How two 6550 tubes compare

I j u s t p u r c h a s e d a n a m p l i f i e r V T L S T - 1 5 0 ( l a t e s t v e r s i o n ) i n t h e u s e d m a r k e t . I h a v e t o r e t u b e t h e a m p a n d I w o n d e r i f I s h o u l d i n s t a l l t u b e s 6 5 5 0 C , a s a d v i s e d b y t h e o w n e r ' s m a n u a l o f t h e c o m p a n y V T L , o r i f p e r h a p s I s h o u l d i n s t a l l K T 8 8 t u b e s . R e a d i n g t h i s t h r e a d , I l e a r n e d t h a t y o u a l s o h a d a n S T - 1 5 0 a n d y o u h a v e d e c i d e d t o " i n s t a l l K T 8 8 t u b e s . I k n o w w h a t v a l u e s o f b i a s i n g d i d y o u d o t h e t u n i n g . I s w h a t i s t h e s a m e a s t h a t a d v i s e d t h e c o m p a n y V T L i n t h e o w n e r ' s m a n u a l f o r t h e 6 5 5 0 C t u b e s ?

T h a n k y o u i n a d v a n c e f o r t a k i n g t h e t i m e t o a n s w e r m e .

R e g a r d s ,

C a m e r i o

Here is Camerio33's post with the proper spaces. I have no idea how your font or your message got the way it did but hopefully with the proper spacing membership here can help you out.

I just purchased an amplifier VTL ST-150 (latest version) in the used market. I have to retube the amp and I wonder if I should install tubes 6550C, as advised by the owner's manual of the company VTL, or if perhaps I should install KT88 tubes. Reading this thread, I learned that you also had an ST-150 and you have decided to "install KT88 tubes. I know what values of biasing did you do the tuning. Is what is the same as that advised the company VTL in the owner's manual for the 6550C tubes?

Thank you in advance for taking the time to answer me.

Camerio,

You can use KT-88s in the ST-150 no problem. Bias to the same range as with the 6550s. I ran the Gold Lion KT-88s in mine for a year and really liked the sound. I did have some tube failures with the GLs, I only had one Tung Sol fail and the SED "Winged C" I never had a fail but they would blow the fuses now and then. Ultimately I went back to the Tung Sols due to the expense of GL and my experience with their reliablity. They were simply too expensive for me to take a chance of trying them again.

I sold the amp before I had a chance to try some of the Shuguang KT-88s but I have read that they sound very good as well.

Cheers,

Jim