[medium jim]

About a 3 weeks ago a bought a near mint Audio Research VS110, but it needed to be retubed.  I was going to buy an octet of Winged C 6550's until I noticed that the 6550EH's had welded plates and not stapled.  I will get some pics up in a day or so.   Naturally, this is what I retubed her with and couldn't be happier.  I used the Fat bottle (same as KT88's) for the cool look.   The bass is thick, but not boomy or funky, the mids are delicious and the highs sweet and sexy.  Okay, the over the top adjectives are out of the way. 

Did you know that both the Reissue Tung Sol's and EH's are from the same factory?  I didn't check to see if the Tung Sol's were also welded, but wouldn't be surprised if they were as well.  Note:  The 6550's were rather stout as they measured between 117-119ma and hold a stable 65ma. 

I had a nice chat with Kalvin at Audio Research and he explained that @ 65ma they will sound more like Class A and could go a bit higher if so desired without ill affects to the amp.  If you bias say at 55ma it will be less dynamic and more like class B.   At 65ma, each 6550 is dissipating 27 watts on the average and will typically stay clean or start to clip at 120 watts in total (30 watts per tube) and with enough stored power for transient bursts of 240 watts. 

Are there other Current Production Output Tubes that are welded and not stapled?   As you know, welded is vastly superior to stapled!

Jim

[FullRangeMan]

According this site the 6550EH are from SOVTEK:
http://www.gstube.com/catalog/?key=6550EH&submit=Find

There is some KT88 also:
http://www.gstube.com/catalog/?key=kt88&submit=Find

[medium jim]

According this site the 6550EH are from SOVTEK:
http://www.gstube.com/catalog/?key=6550EH&submit=Find

There is some KT88 also:
http://www.gstube.com/catalog/?key=kt88&submit=Find

No, they are  manufactured at their Xpo-Pul factory (also known as Reflektor) in Saratov, Russia.

http://www.thetubestore.com/Electro-Harmonix

Reissue Tung-Sols are also made in the same factory:

http://www.thetubestore.com/Tung-Sol-12AX7

The real issue is, are there other new production tubes that are welded?


Jim

[fado]

Are welded plates generally favored over stapled plates for best sound quality? In my case, I am thinking of the NOS GZ34 metal base tubes.  It seems like the ~1951 - ~1955 dates have welded plates while the later production dates have stapled plates. I don't know if the "sr" or "tv" codes indicate welded vs stapled or if those codes have another significance.

[medium jim]

Are welded plates generally favored over stapled plates for best sound quality? In my case, I am thinking of the NOS GZ34 metal base tubes.  It seems like the ~1951 - ~1955 dates have welded plates while the later production dates have stapled plates. I don't know if the "sr" or "tv" codes indicate welded vs stapled or if those codes have another significance.

Welded do sound better and last longer.  It is more time consuming to weld than to staple as well.

Jim

[Freo-1]

Welded do sound better and last longer.  It is more time consuming to weld than to staple as well.

Jim

Jim, I would not get too hung up on the welded vs. stapled thing.  Many of the GE 6550A MIL SPEC tubes were stapled, and rest assured that they are MUCH better tubes than any of the current made 6550's.   If I had your amp (nice pick up, by the way), I would see if I could get a set of GE 6550A's for them. 
 
Check this out for some cool info on this:
http://timeelect.com/400-faq.htm

[medium jim]

Jim, I would not get too hung up on the welded vs. stapled thing.  Many of the GE 6550A MIL SPEC tubes were stapled, and rest assured that they are MUCH better tubes than any of the current made 6550's.   If I had your amp (nice pick up, by the way), I would see if I could get a set of GE 6550A's for them. 
 
Check this out for some cool info on this:
http://timeelect.com/400-faq.htm

Freo-1:

The problem is that the VS-110 was designed with the newer 42 watt 6650's, the older 6550's were only 35 at full dissipation and the bias point would be a major factor as would the idle current. 

I've about burned in the 6550EH's and I couldn't be happier with the results.

Jim

[Steve]

Yes, Jim, my 6550 new Tung Sols have welded plates.

Cheers.