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New Tung Sol 6550s in VTL ST150. My impressions.

Posted by desmondjim (A) on April 11, 2006 at 12:26:15

I bought a used VTL ST150 about a year ago and have been using the winged C 6550c power tubes that came with the amp. I started to notice that I could not keep the bias within the range specified by VTL and I started to blow the B+ fuses. It was time for some new tubes. I have read a few postings about the new Tung Sol 6550 and thought that I would give them a try, just to hear something different. I liked the way the SED tubes sounded but wanted to see if I could hear a differnce between the two.

I shopped around and finally decided to buy them from Jim McShane. Jim was a pleasure to do deal with and I would recommend him to anyone shoping for tubes. I bought two matched quads from him at as good a price as I saw anywhere.

I installed the tubes and slowly brought them up to the correct bias range and then just started using the amp the way I always do. I play my stereo about 5 hours a day during the week and about 12-18 hours a day on the weekends. I seriously listen to one or two albums a night and generally play cds or the tuner for background music in my apartment the rest of the time.

Right out of the box the Tung Sols sounded flat on the top end and heavy but tight on the bottom. They gradually started sounding better and at around 10 hours I could live with the sound. They now have over 130 hours on them and I really have not noticed any differnce from them in a few days.

Compared to the SEDs the Tung Sols have a tighter more controlled, faster bottom end, not necessarily heavier bass but better quality. Plucked bass strings had a faster attack and decayed more naturally for example. The highs were not as extended with the Tung Sols. The SEDs had more sparkle and air. This is not a big difference but it is noticeable. For the mids I think that the Tung Sols hold there own against the SEDs. The SEDs seem more tilted towards the upper mids and the Tung Sols the lower. Both are exellent in this area. The soundstage is a good bit wider with the Tung Sols and the stereo image is rock solid. Musical textures are more palpable with the Tung Sols.

So my take on the Tung Sols is that I traded a little sparkle and top end extension to get clearly superior bass performance. The whole presentation is tilted very slightly towards the bottom end. These tubes are very nice and I am happy with them and intend to keep them for their service life. I'm not blown away by the difference between the SED and these but in my system they made a differnce for the better for a trade off that I can live with.

Cheers,
Jim

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