Tubes 101

B limo No all 6550's or KT88's do not carry a specific sonic signature. Example a SED 6550 is very linear sounding where a original Tung Sol 6550 black plate is better in the bass and have a midrange to die for (similar to EL34's but better highs and lows). EAT KT88 is also extremely linear with a lot more detail than a SED 6550. The SED KT88 is a lot 'warmer' sounding than the SED 6550 with the Gold Lion KT88 re-issue somewhere in between. The original Gold Lion KT88 is also somewhat linear but a tad dry sounding. Ei KT90 type 2 is has an excellent mid range huge soundstage with great highs and very good lows.

That being said the topology of your amp also plays a part in the overall sound. The little input and driver/splitters also make a difference. Honestly you need to try them and form your own opinion. If the tubes are new give them at least 50 hrs. Some tubes take up to 300 hrs to settle down.

TUbe #s/model merely identify a set of standard parameters that enable different ones to be used interchangeably. These alone do not assure a certain "sound", only that certain models are more likely to work best in a particular design, case by case.

Probably more often than not, two different models of the same tube #/type will deliver sonic differences. How much and to what extent it matters still depends.

Beautiful! Thank you everyone! Please keep the info coming. I think it will be helpful to many others, now, and in the future.

Thank you XTI, that was very helpful, you too Mapman, thank you!

B_limo - what tubes are in your amp now? What change would you like to hear? Are your current tubes new or pre owned? If used give them 25 hrs before making a judgement. If new they could take 100 - 200 - 350hrs before they settle down which is why I asked what tube are in there now.

I have been switching between some svetlanna 6550's and electro harmonix el88's. I prefer the el88's bass and highs. The svetlanna 6550's can make some vocals sound really nice, and possibly image better, but they make some rock music sound awful.

My input tubes are a mix of g.e. and others with no names... I have the regular input tubes that came with the prima luna but prefer these others.

I'm thinking that some bugle boy input tubes with some golden lion kt88's might be good...

Ultimately, I'd like extension at both ends; sparkling highs, tight bass and good imaging are probably my priorities.