Author Topic: Tiny Trouble (Read 6159 times)

maverickf1jockey · « **Reply #15 on:** March 11, 2008, 03:53:25 PM »

Quote from: PhilKing

Quote from: maverickf1jockey
Because the JJ in V1 sounded the same as the busted original but was working perfectly well.
Also they only do one type of 12AX7 (the ECC83 S), which is not a high gain valve and is more useful in a HIFI application.

JJ make the ECC803S which is their high gain 12AX7

RS do not stock that one, I think. As far as I have read the '803Ss are purely reduced in noise and are still more at home in a HIFI.

ailean · « **Reply #16 on:** March 11, 2008, 07:31:33 PM »

I have heard from several sources that the TT does not require biasing, it's self biasing.

My TT came with all JJ tubes (power and pre-amp). I put a Phillips JAN spec in the V1 position to brighten it up some as JJ's are a dark tube.

What worries me about your amp is that it's sounding worse than before your valve blew. I think the JJ's are darker than the Orange branded tubes, so I would expect the sound to be darker, but not muddier.

Do you know anyone with a spare you can borrow to try? It's not unheard of for new tubes to be faulty.

maverickf1jockey · « **Reply #17 on:** March 11, 2008, 09:38:43 PM »

I've found an ebay seller whom I think is respectable and they do EH valves. They sound like the sort of thing I'd be after and because the stock Chinese valves are not branded I can't gauge whether they have reliability issues.
A total revalve with EHs may well be in order...

They also had a tung sol and a couple of MESA branded valves but the MESAs, I would expect, are not as great as a third party brand and would be quite dark.

But the first order of business is, indeed, to work out why the sudden change in tone and why the lack of improvement. I was hoping someone such as HTH would pop up and give me a hand...

martinw · « **Reply #18 on:** March 12, 2008, 07:48:15 AM »

The TT is cathode biased and does not need any biasing to replace any valve.
The JJ ECC83S is a standard ECC83/12AX7, and actually tests as one of the highest gain current production valves, so it should be fine. We use hundreds of them at Matamp, with no problems.
I've personally used plenty of EH too, so they should be fine. The differences between brands of valves can be said to be subtle tonal changes, not great/cr@p so I don't think that will be your problem.
The Original Chinese valves can almost certainly be improved upon.

If changing the valves (any and all of them, pre and power amp) doesn't restore the sound quality back to what it was, then you have some other problem. If you're confident enough, you can visually check the innards to see if there's an obvious visible fault, remebering of course all the usual warnings about capacitors storing charge after the amp has been turned off.
Beyond this you will need to take the amp to a tech. If you were anywhere near me (North Derbyshire) I'd have a look FOC. :?
Good luck.

maverickf1jockey · « **Reply #19 on:** March 12, 2008, 04:30:02 PM »

Cheers. I might just get a replacement from the same shop I bought it at as it should still be returnable I believe. The only thing I did to it bar changing that valve was to replace all the screws with torx heads so if I change those back I can get a new one and re-valve that...