New tubes for SFL-1 / SFS40

You won't be able to "ruin" the sound of SF amps just with changing tubes! You have to change complete design, and that means to find some other brand of amp that suit your taste. Try older CJ?

Try Mullard or Philips Mini Watt 6922's for a "tuby" sound (these are the ones). Too many fake and/or legally rebranded Amperex's out there (the namesake was sold) if you do not know how to ID them. Also (unless your'e feeling lucky) avoid Mullards/Philips being sold by a dealer in Hong Kong on Ebay (his seller ID contains the name of a brass instrument). Per feedback on the web some of the stock is authentic and some is not (much written on the subject).

If your amp uses 6550 or KT88 output tubes, then I agree with ElDragon in that you might be better off with a different design (given your stated goals), but a few 6922's in key positions are also worth a try, IMO, and should not cost that much. First find out what positions are more crucial to changing the tone of the preamp (perhaps just two new tubes will do the trick instead of changing all of the 6922's).

If you can sit tight for a while reviews of the new EI Elite 6dj8 tubes (a type of 6922) should start showing up @ audioasylum.com. I don't know what vintage tube/brand they copied in the design, but their current EL84 tube is a very good copy of the vintage Amperex version ($40 a matched quad Vs $300-$400 for the real thing from a NOS tube dealer:-).

Thank you for all your responses.
To clarify, I have SFL-1, not Line 1.

Dekay, do you know where I can purchase EI Elite 6dj8?
I am thinking of trying them out.

Many of you suggested that I change my system. I think you are right but before I do that, I like to try some new tubes. I am purchasing a ZERO Autoformer for my system...I am hoping that will make my system sound more "warmth".

Thanks again.

-Sean

Hi Sean:

This is the only source that I have, though there should be others.

http://www.tube-shop.com/index.asp

Prices are in BPS, so maybe 1.5/$US (haven't checked lately). Includes VAT and shipping is cheap.

I will probably try them eventually along with the 12ax7/12at7's.

Looked it up and now understand the 6DJ8s are for the amp, not the pre. My mistake.

A synopsis of the characteristics of a variety of 6DJ8 tubes is located on the Audio Asylum at http://www.audioasylum.com/audio/scripts/d.pl?audio/faq/joes-tubes.html#6DJ8. Maybe that will help narrow down what tube will do the trick.