[Isaacc7]

I've been doing a shootout of my 28 6SN7s and the plate/anode construction is basically these:
1. T plates, early 6SN7GT
2. ladder plates, many types
3. angled plates
4. round plates e.g. Brimar

The best sounding ones are the T plates, which are mellow, the angled plates which are a tad brighter but still smooth, and the Brimars. I found the ladder plates a tad edgy and hollow, especially on orchestral strings which were smooth with the T plates in particular.

I'm about to make a rig to try out 6J5 types - I have a couple of 6J5G round plates and several 7193/2C22, all of which are ladder plates. I remember from many years ago that the 7193s sounded pretty good, so I was surprised to see they are ladder plates. Maybe the top caps help.

Anyway, looking to buy a few more 6J5 types so looking for recommendations for smooth and mellow sounding ones, maybe some of the very early ones. Loctal 7A4 possible too. Must have a gain of 20.

The 7a4 I have all look like the round plate Sylvania so I haven’t gotten adapters for them. I really like my round plate Sylvania 12j5gt so I’m sure the 7a4 would sound good too.

 

[les24preludes]

The 7a4 I have all look like the round plate Sylvania so I haven’t gotten adapters for them. I really like my round plate Sylvania 12j5gt so I’m sure the 7a4 would sound good too.

Yes - I used to have some 7A4 and 7N7 and I thought they were plentiful. I'm in the UK and there are no 7N7s or 7A4s advertised that I can see. Folks have cleaned them out it seems. Prices for earlier 6J5 types have rocketed up now as well. Frustrating - I want to try some of the earlier ones. I have plenty of 6SN7s so nil desperandum, but all the same.........

Update - I got a pair of early L63/6J5G working, round grey anode. I expected a lot and was disappointed. Bass was quite woolly, violins rather papery. My 6SN7 angled anodes were a lot better and pretty nice in fact. This might save me some money........

 

[Isaacc7]

Yes - I used to have some 7A4 and 7N7 and I thought they were plentiful. I'm in the UK and there are no 7N7s or 7A4s advertised that I can see. Folks have cleaned them out it seems. Prices for earlier 6J5 types have rocketed up now as well. Frustrating - I want to try some of the earlier ones. I have plenty of 6SN7s so nil desperandum, but all the same.........

Update - I got a pair of early L63/6J5G working, round grey anode. I expected a lot and was disappointed. Bass was quite woolly, violins rather papery. My 6SN7 angled anodes were a lot better and pretty nice in fact. This might save me some money........

With a sample of one it's easy to write off an entire line of tubes if you get a bad set. I remember being really disappointed with the 14n7 and figured I should stop looking for them. Tried another pair on a whim and found gold. Even if tubes test well they may not sound great.

7n7 seems to be pretty easy to find in the states. I'll admit to actually having a bunch of 14a4 so I'm not exactly sure what the availability of the 7a4 is like these days.

 

[bcowen]

I've been doing a shootout of my 28 6SN7s and the plate/anode construction is basically these:
1. T plates, early 6SN7GT
2. ladder plates, many types
3. angled plates
4. round plates e.g. Brimar

The best sounding ones are the T plates, which are mellow, the angled plates which are a tad brighter but still smooth, and the Brimars. I found the ladder plates a tad edgy and hollow, especially on orchestral strings which were smooth with the T plates in particular.

I'm about to make a rig to try out 6J5 types - I have a couple of 6J5G round plates and several 7193/2C22, all of which are ladder plates. I remember from many years ago that the 7193s sounded pretty good, so I was surprised to see they are ladder plates. Maybe the top caps help.

Anyway, looking to buy a few more 6J5 types so looking for recommendations for smooth and mellow sounding ones, maybe some of the very early ones. Loctal 7A4 possible too. Must have a gain of 20.

These Hytron 7A4's are some of my favorites. Not just favorite 7A4's, but favorite period. Note they do not have the additional 'CBS' labeling which indicates they were made prior to the CBS acquisition of Hytron.

 

[Slade01]

These Hytron 7A4's are some of my favorites. Not just favorite 7A4's, but favorite period. Note they do not have the additional 'CBS' labeling which indicates they were made prior to the CBS acquisition of Hytron.

Genuine Hytrons are hard to come by these days.

 

[bcowen]

Genuine Hytrons are hard to come by these days.

Yeah, I know. I got these about a year ago roughly -- $20 for five of them. Been looking for some backups for the backups, but I haven't seen any pop up in quite a while.

 

[jonathan c]

Yeah, I know. I got these about a year ago roughly -- $20 for five of them. Been looking for some backups for the backups, but I haven't seen any pop up in quite a while.

…you have them all……

 

[Isaacc7]

These Hytron 7A4's are some of my favorites. Not just favorite 7A4's, but favorite period. Note they do not have the additional 'CBS' labeling which indicates they were made prior to the CBS acquisition of Hytron.

I'm pretty sure Sylvania built all of the US made Loctals regardless of the branding. I have heard that NU made some early 7n7, round plate no less, but I've never actually seen any.

 

[pravous]

I recently got a pair of sylvania and a pair of hytron 7a4 but have not really had a chance to do much listening. I can see why this variety of tube did not take off. Practically had to break out the angle grinder to get the pins clean and finding a decent socket for them is a pita!

 

[gibosi]

I'm pretty sure Sylvania built all of the US made Loctals regardless of the branding. I have heard that NU made some early 7n7, round plate no less, but I've never actually seen any.

Sylvania 7N7 on the left and NU 7N7 on the right. And yes, the NU has round plates.

 

[Isaacc7]

Sylvania 7N7 on the left and NU 7N7 on the right. And yes, the NU has round plates.

I would love to hear of those NU round plates at some point. I have some 14n7 tubes with the grey coating but none of my 7n7 tubes have it.

 

[gibosi]

I would love to hear of those NU round plates at some point. I have some 14n7 tubes with the grey coating but none of my 7n7 tubes have it.

As I recall the NU 7N7 has the same round plates as the NU 6F8G and sounds about the same.

 

[bcowen]

I'm pretty sure Sylvania built all of the US made Loctals regardless of the branding. I have heard that NU made some early 7n7, round plate no less, but I've never actually seen any.

From everything I've read, both Sylvania and National Union made the 7N7's. But they were the only two. NU only made them for a short time, so the majority of what's out there were made by Sylvania. I haven't done a lot of research on the 7A4's, but it would be logical that Sylvania was the main (if not only) manufacturer, and perhaps NU as well.

Sylvania even OEM'd for NU at times. All in the pic are Sylvania, and the NU on the left is a Sylvania too...it has T-plates and is identical to the others internally.

 

[Isaacc7]

As I recall the NU 7N7 has the same round plates as the NU 6F8G and sounds about the same.

Oh, I have one of those! Somewhere... I've used the round plate KEN RAD 6f8g in my preamp, very open sounding. I only have one NU 6f8g round plate so I could put it as the input tube in my amp. Currently using a Raytheon 6f8g there now. Might try swapping it out if I can find the NU.

 

[bcowen]

Oh, I have one of those! Somewhere... I've used the round plate KEN RAD 6f8g in my preamp, very open sounding. I only have one NU 6f8g round plate so I could put it as the input tube in my amp. Currently using a Raytheon 6f8g there now. Might try swapping it out if I can find the NU.

The one on the left is a National Union branded as Hytron. Sylvania on the right. The NU is labeled on both the box and the tube as a 7F7, but it's a 7N7 (tube testers don't lie ). Must have been made on a Friday afternoon...