The Reference 6SN7 Thread

[ColSaulTigh]

Could your guys help to identify these tubes. Are they legit?. I received them today, my first impression is very very positive and thank you for your help.

Legit. Appears someone has already reflowed the solder in the pins, too, so, bonus!

 

[raindownthunda]

Could your guys help to identify these tubes. Are they legit?. I received them today, my first impression is very very positive and thank you for your help.

Those are indeed genuine Melz 1578 and look to be in great condition. Nice score! Only thing I can’t tell is the year. They were made between mid-50’ into the 70’s(maybe early 80’s?) and can sound different throughout the years.

here’s the notorious ID infographic thats been reposted throughout the history of this thread:

 

[VanHai]

Thank you very much @ColSaulTigh and @raindownthunda for your help.

 

[bcowen]

Thank you very much @ColSaulTigh and @raindownthunda for your help.

Great looking tubes! The manufacturing year will be in the outer part of the circle that has the Melz "M" in the center. It's just two digits, and in about the 4:00 position in the circle. None of your excellent photos quite get the angle to be able to read it.

 

[VanHai]

Great looking tubes! The manufacturing year will be in the outer part of the circle that has the Melz "M" in the center. It's just two digits, and in about the 4:00 position in the circle. None of your excellent photos quite get the angle to be able to read it.

Thank you @bcowen, it is 1182. i think Nov 1982.

 

[JeffMann]

Correct, the grid TC for CV6 is above pin 7 and 8, compared to pin 4 and 5 for 7193.
The rest of the pins on the base is exactly the same.

Another simple way to locate the grid or anode TC is just by looking at the wires that connected to the plate assembly, I find it much direct without having any doubts at least. In a vacuum tube, we know that the grid is between the cathode and anode, it is always nearer to the center of the whole plate assembly compared to the anode.



CV6
Right TC to near center of the plate assembly = grid
Left TC to the edge of the plate assembly = anode


7193
Right TC to near center of the plate assembly = grid
Left TC to the edge of the plate assembly = anode


E1148
Bottom TC to near center of the plate assembly = grid
Top TC to the edge of the plate assembly = anode


Lastly, on the adapter, you will see markings on the PCB which indicate the wire connections for the grids or anodes...
A-cap = Anode
G-cap = Grid

Thanks for your information.

So, looking at these images that Wes posted in the Cayin HA300MK2 thread of the Mullard variant of the CV6 tube (left sided image) and the GEC variant of the CV6 tube (the two images of the right) - I presume that the cap for the grid for the GEC variant is on the left where the wire goes towards that central black plate and the cap for the anode anode is on the right where the wire goes to the post at the right edge of the plate assembly.

Is that correct?

Jeff.

 

[TLO]

Thanks for your information.

So, looking at these images that Wes posted in the Cayin HA300MK2 thread of the Mullard variant of the CV6 tube (left sided image) and the GEC variant of the CV6 tube (the two images of the right) - I presume that the cap for the grid for the GEC variant is on the left where the wire goes towards that central black plate and the cap for the anode anode is on the right where the wire goes to the post at the right edge of the plate assembly.

Is that correct?

Jeff.

Yes, correct. In fact, you can see the grid wiring, in the small opening between the top of the plate and top mica, in the second tube.
For anyone who doesnt know, here is a picture of grid assemblies taken from Wikipedia...

 

[Isaacc7]

I am adding the Tung Sol black glass round plate to my list of favorite twin triodes. These have always been a problem for me. I would out them in and initially feel like they sound good but a short time later I would notice a dry kind of texture through the midrange. I have, uh… more than a few of these so it isn’t as though I just had a dodgy pair. Think I have finally found a combo that uses them that works really really well. I have MOV b36 in my preamp, the TS BGRP inputs on my amp, and vt60a output tubes. There are plenty of sound characteristics I can chalk up to frequency variations like a warm sound is just pronounced lower midrange etc. I have never figured out what could lead to a “sweet” tone, maybe some would call it liquid. That’s what this combo gives me in addition to the table stakes of frequency extension, detail, etc. Glad I was able to figure out how to use these, always felt odd to not be able to hear what everyone raves about.

Oh, these are the 12sn7 versions. They’re still fairly affordable even if you need a little patience to find them sometimes. I’m also relieved because they are one of the reasons I paid extra to get 12v capability on my amps and preamp. In the meantime I found the b36 so it wouldn’t have been a complete loss I suppose lol.

 

[David A Silva]

@Isaacc7 , Thanks for the post. Tung Sol Black Glass round plates are my favorite 12sn7 output tubes.

 

[K3cT]

Hello guys, I’m new to the world of 6SN7 so I could use some pointers. So long story short I recently acquired an EC Balancing Act that uses 1 6SN7 driver tube. From what I understand this can be substituted with 6C8G for higher gain or 6SL7 (although Craig doesn’t seem to recommend this particular type).

A local tube dealer is kind enough to lend me some of his leftover tubes that are missing their soulmates since normally people buy 6SN7 in pairs. From left to right, I think they’re Fivre, Ken-Rad black glass, Brimar 6SL7GT, RCA, and Tung-sol black glass.

I still need to listen further but I think the Brimar seems to have a slight edge among the rest followed closely by the TS and KR. The BA (with PX4 power tube) is more to the neutral, airy side of the sound spectrum and I think the sweetness of the Brimar complements it very well. It also doesn’t seem as warm and rounded as the TS and KR.

Now I would like to get an 6SN7 equivalent to match the electrical characteristics of the amp better. I see that for Brimar, CV1988 can still be found (the price is hard to swallow though) but usually with black glass and brown base. From what I can tell this Brimar has bottom O getter and parallel round plates.

Do these sound similar to this particular Brimar?

 

[UntilThen]

That's a very kind local tube dealer. I'd say just roll with those. They seem good enough for me.

The Brimar is a 6SL7 so it's a higher gain - mu of 70 and will sound louder and brighter than the other 6SN7.

 

[TLO]

Hello guys, I’m new to the world of 6SN7 so I could use some pointers. So long story short I recently acquired an EC Balancing Act that uses 1 6SN7 driver tube. From what I understand this can be substituted with 6C8G for higher gain or 6SL7 (although Craig doesn’t seem to recommend this particular type).

A local tube dealer is kind enough to lend me some of his leftover tubes that are missing their soulmates since normally people buy 6SN7 in pairs. From left to right, I think they’re Fivre, Ken-Rad black glass, Brimar 6SL7GT, RCA, and Tung-sol black glass.



I still need to listen further but I think the Brimar seems to have a slight edge among the rest followed closely by the TS and KR. The BA (with PX4 power tube) is more to the neutral, airy side of the sound spectrum and I think the sweetness of the Brimar complements it very well. It also doesn’t seem as warm and rounded as the TS and KR.

Now I would like to get an 6SN7 equivalent to match the electrical characteristics of the amp better. I see that for Brimar, CV1988 can still be found (the price is hard to swallow though) but usually with black glass and brown base. From what I can tell this Brimar has bottom O getter and parallel round plates.

Do these sound similar to this particular Brimar?

No...Brimar 6SL7GT doesnt sound the same as Brimar CV1988 (have only blk glass, brown base, cant comment on the clear glass), at least to my ears. If you prefer the British sound of Brimar over TS and KR, I would highly recommend you try Mullard ECC35. Oh yeah, not cheap...LOL...but it is very much better than Brimar 6SL7 / CV1985, again to my ears.

Lastly, please keep in mind that the gain on these tubes are quite different...
6SN7 = 20
6SL7 / CV1985 = 70
CV1988 = 20.5
ECC35 = 68

 

[K3cT]

Thanks @TLO and @UntilThen. How would you say the black glass, brown base Brimar differ soundwise with the 6SL7GT that I have? I definitely want to pursue this ‘British’ sound for now.

Yeah, the gain part is what concerns me. The designer Craig advises to stick with 6SN7 type or 6C8G (gain of 35 I think?) although if we search the Balancing Act tube rolling thread it seems that HF-ers are able to use the 6SL7 fine.

 

[TLO]

Thanks @TLO and @UntilThen. How would you say the black glass, brown base Brimar differ soundwise with the 6SL7GT that I have? I definitely want to pursue this ‘British’ sound for now.

Yeah, the gain part is what concerns me. The designer Craig advises to stick with 6SN7 type or 6C8G (gain of 35 I think?) although if we search the Balancing Act tube rolling thread it seems that HF-ers are able to use the 6SL7 fine.

On top of my head now...
1. Brimar CV1988 - way better than Brimar 6SL7 / CV1985, there is no comparison
2. Mullard ECC33
3. Mullard ECC35 - high gain

with adapter....
1. Mullard CV6
2. Brimar 13D5
3. Brimar ECC804
4. Brimar 13D9 - mid gain
5. Mullard M8162 - mid gain

 

[K3cT]

On top of my head now...
1. Brimar CV1988 - way better than Brimar 6SL7 / CV1985, there is no comparison
2. Mullard ECC33
3. Mullard ECC35 - high gain

with adapter....
1. Mullard CV6
2. Brimar 13D5
3. Brimar ECC804
4. Brimar 13D9 - mid gain
5. Mullard M8162 - mid gain

Thanks! ECC33 has a gain of 35, very similar to 6C8G so this could work… I need to recheck with the designer.

Would you say that the Brimar CV1988 is warmer and lusher than the 6SL7? I think the TS and KR (especially the KR) sound a bit too lush, at least in my system.