The Reference 6SN7 Thread

[robo24]

Hi all!

I recently bought some nice Melz 1578 produced in 1963 for my Euforia amp. The seller said they were never used and they really look like new. As I started to test them I was amazed with their performance, way better than my previous Melz 6N8S, however later I discovered they produce a slight hum which is independent of the volume and constant in both channels. As with my previous Melz's I owned (that always came with some static noises, pops, etc....) I proceeded to clean all pins with a polish tool and then I re-soldered all pins but nothing changed .

Any ideas what could be happening and how to solve it?

I must have lucked out with mine. Also just got the 90% cheaper 6N8S Melz. Just no contest among the worst I own. Swapping in the 1578 it's immediately different especially with a much more wide and airy stage. With the 6N8S while there is a similarlity to the overall sound, but they're grainy and all compressed into a narrow stage and one is noisy.

 

[paradoxper]

Hi all!

I recently bought some nice Melz 1578 produced in 1963 for my Euforia amp. The seller said they were never used and they really look like new. As I started to test them I was amazed with their performance, way better than my previous Melz 6N8S, however later I discovered they produce a slight hum which is independent of the volume and constant in both channels. As with my previous Melz's I owned (that always came with some static noises, pops, etc....) I proceeded to clean all pins with a polish tool and then I re-soldered all pins but nothing changed .

Any ideas what could be happening and how to solve it?

Did you swap channels? I would think the reflow would solve the issue. You could try also cleaning your tube sockets and reseating.
It is always possible the tube is failing although likely to accompany other noises as a sign.

 

[bcowen]

Hi all!

I recently bought some nice Melz 1578 produced in 1963 for my Euforia amp. The seller said they were never used and they really look like new. As I started to test them I was amazed with their performance, way better than my previous Melz 6N8S, however later I discovered they produce a slight hum which is independent of the volume and constant in both channels. As with my previous Melz's I owned (that always came with some static noises, pops, etc....) I proceeded to clean all pins with a polish tool and then I re-soldered all pins but nothing changed .

Any ideas what could be happening and how to solve it?

How long have you played them? Some of that hum might go away after you get 25+ hours on them. There's also the possibility that the amp doesn't like them. I have no experience with the Euforia, but the Melz are pretty much unusable due to loud hum in an unmodified Darkvoice. Same with Fotons in that amp. I can't tell you why that happens (sorry), just that it does.

 

[ajm87]

Has anyone tried the psvane 6SN7 UK black plate tubes? Assuming these are supposed to be like mullard copy's.

 

[sam6550a]

Hi all!

I recently bought some nice Melz 1578 produced in 1963 for my Euforia amp. The seller said they were never used and they really look like new. As I started to test them I was amazed with their performance, way better than my previous Melz 6N8S, however later I discovered they produce a slight hum which is independent of the volume and constant in both channels. As with my previous Melz's I owned (that always came with some static noises, pops, etc....) I proceeded to clean all pins with a polish tool and then I re-soldered all pins but nothing changed .

Any ideas what could be happening and how to solve it?

Resolder the pins. See many, many, many posts on this thread as to how to do it, or contact @Paladin79 for detailed advice.

 

[BrainSalat]

Thanks guys for all tips

I must have lucked out with mine. Also just got the 90% cheaper 6N8S Melz. Just no contest among the worst I own. Swapping in the 1578 it's immediately different especially with a much more wide and airy stage. With the 6N8S while there is a similarlity to the overall sound, but they're grainy and all compressed into a narrow stage and one is noisy.

I agree with your impressions. I immediately noticed a bigger/airy soundstage and a bass/treble boost of the 1578 compared the 6N8S, lovely.

Did you swap channels? I would think the reflow would solve the issue. You could try also cleaning your tube sockets and reseating.
It is always possible the tube is failing although likely to accompany other noises as a sign.

Yes, I swapped the channels but I have not tried cleaning the socket, however these are my only driver tubes that hum (not my previous Melz for example). No other symptoms, they actually sound fantastic.

How long have you played them? Some of that hum might go away after you get 25+ hours on them. There's also the possibility that the amp doesn't like them. I have no experience with the Euforia, but the Melz are pretty much unusable due to loud hum in an unmodified Darkvoice. Same with Fotons in that amp. I can't tell you why that happens (sorry), just that it does.

No more than 7 hrs so far so I hope this is the reason, thanks!!!. I'll let them running to complete the break-in period and let you know.
In the Feliks Euforia thread other users have tried these tubes many times so they should work.

Resolder the pins. See many, many, many posts on this thread as to how to do it, or contact @Paladin79 for detailed advice.

You may have missed the part of my message where I wrote I did it already . Thanks anyway. This actually worked with my previous noisy Melz 68NS.
I will ask @Paladin79, thanks!

 

[Paladin79]

Thanks guys for all tips

I agree with your impressions. I immediately noticed a bigger/airy soundstage and a bass/treble boost of the 1578 compared the 6N8S, lovely.

Yes, I swapped the channels but I have not tried cleaning the socket, however these are my only driver tubes that hum (not my previous Melz for example). No other symptoms, they actually sound fantastic.


No more than 7 hrs so far so I hope this is the reason, thanks!!!. I'll let them running to complete the break-in period and let you know.
In the Feliks Euforia thread other users have tried these tubes many times so they should work.


You may have missed the part of my message where I wrote I did it already . Thanks anyway. This actually worked with my previous noisy Melz 68NS.
I will ask @Paladin79, thanks!

Some Melz require a few attempts before the rosin cleans the wire inside the pin, be sure to apply plenty of liquid rosin inside each pin and repeat if necessary. Obviously you want to clean the outside of the pins and remove any corrosion or excess rosin. I use a brass brush and a high percentage alcohol, not rubbing alcohol.

 

[ColSaulTigh]

Some Melz require a few attempts before the rosin cleans the wire inside the pin, be sure to apply plenty of liquid rosin inside each pin and repeat if necessary. Obviously you want to clean the outside of the pins and remove any corrosion or excess rosin. I use a brass brush and a high percentage alcohol, not rubbing alcohol.

I've also found it helpful to use a fine point on the soldering pen and heat the wire inside the pin so it becomes loose from the side of the pin.

 

[BrainSalat]

Some Melz require a few attempts before the rosin cleans the wire inside the pin, be sure to apply plenty of liquid rosin inside each pin and repeat if necessary. Obviously you want to clean the outside of the pins and remove any corrosion or excess rosin. I use a brass brush and a high percentage alcohol, not rubbing alcohol.

I've also found it helpful to use a fine point on the soldering pen and heat the wire inside the pin so it becomes loose from the side of the pin.

Thanks for the great tips, my hope is back. Actually in the first try I used only soldering grease which probably doesn't go so deep into the pins as with Flux.
I will try now both of your tips.

 

[Paladin79]

I've also found it helpful to use a fine point on the soldering pen and heat the wire inside the pin so it becomes loose from the side of the pin.

Nothing wrong with that. I also use a dual-ocular Nikon inspection microscope but not everyone has that option. I use Weller and Hakko soldering stations and on occasion have two of them set up with different tips. I also use quality magnifier lights with glass lenses for general inspection.

 

[Paladin79]

Thanks for the great tips, my hope is back. Actually in the first try I used only soldering grease which probably doesn't go so deep into the pins as with Flux.
I will try now both of your tips.

I also like to use a tiny diameter silver inclusive solder that I can extend inside the pin, capillary action does a lot of the work but I like to be thorough. My Melz collection is gaining value all the time so I treat the pins with care. I keep one workbench ready for tubes and intricate repairs and keep another as a test and repair station for bigger projects like this Sansui refurb.

 

[David A Silva]

I also like to use a tiny diameter silver inclusive solder that I can extend inside the pin, capillary action does a lot of the work but I like to be thorough. My Melz collection is gaining value all the time so I treat the pins with care. I keep one workbench ready for tubes and intricate repairs and keep another as a test and repair station for bigger projects like this Sansui refurb.

Thanks for that photo @Paladin79. I remember that fine Sansui!!!

 

[BrainSalat]

Thanks for the great tips, my hope is back. Actually in the first try I used only soldering grease which probably doesn't go so deep into the pins as with Flux.
I will try now both of your tips.

I re-resoldered again all the pins of the picky Melz's following @Paladin79 and @ColSaulTigh recommendations and unfortunately it didn't change anything. The hum continues totally untouched and yesterday even one of the tubes started to make some ugly static noise and pops and interestingly it went away after a while (I am using, of course, some cheap headphones), the only thing I remember, was that I was knocking them gently with my fingers (microphonics check) . Today the tubes have been running for 8 hours in a row without problems, except for the imperturbable hum.

This was my first experience with the flux liquid and I was not aware how sticky it becomes everywhere it fluids. I spend quite some time removing it from the pins and metal base.
I made sure to put enough flux inside the pins which produces quite some smoke when applying the soldering iron and making sure to heat the wire inside each pin. I really thought this time was going to work.

@Paladin79 Any more ideas I could try?

BTW The hum is more prominent on higher impedance headphones (Verite Closed) than on my lower impedance ones (Utopia, K712).

Is it possible to mix tubes in my Euforia? For example, on the left channel the Melz 1578 and in the right a Melz 68NS. I would like to check if the hum is produced by one of the tubes or by both of them.

 

[Paladin79]

I re-resoldered again all the pins of the picky Melz's following @Paladin79 and @ColSaulTigh recommendations and unfortunately it didn't change anything. The hum continues totally untouched and yesterday even one of the tubes started to make some ugly static noise and pops and interestingly it went away after a while (I am using, of course, some cheap headphones), the only thing I remember, was that I was knocking them gently with my fingers (microphonics check) . Today the tubes have been running for 8 hours in a row without problems, except for the imperturbable hum.

This was my first experience with the flux liquid and I was not aware how sticky it becomes everywhere it fluids. I spend quite some time removing it from the pins and metal base.
I made sure to put enough flux inside the pins which produces quite some smoke when applying the soldering iron and making sure to heat the wire inside each pin. I really thought this time was going to work.

@Paladin79 Any more ideas I could try?

BTW The hum is more prominent on higher impedance headphones (Verite Closed) than on my lower impedance ones (Utopia, K712).

Is it possible to mix tubes in my Euforia? For example, on the left channel the Melz 1578 and in the right a Melz 68NS. I would like to check if the hum is produced by one of the tubes or by both of them.

You can swap a 6n8s for the 1578, basically that is the same tube. 1578 just means the triodes are well matched according to many. I may get back to you later, I am in the process of getting a possible torn retina checked out in an hour or so. I may be out of commission for a few days.

 

[David A Silva]

Best of luck with your eye @Paladin79 !