[bcowen]

Anybody out there know their Mullard tubes? I’m looking at these, but something is putting me off, err on the side of caution. It may be that the dozens of tubes I have looked at mostly have more information on them to be able to identify where manufactured and date. Any help much welcome.

I don't know much about these to be honest. However, as there is no getter flashing up top it means that the getters are likely at the bottom...so what is that white ring at the bottom of the glass? Looks to me like powdery white getter flashing which would mean both tubes have lost their vacuum. Is the seller stating these are tested?

 

[JTbbb]

I don't know much about these to be honest. However, as there is no getter flashing up top it means that the getters are likely at the bottom...so what is that white ring at the bottom of the glass? Looks to me like powdery white getter flashing which would mean both tubes have lost their vacuum. Is the seller stating these are tested?

Yes tested as NOS, never opened. I did notice the powdery deposit too. I’m going to stick with my gut feeling and keep looking.

 

[tubebuyer2020]

I don't know much about these to be honest. However, as there is no getter flashing up top it means that the getters are likely at the bottom...so what is that white ring at the bottom of the glass? Looks to me like powdery white getter flashing which would mean both tubes have lost their vacuum. Is the seller stating these are tested?

How could they loose the vacuum if they are very silver in the bottom on the inside? My best guess is that the powdery white stuff is cement glue outside attaching the base to the bulb. I tried to look it up back in the day but could not find out why was it white and not yellow or orange.
Maybe this is why some of the tubes have a gray tape/band around that area?
If Mullard had been allowing tubes with flashing material partially splattered outside through their quality control then the brand should be avoided altogether not just in this instance.

 

[bcowen]

How could they loose the vacuum if they are very silver in the bottom on the inside? My best guess is that the powdery white stuff is cement glue outside attaching the base to the bulb. I tried to look it up back in the day but could not find out why was it white and not yellow or orange.
Maybe this is why some of the tubes have a gray tape/band around that area?
If Mullard had been allowing tubes with flashing material partially splattered outside through their quality control then the brand should be avoided altogether not just in this instance.

It's hard to tell definitively from the pictures, but it looks like the "white stuff" is on the inside, not the outside. That's not shiny silver, it's white. The darker coloration completely surrounding the inside of the bottle is not getter flash -- it's a coating that was used on many tubes of that era intended to absorb stray electrons and keep them more focused between the cathode and the plate.

It would be rather impossible to have getter flash splattered on the outside of the tube unless there was a hole in the glass.

 

[tubebuyer2020]

It's hard to tell definitively from the pictures, but it looks like the "white stuff" is on the inside, not the outside. That's not shiny silver, it's white. The darker coloration completely surrounding the inside of the bottle is not getter flash -- it's a coating that was used on many tubes of that era intended to absorb stray electrons and keep them more focused between the cathode and the plate.

It would be rather impossible to have getter flash splattered on the outside of the tube unless there was a hole in the glass.

I agree that it's hard to say whether it's inside or outside. There is still a lot of silver colour between white material and the gray carbon screen spray you mentioned though.

 

[LoryWiv]

Are ECC32 / CV181 drop in replacements for 6SN7 without adapters, only difference being 0.95 amp heater current rather than 0.6 amp for 6SN7?

 

[JTbbb]

Are ECC32 / CV181 drop in replacements for 6SN7 without adapters, only difference being 0.95 amp heater current rather than 0.6 amp for 6SN7?

Yes that is correct, without adapters. And yes there is the increased heater current you have to take into account.

 

[Old Deaf Donkey]

Yes that is correct, without adapters. And yes there is the increased heater current you have to take into account.

and the price to go with it
https://www.ebay.com/itm/cv181-tube...605545?hash=item3b53d605a9:g:BDoAAOSw~Jhf2ct7

 

[attmci]

Another way to cheat. LOL.




https://www.ebay.com/itm/184611081796?ul_ref=https%3A%2F%2Frover.ebay.com%2Frover%2F0%2Fe11021.m43.l1120%2F7%3Feuid%3D8fec2f866b9947d8a11aa4d98d91bd94%26bu%3D43143433688%26ut%3DRU%26segname%3D11021%26crd%3D20210107074933%26osub%3D-1%7E1%26ch%3Dosgood%26loc%3Dhttps%253A%252F%252Fwww.ebay.com%252Fulk%252Fitm%252F184611081796%26sojTags%3Dbu%3Dbu%2Cut%3Dut%2Cch%3Dch%2Csegname%3Dsegname%2Ccrd%3Dcrd%2Curl%3Dloc%2Cosub%3Dosub%26srcrot%3De11021.m43.l1120%26rvr_id%3D0%26rvr_ts%3Ddebd233d1760a9c16c339c21ffff50a9&ul_noapp=true

 

[JTbbb]

and the price to go with it
https://www.ebay.com/itm/cv181-tube...605545?hash=item3b53d605a9:g:BDoAAOSw~Jhf2ct7

Yes bonkers prices. And they have been there quite a while.

 

[JKDJedi]

Anybody out there know their Mullard tubes? I’m looking at these, but something is putting me off, err on the side of caution. It may be that the dozens of tubes I have looked at mostly have more information on them to be able to identify where manufactured and date. Any help much welcome.

Send those to me for further evaluation.

 

[JKDJedi]

and the price to go with it
https://www.ebay.com/itm/cv181-tube...605545?hash=item3b53d605a9:g:BDoAAOSw~Jhf2ct7

I emailed tubedepot about the ones they have listed for $250... been about two weeks..no answer.

 

[bcowen]

I emailed tubedepot about the ones they have listed for $250... been about two weeks..no answer.

Did you read the fine print at the bottom? "$500 shipping/handling fee per tube."

 

[jonathan c]

[QUOTE="bcowen, post: 16090491, member: 489394"
Did you read the fine print at the bottom? "$500 shipping/handling fee per tube."


[/QUOTE]
That is even before the “cereal” disclaimer?: contents may have settled during shipment....

 

[Tom-s]

Anybody out there know their Mullard tubes? I’m looking at these, but something is putting me off, err on the side of caution. It may be that the dozens of tubes I have looked at mostly have more information on them to be able to identify where manufactured and date. Any help much welcome.

That pair looks fine to me. In my experience with ECC32's they do have single bottom getter. Either the old style Philips foil getter or D getter. One this pair the getter flash as seen looks good. Once the getter gets used because of a leak it'll start to whiten up around its edges. I cannot explain the whit cement like substance at the bottom of the glass. If these pass a test for gas. I'd expect them to stay fine. Once a ECC32 gets worn, the top will start to show silvering / blackening above the heaters in two box shaped forms as a result of the cooling fins.

Are ECC32 / CV181 drop in replacements for 6SN7 without adapters, only difference being 0.95 amp heater current rather than 0.6 amp for 6SN7?

A lot of people will say they are. But really are not. They'll bias up close enough for a lot of occasions but in some amps (with a DC coupled CCS loaded driver stage) a weak pair could bias 30-40% higher plate voltages and trow off the operating point of the second stage significantly. And make the amp distort more easily. And the mentioned higher heater current could overload the heater winding on your amplifier (and burn the house down; I'm such an optimist ). So always ask the manufacturer of your amplifier if it's safe to use these. They're not plug and play 6SN7's.