[paradoxper]

I threw my Mullards back in...and the noise is gone. I had them in previously for about 3 days and had Lyr and Bifrost on during that time.
Just seems weird to me this tube noise appeared, but after I took them out to cool down it's now gone. I am puzzled by the coincidence, but very happy to have my Mullards back.

 

[mikek200]

You mean,you had them running non stop for 3 days?
Couldn't that in itself cause some sort of a noise issue...

did you use detoxit,at any time
 
I remeber when i got my first Lorenz,{from Mr.Crazy}..when i put them in and let them warm up a bit igot a lot of craclking sounds--He told me to take them out & cool down for an hour..which I did,then put them back in and they were perfect..like you said...wierd.
Maybe the Mullard Gods were playing games with you??
Glad they're working again...these & the 2493's are my favorites.

 

[paradoxper]

Quote:

You mean,you had them running non stop for 3 days?
Couldn't that in itself cause some sort of a noise issue...

did you use detoxit,at any time
 
I remeber when i got my first Lorenz,{from Mr.Crazy}..when i put them in and let them warm up a bit igot a lot of craclking sounds--He told me to take them out & cool down for an hour..which I did,then put them back in and they were perfect..like you said...wierd.
Maybe the Mullard Gods were playing games with you??
Glad they're working again...these & the 2493's are my favorites.

Usually I am not one who leaves tube gear on. However I was just feeling lazy and it almsot cost me.
 
I know there are so many variants in regards to tube behavior, but I'd love some kind of
explanation to the reason(s) why a cooling down period could have a positive impact/solution to a noisy tube.
That is...if there are any...

 

[Rope]

Quote:

Usually I am not one who leaves tube gear on. However I was just feeling lazy and it almsot cost me.
 
I know there are so many variants in regards to tube behavior, but I'd love some kind of
explanation to the reason(s) why a cooling down period could have a positive impact/solution to a noisy tube.
That is...if there are any...

The process of heating tube internals (the metal parts) and the slow cooling, is akin to annealing, which releaves stress and makes metal more pliable.  How that relates to your tubes would be a metallurgy question.
 
As an example and one of the issues that surrounded the SR71 Blackbird was the skin of the plane received a heat treatment every time it was flown, which became harder and harder.  They had no idea how long the skin would last.  The other issue was overall plane shrinkage when cold, which lead to fuel weep.  To alliviate the fuel weep issue, they would take off with half fuel and top off in flight when the planes operating temperature was attained. 

 

[paradoxper]

Quote:

The process of heating tube internals (the metal parts) and the slow cooling, is akin to annealing, which releaves stress and makes metal more pliable.  How that relates to your tubes would be a metallurgy question.
 
As an example and one of the issues that surrounded the SR71 Blackbird was the skin of the plane received a heat treatment every time it was flown, which became harder and harder.  They had no idea how long the skin would last.  The other issue was overall plane shrinkage when cold, which lead to fuel weap.  To alliviate the fuel weap issue, they would take off with half fuel and top off in flight when the planes operating temperature was attained. 

Whooop..never should have asked....these specifics go right on over my head.
 
So can someone provide a layman explanation to why the noise was there and after cool down gone?
Also, why isn't it consistent?
 
Thanks Rope! You shed some light, but failed to educate me. 

 

[Rope]

Simply put, metal does strange things when heated and cooled (expansion/contraction) which can and does change the molecular structure.
 
Someone who has expertise in both metallurgy and tube structure could without a doubt determine why your tubes became functional.  I have a sneaky suspicion it has to do with the metal parts expanding and contracting.

 

[paradoxper]

Quote:

Simply put, metal does strange things when heated and cooled (expansion/contraction) which can and does change the molecular structure.
 
Someone who has expertise in both metallurgy and tube structure could without a doubt determine why your tubes became functional.  I have a sneaky suspicion it has to do with the metal parts expanding and contracting.

I've had the Mullards in today/last night/ w/e playing for over 18 hours or something, consider me grateful. They are my fav tube.

 

[Rope]

Quote:

I've had the Mullards in today/last night/ w/e playing for over 18 hours or something, consider me grateful. They are my fav tube.

Do not question the audio Gods.  I'm glad your beloved Mullards are back from the dead.
 
When my Stutts go to the land beyond, I'm selling all my full size listening gear and going strickly IEM.

 

[paradoxper]

Quote:

Do not question the audio Gods.  I'm glad your beloved Mullards are back from the dead.
 
When my Stutts go to the land beyond, I'm selling all my full size listening gear and going strickly IEM.

You are a nut! Just buy more Lorenz!!! Why go full IEM?

 

[W0lfd0g]

Does anyone have experience buying from this site: http://www.mullardmagic.co.uk/mullard/products/269-triode-ecc88-e88cc-6922-cv2492-gold-pin-valve-mullard.aspx
 
Have just ordered a used pair of CV2492s (1963) that seemed to test OK for 55 GBP.  The email response I got was immediate, but included numerous errors.  Are they legit?
 

 

[mikiphile]

Quote:

Does anyone have experience buying from this site: http://www.mullardmagic.co.uk/mullard/products/269-triode-ecc88-e88cc-6922-cv2492-gold-pin-valve-mullard.aspx
 
Have just ordered a used pair of CV2492s (1963) that seemed to test OK for 55 GBP.  The email response I got was immediate, but included numerous errors.  Are they legit?
 

 
Im not sure if this is for NOS (only), but I havent seen a matched pair of the cv2492 to go below 120 usd. But thats just me, the rest of the folks are much more experienced... they should know better.

 

[MickeyVee]

Checked Tube Monger this morning for the Mullards and they were at $125. Should pick them up as there is 1 set left but taking a chance on these: http://www.tubemonger.com/Mullard_MPs_Like_New_1969_78_E88CC_CV2492_MitchamL_p/555-low.htm
Quote:

 
Im not sure if this is for NOS (only), but I havent seen a matched pair of the cv2492 to go below 120 usd. But thats just me, the rest of the folks are much more experienced... they should know better.

 

[paradoxper]

Quote:

 
Im not sure if this is for NOS (only), but I havent seen a matched pair of the cv2492 to go below 120 usd. But thats just me, the rest of the folks are much more experienced... they should know better.

Almost exclusively buying from Upscaleaudio under $120 seems sketchy, unless they are used.

 

[W0lfd0g]

Advertised as used:
 
[size=small]"These examples which consititute a matched pair ares ex-equipment an carries the UK military date code TE & TF respectively which equates to May & June  1963.   They both test as GOOD using my AVO Valve Characteristic Meter VCM163 with the following results: 2.0V[/size]

[size=small]Valve A[/size]

[size=small]Section 1: Ia = 12mA; gm = 11.0mA/V[/size]

[size=small]Section 2: Ia = 12mA; gm = 11.0mA/V[/size]

[size=small]Factory code: 7Li  R1L1[/size]

[size=small]Valve B[/size]

[size=small]Section 1: Ia = 12mA; gm = 11.0mA/V[/size]

[size=small]Section 2: Ia = 12mA; gm = 11.9mA/V[/size]

[size=small]Factory code: 7Li R2L3[/size]

[size=small]The specification for a new/100% emission valve is:[/size]

[size=small]Ia = 15mA; gm = 12.6mA/V[/size]"

 

[333jeffery]

I tried some Telefunken E288CC tubes in my Lyr, and fell in love with the amp all over again. Warmth and crystal clarity, dead silent, too. My HD600's work great with them. If only they weren't so pricey, I'd buy several pairs of them.