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.
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!
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.
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.
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 ;-)

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.
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.
Good to hear that. Please keep us posted.
But but I prefer Charlize ...
Pauly....I agree. ; )
Evening two: Amp is sounding great, very much to my liking..I will say this though. I have this CD called Superbass which is an excellent mid-bass reference CD I use. I have to admit that this CD sounded ever so slightly better with the 85.

But, the 150 makes human voice sound incredible. Not as lush as the 85, but more forward and real. Piano also sounds incredibly good with this amp as opposed to the 85.

One thing is for sure, I can't take my eyes off it. I love the way it looks. The black shows of the glow of the tubes really well.
Have you listened to it in triode yet?
I prefer Charlize too but seriously, Keep talking about the comparisons between the 150 and the 85, I am particularly interested in this thread because several years ago I was also enthralled with the st-85 and it was also the amp that drove me away from SS into tubes... the EL-34's were very much as you describe, romantic and almost billowy in the midrange. My local dealer had demo'ed the st-85 for me and it was great but just before I handed over the $$$ I noticed a new pair of MB-125's and asked him about those instead. He told me they had a very similar sound to the st-85 but just "more/better/ and more powerful" of everything the 85 did , so I dug deep and bought them instead. I've been in love ever since. A good friend was visiting sometime later and heard them with my [then] Audio Physic Tempo 3's and instantly joined the VTL bandwagon, only he went straight for the MB-450's (6550's) and the deluxe signature transformers and all the other goodies which make it a superior amp, (not to mention the gutsy power). But, as awesome as they drove his Maggie 3.6's I've been quite content with my 125's (and those EL-34's). He told me I'll always have "first rite of refusal" if he ever decides to sell them but that hasn't come up yet (about 6 years so far)and I've always wondered when/if the day ever comes (and my finances permit) if I made the switch would there be anything about the change that wasn't better? I'm sure there's an across the board improvement in probably every important aspect of performance with this substantially superior product, but just like you and the essence of this thread... are the fundamental differences in character between the 2 tube types even in the same brand of amplifier, going to be significant enough to evoke a preference? Keep lissn'n. P.S. The 125's also have a tetrode/triode switch... the tetrode is my "most of the time", triode is for the late night wine/dim lights/atmosphere.
Cyto..Yes I have, am now actually..Not really with much volume though since I am using it when my wife goes to bed.

Bea at VTL said for break in Terode was best since it runs at full power. So for the most part it has been tetrode.

I notice a difference in the two for sure. And triode is definately cool for low level listening.
Couldn't help but chime in here gents.
I just took a leap of faith and went from the ST 150 (going to hang onto for a while) to a new pair of the MB 185 signatures. Both use 6550's, with the 150 having the SED winged, and the 185's having oem's.
Out of the wrapper the 185's present a larger soundstage, to the point of having to reposition my speaks. They sound considerably "leaner" which may be due to tubes not settled in quite yet.
I began with Antique Sound Labs AV-20's, and it was instant tube mania, but they would run out of steam with some volume applied, so it was onto the ST 150.
The ST 150 is a gem, its reliable, sexy, and a brute at only 150-side.
I also noticed a gain change between the 150-185's as the pre's volume doesn't get to far from home before the room is full of sound. Both are very quiet amps, with the 185's having a tad more background hum, but not noticable from the listening area.
I use a lowley VTL LS 2.5 (with Steve Huntley magic) to drive them, and am considering trying a 5.5 to try the balanced i/o.
I have never heard piano sound like it does on this amp...Incredibly real.
I hear ya Jc, piano along with acoustic guitar are so life like it isn't funny. I have listened to Clapton unplugged swapping between my favorite ss amp and the 150, and the difference is not subtle. Fingers sliding on strings, or the hammers strike of a piano key are soooooo life like you'd swear, well, you know........
Cheesehead, what is the favorite ss amp you refer to?

JC51373 who did you order your amp from? I've been interested in the VTL's for some time, but don't have a dealer that's close. Did you get an in-home trial period?

Cheese, you described it exactly. Piano strikes are profound and the decay of a piano (which is an important characteristic of the instrument) are recreated accurately. Guitar is also incredibly well represented, best I have heard for either instrument.

Jack-where do you live? I got lots of in home trials before committing, for extended periods too. This is important, although the flexibility seems to vary from dealer to dealer, and the piece of equipment you audition. Some have different rules than others it seems.
with the speaks I have used it is a Rotel RB-1080.
I had a Rotel a few years back, same one I think. never looked back after I heard a krell amp next to the Rotel..Then I hearxd VTl and it put the krell to shame. Never been so satisfied with my audio system as I am now. Rotel and Krell are in my past, and I thank them kindly, but neither hold a candle to the VTL sound stage and overall liquid musical presentation. My sonic memory of the Rotel and both Krells were sterile.
Ah yes Jc,
I attribute the "sterile" or "digital" to tubes vs ss.
Even the whimpy little ASL AV 20's I first tried enlightened me to the possibilities of tubes. The VTL's are music makers with authority. I never would have believed tubes (transformers) could provide the deep bottom end that these things do.
I just wish the dealers I visited over the years introduced me to tubes much earlier. I spent so much time looking for SS that sounded like this system that I feel like I wasted time.
JC, I think so many dealers do a disservice to their customers by not offering them choices such as VTL. It has led me really to distrust dealers. I've had so much bad advice from dealers. I'm afraid everytime somebody on agon says check with your local dealer, I cringe. Jeff
I agree..There are as many bad dealers out there as there is bad advice. I am lucky to have found the dealer I did, and their loaner policy was extremely flexible, and they were patient. Thats all one can really ask.

I personally look back and still can't believe that I once thought the buck stopped with solid state.