Tubes for an Avalon Pre

[Cheech]

Fellas, i am having a bit of an issue lately. I ran my U87 through the Avalon (737 VT not sure exactly what the full model name is)
Its the channel strip with the compressor and EQ.

Anyway, running my u87 through it is sounding fairly ratty, and thin lately. I bought the Avalon used, and I am not sure how old it is, but my question is this:

Would the tube cause that?

How often should that tube be replaced?

Which tubes would be best to replace it with?

Any help would be great.

[waterboy]

Dood!

Totally forgot to check into this!

Sorry 'bout that.

[Cheech]

NO problem bro....im gonna check some more into it today.
I just thought that there may be some peeps here, that may have changes the tube in this pre, and learnt some things, that they could skool me on.:grin:

[MichaelK]

I replaced my tubes last year after 8 years. They hadn't gone microphonic but the noise level had increased.

Avalon told me to use 6922 only, did not recommend using ECC88 or E88CC. They were selling sets for $80, EH specially selected for low noise. The old tubes were Sovtek.

I called Mike at KCA and he said that new ECC88s could be a problem, but NOS would not. I bought some NOS Teslas from him, specified low noise and they work great.

[Cheech]

Im not having a noise problem as much as the whole thing just sounds really thin, and harsh.
Does that sound like it could be a tube issue?

[Cheech]

Also... I know this sounds dumb, but I have never cracked the top of my pre open..... How many tubes does it require?

I just ran across your note you left for Mike over at KCA.
So is this the ones you bought > "NOS Tesla E88CC (NOT JJ!)" ?