Author Topic: No love for the 6550?  (Read 132 times)

Offline Emil

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No love for the 6550?
« on: January 08, 2018, 08:15:49 AM »
Once upon a time many amplifier companies used them but not anymore it seems.

Supply? Sonics?
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Offline richidoo

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Re: No love for the 6550?
« Reply #1 on: January 08, 2018, 09:44:33 AM »
The Svetlana ("SED" in the US) 6550C "Winged C" was the standard power tube for VTL, Audio Research, Cary Audio, and many others for many years. SED Svetlana stopped making tubes a few years ago, and the supply of 6550 dried up in about a year as people horded them for these popular amplifiers. The discontinuation of this tube was the cause for AR to switch to KT120 tubes as standard and redesign their entire power amp lineup.

Svetlana's old website lists Antique Electronic Supply (Tubes and More) as their direct sales agent in US, and they still have 6550C for sale, but it is not made in the original St Petersburg Svetlana tube factory, and the internal construction is different, according to customer comment on the 6550C detail page.

American company Tung-Sol invented the original 6550 tube in the 50s.

New Sensor's (Russian made) Tung-Sol 6550 and Gold Lion KT-88 are excellent replacements for the SED 6550C. Shuguang Black Treasure KT88 is also excellent. I think Gold Lion KT88 is much better than SED 6550.
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Offline steve

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Re: No love for the 6550?
« Reply #2 on: January 11, 2018, 04:07:53 PM »
Once upon a time many amplifier companies used them but not anymore it seems.

Supply? Sonics?

It is a shame. I still have 6 of Winged C 6550s from late 90s/early 2000s. I also have 7 Winged C KT88s from same dates (both St. Petersburg). The two do sound different, but both are easily usable and sound fantastic; just have to tweak the amp to whichever one wishes to use. Right now I am saving them for special times.

I am currently using the SED KT88s, much less expensive, but would one day like to test the new Tung Sol 6550s in my monoblocks. The monos can use either 6550, KT88 tube, and with the high/low tonal switches in the power supply I designed in, all I have to do is flip one, two, or both tonal switches and install other tubes.

I suppose manufacturers are considering the new KT120s, or KT150s? Any input?

Cheers

steve
« Last Edit: January 11, 2018, 04:11:20 PM by steve »
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Offline richidoo

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Re: No love for the 6550?
« Reply #3 on: January 11, 2018, 05:17:07 PM »
They have the same pinouts, but they draw more heater current, and output more power, which would overload some OPTs that are barely big enough for 6550. KT120 are also heavier tube than 6550, so you can't run them sideways in amps with vertical PCBs like old ARs, even though those have enough PS and tranny to handle them. The later AR amps with horizontal PCB like Ref110 can run KT120s. The new AR Ref75 is able to make 75W with single pair of KT120, said to be a real honey of an amp.

Jim McShane recommends the new TungSol 6550s for amps that used SED 6550. He says his customers are happy with them.
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline tmazz

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Re: No love for the 6550?
« Reply #4 on: January 12, 2018, 05:37:52 AM »
Carl Marchisotto, owner and designer at NOLA keeps telling me that I just have to get Ref 75 is hands down the best amp to run my Boxers with.

Unfortunately, there are about 8,995 reasons why I can't run out and order one right away.  :roll:
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Offline sleepyguy24

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Re: No love for the 6550?
« Reply #5 on: January 12, 2018, 07:46:49 PM »
For me when I had my Jolida 502P amp I had the best sound with a quad of NOS matched GE 6550 tubes  that were cryo treated in the amp. The problem for me is the cost. I paid a lot of money for those tubes then one of them blew up. I had to then sell the trio at a loss. I was heartrbroken and didn't want to buy a NOS quad of 6550s again. Then after that I got onto the Tung Sol KT 150s in the Jolida.

My conspiracy theory is that people wanting more wattage numbers just kept pushing the KT88s KT120s and the KT150s. The good ol 6550s got left in the dust. Plus the KT88s look so cool.I remember having a quad of blue Glass JJ KT88s and they looked so big and cool.

Offline tmazz

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Re: No love for the 6550?
« Reply #6 on: January 12, 2018, 08:27:02 PM »
It is also a matter of cost and complexity in the amp design. It is certainly easier and cheaper to design a circuit with a pair of KT-120s as opposed to a quad of 6550s.

And it is also a marketing thing because there is also the prestige of owning and amp with the biggest, baddest tubes on the block that can help sell an amp.
« Last Edit: January 12, 2018, 08:29:01 PM by tmazz »
Remember, it's all about the music........

Nola Boxers
Sunfire True SW Super Jr (2)
Quicksilver Mid Monos
ARC SP-9
VPI HW-19 Mk IV/SDS/SME IV/Sumiko Blue Pt. Special
EE Minmax DAC/Bluesound Node/Denon 2910
TWL Power Cords/MIT Cables