Anyone try modern 6sn7 Shuguang WE type vs NOS RCA,Ken Rad

Lots of words in this rant from about 2009, and worth reading it all at one’s leisure.

In the meantime, this is the relevant message, about half way down just above the picture of the tube on the left -

This is why the CV181Z might not be a drop in replacement for the 6SN7. Typical 6SN7 heaters draw about 0.6A and the CV181z draws about 0.9A (900mA), the old Mullard CV181 drew 950mA. This 50% increase in heater current amounts to 0.6A for a pair of CV181 in a circuit, which as you can see represents the load of a whole extra double triode.

I’d be more decisive. "This is why the CV181 (Z, whatever) IS NOT a drop in replacement for the 6SN7." Eventually your amp will take up smoking.

I too have a stash of NOS 6SN7, all of the above and more, bought about 10+ years ago. I now use new production Tung-Sol coz these NOS babes are getting too expensive to get out of the box and use!

The new production TS 6SN7 (they are GTBs - actually heaps more robust than GT types) sound perfectly fine with my amp (EL34 push pull with 5AR4/GZ34 rectifier).

So Shuguang have always been on my radar, and they look pwetty. This is important, of course.

However -

I am confused about all the variants, and they are sometimes (often, usually) shown as CV181, which are in fact electronically not equivalent and are likely to blow up the amp. The current draw of CV181s is 50% more than 6SN7s. Ouch.

So, I’d like to see a test/specifications before I use any. Google is usually my friend to find specs but computer says no with Shuguang 6SN7/cv181. Might be someone else here who can help.

@invalid That is blatant misinformation. It has to be also deliberate as you have clearly read the quote I provided which mentions Mullard (drawing 950mA, by the way).

Care to explain to the community?

Surely someone here who has bought the Shung CV181z can obtain a spec sheet from the manufacturer to confirm or refute the reviewers words?

This would clear up any issues and I’d be happy to shut up and buy some should they be 600mA.

Easy. If not, why not? These tubes have been manufactured for at least a decade.

@invalid You must have read my post wrong, I acknowledged that the nos mullard’s are not drop in replacements, but the shuguang CV 181’s are, as they are not the same as the Mullard cv181’s. I have no idea why shuguang labeled them this way.

OK, I’ll make bold the bit that seems to be invisible. 900mA is 50% more current draw than a 6SN7. This is known and accepted, and poses a risk to your amplifier. edit - of course, ask your amp manufacturer if CV181z are compatible with it. If so, all is well - this may very well be the situation.

So -

One - The Shung tubes are clearly marked as CV181z. This is not in doubt.

Two - Being a reviewer and something of a shill, I trust that he had access to the spec sheet.  Evidence of this is that he rates the CV181z as 900mA, not 950mA which is the Mullard specs.  He is not merely guessing.

Three - He also repeats words to this effect elsewhere and also in a follow up review some years later, so its no typo.

Four - that the CV181z does sound better (brighter, more lively etc) than any 6SN7 is corroborative evidence that it is rated higher. An EE may be able to confirm this.

So people, unless you have evidence to the contrary which I will happily bookmark, this stands as reference in the meantime.

Failing this, it is not a 6SN7 and it is negligent of the manufacturer to market this as a 6SN7.

This is why the CV181Z might not be a drop in replacement for the 6SN7. Typical 6SN7 heaters draw about 0.6A and the CV181z draws about 0.9A (900mA), the old Mullard CV181 drew 950mA. This 50% increase in heater current amounts to 0.6A for a pair of CV181 in a circuit, which as you can see represents the load of a whole extra double triode.

@invalid Thankyou for those specs, I am sufficiently comforted and will indeed buy at least a pair or two in the new year.

My amp has good space - I can even fit those round globe ones you may or may not have seen - they are kinda cute, but possibly no longer in production. Something of novelty value.

Now I have to figure out the nuances of the different types available - I’ve seen a at least a couple versions on AliExpress. I prefer premium.

Edit - just checked, Psvane (Cossor?) make the round ones, smokey glass. Tempted!

Who's the most trusted vendor to buy from? 

A prudent question.  I'm currently looking on eBay, although AliExpress is a good alternative if paypal is available.  All from China, I can't see that there is any organised distribution/dealer network.

Focused on one with 6,000 transactions, 99.3% positive feedback   That's for a pair of premium shuguang's, in a fancy solid looking box.

The box is a signal (information) that they are genuine, however defined.  I don't care for the box itself, pffftt.

Oh, there are outfits like Grant Fidelity that are dealers. I dunno, perhaps others.

I still think its outrageously disingenuous for the manufacturer to use the CV181 name. Its an identity which contains important information.

Its inaccurate and sloppy and absurd.... have the post-modernists taken control of the asylum?

Things are tricky enough at the best of times with tubes without us poor sods (I’m sure I’m not the only one) having to go in circles trying to figure stuff out.

End rant. Phew.