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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
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.
pauly
1,012 posts
 
Jc51373, In line with what Dennis posted. You’ll find that brands like VTL, Cary, Manley, etc all have a ‘house sound’. A VTL sounds different from a Cary, no matter which tubes you use.

The reason for this is that the actual sound produced is all down to the combination of circuit design, build, component selection and (lastly) tube used. So a given designer can achieve his/her brand of house sound using EL34s, 6550s, or KT88s, while another can produce a totally different sound using the very same tubes. This is not black magic, but comes down to electronics and a bit of experience.

While some a particular tube may lend it self more to a particular sound than another, it is total ignorance to presume an amplifiers sound based on the tubes they employ. A Sli80 with KT88s will still sound warm and ‘tubey’ like all Cary amps, while an Art Audio using EL34s sounds way more detailed and precise.

If you enjoyed the ST-85, you will most certainly enjoy the ST-150 also. So don't worry ;-)

Regards
Paul
jc51373 OP
524 posts
 
thank for the responses guys...

DesmondJim, you bring up a good point. In regards to the bass however, I have a monitor speaker (805s) and to be totally honest I am not overly concerned about bass. The speaker can't reproduce it that well anyway. What I am interested in is the midrange splendor I got from the 85. It was delicious. It's interesting you mentioned the MB125s, I noticed they share the EL34, after I ordered the 150 of course. So if this amp leaves me longing, they will be on my target list. But lord knows I don't want to go through selling and buying again.

I picked up the amp today, sitting in my car now as type here at work. First impressions won't be accurate enough to say how I feel about it, so I will live with it for a while before I pass total judgement.

Thanks for the reassurances guys. It's nice to hear from people with actual experience with the product.
jc51373 OP
524 posts
 
First impressions:

Holy Sh*t what a difference from the 85. I get what you guys were saying now, so far I like it. Listening in Tetrode at the moment and the detail is quite nice..Everything sounds bigger than the 85, even the midrange, although not as lush, is still very seductive. Lets put it this way, if the 85 is Charlize Theron, the 150 is Angelina Jolie. Sexy, seductive, with a slight edge, and nice fat lips....And I personally, am melting into the crystal serenity of this amp nicely so far.

But....Time is the true test.
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