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I'd like to get members' opinions regarding the best current production manufacturer of 6550 output tubes. I'm currently using Svetlana. Thanks.
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I'm using Billington Gold 6550As in my Cary SLA70B, and I'm very satisfied with them. My brother tried the same tubes in his Lumley Reference monos and he liked the results too. (BTW - Svetlanas worked well for him too.)Johan-Kr
The Shuguang manufactured KT88 that is marketed by Valve Art is a good tube. I understand Shunguang manufactured some tubes for GEC years ago & uses the same tooling, good quality control plus a high vacuum.One important parameter is to produce a tube with high vacuum of 10-6 Torr or better. Some manufactures do not take the extra time & care to achieve that specification (Eric Barber had talked about that parameter in the past).
The problem of some later manufactured tubes was the Dow Chemical synthetic oil was discontinued in the early 1970s. Using the very common oil dispersion vacuum pump with poorer quality oil did not allow that spec without an additional refridgerated cooler in-between the pump and tube. (That 10-6 Torr spec includes the extra vacuum using the getter flash during manufacture).
I have not any idea of vacuum oil quality overseas or if high vacuum turbines are used for vacuum. Some vacuum turbines are able to achieve 10 to -11 Torr with magnetic bearings.
I used Valve Art 6550 and they sounded nice but were very microphonic.
At the end I said to my very experienced technician I used them and he said me: "Throw them out if you don't want fire in your house"...
So I did...
I know little about the Valve Art 6550 beyond it exists.
I think you have already found the best current production 6550's. The EH Kt88's are good by comparison.
The new "winged C",or S.E.D 6550 is the same tube that used to be branded as Svetlana. This can cause some confusion. My understanding is that what is now branded as a Svetlana 6550 is marketed by New Sensor and is made in a Sovtek plant.
Can you describe the sound difference between the SED6550 and
the EH KT88?
This one's easy. The EH KT-88 tube has much more energy on the top end than the SED. I don't mean it's too hot (except for the first few hours maybe), I mean it seems to be somewhat better balanced looking at the entire frequency spectrum. It also images better IMHO. Not that the SED is bad, it isn't. But the KT-88 EH is an exceptional tube, I like 'em a lot.
Does it means they sounds brighter than the SED?
Which one has a stronger bass?
thanks
Yes, they sound brighter than the SED. I think both have about equal bass, but the SED may seem a bit "bassier" due to the more subdued high end (as compared to the EH tube).
I like the sed 6550's far better than the EH kt-88 in my ARC vt-50. I had the EH kt-88s in for about 100-125 hours and they sounded enemic. The bass was AWFUL compared to the 6550's. I now have about 75 hours including burn in on the seds. Night and day difference. I agree that the kt-88s may be more open and image a little better, but In my setup the seds are more musical.
I called ARC and the sent them out to me in the mail. If you have a fax they will sent them that way as well.
They are very similar to the vt 100. You have to bias the 6922's. I had someone do it as I am electrically inept. I didn't like those balck heat sinks right next to the bias points.
What do you think of the amp now compared to the VT 60?
As I mentioned, the vt-60 was used with an ls-7 (which had a great linestage). With the AI 3a, the vt-50 is sounds superior (by far). I am having non-audiophiles blown away by this amp. MY wife, myself and another couple sat and listened for 2.5 or three hours. There was little talk except for "wow", "nice", "this is fun."What is really scary is that the system sounds this good with the cd and tuner. When my VPI finally arrives, and I can spin some vinyl, I think this set up is really going to shine.
One other thing. At least in my experience a tube recommendation for ARC stuff is a completely different animal than recommending for other brands of gear. ARC is in a world of their own tube-wise, in the way of what works and what doesn't!
I don't have your email address, and you don't accept mail through the Asylum. Drop me a note if you would, I do have GEs.
Jim, you can send me email now.
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