Optimum Tube Temperature

[JammyBStard]

I just got my first piece of valve kit working (See Here). It's a Cathod Follower Pre-Amp using a pair of ECC88's, when I first powered it up I thought is sounded quite harsh, I've been listening for over an hour now and the harshness seems to have all but gone; does it take a while for tubes to get up to an optimum temperature? or have I just got used to the sound?

[Eli Duttman]

Many parts, especially caps., have a run in time requirement. Get 100 hours play time under your belt and post again.

Also, waiting a few minutes after turn on, prior to listening, can't hurt. Let everything stabilize, temperature wise.

[pjp]

Every amp sounds harsh at first.
After you listen to it for a while, your brain begins to filter out the harshness.
Then it starts to sound good.

[JammyBStard]

A bit of both then!
Another thing I've noticed is the Stereoness (I dont know the correct term) seems far more lively than I'm used to, sounds are coming from all over the room rather than from the speakers, I cant think of a reason for this, I never really noticed this with the old SS preamp but maybe I'm listening harder!

[Eli Duttman]

No, it's not your imagination. Tubed circuitry most definitely offers a superior sterephonic sound stage. It's not at all uncommon for all 3 dimensions to be present. AAMOF, "us tubeheads" have been known to rail at flat sound stages.

[Miles Prower]

Originally Posted by JammyBStard

I just got my first piece of valve kit working . It's a Cathod Follower Pre-Amp using a pair of ECC88's, when I first powered it up I thought is sounded quite harsh, I've been listening for over an hour now and the harshness seems to have all but gone; does it take a while for tubes to get up to an optimum temperature? or have I just got used to the sound?

There really is no such thing as an "optimum temperature". There is a specced limit as to envelope temps, but that's all. Some of the high power types will specify a certain operating temp since these use the plate to help getter the vacuum. Running these too cool can lead to degradation of the vacuum.

Unlike solid state, it takes minutes to hours for the bias to settle down when new tubes are put into service. This is the likely cause of that "harshness" you noticed: the ECC88's hadn't settled down yet. I've seen and heard the same thing.

[Miles Prower]

Originally Posted by JammyBStard

Another thing I've noticed is the Stereoness (I dont know the correct term) seems far more lively than I'm used to, sounds are coming from all over the room rather than from the speakers, I cant think of a reason for this, I never really noticed this with the old SS preamp but maybe I'm listening harder!

The term you're looking for is "sound stage". It's a very real phenomenon, and what kills it is gNFB. When running an 807 stereo amp completely open loop, it also had a wide open sound stage, just as you describe. It also had just esssssssss-loads of pentode nastiness (at least with some program material). Adding local and global NFB to fix that cost sound stage. Run too much gNFB and your hollow state amp starts sounding like an SS amp. It's one of the reasons I don't like overdoing the NFB.

Since SS amps run with a good deal more gNFB than most hollow state designs, SS completely obliterates sound stage. As to why that should be, who really knows? It's been proposed that, since NFB fills the noise floor with uncorrelated, low level, harmonic distortion that this has something to do with obscuring the aural hints as to distance and direction. It could also explain why some people find CDs and MP3's unsatisfactory. The analog-to-digital conversion process fills the noise floor with uncorrelated quantizing noise. With the MP3 file compression, the bits that encode that low level information are thrown away.

[pointy]

it will be down to what is called burn in period.
as for Optimum Tube Temperature the temperture will be different at the bottom of the valve to the top.
and so there tends to be a sweet area somewhere in the middle.

[jcx]

gee somehow these people completely missed that clue:

Blind Listening Tests & Amplifiers

or are you going to complian that their tube amp had too much gNFB? - seems like a silly mistake for such an experienced crew wanting to "prove" tube amps sound different than ss

[JammyBStard]

Originally Posted by Eli Duttman

No, it's not your imagination. Tubed circuitry most definitely offers a superior sterephonic sound stage. It's not at all uncommon for all 3 dimensions to be present.

It's fantastic, I'ts a bit like a live performance; Any idea why this is the case?