Ultravalve Warm Up Time?

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adydula

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Ultravalve Warm Up Time?
« on: 17 Aug 2010, 05:15 pm »
Simple question for Frank and Ultravalve owners and other tube amp owners:

How long do you let your tube amp warm up before any serious listening?

Do you notice any appreciable difference in sound quality, imaging etc...

Alex

Wayner

Re: Ultravalve Warm Up Time?
« Reply #1 on: 17 Aug 2010, 06:53 pm »
This is a great question. As you may have read, I did a bias study awhile back. I would recommend running the amp for several minutes before putting any music to it. I think 2 minutes should be fine, to let the bias voltage come to some reasonable levels (like 1.7 volts). Then I would play some music, but at softer levels for about another 5 to 10 minutes. Frank may have other time suggestions, but this is how I like to do it. The bias voltage will settle in about an hour, but can vary depending on incoming voltage. Just let the tubes warm up and the caps charge and you should be good to go, using my guidelines.

On a side note, if you should accidentally shut the amp off, do not switch in on right away. Let it sit for a few minutes, then switch it on.

Have fun listening to this amp, it's detail is wonderful.

Wayner 

mchuckp

Re: Ultravalve Warm Up Time?
« Reply #2 on: 17 Aug 2010, 07:09 pm »
Biasing question.  Should one hear any sort of audible difference if the bias is higher or lower than the 1.6V that Frank states in his manual?

I've had my UV since spring and never checked the bias until now.  Finally bought a multimeter and they were about 1.46 and 1.49 after warm up.  I raised each to 1.6.  I'd swear things sound a tad brighter after bumping up the bias to 1.6.

turkey

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Re: Ultravalve Warm Up Time?
« Reply #3 on: 17 Aug 2010, 07:23 pm »
Simple question for Frank and Ultravalve owners and other tube amp owners:

How long do you let your tube amp warm up before any serious listening?

Do you notice any appreciable difference in sound quality, imaging etc...

I would think it would be ready to play music within a minute or so, and fully warmed-up within 5-10 minutes.

There probably is tube gear out there that requires a long time to reach some semblance of stability, but I don't think anything AVA sells is like that.


Wayner

Re: Ultravalve Warm Up Time?
« Reply #4 on: 17 Aug 2010, 08:14 pm »
I can't hear any difference with bias settings. I really think that it's not ultra critical at all. It's nice to have the bias at 1.56 when the voltage is at 120, but it's going to fluctuate, and it's just no big deal to be + or - something other then design voltage of 1.56.

I think it's a good idea to do the diode upgrade on the 5AR4 tube, if you haven't done so. (see thread in AVA circle).

Wayner

jaw5279

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Re: Ultravalve Warm Up Time?
« Reply #5 on: 17 Aug 2010, 08:21 pm »
Simple question for Frank and Ultravalve owners and other tube amp owners:

How long do you let your tube amp warm up before any serious listening?

Do you notice any appreciable difference in sound quality, imaging etc...

Alex

Purely my perception only, but my Ultravalve seems to open up and really start to sound good after being on between 15 and 20 minutes. 

John

adydula

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Re: Ultravalve Warm Up Time?
« Reply #6 on: 17 Aug 2010, 09:52 pm »
Cool, thanks for the responses....

When I got mine the bias was 1.29 or so and I called Frank and he said to just play some music, no real issue. It sounds great as you all know. I did adjust it to 1.6 vdc and like Wayner indicated it takes a while for it to settle down to 1.6 while warming up. I honestly dont think I hear any real difference in voltages but I do seem to have fallen prey to having to wait 15 min or so before I do serious listening...this just may be my brain getting into the 'groove' so to speak!!  :lol:

Beng an old Amateur Radio operator, Extra Class AG1Q/4, I have built a lot of tube crap over the years mainly transmitters, and test gear, none of which i have any more. Can you say Heathkit bigtime!!..

I understand not to turn off tubes and then back on again...ripping the crap out of those elements inside those wonderful little glass bottles!!

Anyone have any observations  please chime in!

Alex
 :o


mchuckp

Re: Ultravalve Warm Up Time?
« Reply #7 on: 18 Aug 2010, 12:35 am »
I concur with the consensus that it does take at least some warm up time.  I usually say about 20 min.  If I know I'm going to have a listening session ahead of time, I make an effort to turn it on early (along with my T8 preamp).  But it isn't like it sounds like trash without warm up.

Rolled my first tubes yesterday.  Friend sent me some Mesa EL-34's STR-447s.  Gotta say, I was not impressed.  Very flat sound and uninvolving.  It's funny because I emailed him to give him my impressions and he said he felt the same thing.  LOL!  He just wanted me to try them without being influenced.

I'm ready to put the the EH's back in but it does have me intrigued to try something else for kicks.  Any suggestions?

zybar

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Re: Ultravalve Warm Up Time?
« Reply #8 on: 18 Aug 2010, 12:46 am »
This is a great question. As you may have read, I did a bias study awhile back. I would recommend running the amp for several minutes before putting any music to it. I think 2 minutes should be fine, to let the bias voltage come to some reasonable levels (like 1.7 volts). Then I would play some music, but at softer levels for about another 5 to 10 minutes. Frank may have other time suggestions, but this is how I like to do it. The bias voltage will settle in about an hour, but can vary depending on incoming voltage. Just let the tubes warm up and the caps charge and you should be good to go, using my guidelines.

On a side note, if you should accidentally shut the amp off, do not switch in on right away. Let it sit for a few minutes, then switch it on.

Have fun listening to this amp, it's detail is wonderful.

Wayner

Good general advice for most (if not all) tube amps. 

This procedure will definitely extend tube life.

George

Brett Buck

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Re: Ultravalve Warm Up Time?
« Reply #9 on: 18 Aug 2010, 03:05 am »
On a side note, if you should accidentally shut the amp off, do not switch in on right away. Let it sit for a few minutes, then switch it on.

   I was a little surprised how long "hot restart" effects last. I did some experiments and found that the normal cold start differed from a restart after something like 15 minutes or more. After about 5-6 minutes, it would reliably restart without killing the rectifier tube but with an obvious inrush current spike. That's about the least amount of time I would use. Longer would be better and less stressing.

      Brett

 

adydula

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Re: Ultravalve Warm Up Time?
« Reply #10 on: 19 Aug 2010, 01:08 pm »
Ok now for the 64 million dollar question....I hope Frank replies here with some engineering background.

What if anything in the tube design could be engineered in to help elliviate the damaging in rush of current etc in a tube amp design? Is there a way to design a timed turn on cycle to solve this? OR Is this one of those things that 'its just the way it is'...??

Just Asking?
Alex
 :D

Listens2tubes

Re: Ultravalve Warm Up Time?
« Reply #11 on: 19 Aug 2010, 02:23 pm »
My system is set up to be switched on as follows: Power up front end first - wait 30 sec - power up amps. Reverse for shut down: Power down Amps - wait 30 - sec power down front end. This is manually done. Meanwhile I have been using a SS rectifier with a 30 delay. So the turn on sequent becomes redundant.

I recently had a pair of the Arion http://www.analysisaudio.com/Arion.htm amps to audition in my system. When the maker came to pick them up we listended for a while. Then I put my stone cold amps back in the system. With only a few minuted warm up the amps had a soft edge. Letting them warm another 30 min was the "fix". I normally let my system settle in for at least an hour while the tuner plays low in the backround. Lesson learned. :oops:

I keep my amps biased at 1.4v. When I was biasing to 1.56 they would become hard sounding id they drifted above 1.62v. In testing I found no softness with less bias voltage, ergo 1.4v. :thumb: New sockets gleen rock solid bias these days 8)

Neal :wave:

Brett Buck

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Re: Ultravalve Warm Up Time?
« Reply #12 on: 19 Aug 2010, 02:48 pm »
Ok now for the 64 million dollar question....I hope Frank replies here with some engineering background.

What if anything in the tube design could be engineered in to help elliviate the damaging in rush of current etc in a tube amp design? Is there a way to design a timed turn on cycle to solve this?

  A lot of them do have a timer to turn things on. But the easiest way is to just let it cool off for a while before you turn it back on.

   If it's cool to start with, the turn-on is pretty gentle.

    Brett

Wayner

Re: Ultravalve Warm Up Time?
« Reply #13 on: 19 Aug 2010, 02:51 pm »
My system is set up to be switched on as follows: Power up front end first - wait 30 sec - power up amps. Reverse for shut down: Power down Amps - wait 30 - sec power down front end. This is manually done. Meanwhile I have been using a SS rectifier with a 30 delay. So the turn on sequent becomes redundant.

I recently had a pair of the Arion http://www.analysisaudio.com/Arion.htm amps to audition in my system. When the maker came to pick them up we listended for a while. Then I put my stone cold amps back in the system. With only a few minuted warm up the amps had a soft edge. Letting them warm another 30 min was the "fix". I normally let my system settle in for at least an hour while the tuner plays low in the backround. Lesson learned. :oops:

I keep my amps biased at 1.4v. When I was biasing to 1.56 they would become hard sounding id they drifted above 1.62v. In testing I found no softness with less bias voltage, ergo 1.4v. :thumb: New sockets gleen rock solid bias these days 8)

Neal :wave:

I believe the power output drops a little with lower bias voltages.

Wayner

adydula

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Re: Ultravalve Warm Up Time?
« Reply #14 on: 19 Aug 2010, 02:54 pm »
Thanks for the input.

I know based on Franks statements that the tubes are not being driven as hard as they are designed to , ie the 100 ma of current via the precision 16 (forget if this is Kohms or just ohms...) etc..the 1.6 volts and 16 some math help here gets the 100ma which makes the Ultravalve be able to output its 35 watts or so. So I would assume a lower bias voltage is less watts out?? or more watts out?

Thanks
Alex

turkey

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Re: Ultravalve Warm Up Time?
« Reply #15 on: 19 Aug 2010, 03:21 pm »
What if anything in the tube design could be engineered in to help elliviate the damaging in rush of current etc in a tube amp design? Is there a way to design a timed turn on cycle to solve this? OR Is this one of those things that 'its just the way it is'...??


I kind of think that Frank's designs are fairly well optimized in terms of tube life. Some things, however, just can't be fixed, and they're why tubes are in sockets so you can easily replace them. :)

I haven't seen anyone complaining about short tube life (or short amp life) with Frank's products. Small signal tubes should last for years and rectifiers also probably for years. Output tubes may not last quite as long as the others, but I would think they'd still last for years for the average person.

If I remember, there was some discussion of tube life in some of the old issues of Audio Basics. Maybe in one of the articles on the ST-70 rebuilds?

It's one of those cases where you can fix one thing, but then that causes another problem, and so on.

turkey

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Re: Ultravalve Warm Up Time?
« Reply #16 on: 19 Aug 2010, 03:26 pm »
  A lot of them do have a timer to turn things on. But the easiest way is to just let it cool off for a while before you turn it back on.

I suppose you could put in a thermistor to ramp up the voltage to the heaters and protect them. But then you need a delay for the B+ because you don't want to apply full voltage to a cold tube.

It's probably better as it is, and you just live with the possibility that a heater will go ker-flooey once in a while. Right now the heaters come on immediately and start warming up the tubes (including the rectifier). By the time the rectifier comes up, the other tubes are warm and ready for full B+.

avahifi

Re: Ultravalve Warm Up Time?
« Reply #17 on: 19 Aug 2010, 07:57 pm »
In general, I allow no warm up time at all using any AVA components, even when doing a local demo here.

By the time I get the system turned on and have selected the music I want to play back, the playback quality is good enough for me, and I am reasonably fussy.

Regards,

Frank Van Alstine

trebejo

Re: Ultravalve Warm Up Time?
« Reply #18 on: 19 Aug 2010, 10:44 pm »
I can't hear any difference with bias settings. I really think that it's not ultra critical at all. It's nice to have the bias at 1.56 when the voltage is at 120, but it's going to fluctuate, and it's just no big deal to be + or - something other then design voltage of 1.56.

Here's the post where you listed the values as a function of time,

http://www.audiocircle.com/index.php?topic=72057.msg750380#msg750380

(That puppy merits a thread all by itself).

As Wayner mentioned there and elsewhere, this bias parameter will be a function of the AC voltage coming in from the wallplug. So the other (warm) day, I was sweating little buckets with the A/C and refrigerator running at full blast, when I decided to check the bias on the U70 and it was about 1.4.  :o :o

I shrieked, turned off those two appliances and sure enough, it was back up to 1.56ish.

This bugged me enough to actually websurf a bit on the topic of AC conditioners and regenerators (a new dedicated AC line is not an option for this rental unit). Then I decided that the noise from the A/C was so bad, that it was not proper to have audiophillic aspirations anyway... i.e. if the A/C is messing with the bias, then it's too loud to worry about the bias in the first place.   :cry:

adydula

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Re: Ultravalve Warm Up Time?
« Reply #19 on: 20 Aug 2010, 05:20 pm »
Frank question,

At 1.6vdc bias what is the watts output?

VS

1.4vdc...

just curious, i kmow i read somewhere that the output tubes are being driven conservatively and the
current was 100ma (1.6vdc/16 ohm precision resistor?).

Thanks
Alex
« Last Edit: 20 Aug 2010, 11:16 pm by adydula »