[Ahzari]

Quote:

 
An observer @ Newport, L.A. or both? Not ready to take a table for your Woo and accessories at the L.A. Meet? 

 That, you already know a Headphone Model 

 would be a HUGE draw!

oh just at the Newport event, I'll try to bring something to the meet in LA (the real deal) 

 

[2359glenn]

Quote:

Could someone help refresh my memory about EML 5U4G Mesh failures? I tried the search function but could not find the threads that I thought I remembered.
 
I have had the same, original EML 5U4G mesh in my WA22 for almost 1 1/2  years now and last night while testing a new pair of Western Electric 421As, I heard a loud pop and saw a flash at start up. I listened for a while and heard/saw no problems. Luckily, no damage to the HD800s.
 
I then allowed the amp to cool completely. I pulled the 421s out and put some TS 5998s that have been used for many hours. (great tubes!) What I saw this time at start up was a white spark in the EML. I heard no pop because this time the volume was at minimum (note to self...always power up with volume at zero/minimum, which I usually do)
 
Now, according to the EML site:
If you ignore this design rule, tube damage will result. Also in many "professional" amplifiers, this design rule is not used by designers who do not read the historical data sheets Tube damage can result as a white spark inside the tube at switch on, filament material can chip off, or the tube life will be much reduced. With most amplifiers, the transformer winding is directly connected to the tube socket, and no protective series resistors are used. In most cases, the transformer resistance can be conveniently measured by a specialist, directly at the tube socket, when the rectifier tube is removed first.
 
The rule referred to above is about resistors. Has this been discussed before, perhaps by Glenn?

Hello
The amp has a resistor that gets jumped out with the time delay circuit. BUT the input capacitor after the rectifier is still way to big for a 5U4 that has a max capacitance
of this cap at 40uf and they use 400uf.
   You can try and use the 596 rectifier if you can find one they will hold up better then a 5U4.
You can't just add resistors without changing the power transformer or they will lower the B+ voltage in the amp seriously changing the sound and power.

 

[jc9394]

Glenn, welcome back.  Hope all is well.

 

[grokit]

Could someone help refresh my memory about EML 5U4G Mesh failures?

I had an EML 5U4G blow prematurely, and from what I remember at the time, EML had just done their second manufacturing revision to make them more reliable; I think that they were actually working with Jack Wu on this. I don't know the technicalities, but from what I understand the tubes are much more reliable now. Too bad yours didn't fail within the 1-year warranty period if you bought it new.

 

[Golfnutz]

Quote:

Glenn, welcome back.  Hope all is well.

X2 - Nice to see you on the boards again Glenn.

 

[Clayton SF]

Glenn---It is great to see you posting once again even though don't understand some of it--But, mind you, one day I will comprehend all of it!

 

[john57]

On the EML web page
http://www.emissionlabs.com/datasheets/EML5U4G.htm
 
They stated that the tube heaters were improved after May of 2011. Not sure about the first cap issue.

 

[2359glenn]

Quote:

On the EML web page
http://www.emissionlabs.com/datasheets/EML5U4G.htm
 
They stated that the tube heaters were improved after May of 2011. Not sure about the first cap issue.

Hello
The cap issue cannot be resolved and the tube still be a 5U4. Even the powerful 3DG4 that I like to use
can only handle a 40uf input capacitor unless the amp has choke input before the cap.
 
Buy the way I have to go back to the Hospital tomorrow hopefully for the last surgery.
Glenn 

 

[jc9394]

Good luck, take some rest after the surgery.  Health is more important.

 

[Silent One]

Quote:

Good luck, take some rest after the surgery.  Health is more important.

 
x2!

 

[Silent One]

For those following @ home, this is how Glenn arrived at introducing the USAF-596 initially, over blown EML Glass issues in dannie01's amp.

 

[Silent One]

Quote:

Quote:

On the EML web page
http://www.emissionlabs.com/datasheets/EML5U4G.htm
 
They stated that the tube heaters were improved after May of 2011. Not sure about the first cap issue.

Hello
The cap issue cannot be resolved and the tube still be a 5U4. Even the powerful 3DG4 that I like to use
can only handle a 40uf input capacitor unless the amp has choke input before the cap.
 
Buy the way I have to go back to the Hospital tomorrow hopefully for the last surgery.
Glenn 

 
 
Best to you , my friend!
 

 

[john57]

Glenn,
 
Wish the best and a speedy recovery!

 

[nututubes]

Hello
The amp has a resistor that gets jumped out with the time delay circuit. BUT the input capacitor after the rectifier is still way to big for a 5U4 that has a max capacitance
of this cap at 40uf and they use 400uf.
   You can try and use the 596 rectifier if you can find one they will hold up better then a 5U4.
You can't just add resistors without changing the power transformer or they will lower the B+ voltage in the amp seriously changing the sound and power.

Thanks Glenn and best wishes.

 

[nututubes]

Too bad yours didn't fail within the 1-year warranty period if you bought it new.

Actually, it has not failed. It sounds as good as it ever did. I was just inquiring about the past threads that had slipped from my memory. I have a spare EML and a Pricess 274B and a couple of Mullard rectifiers, GZ37, GZ33 & CV378, so I'm covered in an emergency.

But, I love the EML best. I have been thinking about trying a Mullard High Wycombe, and now the USAF 596 that is being discussed.