[CAPT Deadpool]

@larcenasb Thank you for your detailed advice here. I really appreciate the time you took to put this together.

 

[larcenasb]

You're welcome! Thank you for the kind words, and I hope you find the sound you're looking for.

 

[TheSnafu]

Thanks for the pics and write ups

Any experiences for EF86 -> EF37A / ME1400 ? Is there sound difference between straight bottle or "shoulder" bottle red Mullards ?

That's my last step to get rid off 9-pins... I have already used adapters to E88CC -> CV181-Z and 12AU7 -> 6SN7GTB, and EF86 is that only weak link (9-pin) at the moment...

and about sockets/adapters, have you noticed if using ceramic socket savers/adapter help with octals ?

Thanks again

 

[larcenasb]

You're welcome! But I'm sorry, I don't have experience with the EF86 -> EF37A / ME1400 or those Mullards. If you get them, I'd love to hear your impressions though. Vintage Mullards have been pretty consistent in my experience (12AU7/CV491 and the EL84), they consistently produce a smooth and masterful sound, and I'd be surpised if either of those Mullards just flat-out sucked.

I would avoid socket savers in general, especially if you're already using an adapter for a different tube type. An adapter on an adapter just isn't a good idea in principle. But if it's not for a tube already using an adapter, then that's not too egregious an idea. If you mean do socket savers help with octals that may be microphonic, that I don't know.

I've never heard a CV181-Z (or CV181), what amp are you using it in? I know it's not a direct replacement for the 6SN7GT but some have said their 6SN7GT amp accepts it. How would you describe the sound compared to your 6SN7GTB?

 

[TheSnafu]

I posted this to 6SN7 rolling thread:

Sometime ago i replaced E88CC's with TungSol 6SN7GTB's (with adapters obviously). Sockets sit pretty closely but with socket saver i managed to fit in CV181-Z's... Gap between is around 1mm...

Pre amp is Copland CTA-301 mkII and it uses 6922 and variants. I first replaced them with Tungsol 6SN7GBT's and they were imo better than any new production 6922/E88Cc's. Level with some Philips and other NOS's i have used while i have had this amp (+15 years).
Lately it developed habit of hogging tubes. Tubes rarely lasted 4-6 months, some were done in weeks. After i swapped to 6SN7's no problems with tubes dying quickly.

About Shuguang Treasure CV181-Z , hands down best tube i have had in my pre amp. Even compared to mentioned NOS 6922's (or Tungsol 6SN7GTB's). Soundstage is wide with extended to highs and lows. Specially bass is excellent.
I use this preamp with Nelson Image M9 power amps that use EF86 + 12AU7 + 4 x EL34 /unit. I replaced 12AU7's with Tungsol 6SN7GTB's and results were similar, extended and laid back sound that has everything on it.
Highs maybe aren't as sharp as with best 12AU7 and E88CC's but they had some kind of unnatural brightness that's gone now. Maybe "natural timbre" is what i got now. That's why i'd like to try octals instead of EF86's.

I would be very interested to know how floor noise changes, ME1400's should have better characteristics in that matter compared to EF86 (?). All EF86's i have tried developed slight hiss at some point, audible 20-30cm from speaker.

I currently use Meridian Explorer2 for Oppo PM3's and i'm looking for some headphone tube amp and if it has 9-pins possibility to swap to octals. Some tube headphone amps/DACs, like Copland DAC 215 or Pathos Aurium are built so tight that octals don't fit.

cheers

 

[TheSnafu]

You're welcome! But I'm sorry, I don't have experience with the EF86 -> EF37A / ME1400 or those Mullards. If you get them, I'd love to hear your impressions though. Vintage Mullards have been pretty consistent in my experience (12AU7/CV491 and the EL84), they consistently produce a smooth and masterful sound, and I'd be surpised if either of those Mullards just flat-out sucked.

A bit surprising results with EF86 -> EF37A (+adapters). Sound itself was good, nothing wrong or better than EF86/E80F's BUT EF37A's (both) picked buzzing sound from my plasma tv that's 2 meters away...
When tv is off, no problems but when i turn it on.....audible bzzzzzzzz from speakers. Didn't wan't to spend time searching how this happened (through cables or something else) so i just switched E80F's back.
Haven't had this kind of problem with any of the other tube types i have used during the years.

 

[highstream]

if anyone is still watching this thread... Were there some flat plate black glass Tung-Sol 6F8G’s that were rebranded as Sylvania?

 

[Ranger Ron]

if anyone is still watching this thread... Were there some flat plate black glass Tung-Sol 6F8G’s that were rebranded as Sylvania?

Hello! I would absolutely say yes. I have a decent collection of 6f8g’s and rebranding seems very common. I have NU round plates in Sylvania, Raytheon, KenRad and GE labels, not one is labeled National Union. Some may argue but I believe these are all NU made. I personally love finding rebranded tubes as they tend to be cheaper.

 

[highstream]

I'd like to find a pair of early 1950's Tung-Sol's at a reasonable price, perhaps rebranded. I do worry about rebranded tubes' quality, that is, if the manufacturer is keeping the best for themselves and the military and giving the lesser quality ones are going to the other companies. Another problem I've just had looking for T-S 6SN7GT's is that they can be made by someone else with the actual producer's design, but Tung-Sol and its EIA/date code on the tube. Knowing how to figure out if that's been done is not necessarily easy, unless the seller is knowledgeable. For example, I was looking at a Tung-Sol that the seller was advertising as really an RCA. How did he know, given that the glass was entirely black? He shined a light from a few angles. Even then, when I asked with a photo on the Antique Radio Forum site, there was partial disagreement about one of the criteria the seller had used to figure it was RCA.

In addition to a pair of Sylvania 6F8G VT-99, which are my favorites so far, I have a pair of NU 6F8G. I have to admit not knowing whether "round plate" refers to the top plate or the verticals -- usually desired round plate tubes have dark covering -- but in the case of the NU the top plates are oval with eight sides, two long.

 

[Ranger Ron]

I haven’t noticed any quality concerns with my rebrands. I typically reheat/resolder all of my tube pins. Seems to help quite a bit, I’ve even brought ‘dead’ sections back to life by doing this. I have one sylvania 6f8g that I swap back and forth with a NU round plate. Indeed a very nice tube. I’ve seen round micas and more of an oblong shaped mica with my round plate national unions. I suppose they just used what they had.

 

[buckaroobarnes]

What you are calling a ”round plate” is what we always call a KenRad “T plate”. I have both RCA and GE T plate 6fg8 tubes that are just rebranded Ken Rad tubes.

 

[Ranger Ron]

What you are calling a ”round plate” is what we always call a KenRad “T plate”. I have both RCA and GE T plate 6fg8 tubes that are just rebranded Ken Rad tubes.

I definitely know the difference between round/oval style plates and the T plates you are talking about.

 

[Ranger Ron]

What you are calling a ”round plate” is what we always call a KenRad “T plate”. I have both RCA and GE T plate 6fg8 tubes that are just rebranded Ken Rad tubes.

The common T plate 6F8G tubes that are rebranded by everyone look a lot like Raytheon 6SN7 to me.

 

[Ranger Ron]

These KenRad have a T style plate but if you look closely the edges are rounded a little bit. These also have different top and bottom micas compared to the later T plate 6F8G. Fantastic sounding tubes.

 

[buckaroobarnes]

A ”round plate” would be round not T shaped the Tung Sol and NU tubes have the “round“ style plates.