Tube rolling the Purity One

[etcarroll]

Question - What do 'microphonic' tubes sound like?

Went to Boston for New Years, and with the words of Obi Wan Rollo in my head, not only did I power down everything, put also pulled all power plugs from wall.

On return, plugged it all back in, powered up all except amp to allow warm-up, then powered up amp. For first hour or two, all kind of audio crap and sonic hash, humming like a vacumn in the distance behind my speakers, 'scratchy' finish to notes, if it was an lp I'd of been looking for dust under the stylus, and a hum that shows up and slowly increases in volume necessitating a 'reboot' of amp to clear it. After 2 days the system seems to be returned to normal, but now, as a toob noob, I have the question I started this post with, wondering if that's my problem?

Edit: None of this was occurring prior to 2 day power down.

Meanwhile, right now listening to Miles' "Cookin'", and with just over 100 hours on the blackplates, it sounds great. But.............

I'd hate to think I put 100 hours into tube break in only to realize these tubes may have a problem, I guess that's my real concern.

[rollo]

    Does the weird sound come from both channels ? If not reverse tube if you can or take it out and try another. If the noise does not go away it is the tube. Have you had this issue again ? I know this is a dumb question but anyway . When you powered down was it the amp, then Pre then source? Power on was source, pre, amp ? Just curious.
   Tubes can fail at turn on, however sometimes they are just settling. Was the tube seated properly ? the shutdown and turn on should not harm a thing as it is a normal function . If the tube didn't start glowing or turn blue, orange and blow your good to go.
  Reboot the amp to clear a hum ? Got me there. Esplain. 


charles
   

[mdfoy]

etcarroll,

I have experienced the same thing.  At around 100 hours, and around 200 - 300 hours.  Around 100 hours on one set of tubes(NOS), really bad hum, on another set really bad crackle, pop and hiss(new). These are now pretty much unusable.  On another set of tubes, around 200 hours, after being on around 4 - 5 hours an intermittent SHHHH sound.  The SHHHH does not occur at turn on, only after being on for a while. 

What's up with that? It is the high end...

This stuff doesn't happen to my cheap receiver

[richidoo]

Good advice from Charles... Also I assume you power everything down everyday but don't get this reaction normally. You don't normally unplug everything either.

Could it be a static charge built up while not plugged in, causing caps or wires to malform? It is winter and snowy, so static risk is at a peak from dry air. You may need a humidifier. The increasing hum and reboot have me thinking along those lines of static build up, especially with the reboot fixing the hum immediately, but I can't think of an actual mechanism. A Brickwall filter will allow you to leave it all plugged in and grounded while you're away which would help the problem if it is static related, by keeping everything grounded. I doubt it is the tubes themselves, especially if it is coming from both channels equally. I wouldn't assume it is the new preamp until you do some testing. If it happens again, take the time to determine which component is causing it by process of elimination. You can run the power amp with with a DIY shorted RCA plug to mute the input, or if you know the amp and are careful, without a mute is OK, but there is some risk. Make a shorting plug with an old junk RCA cable, cut off the plugs along with 6" of wire, strip the wire and twist the conductors together, then optionally solder them if you can. A static shock on the input of an unmuted amp could hurt your speakers. Then if the amp is quiet add the preamp, then add sources, listening for the noise. Don't forget wires. They sit on the carpet and are subject to static issues too. If you hear the noise after adding a component, swap the wires to make sure it is not them. When you isolate the noise, report back with all the details. Maybe we can figure something out...    Glad it healed itself in time.

[etcarroll]

Good advice from Charles... Also I assume you power everything down everyday but don't get this reaction normally. You don't normally unplug everything either.

Correct, power all down at bedtime, but as a rule don't unplug from the wall. Only tried it this time as at last NYAR meeting Rollo thought I might realise improvement in sound if I unplugged system to allow static to discharge. And I do have static, especially since putting on heat for Winter.

Obi Wan - bad sound from both channels - check.  So I don't see need to swap tubes. I hadn't thought about seating, next time I shut down I'll pull and reseat both tubes.

Reboot - as a software designer I spend all day in front of Wintel computers, they get hinky from time to time, and my 1st troubleshooting step is to shut the damn thing off, count to 5, turn back on, cures over 90% of the issues. That's so ingrained in me that when hum began to escalate, I punched the amp power button w/o even thinking of why I was doing it. Counted to 5, power on, hum gone. It did it this morning on initial system power up, but you know what, the pre amp may not have had a chance to power up/warm up/settle in before I 1st powered the amp, and while rebooting the amp and counting to 5 that gave the pre the extra time it needed.

Regardless, it's playing fine now.

mdfoy - I know...... right. My 25 year old Carver receiver with the bent speaker posts doesn't give me this kind of concern, just once and awhile I have to reach behind it and wiggle the speaker post to re-establish the connection.

[richidoo]

Any tube preamp needs a period of time to get up to temp before it sends signal to the amp. Because tubes depend on heat to conduct, and heat transfer in all the metal parts of the tube and transformers is not balanced throughout the startup, there is all kind of holy hell lurking before it reaches stable temp and voltages. Most preamps have a timed relay to prevent any signal from getting out too soon, usually 30-90 seconds. Before then hum, DC and plenty of noise would come out the back without an auto muting function. Even after the relay opens there can still be DC offset that would upset some sensitive SS amps. For kicks, you might want to check out the manual just to see how long you should wait to turn on the amp, if at all. What kind of amp do you have Gene?
Rich

[etcarroll]

Holy Hell, that's what I yelled as junk came out the speakers.  

No manual, I bought Bill's pre-production unit, but I'll followup with him concerning that.

A 29 year old Bryston 4B that I sent back to Bryston early last summer to be upgraded/recapped.

Amp plugged direct into wall outlet, everything else into PS Audio Quintet, which goes into same outlet as amp.

And the outlet is a Leviton Hospital grade unit.

[Response Audio]

Sorry I have been out of the loop for a while. I was just notified about the current discussion in this thread. Maybe I can be of some help here.

 As far as warm up goes, tube preamps need about a minute to come to temp before turning on the power amp(s). It is a bit less but to be on the safe side, give it a minute.

 You never want to turn you amp on immediately after turning on a tube preamp. A general rule of thumb is: sources first (wait 30-60 seconds if tubes are involved), preamp (give it a minute) and then amp(s). Wait about a minute after powering up the complete system to start playing music.

I am wondering if some of the noise mentioned here is not a static build up as richidoo mentioned. I have has this happen to me a few times and "rebooting" the system always took care of it. With winter here and the heating system on, the air is quite dry and I am experiencing this more regularly. If you have cables running along the floor, the pick up and deliver static to the components. I can think of no other reason for a component or system to develop noise after being on for so long with no issues.

I will have manuals available on line very soon for all of our products as well as a general manual for system setup and powering sequence.

[Response Audio]

By the way etcarroll, your Harvest II interconnects left yesterday via Priority Mail.

[etcarroll]

Spoke too soon about 'all is well', just sat down to listen to system while taking a break from updating my resume, (why is it so painfull, and time consuming to write about myself), and realized a noise had returned. Not as bad as the vacumn cleaner motor I heard earlier, more muted, but there and steady. Killed CDP, and quickly realized the sound only in right speaker.

Swapped tubes, sound now in left speaker. Does this mean tube goes in the trash?

Oh well, was looking for a reason to put in the Siemens tubes Shadowlight lent me.

[etcarroll]

By the way etcarroll, your Harvest II interconnects left yesterday via Priority Mail.

That's great Bill, looking forward to replacing the LAT ic presently in place between pre and amp to see what the result is.

[richidoo]

Yup, tubes in pre need replacement... Sometimes they will be flakey on and off when they are dying.  But the hum and stuff was from turning on the amp too soon before the preamp was warmed up.  Bryston can take it no problem, as can most amps with a cap or transformer on their input to stop the DC.

[Werd]

Hi etcarrol

i know what you are talking about. What worked for me was my gutwire powerclef/2. I mentioned this earlier.
That power cord on that pre made it quiet. I had it pretty much permanent assignment on my 14B(so i thought). Its as quiet now as my old bp25 and that was solid state. I did everything i could think of with moving stuff around and plugging in and out. I even changed out tubes to no avail. Here is the link. Check out the discontinued products and look at it. It has a ground that you can attach back on to the chassis. Its a good power cord for that pre. Its always hard to say how it will work for you but its something you can consider.

http://www.gutwire.com/power.htm

[etcarroll]

Thanks for the gutwire tip.

Actually, I have a length of DH Labs Power Plus Reference Series Power Cord I want to use, just waiting for the appropriate Wattgate terminators to come up on sale.

[mdfoy]

etcarroll,

Swapped tubes, sound now in left speaker. Does this mean tube goes in the trash?
Oh well, was looking for a reason to put in the Siemens tubes Shadowlight lent me

Don't you hate when that happens.  And it ALWAYS happens to the tubes you like   I have swapped out Telefunken( really liked,really liked, and may look for another pair), Tung-Sol(really liked, and may look for another pair), JJ gold pins, RCA Cleartop, CBS/Hytron really liked, and got another quad), all because they had issues around 100-200 hours.  Old tubes, new tubes, it doesn't matter.

The saving grace is that they all sound SOOOO good when working, and well worth the angst. The Purity is all that 

Raytheon Blackplates(thanks Bill for the recommendation) are going strong .