NEW KT66's

[Trout]

Picked this new up over at a guitar forum,

Finally, JJ has a New tube that offers a golden ray of hope

The KT66 http://www.eurotubes.com/euro-u.htm

Lets hope it sounds as good as it looks!!!

Kudos to JJ

Trout

[JandG]

My best amp is a Whitney DV-66. A kt-66 amp,, with dual rect, hi-lo, modern, vintage, w/ vari-slope @ 22k- 33k- 47k- 56k. I just frinkin love kt-66 amps..Got Gt's in there now. I will try these.

[Klimon]

What about Chinese kt66, I heard those are good (for hifi atleast)?

Simon

[Jim McShane]

Originally posted by Klimon
What about Chinese kt66, I heard those are good (for hifi atleast)?

Simon

They are. And JJ build quality is rough, to say the least. 66% rejects in my last KT-77 batch...

[Trout]

Originally posted by Jim McShane


They are. And JJ build quality is rough, to say the least. 66% rejects in my last KT-77 batch...

66%???

Out of the last hundred KT77's I have bought, I had 3 bad ones, Are you buying direct?

Or should I say 5 bad ones because I fried the screens on a pair lol

I Find 66% rather hard to swallow, But Your a Tube dealer and I guess your right. I have experienced a similar reject rate with New Sensor tubes.


I have however noticed ( Not Saying you Jim, Because your rep is outstanding) it is very common amoung tube dealers to slam JJ tubes. I see this a lot on many musician forums, Each one has its tube " Hero" for NOS and other quality tubes, But JJ is one of the worst slammed products.

Is that because of sour grapes over the original pin problem? Or are they leaking out seconds to cut rate distributors like New Sensor does?

I have experienced close to the same 66% reject rate with New Sensor. I stopped buying anything New Sensor makes entirely.

Trout

[Jim McShane]

Here is a post I recently made in another forum regarding the KT-77:

"As promised, I got another sampling of JJ KT-77 tubes in yesterday and today I examined them. Let me offer a word of advice - forget the KT-77, I rejected 66% of the tubes I got due to abysmal build quality.

Here's the reasons:

1. Almost all had crooked bottles - not just slightly off, but some were so crooked I actually burst out laughing when I saw how bad they were!

2. On some tubes I found burn spots on the glass where they don't belong.

3. The top edge of the tube bases are all nicked and gouged.

4. The base pins are soldered poorly, and the pins themselves are crooked in the base! You know how a 9 pin tube sometimes has bent pins? Well, these KT-77 pins are so far out of alignment in many cases that they won't allow the tube to be put in a socket!! I'd have to get a heavy needle nose pliers and carefully try to bend the pins back into alignment. Plus the pin tips often have sharp, squared-off edges, and this will tear up a socket.

5. About 10% of the tubes in my sample still have the small pins! Amazing!!

What's even more amazing is pin diameter on the same tube varies by over 0.005" on a number of tubes. Between the crooked pins and the pin size variation these tubes will be murder on your sockets.

They might sound good, but these tubes are appallingly bad quality. This sample had virtually the same problems as my sample from last spring (there is a bit less loose material in the bottles, that is improved); therefore I would not use them in my own gear. And if I won't use them in my own gear then I won't carry them. Note that the total size of both samples is around 50 tubes."

My rejections were based on build quality, not electrical performance. I wouldn't use those tubes in my own gear, so I won't ask someone else to put them in theirs.

The reason JJ stuff is so often disliked is simple:

1. The ECC83 family tubes they build are VERY often microphonic. As well, one triode tested weak quite often. The reject rate on their ECC83S was up at about 40% when I gave up (and I'm far from the only one who did).

2. I had to scrap 60% of the initial shipment of the JJ 5AR4/GZ34s due to internal miswiring. As well, there have been many reports of shorts and fuse blowing with this tube. I have to VERY carefully test them at rated current before I'm willing to send them out.

3. The pin diameter fiasco - which was present on all JJ octals, not just the KT-77.

4. Remember the neat red base on the early JJ 6L6GCs? Well, it disappeared, and it was replaced with a poorly soldered cheap base that often features a top end full of chips and gouges

5. Loose material and unusual deposits of various sorts show up inside JJ power tubes routinely.

If you bought JJ tubes from me, would you want tubes that featured the "issues" above?

The JJ EL84 and some others are quite good. I wish they were all good, as I would like to sell them all. But I can't abide by the level of build quality they pass off.

I don't buy direct - I would, but dealing with rejects is VERY costly when they have to go back to Slovakia. And I can assure you that it isn't a distributor thing. I have had many reports of JJ stuff bought elsewhere (since I don't carry much of it) - including the US dealer who has a pipeline to the Jamona and Jurco families - that are consistent with my experiences. I've bought JJs from multiple sources too, and all have had "issues".

FWIW, my reject rate on the New Sensor tube families is well under 5%, in some lines it's about 2% is all. They do a great job - they didn't always but they do now and they keep getting better. The one exception is the 7868 - the pin diameter is simply too large for a fresh novar socket. It's great for taking up slack in a worn one, but once you use an EH 7868 you can't really get good contact anymore with old stock stuff.

Anyway, that's my viewpoint on the whole situation.

[SY]

That's disappointing. I've had excellent experience with their EL84 and ECC81, the latter being far and away the best of the species I've ever used.

[Trout]

Great Write up and response Jim!!

Its kind of Ironic we have had similar experiences With opposite companies in many of the listed issues.
And I bet we only live about 2 hours apart.

I only resell a minimal number of tubes as tube onlys, Generally mine go into units being sold.
I gave up on New Sensor VERY Fast.

So I am sure I have some sour grapes over that investment.
Especially in a flat of 12AX7LPS and 5Y3's

I generally only buy JJ's KT77's, 34L's, 6L6's and ECC83's and have had great luck.

I have seen a number for leaning towers in both the 77's and 34's
But nothing totally outragous. I have seen that even in some of my NOS collection.

But all of you comments are noted and I will be watching these more closely also.

Trout

[coolmaster]

Reading your views, I'm now hesitating on my next purchase of quad set of either JJ KT66 or KT77. My clone Mullard amp can be fed with any KT66, KT77 or EL34, optimized by swap of cathode resistors. In practice, the amp is almost entirely on JJ tubes and so far so good for 3 years now (GZ34, EL34S, ECC81, except the front end RCA 5789)

I just can't get any JJ KT77 here in South East Asia, and at reasonable prices. I just happen to luv the JJ sound.

[Jim McShane]

Originally posted by SY
That's disappointing. I've had excellent experience with their EL84 and ECC81, the latter being far and away the best of the species I've ever used.

Hi Sy,

The EL84 is fine - I stock them and am glad I do. Thje 12DW7 (despite it being such a close cousin to the ECC83) seems fine.

I have a good supply of NOS, so I haven't dealt with any new production as yet so I'm not able to comment on the ECC81.