is possible that some could say I should be saying things like that and wishing I would, but if your'e getting 90% "up time" with the HD250 - a seemingly difficult headphone to drive, then the 2006 vintage Solo still looks a very viable amp.

In the old days when the BBC was still a British company, BBC Stores AKA Canford Audio had persuaded Sennheiser to bring back the much beloved HD250 because nothing could match its neutrality in balancing the EQ controls for the "best average" radio performance. The result is the HD250 linear II you, I and a few others still use.

After many years of being heavily influenced (and I make out that nobody influences me...) by the 120R series resistor of the DIN and IEC audio matching system was absolute tripe! I had a wise and common sense realisation: with Sennheiser being Deutsche (the D in DIN) there could be some sense in the DIN/IEC audio matching system - after all, it had it right for phono stages.

So there's a clue to where the extra bass was found...

The SRG still features the secondary negative feedback loop that corrects for the comb effect many have found while testing all kinds of headphones - something that the 120R was criticised for emphasizing - but with this secondary negative feedback loop in place, the 120R becomes, dare I say it? Blameless!

So, for SRG (non i or II) owners, is it just a matter of swapping two 33R resistors for two 120R resistors? Well, I did a lot more than that before arriving at such a conclusion, but if the Spirited DIYer wants to give it a try, that single change may do the trick...

Now, the really technical may want to know how I justify such an allegiance with DIN/IEC? The answer can be read above by Mr jamescodway.

But really, it is just transmission line stuff - the stuff that makes it possible for the telephone network to exist - the stuff that makes it possible to send RF up a transmitter pole - the stuff that makes DMX lighting cable runs work, and in actual fact it is also known as maximum power theorem.

What it isn't is someone else's say so.

Nice post to read Graham! For those not technically competent will you be providing them w/ an sketch on which resistors to change? Yes I am technically challenged. ;)