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VTL ST-85 vs. VTL ST-150 or rather EL34 vs 6550

I am curious to know the sonic differences between these two amps. Aside from the obvious that one is higher power than the other, how much different are they in terms of sonic character from one another? I ask since the 85 uses the EL34 (which seems to have a following in Tube circles) and the 150 uses the 6550, also well-respected but different. At the present time, I am using an 85 until my brand new 150 arrives tomorrow. I really like the overall nature of the 85 quite a bit, and my line of thinking in ordering a 150 was that it would provide the same sound, but with just a little more crunch. Now I am finding out that may not be the case since the output stage tubes are completely different, 85 having EL34 and 150 having 6550.

So my question is; are these two amps in any way different as far as how they present the music (not the power they have)? Or should I expect the overall house sound of VTL (which I obviously like)to show through on either amp? I don't want a harsh sound, and the EL34 seems to be quite the opposite, very nice, slow, romantic, smooth etc. Just not sure about the 6550 since I have no experience with it, and this has me worried that I won't like it on my 805s speakers, like I like the 85/EL34.

Thanks for any help anyone can provide, much appreciated.
jc51373
cytocycle
1,043 posts
 
Don't worry, the 6550's have more highs and way better bass definition in tetrode mode.. but the cool thing about the VTL 150 is you can switch to a warm triode mode with 75-90 watts, and triode will always trump tetrode EL34's in the warm/mellow tonality! So you can rock and roll plus Jazz it up when you want with a flick of the switch!
dennis_the_menace's avatar
dennis_the_menace
467 posts
 
the st150 has the same general house sound as the st85. it's not just about the tube, it's also about the circuit. the st150 is a better amp, you'll like it even more than the st85. and agree w/ cytocycle... you can flip to triode, which is even better. the 6550s in the vtl are very sweet sounding. you'll see.
desmondjim
67 posts
 
When I bought my ST-150 I first tried to use an ST-85. The mid range of the 85 had more of that classic tube sound. Kind of a billowy full and beautiful mid range. Very romantic sounding. The ST-85 was the tube amp that killed my desire for a SS amp. I compared it to some very nice Ayre and Bryston amps at the store and they just didn't cut it for me anymore.

The problem was the bass. The ST-85 was not up the the task of controlling the bass with my speakers. I tried the MB-125s, they use EL-34s too, and they sounded great and were a better match with my speakers but I didn't have the room for monoblocks.

I then bough the ST-150. It does everything the ST-85 does only better except for that billowy mid range. It is a little less romantic but far more versatile and powerful. I don't think you will regret getting the ST-150.
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