[cddc]

I am also in the camp for WE421A=5998. I have only heard them side by side briefly as I dont own the 421A but in all my tubes same internals=same sound, excluding individual tube difference. If the 421A were simply tubes that were cherry picked for testing better, that would be more than enough to explain any perceived difference.

I used to think WE 421A is a cherry-picked TS 5998 too, but it's just some hearsay, no concrete proof. But the more I think about it, the more I feel like it's unlikely to be some cherry-picking. No company will pick out its best products for other companies to sell and leave only those low quality products for itself to sell, coz that will only promote its rivals and ruin its own reputation. Tung Sol has a good reputation in the industry, so I don't think it would cherry-pick its 5998 tubes.

I think the most likely scenario is like this:
Western Electric received some request from its parent company AT&T to design and manufacture some special tubes for their telecom facilities, so Western Electric did the R&D job and came up with the 5998 prototype. But somehow WE felt it's not economically favorable to set up a new product line to fulfill the orders from AT&T - maybe the order size from AT&T was not large enough for them to break even, maybe WE did not have enough resources at that time.....So Tung Sol saw the opportunity and proposed to Western Electric, "Hey Bro, I've got plenty of extra capacities, I can help you manufacture these tubes. But you know your order size is too small for me to break even. So how about you license me to make and sell these tubes under my label so that I can break even? And of course I will give you a very good price for your orders (cost + 5% profit margin)." "Deal!" said the WE managers after seeing the price TS offered. So TS set up new product lines and started to manufacture these 5998 tubes, the ones for WE would be labelled as WE 421A, and the ones for themselves to sell would be labelled as TS 5998 / TS 421A / Chatham 5998 / TS 2399 / TS 6520 / etc. Of course, WE had some special specifications to meet, in order for these tubes to be used in AT&T equipment. So TS tested its WE 421A tubes using the WE specs, those not meeting the WE specs would be discarded. Some people may think of this process as cherry-picking. But it doesn't mean TS did not QA its own 5998 tubes, I think TS would also ditch these TS 5998 tubes that failed to meet its own QA specs.

And below is a solid proof that Tung Sol manufactured 5998 under contract to Western Electric. It's an article by Eric on the 17th issue of the Vacuum Tube Valley magazine (the article was found by @attmci).

 

[Little Bear]

I don't have any experience (yet) with either tube, but I'm inclined to believe that any sonic differences between them most likely comes down to individual tube variations in measurements due to age and hours of use. I suspect that when new, they sounded identical, and most of them with similar hours probably still do. But one specific tube might sound better than another one (even of the same variety), which may explain the ongoing debate.

I recently bought an unused TS 5998 for $195 to use in my Crackatwoa. I think an unused WE421a goes for, what, $500? Even $195 for a 5998 isn't easy to justify, IMO.

 

[HiFiHawaii808]

I don't have any experience (yet) with either tube, but I'm inclined to believe that any sonic differences between them most likely comes down to individual tube variations in measurements due to age and hours of use. I suspect that when new, they sounded identical, and most of them with similar hours probably still do. But one specific tube might sound better than another one (even of the same variety), which may explain the ongoing debate.

I recently bought an unused TS 5998 for $195 to use in my Crackatwoa. I think an unused WE421a goes for, what, $500? Even $195 for a 5998 isn't easy to justify, IMO.

the market certainly thinks there is some differential value for a WE421a vs TS5998. I haven't yet done an A/B comparison, but I am switching the tubes. It feels like the 421a has a bigger sound stage and has a more dynamic sound. Not sure if that is confirmation bias or tube variation. But the 421a seems to have a slight advantage. I won't know for sure until I do an A/B comparison test. Could be a while because I only feel comfortable doing it if I have 2 BHCs with similar build.

 

[tintinsnowydog]

the market certainly thinks there is some differential value for a WE421a vs TS5998. I haven't yet done an A/B comparison, but I am switching the tubes. It feels like the 421a has a bigger sound stage and has a more dynamic sound. Not sure if that is confirmation bias or tube variation. But the 421a seems to have a slight advantage. I won't know for sure until I do an A/B comparison test. Could be a while because I only feel comfortable doing it if I have 2 BHCs with similar build.

Would be great to hear your findings! If you’re able to measure the plate voltages that would be even better to see if they are doing anything different electrically.

Have been enjoying dual GEC CV4079 as power tubes the last few days. They’re a great budget alternative to the GEC 6AS7G, with all its technicalities and only a little less warmth and soundstage. RCA 6SN7 in the driver slot gives great bass while warming up the mids and highs, without being too aggressive like the Ken Rad 6SN7 in the low end. Currently enjoying Sylvania VT-231 with HD800, incredibly smooth highs (one could argue it’s rolled off... but definitely enough detail still), singing midrange, and high quality, non-exaggerated bass. They are definitely not bass light paired with the right power tubes- at least not for classical symphonies

 

[bagwell359]

I don't have any experience (yet) with either tube, but I'm inclined to believe that any sonic differences between them most likely comes down to individual tube variations in measurements due to age and hours of use. I suspect that when new, they sounded identical, and most of them with similar hours probably still do. But one specific tube might sound better than another one (even of the same variety), which may explain the ongoing debate.

I recently bought an unused TS 5998 for $195 to use in my Crackatwoa. I think an unused WE421a goes for, what, $500? Even $195 for a 5998 isn't easy to justify, IMO.

When I was looking this summer for a power tube, I'd have taken yours for that money. It's not a steal, but if its what it purports to be, it's a good deal.

 

[HiFiHawaii808]

I did some moderate testing between my bottom getter TS 5998 and WE 521A. A few hours of testing across many different music genres. It's pretty conclusive to me that for these tubes, the 421A sounds better. It has a slightly larger sound stage and a much sweeter timber to violins. I can hear it at all volume levels. It's like the 5998 has a slight veil in comparison for the highs. The 421a sounds grander and more open.

I am sure it is not confirmation bias because I can hear the difference in most tracks. I don't know if the difference in sound is just tube variation. I'd have to get a few more of each to test them.

After hearing these tubes and reading the reports that they appear to be the same tubes, I can only conclude that the most likely way to account for the differences is that the better tubes were pulled from various lots and branded as 421a vs TS5998. I know that sounds unlikely, but I don't know how to account for the sound difference. I would do a double blind test, but it's just too hard with these tubes on this amp given their warm up and cool down requirements and potential for operator error.

 

[DenverW]

I have had both the 5998 and the different types of 421A. YMMV but I found a clear difference in the 421A tubes, of either type. Better separation and clarity.

But hey, lets talk bottlehead power cord. I have two stock, and I'm considering making a third with different wire, perhaps the duelund 20awg tin plate copper hook up wire (600vdc). Wonder if the different wire would make a different. The other thing I'm considering is filling one of the cables with fine steel shot like the old audio dynamic power 3 cables.

 

[HiFiHawaii808]

I have had both the 5998 and the different types of 421A. YMMV but I found a clear difference in the 421A tubes, of either type. Better separation and clarity.

But hey, lets talk bottlehead power cord. I have two stock, and I'm considering making a third with different wire, perhaps the duelund 20awg tin plate copper hook up wire (600vdc). Wonder if the different wire would make a different. The other thing I'm considering is filling one of the cables with fine steel shot like the old audio dynamic power 3 cables.

I purchased an upgraded power cord. It definitely impacts the sound. It really deepened the bass and closed in the sound stage. Felt like I was sitting right next to the bass player. Live feel to the music with a more intimate feel. It was really good for small 4 piece bands in intimate settings. Jazz combos and rock and roll, but no strumming guitars like with the Eagles. The elevated bass put a veil on the mids. I used it before I did any tube rolling. Once I got really nice tubes, I found the upgraded power cord was bringing the sound out of balance. Too much bass and closing in the sound stage rather than letting it open up. So, now I have stopped using it completely. I would use it with the stock tubes or maybe the stock BHC with speedball.

 

[DenverW]

I found the bottlehead power cord to be one of the bigger jumps in sound quality overall, thats why I have one for both my amps. I'm just getting the itch to DIY a different type, or to modify one of the two that I have.

 

[PsilocybinCube]

I found the bottlehead power cord to be one of the bigger jumps in sound quality overall, thats why I have one for both my amps. I'm just getting the itch to DIY a different type, or to modify one of the two that I have.

I found I was still getting some interference from my PC after making this. I purchased some shielded tech flex and it helped greatly. Also, the tech flex that ships with the BHC is oversized relative to what is actually needed so it's nice to have the cord be a bit more tidy.
https://www.wirecare.com/category/braided-sleeving/metal-shielding-sleeving/flexo-shield

 

[DenverW]

I found I was still getting some interference from my PC after making this. I purchased some shielded tech flex and it helped greatly. Also, the tech flex that ships with the BHC is oversized relative to what is actually needed so it's nice to have the cord be a bit more tidy.
https://www.wirecare.com/category/braided-sleeving/metal-shielding-sleeving/flexo-shield

What size did you order?

 

[PsilocybinCube]

What size did you order?

I purchased one 10 ft cut of 1/2 inch shielded techflex. Also, you can really use a smaller diameter heat shrink and just not have it go over the male end, instead have the mail end clamp onto the heat shrink as most people do with DIY power cords. It results in a much cleaner finish.

 

[GreenNeedle]

Does anyone know who made tubes for RTRA?

https://www.ebay.co.uk/itm/RTRA-6SN...700047?hash=item340924b54f:g:SekAAOSwMYRaftSa

 

[tintinsnowydog]

Does anyone know who made tubes for RTRA?

https://www.ebay.co.uk/itm/RTRA-6SN...700047?hash=item340924b54f:g:SekAAOSwMYRaftSa

Those photos are so blurry.. The plates and top mica supports look similar to Foton 6N8S but I am not sure. 'Foreign made' so it is possibly a euphemism for lesser known branding. Would be beneficial to post it here too https://www.head-fi.org/threads/the-6sn7-identification-guide.209782/page-22

 

[cebuboy]

Does anyone know who made tubes for RTRA?

https://www.ebay.co.uk/itm/RTRA-6SN...700047?hash=item340924b54f:g:SekAAOSwMYRaftSa

Looks like a '60s Foton.