Which tubes to roll

On every tube amp I've ever had the input tubes made more difference in tone than the power tubes.

If that amp is tube rectified you can also roll that for different presentation. A rectifier thats higher voltage will bias the amp towards a more agressive sound, lower voltage more relaxed.

You can run 6550C's, 6L6, or EL34 as power tubes instead of KT88's in that amp.

After you change tubes you should let them warm up, and reset the bias(140ma) as per the manual. When I swap tubes I first set the bias low with the old tubes, swap tubes, then once warm bring the bias up to spec. The eliminates the chance of being over bias on different type tubes.

John C.

For whatever power tubes you decide on: Upscale Audio's quality and customer service are hard to beat. Check out Kevin's procedures and offerings: (http://www.upscaleaudio.com/view_category.asp?cat=85) Both power and driver tubes have a major impact on your presentation. Try some NOS 6SN7GT/VT-231 (Sylvania or Ken-Rad)bottom getters from the 40's for a real treat: (http://shop.ebay.com/?_from=R40&_trksid=m38&_nkw=vt-231&_sacat=See-All-Categories) Neither are expensive right now, and both provide an expansive sound stage, excellent imaging, accurate timbre and frequency response. Here are some comments on what to expect with some of the different brands available: (http://home.att.net/~chimeraone/6sn7sound.html) I've purchased quite a few tubes on the "Bay" over the past few years, and only had one bad experience.

I agree with Rodman, Kevin is a very knowledgable guy and stands behind whatever he sells. He also has the SED KT88's that you mentioned and for the same price.

Tube rolling priorities -

Power tubes make the bigger difference which can be good if you are looking for major tonal changes.

Small tubes are more for fine tuning than major changes BUT, proper selection can make or break the sound of the power tube.

So there is not easy answer - as with everything else its about synergy, including synergy with your speakers and other electronics.

SED KT88's have a very different sound than a lot of KT88's in that they have a warm upper bass and extended highs. They are not a sonically linear tube. Whether you like them or not depends on your amp, which I have never heard. FWIW, I use them in two amps (a Cayin and Primaluna) and they sound fine, but in a Cary CAD50M they are far too warm/dark on the bottom and a bit peaky in the upper mids/highs. I use SED 6550's in this amp.

So I agree with Rodman 5 9's, call Keven Deal - he sells both Cary products and SED's, he will be able help you match the tubes to you sonic preference and can even help you, if you need it later, select the 6sn7's to match the power tubes AND your tastes.

Good luck........

Thanks. I noticed in the manual it says that the following tubes can be substituted for the KT88s: 6L6, 6CA7, KT-66, 6550C, KT-90, KT-99 or EL-34.

Just reading another thread and the poster likes the Mullard EL-34s much better than the KT88s. I notice the 34s are less expensive. What, in general, is the difference between tubes that can be substituted for each other?