Tubes 101

I'm very new to tubes. Is there a sonic signature to different tubes? For instance, do Kt-88's have more highs and bass? Do 6550's have better midrange?

It seems like KT-88's, 6550's, EL-34's are the most common, or at least those are the ones that I keep seeing pop up.

I can use KT-88, 6550, KT-90, EL-34, 6L6GC, 7581A, KT66...

In terms of sound, I want it all, and why save $100-$200 on tubes when I'm already this deep in the rabbit hole?

To further complicate things, which brands are better? I'm thinking a matched quad set of Cyro'ed Gold Lion Kt-88's might look pretty sitting in my PrimaLuna Prologue 5....
Congrats on the new Primaluna. Look at the Tube Store plus Brent Jesse provides very good info on tube types, country of origin, and how they sound.
Brent lists of all the brands and their sonic signature. ie: Telefunken...detailed, Mullard...warm, etc.

Upscale is very good for recommendations, also the Agon Archives.
Google Joe's Tube Lore and you'll get enough detail to make your head explode!!! Welcome to the "tube side". It's where the music lives.!
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.
B limo
I have SED 6550 and KT88's. Not sure how close the Svetlana sounds compared to SED. But from what you are describing I would suggest Ei KT90's (type 2 or 3). Besides great extension at both ends it has great mids too not to mention a huge soundstage. They are a little pricey but nothing like original vintage 6550's or KT88's. I also have no experience with EH but a local tube seller prefers the Ei KT90 over the Eh KT90 by a long shot. Finding Ei KT90's can be a little difficult since production was halted in the early 90's. Ending in a few hrs - no affiliation
Ei KT90 Type II is wonderful. However, I advise you to avoid Type III which is unreliable junk that may destroy your amp, start a house fire, etc.
Jburidan - Per Jim McShane (one of two local tube sellers) the type 3 is a wonderful tube as long as you didn't get the last from the factory. The last ones had mis-aligned heaters which caused the anodes to get cherry red (typically in a few hrs) before arcing over resulting in premature failures. Probably not many left. I have 2 quads of type3 and 3 quads of type2. Except for the type3's being slightly lighter (thinner glass) and the lack of spot welds on the anodes they sound the same to me.

So I do agree there may be a handful of bad type3's still out there there are a lot more good ones left. The type1's were the worst by far.
Thank you! I will research them today, as I am snowed in and listening to some music.

Any oppinions on input tubes?

Btw, I'm still absolutely loving this switch. It has resparked my interest in audio equipment, but more importantly, my interest in music. The combination of this amp and my current speakers that use seas excel drivers has been enlightening. What a revelation when the music starts to make more sense because of the nuances, timing and dynamic swings that are present now.
B_limo don't get too ahead of yourself swapping tubes. For any advice to be meaningful you need to know what you want to change the sound to with your current tubes. Looks like the PL5 comes with Gold Lion KT88's for outputs. But what brand are the 12ax7's and 12au7's? Also the PL5 is autobiasing so another word of caution before swapping output tubes. You want to get matched quads. Unlike manual biasing the autobias has a tighter window for biasing.

Where are you that you are snowed in?
I bought my prima luna used. It came with svetlanna 6550's, Electroharmonix KT-88's (my preference), stock prima luna input tubes, and a different set of input tubes (one pair says "usa" the other pair says "ge".

I figure if Electroharmonix KT-88's get slightly poor reviews, that it might be good to swap them out for something else...

I do agree though that itsbest to listen to new piece of equipment to become familiar with its sonic signature before you start tweaking things, so you can tell the difference and whether its an improvement or not.

I live in Colorado. It's been snowing here like crazy, and a bmw m3 on coilovers with michelin pilot super sports isn't exactly a snow mobile, lol.