[HTSkywalker]

Now that am doing more listening, I realized a small hum starting around 10 and increasing with the volume but nothing that can really affect the music listening experience.
this hum could also be heard on my 2 other headphones amp while the DV is only ON. Am using a Rolls Switch box with input from the DAC and a switched output to either 3 amps.
Hum disappears from the other 2 amps if I either switch Off the DV or unplug its RCA input from the switch box.
Removing both tubes eliminates the hum, re-installing the 6AS7G tube introduce no hum, only when the 6SN7 is plugged again the hum returns.
Having no ground in place works same as a cheater plug though.

 

[bcowen]

He knows I am into variations on specific Russian tubes so he plays to my weakness.

Did you ever get that Melz I sent you the link on? IIRC, it had the holey plates like a 1578, but all the other construction details were of a regular (non-1578) Melz.

 

[Paladin79]

Did you ever gat that Melz I sent you the link on? IIRC, it had the holey plates like a 1578, but all the other construction details were of a regular (non-1578) Melz.

I will have to check, I have several in transit right now.

I got it, maybe I should listen to it sometime lol.

 

[bcowen]

Having no ground in place works same as a cheater plug though.

And also pretty dangerous. The DV is probably the last amp in existence I would run with no earth ground connection....

 

[HTSkywalker]

And also pretty dangerous. The DV is probably the last amp in existence I would run with no earth ground connection....

Any idea about the hum source ? is it the tube ?

 

[bcowen]

Any idea about the hum source ? is it the tube ?

Maybe, but probably the DV. Can you run that tube in either of your other amps (don't know what tubes they use) to see if it hums in one of them?

 

[HTSkywalker]

Maybe, but probably the DV. Can you run that tube in either of your other amps (don't know what tubes they use) to see if it hums in one of them?

The CTH uses 6922 and have no cross adapters but I can switch tubes. Does it make sense that the DV makes the hum only with the 6SN7 installed ? or it could also be be the DV regardless, probably the transformer.

 

[Paladin79]

Did you ever get that Melz I sent you the link on? IIRC, it had the holey plates like a 1578, but all the other construction details were of a regular (non-1578) Melz.

The tube in question is a Melz from 1954, an early version of the perforated plate with oval micas. I plugged it in now, I will get back with you later.

 

[bcowen]

The CTH uses 6922 and have no cross adapters but I can switch tubes. Does it make sense that the DV makes the hum only with the 6SN7 installed ? or it could also be be the DV regardless, probably the transformer.

The transformer may have some mechanical (external) hum, but unlikely it is causing hum to be heard through your headphones unless something has gone wrong with it. More likely the tube AND the DV, or said another way, the method in which the 6SN7 is handled electrically in the DV. That issue alone is probably responsible for 50% of the posts in this thread, and the genesis of the "Fitz Mod" and all the subsequent mods people have implemented to reduce or eliminate it.

 

[Paladin79]

https://www.ebay.com/itm/Tube-6SN7G...883252?hash=item3b524d87f4:g:Cw4AAOSw6xZeus3D

I am not sure if this is a popular Raytheon but the price seems decent.

Now go into the store, and there are ribbed Fotons of various years, if you look hard enough there is a 1961 Melz 1578 that would be a steal. Do not be fooled by the Melz with solid plates and metal upper supports, I bought one and it is not the same as the shiny black plate. The tube I got did not even say Melz on it, it is decent but not the holy grail.

If interested you should be able to find the 61 Melz 1578 in some of the tubes for sale, if still there tomorrow I will own it.

I bought the tube there Bill and I were discussing, I got it for $20 shipping included. I would place it well above the lower end Melz with round micas and ribbed Fotons, not on the same level with 63 1578's but I need to listen more. Dead quiet background. If the high end settles in, this will be a remarkable tube for the price. Melz can be very year specific, and construction specific. I have yet to replace the solder in the pins on this one and so far it is quite solid.

The same tube I bought for $20...

https://www.ebay.com/itm/MILITARY-M...860083?hash=item4475c8a5f3:g:o94AAOSwdttgOJRe

From another seller.

 

[HTSkywalker]

So far my preferred are the 6J5 Naughty Girls (The name was given for a good reason) duo as well as the Dark Glass RCA Hands down

 

[bcowen]

https://www.ebay.com/itm/Tube-6SN7G...883252?hash=item3b524d87f4:g:Cw4AAOSw6xZeus3D

I am not sure if this is a popular Raytheon but the price seems decent.

Now go into the store, and there are ribbed Fotons of various years, if you look hard enough there is a 1961 Melz 1578 that would be a steal. Do not be fooled by the Melz with solid plates and metal upper supports, I bought one and it is not the same as the shiny black plate. The tube I got did not even say Melz on it, it is decent but not the holy grail.

If interested you should be able to find the 61 Melz 1578 in some of the tubes for sale, if still there tomorrow I will own it.

I bought the tube there Bill and I were discussing, I got it for $20 shipping included. I would place it well above the lower end Melz with round micas and ribbed Fotons, not on the same level with 63 1578's but I need to listen more. Dead quiet background. If the high end settles in, this will be a remarkable tube for the price. Melz can be very year specific, and construction specific. I have yet to replace the solder in the pins on this one and so far it is quite solid.

The same tube I bought for $20...

https://www.ebay.com/itm/MILITARY-M...860083?hash=item4475c8a5f3:g:o94AAOSwdttgOJRe

From another seller.

You're welcome then. LOL!!!!

Aren't these the Melz that don't exist? 1578 micas and mica supports, yet solid plates?

 

[Paladin79]

You're welcome then. LOL!!!!

Aren't these the Melz that don't exist? 1578 micas and mica supports, yet solid plates?

Think back grasshopper or read my post again lol. I bought one of these, there is no Melz logo, they need shiny black plates, not grey. The one I got looked like the metal base had been added on. Maybe you can see some of the crimp marks on those tubes. I buy anything that might be close to the real things and these are not it lol.

Also the print they added to the base is pretty sloppy, I could not even make out the year, maybe 1984.

I even posted pictures of both types some time ago, but you may have slept through that. Oh and the proper ones have a ribbed plate exactly like the perforated plates if you ignore the perforations.

I own the one on the left in your photo, lucky me lol.

 

[bcowen]

Think back grasshopper or read my post again lol. I bought one of these, there is no Melz logo, they need shiny black plates, not grey. The one I got looked like the metal base had been added on. Maybe you can see some of the crimp marks on those tubes. I buy anything that might be close to the real things and these are not it lol.

Also the print they added to the base is pretty sloppy, I could not even make out the year, maybe 1984.

I even posted pictures of both types some time ago, but you may have slept through that. Oh and the proper ones have a ribbed plate exactly like the perforated plates if you ignore the perforations.

I own the one on the left in your photo, lucky me lol.

I don't remember what I had for breakfast, so thanks for the refresher.

 

[Paladin79]

I don't remember what I had for breakfast, so thanks for the refresher.

I even sent you one of the good ones but you may not remember. You said something along the lines of “it ranks with some of the best tubes I have heard” or some such lol. From now on all amazing tubes go to Ripper!!!!