Audio Research 250SE Versus VTL MB-185 Series III/MB-450 Series III
- Thread starter Ron Resnick
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I have a VAC SigMKIIa SE Pre driving ARC REF250SE and it's a superb match. I was going to replace SigMKIIa with ARC REF10 but after SE upgrade, I decided to keep the VAC ... a totally different and IMPrOVED pre. Anyone wIth SigMKII, I highly highly recommend the upgrade.
As long as the impedance is compatible, I find zero disadvantages mixing brands. I had a fully balanced SS H-CAT Pre built last summer so I can use it with ARC REF250SE and also excellent match. Impedance!!!
I did before upgrade. ARC has bigger sound stage, quieter, more transparent ... different presentations. I was only concerned with noisier and transparency and felt they were addressed in the upgrade.
VAC a bit more liquid and ARC more neutral / larger sound stage. VAC uses e88cc/6922 so easy roll to your taste and transformer coupling that can drive more difficult amps. Both are excellent so CAN'T go wrong with either.
Curious that I feel the same about the cj GAT (also using 6922) versus the ARC REF40. The GAT is more liquid and more enjoyable with vocal/instrumental pop music, but the REF40 is much more realistic with classical music, either instrumental or vocal. Particularly with recordings of performances I have assisted my preference goes towards the REF40.
What do you theorize best explains this difference in sound? Different tubes? Different circuit designs? Different transformers?
Should one wish to up ones game with the ARC Ref pre's replace the factory supplied Sovtek power regulators in an Ref 40 or Ref 10 with dealer tested NOS General Electric 6550A's circa 1970's, the Sovtek's IMHO sounding Hard and 'Glassy' by comparison.
Should one wish to 'Out Liquify' an cj GAT or VAC try rolling with very early 60's Solid Grey plate or Late 50's Solid Black plate TungSol 6550's , altho one then plays a game of Snakes and Ladders with the neutrality of the ARC's that favoures Classical so well.
Should one wish to 'Out Liquify' an cj GAT or VAC try rolling with very early 60's Solid Grey plate or Late 50's Solid Black plate TungSol 6550's , altho one then plays a game of Snakes and Ladders with the neutrality of the ARC's that favoures Classical so well.
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Did you try the JJ 6550? Some people say it is a much better replacement than the Sovtek.
I did Yes....I wouldn't say that I found it much better tho, Early production Winged =C= were nice, tho not easy to source these days. Harma Retro Cryo'd were pretty good also.
microstrip, have you ever compared directly the VTL MB–750 to the MB-185 Series III or to the MB-450 Series III?
No, the only modern tube amplifier I have directly compared to the MB–750 was the Audio Research REF150. Although the mono MB-750s were much more powerful, the REF150 had much better bass depth, detail and articulation, and was more transparent in the middle and treble. The REF150 sounded much more natural and voices were more like the real thing. So much that after a few months of coexistence I traded the VTLs for the best amplifiers I have owned - the REF750's ...
Many people believe that the smaller amplifier wih fewer tubes in the same model line sounds better than the scaled-up, larger amplifier. Did the Ref 750 take anything away from the naturalness of the Ref150?
Was there any downside to the Ref750 compared to the Ref150?
Was there any downside to the Ref750 compared to the Ref150?
The large REF750 amplifiers sounded different and significantly better than the REF150. However it needed a longer warm-up time, and if we compared them in a hasty way we could get the idea that the REF150 was more natural. Usually the larger amplifiers have an higher damping factor and in most systems the result is a more controlled, deeper and more defined bass sound - if the room, system and listener are tuned to a small amplifier they can find the "true" bass lacking in warmth.
The downside of the RF750 was heat and tube replacements - it needs four matched octets every 2000 hours. In order to get matched octets you have to analyze and burn-in thousands of tubes. The REF250 only needs sets of three matched tubes.
Did you run the MB-750's in triode or tetrode mode and can you recall which tubes you were using? Thanks!
Most of the time in pentode mode - triode mode was not the best way of using them in either the Soundlab's or the Sonus Faber Aidas. Tubes were 6550C Svetlana C-wing - I could get them easily from Germany.
Ok, I've always found my 750's slow, muddy and dynamically restrained sounding in triode mode, even with the much more transparent sounding A selection Shuguang KT-88's (TAD, penta labs etc). I ditched my Ref150 because it was a bit polite, overly well mannered and small sounding for my tastes. Would you say the Ref 750's are a big step up in scale / dynamic impact / soundstage size over the Ref 150?
The REF750 had a sense of scale I only got recently again with the Constellation Audio Centaur II. I owned them before getting the XLF's, they were used in the Magico Mini II's, Alexia and Soundlab's. There were no possible comparison with the REF150 in the parameters you refer - even on small speakers. Even at low volumes they poured energy in the speakers. But they did not transform these speakers in XLF's
- the scale of the XLF is also due to its size, bass extreme correctness in the small detail, nuance and full range seamless.Please note I listen mainly to acoustical music - little pop, almost no rock or electronics.
Thank you microstrip, very helpful. I'm looking to replace my MB-750's mainly due to "flatness and greying" of midrange images to a certain degree however my musical preference is classical / large scale orchestra and I would not trade scale for anything. I do have an experiment in mind involving a 6-pack of Rel no.25 subwoofers combined with a more monitor sized speaker to which I could apply extensive vibration control which could possibly also allow me to switch to a more moderate powered amplifier. But of this fails the Ref 750's sound like something worth to try.
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